Dangerous Goods 

 

Classes, divisions, packing groups

Definitions

Substances (including mixtures and solutions) and articles subject to the provisions of this Code are assigned to one of the classes 1 -9 according to the hazard or the most predominant of the hazards they present.  Some of these classes are subdivided into divisions.  These classes or divisions are as listed below:

Class 1: Explosives

Division 1.1: substances and articles, which have a mass explosion hazard

Division 1.2: substances and articles, which have a projection, hazard but not a mass explosion hazard

Division 1.3: substances and articles, which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard

Division 1.4: substances and articles, which present no significant hazard

Division 1.5: very insensitive substances, which have a mass explosion hazard

Division 1.6: extremely insensitive articles which do not have a mass explosion hazard

Class 2: Gases

Class 2.1: flammable gases

Class 2.2: non-flammable, non-toxic gases

Class 2.3: toxic gases

Class 3: Flammable liquids

Class 4: Flammable solids; substances liable to spontaneous combustion; substances which, in contact with water, emit flammable gases

Class 4.1: flammable solids, self-reactive substances and desensitized explosives

Class 4.2: substances liable to spontaneous combustion

Class 4.3: substances, which, in contact with water, emit flammable gases

Class 5: Oxidizing substances and organic peroxides

Class 5.1: oxidizing substances

Class 5.2: organic peroxides

Class 6: Toxic and infectious substances

Class 6.1: toxic substances -

Class 6.2: infectious substances

Class 7: Radioactive material

Class 8: Corrosive substances

Class 9: Miscellaneous dangerous substances and articles

The numerical order of the classes and divisions is not that of the degree of danger.

Marking, labelling and placarding

Packages containing dangerous goods shall be durably marked with the correct technical name; trade names alone shall not be used.

Packages containing dangerous goods shall be provided with distinctive labels or stencils of the labels, or placards, as appropriate, so as to make clear the dangerous properties of the goods contained therein.

The method of marking the correct technical name and of affixing labels or applying stencils of labels, or of affixing placards on packages containing dangerous goods, shall be such that this information will still be identifiable on packages surviving at least three months’ immersion in the sea. In considering suitable marking, labelling and placarding methods, account shall be taken of the durability of the materials used and of the surface of the package.

Packages containing dangerous goods shall be so marked and labeled except that:

.1 packages containing dangerous goods of a low degree of hazard or packed in limited quantities or

.2 when special circumstances permit, packages that are stowed and handled in units that are identified by labels or placards; may be exempted from labelling requirements.

General information prior loading/ discharging

The duty officer entrusted with the loading of the dangerous goods should have all the relevant data regarding the dangerous goods that would be loaded, these would include:

Copy of the document from the shipper regarding the cargo

Classification of the DG

Quantity to be loaded

Proposed stowage

Type of packages

Shipping name – that is the correct technical name

Segregation required from other cargo as well as from other DG

MFAG and EmS requirement for the safe handling of the cargo

Any fire hazard as per IMDG

Any temperature/ wetness restriction for the loading of the cargo

UN Numbers and Proper Shipping Names

Dangerous goods are assigned to UN Numbers and Proper Shipping Names according to their hazard classification and their composition.

Dangerous goods commonly transported are listed in the Dangerous Goods List. Where an article or substance is specifically listed by name, it should be identified in transport by the Proper Shipping Name in the Dangerous Goods List.  For dangerous goods not specifically listed by name, “generic” or “not otherwise specified” entries are provided to identify the article or substance in transport.

Each entry in the Dangerous Goods List is assigned a UN Number.  This list also contains relevant information for each entry, such as hazard class, subsidiary risk(s) (if any), packing group (where assigned), packing and tank transport provisions, EmS, segregation and stowage, properties and observations, etc.

Entries in the Dangerous Goods List are of the following four types:

Single entries for well-defined substances or articles e.g.

UN 1090         acetone

UN 1194       ethyl nitrite solution

Generic entries for well-defined groups of substances or articles e.g.

UN 1133         adhesives

UN 1266       perfumery product

Information on the special measures to be taken when a certain dangerous cargo is handled

Additionally the chief officer should have attached relevant extracts from the IMDG code in particular all the emergencies that could arise with the handling of the cargo. Also the emergency clean-up measures as well as the first aid requirement as per the EmS (Emergency Schedule of the IMDG) and MFAG.

Any special precautions mention as per the Dangerous List should be extracted. Compatibility risks should be ascertained.

For example if the following cargo (class 3) is to be loaded, then:

Stowage of goods of class 3

The vapours from all substances of class 3 have a narcotic effect, and prolonged inhalation may result in unconsciousness.  Deep or prolonged narcosis may lead to death.

Class 3 substances should be stowed as indicated in the Dangerous Goods List. However, substances with a flashpoint of 23˚C (c.c). or less packaged in jerricans, plastics (3Hl, 3H2), drums, plastics (lHl,lH2) and plastics

receptacles in a plastic drum (6HH1,6HH2)should be stowed on, deck only unless packed in a closed cargo transport unit.

The substances of this class should be kept as cool as reasonably practicable during transit.  They should, in general, be stowed “away from” all possible sources of heat.

Adequate precautions should be taken to protect the flammable liquids from heat emanating from bulkheads or other sources.  Ventilation should be provided which should effectively remove flammable vapours from the cargo space.

Adequate measures should be taken to prevent the penetration of leaking liquid or vapour into any other part of the ship.  Vapours may not necessarily be lighter than air and may sink to the lower levels of a cargo space where they may be accidentally ignited and a “flashback” to the flammable liquids may occur.

Whenever flammable liquids with a flashpoint of 23˚C c.c. or less are transported in portable tanks, the stowage should be such that leaking vapours are unlikely to penetrate the accommodation, machinery spaces and other work areas via entrances or other openings in bulkheads or through ventilation ducts.

Where it is deemed necessary for a substance of this class to be stowed “clear of living quarters”, it is included in the Dangerous Goods List.

On ships carrying passengers, substances in this class should be stowed well away from any deck or spaces provided for the use of passengers.  When such substances are transported on board roll-on/roll-off ships, see chapter 7.4.

End extract

Reporting of incidents involving dangerous goods

When an incident takes place involving the loss or likely loss overboard of packaged dangerous goods into the sea, the master, or other person having charge of the ship, shall report the particulars of such an incident without delay and to the fullest extent possible to the nearest coastal State. The report shall be based on the guidelines and general principles adopted by IMO for dangerous goods, harmful substances and/or marine pollutants.

In the event of the ship referred to in paragraph 1 being abandoned, or in the event of a report from such a ship being incomplete or unobtainable, the owner, charterer, manager or operator of the ship, or their agents shall, to the fullest extent possible, assume the obligations placed upon the master by this regulation.

The duty officer when he discovers an incident or accident has to immediately raise the alarm and inform the Master regarding the same. The crew on deck should be the first to renders assistance as well as start the clean up operations as well as try to minimise the incident under the supervision of the duty officer as per the guidelines laid down for that cargo as per the IMDG code and the Dangerous cargo list.

Actions to be taken

All actions after an accident are to be as per the following documents – which have detailed instructions for all types of emergencies.

The following gives a basic layout of a rescue scenario.

The IMO/WHO/ILO Medical First Aid Guide for Use in Accidents Involving Dangerous Goods (MFAG) is the Chemicals Supplement to the International

Medical Guide for Ships (IMGS), which is published by the World Health Organization (WHO), Geneva.

The Maritime Safety Committee adopted this revised text of the Guide in May 1998, for use in association with Amendment 30-00 of the IMDG Code, and will be further amended as and when, necessary.

Table 1

RESCUE

Rescuers must be adequately protected from exposure before entering a contaminated area in order to avoid injury.

When a chemical is unidentified, worst-case assumptions concerning toxicity must be assumed.

ARRIVAL AT SCENE

Upon arrival at the scene, an initial assessment of the situation should be made and the size of the incident should be determined.

Rescuers must NOT:

Enter a contaminated area without using a pressure-demand self-contained breathing apparatus and wearing full protective clothing;

Enter an enclosed space unless they are trained members of a rescue team and follow correct procedures;

Walk through any spilled materials;

Allow unnecessary contamination of equipment;

Attempt to recover shipping papers or manifests from contaminated area unless adequately protected;

Become exposed while approaching a potentially contaminated area;

Attempt rescue unless trained and equipped with appropriate personal protective equipment (PPE) and protective clothing for the situation.

QUICKLY ESTABLISH AN EXCLUSION OR HOT ZONE

Assume that anyone leaving the exclusion zone is contaminated and should be assessed and decontaminated, if necessary.

Do not remove non-ambulatory casualties from the exclusion zone unless properly trained personnel with the appropriate PPE are available and decontamination has been accomplished.

INITIAL TRIAGE OF CASUALTIES (SORTING AND PRIORITY)

One unconscious casualty

Give immediate treatment to the unconscious casualty only, and

Send for help.

Several unconscious casualties

If there is more than one unconscious casualty:

Send for help, and

Give appropriate treatment to the worst casualty in the priority order of:

Casualties who have stopped breathing or have no pulse (see Table 2).

Casualties who ARE UNCONCIOUS (see Table 4).

Casualty is unconscious but breathing

If the casualty is unconscious or cyanotic (bluish skin) but breathing, connect to portable oxygen.

Neck or back trauma

Apply neck and back support before moving casualty if there is any question of neck or back trauma. Priority.  Airway, Breathing, Circulation (A-B-C)

Initial management of Airway, Breathing and Circulation (A-B-C, see table 2) is all that should be undertaken while there is potential for further injury to the casualty or to response personnel.

Gross decontamination

If the casualty is contaminated with chemicals, gross decontamination should be performed.

Cut away or remove all suspected contaminated clothing, including jewellery and watches.

Brush or wipe off any obvious contamination.

Care should be taken to protect open wounds from contamination.

Every effort should be made by personnel to avoid contact with potentially contaminated casualties.  Rescuers should wear protective clothing, if necessary.

Cover or wrap casualty to prevent spread of contamination.

Removal of casualties from exclusion zone

Once gross decontamination has been performed, the casualties should be removed from the exclusion zone.

If casualties can walk, lead them out of the exclusion zone to an area where decontamination and further evaluation can take place.

If casualties are unable to walk, remove them on stretchers.  If stretchers are unavailable, carefully carry or drag casualties to an area where decontamination and further evaluation can take place.

DECONTAMINATION

Decontaminate from head down

Take care not to introduce contaminants into open wounds.

Decontaminate exposed wounds and eyes before intact skin areas.

Cover wounds with a waterproof dressing after decontamination.

 

For external contamination, begin with the least aggressive methods

Limit mechanical or chemical irritation of the skin.

Wash contaminated area gently under a stream of water for at least ten minutes, and wash carefully with soap and warm (never hot) water, scrubbing with a soft brush or surgical sponge.

Reduce level of contaminants

Remove contaminants to the level that they are no longer a threat to casualty or response personnel.

Isolate the casualty from the environment to prevent the spread of any remaining contaminants. Contain runoff; bag contaminated clothing

If possible, contain all runoff from decontamination procedures for proper disposal.

Ensure that all potentially contaminated casualty clothing and belongings have been removed and placed in properly labelled bags.

SUMMARY OF TREATMENT OF CASUALTIES

Assign highest priorities to Airway, Breathing, Circulation (ABC) and then decontamination.

Complete primary and secondary assessments as conditions allow.

Obtain information on chemicals to which the casualty has been exposed from shipping papers, labels or other documents.

If there are multiple casualties, direct attention to the most seriously affected individuals first.

Treat symptoms and signs as appropriate and when conditions allow.

Obtain RADIO MEDICAL ADVICE when conditions allow.

Perform invasive procedures only in uncontaminated areas.

Reassess the casualty frequently, because many chemicals have latent physiological effects.

Delay preventive measures until the casualty is decontaminated.

TRANSFER TO SHIP’S HOSPITAL

Casualties who have been stabilized (airway, breathing and circulation) and decontaminated can be transported to the ship’s hospital for further evaluation.

Further advice: see IMDG appendix 1

Packing requirements as per the Dangerous Goods List of the IMDG Code

 Structure of the Dangerous Goods List.

The Dangerous Goods List is divided into 18 columns.

Among them the packing requirements are specified in column 8 and in column 9

Column 8 Packing Instructions: This column contains alpha – numeric codes, which refer to the relevant packing instructions. The packing instructions indicate the packagings (including large packagings) which may be used for the transport of substances and articles.

A code including the letter ‘P’ refers to packing instructions for the use of packagings described in IMDG Chapters – 6.1, 6.2 or 6.3

A code including the letter ‘LP’ refers to packing instructions for the use of large packagings described in IMDG Chapters – 6.6

A code including the letter ‘BP’ refers to the bulk packagings described in IMDG Chapters – 4.3

When a code including the letters ‘P’, ‘LP’ or ‘BP’ is not provided, it means that the substance is not allowed in that type of packaging.

When ‘N/R’ is included in this column, it means that the substance or article need not be packaged.

Column 9 Special packing provisions: This column contains alphanumeric codes, which refer to the relevant special packing provisions specified in 4.1.4. The special packing provisions indicate the packagings (including large packagings).

A special packing provisions including the letters ‘PP’ refers to a special packing provision applicable to the use of a packing instruction bearing the code ‘P’ in 4.1.4.1

A special packing provision including the letter ‘L’ refers to a special packing provision applicable to a packing instruction bearing the code ‘LP’ in 4.1.4.3

Reporting if the suitability and integrity of packages is found to be suspect

Documents

In all documents relating to the carriage of dangerous goods by sea where the goods are named, the correct technical name of the goods shall be used (trade names alone shall not be used) and the correct description given in accordance with the classification.

The shipping documents prepared by the shipper shall include, or be accompanied by, a signed certificate or declaration that the shipment offered for carriage is properly packaged and marked, labelled or placarded, as appropriate, and in proper condition for carriage.

The persons responsible for the packing of dangerous goods in a freight

container or road vehicle shall provide a signed container packing certificate

or vehicle packing declaration stating that the cargo in the unit has been

properly packed and secured and that all applicable transport requirements

have been met. Such a certificate or declaration may be combined with the

document above.

Where there is due cause to suspect that a freight container or road vehicle in which dangerous goods are packed is not in compliance with the requirements, or where a container-packing certificate or vehicle packing declaration is not available, the freight container or vehicle shall not be accepted for shipment.

Each ship carrying dangerous goods shall have a special list or manifest setting forth, in accordance with the classification, the dangerous goods on board and the location thereof. A detailed stowage plan, which identifies by class and sets out the location of all dangerous goods on board, may be used in place of such a special list or manifest. A copy of one of these documents shall be made available before departure to the person or organization designated by the port State authority.

Cargo transport units, including freight containers, shall be loaded, stowed and secured throughout the voyage in accordance with the Cargo Securing Manual approved by the Administration. The Cargo Securing Manual shall be drawn up to a standard at least equivalent to the guidelines developed by the IMO.

The above are as per SOLAS. If the duty officer feels that there is some discrepancy between the document submitted and the markings on the cargo, he is to stop loading and inform the Master.

If the packaging is suspect or if the duty officer feels that the packaging looks worn out or is not sufficient then again he is to stop the loading and inform the Master.

General fire precautions

The prevention of fire in a cargo of dangerous goods is achieved by practicing good seamanship, observing in particular the following precautions:

        I.      keep combustible material away from ignition sources;

        II.      protect a flammable substance by adequate packing;

        III.      reject damaged or leaking packages;

        IV.      stow packages protected from-accidental damage or heating;

        V.      segregate packages from substances liable to start or spread fire;

        VI.      where appropriate and practicable, stow dangerous goods in an accessible position so that packages in the vicinity of a fire may be protected;

    VII.      enforce prohibition of smoking in dangerous areas and display clearly recognizable “NO SMOKING” notices or signs; and

   VIII.      the dangers from short-circuits, earth leakages or sparking will be apparent.  Lighting and power cables, and fittings should be maintained in good condition.  Cables or equipment found to be unsafe should be disconnected.  Where a bulkhead is required to be suitable for segregation purposes, cables and conduit penetrations of the decks and bulkheads should be sealed against the passage of gas and vapours.  When stowing dangerous goods on deck, the position and design of auxiliary machinery, electrical equipment and cable runs should be considered in order to avoid sources of ignition.

Fire precautions applying to individual classes, and where necessary to individual substances, are recommended in following paragraphs and in the Dangerous Goods List.

Special fire precautions for class 1

The greatest risk in the handling and transport of goods of class 1 is that of fire from a source external to the goods, and it is vital that any fire should be detected and extinguished before it can reach such goods.  Consequently, it is essential that fire precautions, fire-fighting measures and equipment should be of a high standard and ready for immediate application and use.

Compartments containing goods of class 1 and adjacent cargo spaces should be provided with a fire detection system.  If such spaces are not protected by a fixed fire-extinguishing system, they should be accessible for fire-fighting operations.

No repair work should be carried out in a compartment containing goods of class 1. Special care should be exercised in carrying out repairs in any adjacent space.  No welding, burning, cutting, or riveting operations involving the use of fire, flame, spark, or arc-producing equipment should be carried out in any space other than machinery spaces and workshops where fire-extinguishing arrangements are available, except in any emergency and, if in port, with prior authorization of the port authority,

Special fire precautions for class 2

Effective ventilation should be provided to remove any leakage of gas from within the cargo space or spaces, bearing in mind that some gases are heavier than air and may accumulate in dangerous concentrations in the lower part of the ship.

Measures should be taken to prevent leaking gases from penetrating into any other part of the ship.

If there is any reason to suspect leakage of a gas, entry into cargo spaces or other enclosed spaces should not be permitted until the master or responsible officer has taken all safety considerations into account and is satisfied that it is safe to do so.  Emergency entry under other circumstances should only be undertaken by trained crew wearing self-contained breathing apparatus, and protective clothing when recommended, and always under the supervision of a responsible officer.

Leakage from receptacles containing flammable gases may give rise to explosive mixtures with air.  Such mixtures, if ignited, may result in explosion and fire.

Special fire precautions for class 3

Flammable liquids give off flammable vapours which, especially in an enclosed space, form explosive mixtures with air.  Such vapours, if ignited, may cause a “flashback” to the place in which the substances are stowed.  Due regard should be paid to the provision of adequate ventilation to prevent accumulation of vapours.

Special fire precautions and fire fighting for class 7

The radioactive contents of Excepted, Industrial, and Type A packages are so restricted that, in the event of an accident and damage to the package, there is a high probability that any material released, or shielding efficiency lost, would not give rise to such radiological hazard as to hamper fire-fighting or rescue operations.

Type B (U) packages, Type B (M) packages and Type C packages are designed to be strong enough to withstand severe fire without significant loss of contents or dangerous loss of radiation shielding.

Precautions while loading discharging explosives

Following are the emergency schedule1-01 with respect to explosives under Class 1 Division 1.1

Primary hazard: Explosive substances and articles, which may detonate all at once in a fire

Associated hazards: Heavy debris and high speed fragments; possibility of the formation and escape of toxic fumes.

Special Emergency equipment to be available: Protective clothing – gloves, fire resistant coveralls, fire mans helmet with visors

SCBA

Non sparking footwear

Soft brushes and plastic trays – to pick up spillage

Emergency procedures:

Wear non sparking footwear when dealing with spillage. Use SCBA and protective clothing when dealing with a spillage of materials having a subsidiary class 6.1 and or 8 label. Avoid sources of ignition – naked lights, unprotected light bulbs, electric hand tools, mechanical shock and friction.

Use SCBA and protective clothing when dealing with fire.

Understanding the nature of the precautions that have been laid down under the EmS (Emergency Schedule) it is important to note that all the above precautions need to be taken.

Regarding whether water is to be kept available with a charged hose, is debatable as far as the cargo is concerned – however the likelihood of other non IMDG cargo catching fire does remain as such for the other cargo the fire mains may be utilized.

Water if warranted by the IMDG code for the particular cargo may be used else it should not be used unless shipper says it is OK to use water or to cover spillage on deck with water.

Additionally fire extinguishers – CO2 systems should be kept in readiness.

The ship generally loads this type of cargo last – some ports have special anchorages or berths where such cargo is loaded, thus it is necessary to

have the ship ready to leave berth in case of any fire. As such prior loading the ship should be ready to sail at a short notice.

Segregating of dangerous goods

 

 

Segregation

General

The provisions of this chapter should apply to all cargo spaces on deck or under deck of all types of ships and to cargo transport units.

The International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended, requires in regulation 6.1 of part A of chapter VII that incompatible goods should be segregated from one another.

For the implementation of this requirement, two substances or articles are considered mutually incompatible when their stowage together may result in undue hazards in case of leakage or spillage, or any other accident.

The extent of the hazard arising from possible reactions between incompatible dangerous goods may vary and so the segregation arrangements required should also vary as appropriate.  Such segregation is obtained by maintaining certain distances between incompatible dangerous goods or by requiring the presence of one or more steel bulkheads or decks between them, or a combination thereof.  Intervening spaces between such dangerous goods may be filled with other cargo compatible with the dangerous substances in question.

The following segregation terms are used throughout this Code:

“Away from”;

“Separated from”;

“Separated by a complete compartment or hold from”;

“Separated longitudinally by an intervening complete compartment or hold from”.

The general provisions for segregation between the various classes of dangerous goods are shown in the

segregation table”.

In addition to the general provisions, there may be a need to segregate a particular substance, material or article from other goods, which could contribute to its hazard.  Particular provisions for segregation are indicated in the Dangerous Goods List and, in the case of conflicting provisions, always take precedence over the general provisions.

For example:

In the Dangerous Goods List entry for ACETYLENE, DISSOLVED, class 2.1, UN 1001, the following particular segregation requirement is specified:

“separated from” chlorine

In the Dangerous Goods List entry for BARIUM CYANIDE, class 6.1, UN 1565, the following particular

segregation is specified:

“separated from” acids

Where the Code indicates a single secondary hazard (one subsidiary risk label), the segregation provisions applicable to that hazard should take precedence where they are more stringent than those of the primary hazard.

Except for class 1, the segregation provisions for substances, materials or articles having more than two hazards (2 or more subsidiary risk labels) are given in the Dangerous Goods List.

In the Dangerous Goods List entry for BROMINE CHLORIDE, class 2.3, UN 2901, subsidiary risks 5.1 and 8, the following particular segregation is specified:

“segregation” as for class 5.1 but “separated from” class 7”.

Segregation of packages

Applicability

The provisions of this subsection apply to the segregation of:

packages containing dangerous goods and stowed in the conventional way;

dangerous goods within cargo transport units; and

dangerous goods stowed in the conventional way from those packed in such cargo transport units.

Segregation of packages containing dangerous goods and stowed in the conventional way

Definitions of the segregation terms Legend

Reference package - BLUE

Package containing incompatible goods - RED

Deck resistant to fire and liquid – BOLD LINE

NOTE. Full vertical lines represent transverse bulkheads between cargo spaces (compartments or holds) resistant to fire and liquid.

Away from:

Effectively segregated so that the incompatible goods cannot interact dangerously in the event of an accident but may be transported in the same compartment or hold or on deck, provided a minimum horizontal separation of 3 metres, projected vertically, is obtained.

Separated from:

In different compartments or holds when stowed under deck.  Provided the intervening deck is resistant to fire and liquid, a vertical separation i.e. in different compartments, may be accepted as equivalent to this segregation.  For on deck stowage, this segregation means a separation by a distance of sit least 6 metres horizontally.

Separated by a complete compartment or hold from:

Either a vertical or a horizontal separation. If the intervening decks are not resistant to fire and liquid,      then only a longitudinal separation, i.e. by an intervening complete compartment or hold, is acceptable. For on deck stowage, this segregation means a separation by a distance of at least 12 metres horizontally. The same distance has to be applied if one package is stowed on deck and the other one in an upper compartment.

Note: One of the two decks must be resistant to fire and to liquid.

Separated longitudinally by an intervening complete compartment or hold from:

Vertical separation alone does not meet this requirement. Between a package under deck and one on deck, a minimum distance of 24 metres, including a complete compartment, must be maintained longitudinally. For on deck stowage, this segregation means a separation by a distance of at least 24 metres longitudinally.

Containment covered by the term “packaged form”

Chapter 4.1 describes the different types of packaging for use with goods

under the IMDG code.

Definitions

Effectively closed: liquid-tight closure.

Hermetically sealed: vapour-tight closure.

Securely closed: so closed that dry contents cannot escape during normal handling; the minimum provisions for any closure.

General provisions for the packing of dangerous goods, other than goods of classes 2, 6.2 or 7, in packagings, including Intermediate Bulk Containers (IBCs) and large packagings

Dangerous goods should be packed in good quality packagings, including IBCs and large packagings, which should be strong enough to withstand the shocks and loadings normally encountered during transport, including trans-shipment between cargo transport units and/or warehouses as well as any removal from a pallet or overpack for subsequent manual or mechanical handling.  Packagings, including IBCs and large packagings, should be constructed and closed so as to prevent any loss of contents when prepared for transport, which might be caused under normal conditions of transport, by vibration, or by changes in temperature, humidity or pressure (resulting from altitude, for example).  No dangerous residue should adhere to the outside of packages, IBCs and large packagings during transport.  These provisions apply, as appropriate, to new, re-used, reconditioned or remanufactured packagings and to new and re-used IBCs and large packagings.

Parts of packagings, including IBCs and large packagings, which are in direct contact with dangerous goods:

.1 should not be affected or significantly weakened by those dangerous goods; and

.2 should not cause a dangerous effect, such as catalyzing a reaction or reacting with the dangerous goods. 

Where necessary, they should be provided with a suitable inner coating or treatment.

Unless provided elsewhere in this Code, each packaging, including IBCs and large packagings, except inner packagings, should conform to a design type successfully tested in accordance with the provisions in the IMDG code.

When filling packagings, including IBCs and large packagings, with liquids, sufficient ullage (outage) should be left to ensure that neither leakage nor permanent distortion of the packaging occurs as a result of an expansion of the liquid caused by temperatures likely to occur during transport.  Unless specific provisions are prescribed, liquids should not completely fill a packaging at a temperature of 55˚C.  However, sufficient ullage should be left in an IBC to ensure that at the mean bulk temperature of 50˚C it is not filled to more than 98% of its water capacity.

Inner packagings should be packed in an outer packaging in such a way that, under normal conditions of transport, they cannot break, be punctured or leak their contents into the outer packaging.  Inner packagings that are liable to break or be punctured easily, such as those made of glass, porcelain or stoneware or of certain plastics, materials, etc., should be secured in outer packagings with suitable cushioning material.  Any leakage of the contents should not substantially impair the protective properties of the cushioning material or of the outer packaging.

Cushioning and absorbent material should be inert and suited to the nature of the contents.

The nature and the thickness of the outer packagings should be such that friction during transport does not generate any heating likely to alter dangerously the chemical stability of the contents.

Dangerous goods should not be packed together in the same outer packaging, or in large packagings, with dangerous or other goods if they react dangerously with each other and cause:

.1         combustion and/or evolution of considerable heat;

.2         evolution of flammable, toxic or asphyxiant gases;

.3         the formation of corrosive substances; or

.4         the formation of unstable substances.

Unless otherwise specified in the Dangerous Goods List, packages containing substances should be hermetically sealed:

.1         evolve flammable gases or vapour;

.2         may become explosive if allowed to dry;

.3         evolve toxic gases or vapour;

.4         evolve corrosive gases or vapour; or

.5         may react dangerously with the atmosphere.

Liquids may only be filled into inner packagings which have an appropriate resistance to internal pressure that may be developed under normal conditions of transport.  Where pressure may develop in a package by the emission of gas from the contents (as a result of temperature increase or other cause), the packaging may be fitted with a vent, provided that the gas emitted will not cause danger on account of its toxicity, its flammability, the quantity released, etc.  The vent should be so designed that, when the packaging is in the attitude in which it is intended to be transported, leakages of liquid and the penetration of foreign matter are prevented under normal conditions of transport.

New, remanufactured or re-used packagings, including IBCs and large packagings, or reconditioned packagings and repaired IBCs should be capable of passing the tests prescribed in IMDG code.  Before being filled and handed over for transport, every packaging, including IBCs and large packagings, should be inspected to ensure that it is free from corrosion, contamination or other damage and every IBC should be inspected with regard to the proper functioning of any service equipment.  Any packaging which shows signs of reduced strength as compared with the approved design type should no longer be used or should be so reconditioned that it is able to withstand the design type tests.  Any IBC which shows signs of reduced strength as compared with the tested design type should no longer be used or should be so repaired that it is able to withstand the design type tests.

 

Empty packagings, including IBCs and large packagings, that have contained a dangerous substance should be treated in the same manner as is required by this Code for a filled packaging, unless adequate measures have been taken to nullify any hazard.

Every packaging, including IBCS, intended to contain liquids should successfully undergo a suitable leak proofness test, and be capable of meeting the appropriate test level indicated in IMDG code for the various types of IBCs:

.1  before it is first used for transport;

.2  after remanufacturing or reconditioning of any packaging, before it is re-used for transport;

.3 after the repair of any IBC, before it is re-used for transport.

For this test, the packaging, or IBC, need not have its closures fitted.  The inner receptacle of a composite packaging or IBC may be tested without the outer packaging, provided the test results are not affected.  This test is not necessary for inner packagings of combination packagings or large packagings.

Packagings, including IBCS, used for solids which may become liquid at temperatures likely to be encountered during transport should also be capable of containing the substance in the liquid state.

Packagings, including IBCS, used for powdery or granular substances should be sift-proof or should be provided with a liner.

Explosives, self-reactive substances and organic peroxides

Unless specific provision to the contrary is made in this Code, the packagings, including IBCs and large packagings, used for goods of class 1, self-reactive substances of class 4.1 and organic peroxides of class 5.2 should comply with the provisions for the medium danger group (packing group 11).

Use of salvage packagings

Damaged, defective or leaking packages or dangerous goods that have spilled or leaked may be transported in special salvage packagings. This does not prevent- the use of a bigger size of packagings of appropriate type and performance level.

During transport, packagings, including IBCs and large packagings, should be securely fastened to or contained within the cargo transport unit, so that

lateral or longitudinal movement or impact is prevented and adequate external support is provided.

Additional general provisions for the use of IBCs

When IBCs are used for the transport of liquids with a flashpoint of 61˚C (closed cup) or lower, or of powders liable to dust explosion, measures should be taken to prevent a dangerous electrostatic discharge.

For rigid plastics IBCs and composite IBCs with plastics inner receptacles, unless otherwise approved by the competent authority, the period of use permitted for the transport of dangerous liquids should be five years from the date of manufacture of the receptacle except where a shorter period of use is prescribed because of the nature of the liquid to be transported.

General provisions concerning packing instructions

Packing instructions applicable to dangerous goods of classes 1 to 9 are specified in chapter 4.1. They are subdivided in three sub-sections depending on the type of packagings to which they apply:

sub-section 4.1.4.1 for packagings other than IBCs and large packagings: these packing instructions are designated by an alphanumeric code comprising the letter “P”;

sub-section 4.1.4.2       for IBCS; these are designated by an alphanumeric code comprising the letters “IBC”;

sub-section 4.1.4.3       for large packagings; these are designated by an alphanumeric code comprising the letters “LP”.

Special packing provisions may also be specified in the packing instruction for individual substances or articles.  They are also designated by an alphanumeric code comprising the letters:

“PP”     for packagings other than IBCs and large packagings

“B”       for IBCs

“L”       for large packagings.

Column 8 of the Dangerous Goods List shows for each article or substance the packing instructions) that should be used.  Column 9 indicates the special packing provisions applicable to specific substances or articles.

Each packing instruction shows, where applicable, the acceptable single and combination packagings.  For combination packagings, the acceptable outer packagings, inner packagings and, when applicable, the maximum quantity permitted in each inner or outer packaging are shown.  Maximum net mass

and maximum capacity are as defined in chapter 1.2.1.

Where the packing instructions in this chapter authorize the use of a particular type of outer packaging in a combination packaging (such as 4G), packagings bearing the same packaging identification code followed by the letters “V”, “U” or “W” marked in accordance with the provisions of part 6 (such as “4GV”, “4GU” or “4GW”) may also be used under the same conditions and limitations applicable to the use of that type of outer packaging according to the relevant packing instructions.  For example, a combination packaging marked with the packaging code “4GV” may be used whenever a combination packaging marked “4G” is authorized, provided the

provisions in the relevant packing instruction regarding types of inner packagings and quantity limitations are respected.

The capacity of gas cylinders should not exceed 450 litres. The capacity for gas receptacles should not exceed 1000 litres.

Bulk Cargo (Grain) 

 

Loading and Stowage of Bulk Grain

Before loading bulk the following preparations should be done:

Holds and tween deck thoroughly swept down.

All dunnage removed from cargo spaces or stowed at one and covered.

Bilges should be cleaned and sweetened

Bilges suctions should be tested

Tween deck scuppers should be covered with double weave separation cloth, edges to be fixed with cement.

Any cracks between limber boards to be covered with separation cloth nailed down to prevent the cargo from going into the bilges.

All pipelines passing through the bilges should be tested and any leaks discovered should be fixed – esp. fire mains, water ballast lines and bilge pumping out lines.

After the holds are swept and if required hosed down, the holds/ compartments are to be inspected for any infestation.

The inspection should include all easily accessible areas together with inaccessible areas including under the beams and hatch pontoon frames. In case fumigation is carried out prior loading then the compartment has to be swept and again inspected for any dead insects and rodents. The fumigant used should be compatible with the cargo to be carried.

For loading of Rice the fumigation may be carried out twice – prior loading and on completion of discharging.

The inspection for infestation should be very thorough since apart from later claims, some ports especially in the US, the USDA inspectors would have to clear the ship for loading – and these inspectors are known to be very thorough.

Shifting of cargo

Certain bulk cargos have a tendency to shift and precautions must be taken to counteract this tendency.  These precautions are dealt with below:

Recommendation are made about the stowage of the cargo:

            Weight =          db (3L+B)                 tonnes                                                4.6

where d is the summer load draft

b is average breadth of lower hold

L is length of lower hold

B is the maximum moulded breadth

The height of the cargo pile peak should not exceed:

1.89 x d x S. F. (m3/tonne) metres

Angle of repose

This is the greatest angle from the horizontal to which a substance can be raised without it shifting. Cargoes most liable to shift are those having a small angler of repose.

Angle of repose of 35˚ is taken as being the dividing line for bulk cargoes of lesser or greater shifting hazard and cargoes having angles of repose of more or less than this figure are considered separately.

Trimming

In compartments entirely filled with bulk grain the grain shall be trimmed so as to fill all the spaces between the beams and in the wings and ends.  In compartments partly filled with bulk grain the grain shall be levelled whenever practicable.

The provision of a shifting boards or longitude bulkheads within 5% of the vessel’s moulded breadth from the centre line or two or more longitudinal bulkheads or shifting boards with a distance between of not more than 60% of the vessel’s moulded breadth.  In the latter case suitable sized trimming hatches are to be provided in the wings at intervals of not more than 7.62m., the end hatches being not more than 3.66m from transverse bulkheads.

In holds the shifting boards must extend downwards from the deck at least 2. 44m or ½ depth of hold whichever is the greater.  In ‘tween decks and in feeders, unless there is some exemption they must extend from deck to deck.  If the compartment is only partly filled with grain, the shifting boards must extend from the bottom of the compartment to at 0.6m above the surface of the bulk grain, however no shifting boards are necessary if the

bulk grain does not occupy more than ½ of the hold or ½ of the hold where there is a shaft tunnel.

The Shifting boards must not be less than 50mm in thickness and are to have a 80mm housing at the bulkhead.  They must be adequately supported by wood minimum size 250mm x 50mm or metal uprights with a maximum spacing of 3.96mm and set in 80mm housings top and bottom.  The jointing of 50mm shifting boards must overlap by at least 230mm in way of the uprights.

If the uprights are made sufficiently strong and the length is not too great, shoring or staying may be unnecessary. If wood shores are used they must be in a single piece securely fixed at each end and heeled against the permanent structure of the ship, but not directly against the side plating. The angle between the shore and the horizontal should be kept as small as possible and must never exceed 45˚.

The size of the shore is dependent upon its length; a shore over 6.1m in length would be at least 200m x 150mm. If stays are used they will be fitted horizontally and will consist of 75mm – 6 x 12 galvanised flexible steel wire rope, secured with 25mm shackles to uprights and frames and fitted with 32mm rigging screws in accessible positions.

If the uprights are not secured at the top, the uppermost shore or stay is to be not less than 0.46m from the top.

The vertical spacing of the shores or stays is obtained from tables in the rules.

GM

If a GM after correction for FSC of not less than 0.31m is maintained throughout the voyage in one or two deck ships or 0.36m in other ships longitudinal bulkheads or shifting boards are not required in the following positions, (except when linseed in bulk is being carried therein)

Below and within 2.13m of a feeder which contains not less than 5% of the quantity of grain in the space it feeds, but only in way a hatchway,

In feeders as above provided that the free grain surface will remain within the feeders throughout the voyage allowing for a sinkage of 2% of the volume of the compartment fed and a shift of the free grain surface to 12˚,

In way of the hatchway where the bulk grain has been saucered, provided that the hatchway is filled with bagged grain or other suitable bagged cargo. The minimum depth of the bagged cargo in the centre of the saucer to be 1.83m below the deck level. The grains to be stored tightly up to the deck head in the other parts of the compartment,

In way of a hatchway in a compartment partly filled with bulk grain.

The surface of grain in a partly filled compartment is to be saucered with a minimum height of 1.52m of bagged grain or other suitable cargo over the portion where there are no shifting boards and 1.22m where there are shifting boards. This latter height is also required when the bulk grain does not occupy more than 1/3 of the hold or ½ of the hold where there is a shaft tunnel.

 

 

The bagged grain shall be carried in sound bags, which shall be securely closed and well filled. The bags or other suitable cargo shall be supported on suitable platforms which consist of strong separation cloths with adequate overlapping or 25mm boards spaced not more that 100mm apart laid on bearers not more than 1.22m apart.

Feeders are to be fitted to feed compartments entirely filled with bulk grain, except in deep tanks not over ½ moulded breadth of vessel in case ‘GM c’ above.

They are to contain not less than 2% of the quantity of grain carried in the compartment, which they feed. The boarding may be horizontal or vertical but must be sufficiently supported by binders, shores or stays as laid down in the rules. Feeding holes are to be provided about 0.61m apart in coamings, which extend more that 0.39m below the deck. The diameter of the hole is 50mm or 88mm depending on coaming depth. Feeders are assumed to be capable of feeding a distance of 7.62m.

If any part of the compartment is more that 7.62m (measured in a fore and aft line) from the nearest feeder, the grain in the space beyond 7.62m is to be levelled off at a depth of at least 1.83m below the deck and the space above is to be filled with bagged grain or suitable cargo.

Loading two different cargoes in the same hold

Very occasionally, different types of grain are loaded into the same hold. The heavier grain is loaded first and trimmed level over the entire area of the hold. The surface is covered with separation cloths/ canvas, allowing for ample overlaps, at least 1m. The cloths are carried well up the sides and ends of the compartment so that the next grain loaded will force them against the plating between the frames and stiffeners, it has to be ensured that adequate leeway is allowed for the separation cloth being taken up the sides and ends of the compartment, since the lower cargo would settle down during the voyage and if this leeway is not allowed for the cloth would exert a pull and tear off from the side moorings. This would result in the cargo being mixed.

The lighter grain should be loaded carefully at first to avoid displacing the separation cloths. Once the lighter cargo has been leveled off to a height of 0.5m all over the loading may begin at the usual rate, care being taken to see that it is constantly leveled by adjusting the loading chute inflow direction.

When bulk grain is carried in the ‘tween deck of a two deck ship or in the upper ‘tween deck of a ship having more than two decks or above deck the following are to be complied with:

Either the GM shall not be less than that specified in paragraph ‘GM’ or the total quantity of bulk grain or other cargo carried in the specified space shall not exceed 28% by weight of the total cargo below the ‘tween deck.

Partly filled deck area in the above space is not to exceed 93m2,

The spaces which contain bulk grain are to be divided into lengths of not more than 30.5m by transverse bulkheads, or if not so divided the excess space – beyond 30.5m is to be entirely filled with bagged grain or other suitable cargo.

Vessels having a GM less than that specified in paragraph ‘GM’ are not permitted to have more than two holds or compartments partly filled with bulk grain wherein the overstowing cargo does not fill the space to the deck head. Feeders are not compartments and so they are exempted from this requirement.

Double bottom tanks used to meet a stability requirement are to be adequately subdivided longitudinally unless the width of the tank at its ½ length does not exceed 60% of the vessel’s moulded breadth.

A grain-loading plan may be supplied to certain ships, which may then be exempted from some of the provisions outlined above due to their special construction (such as tanker and bulk carriers), which prevents shifting of the bulk cargo. However, the resulting list of the vessel must not exceed 5˚ if the grain settles by 2% and shifts to an angle of 12˚ from its original position.

 

Bulk Cargo (Not Grain)

 

 

Bulk cargoes (other than grain)

The officer of the watch should know the pre-planned loading procedure

regarding quantities to be loaded in each space, the order of deballasting

tanks and shifting the vessel under loading chutes. The procedure will have

been worked out to keep stresses within acceptable limits and to finish with

a satisfactory weight distribution and trim. The officer of the watch should

see that the plan is followed, particularly at berths with only one loading

chute, to avoid over-stressing the ship.

Code of Safe Practice for Solid Bulk Cargoes BC Code is intended to set a standard for the safe stowage and carriage of solid bulk cargoes.

This Code is a recommended guide for ship owners, shippers and masters and shall apply to all shipments of bulk cargoes.

The list of products appearing in the Appendices of the BC Code, however, is by no means exhaustive. Consequently, before any bulk cargo is loaded, it is essential to ascertain (normally from the shipper) the current physical and chemical properties of the cargo, as required under SOLAS Chapter VI.

General requirements

Before and during loading, transport and unloading of bulk cargoes, all necessary safety precautions including any regulations or requirements should be observed, including the following:

1. Dangerous Bulk Material Regulations

2. Safe Working Practices Regulations

3. International Maritime Dangerous Goods Code (IMDG Code)

4. Emergency Procedures For Ships Carrying Dangerous Goods

5. Medical First Aid Guide for Use in Accidents Involving Goods (MFAG)

6. IMO BC Code - Code of Safe Practice for Solid Bulk Cargoes

Poisoning and asphyxiation hazards

Certain bulk cargoes are liable to oxidation, which in t urn may result in oxygen depletion, emission of toxic fumes and self-heating. Other bulk cargoes may not oxidize but may emit toxic fumes.

It is important therefore that the shipper inform the master before loading of the existence of any chemical hazards. The master should refer to Appendix B of the BC Code and take the necessary precautions, especially those pertaining to ventilation.

Certain cargoes may emit toxic gases when wetted. In these cases the ship should be provided with the appropriate gas detection equipment.

A flammable gas detector is only suitable for testing the explosive nature of gas mixtures.

Emergency entry into a cargo space should be undertaken only by trained personnel wearing self-contained breathing apparatus, and protective clothing if considered necessary, always under the supervision of a responsible officer.

In the event of emergency entry into a cargo space, in addition to the above requirement, spare self-contained breathing apparatus, safety belts and safety lines should be readily available.

Health hazard from dust

To minimize the chronic risks from exposure to the dust of certain materials carried in bulk, a high standard of personal hygiene for those exposed to the dust cannot be too strongly emphasized. The precautions should include not only the use of appropriate protective clothing and barrier creams when needed but also adequate personal washing especially before meals, and laundering of outer clothing.

Flammable atmosphere

Dust created by certain cargoes may constitute an explosion hazard, especially, during loading, unloading and cleaning. This risk can be minimized at such times by ensuring that ventilation is sufficient to prevent the formation of a dustladen atmosphere and by hosing down rather than sweeping.

CARGOES THAT MAY LIQUEFY (section 7 of the BC Code)

Properties, characteristics and hazards

Cargoes that may liquefy include concentrates, certain coals and other materials having similar physical properties. Appendix A of the BC Code contains a list of such cargoes, which generally consist of a mixture of small particles in contrast with natural ores that include a considerable percentage of large particles or lumps.

Section 5 of the BC Code - Trimming Procedures

At moisture content above that of the transportable moisture limit, shift of cargo may occur as a result of liquefaction.

The major purpose of the sections of this Code dealing with these cargoes is to draw the attention of masters and others to the latent risk of cargo shift, and to describe the precautions deemed necessary to minimize this risk.

Such cargoes may appear to be relatively dry and granular when loaded, but may contain sufficient moisture as to become fluid under the stimulus of compaction and the vibration that occurs during a voyage.

In the resulting viscous fluid state, cargo may flow to one side of the ship when it rolls one way, but not completely return when it rolls the other. Thus, the ship sways progressively until it reaches a dangerous heel and capsizes.

To prevent subsequent shifting, and also to decrease the effects of oxidation of material with a predisposition to oxidize, these cargoes should be trimmed reasonably level on completion of loading, irrespective of the angle of repose.

Amended Extract from SOLAS Chapter VI

Part B

Special provisions for bulk cargoes other than grain

Regulation 6

Acceptability for shipment

Concentrates or other cargoes which may liquefy shall only be accepted for loading when the actual moisture content of the cargo is less than its transportable moisture limit. However, such concentrates and other cargoes may be accepted for loading even when their moisture content exceeds the above limit, provided that safety arrangements to the satisfaction of the

Administration are made to ensure adequate stability in the case of cargo shifting and further provided that the ship has adequate structural integrity.

Prior to loading a bulk cargo which is not a cargo classified but which has chemical properties that may create a potential hazard, special precautions for its safe carriage shall be taken.

Regulation 7

Loading, unloading and stowage of bulk cargoes

To enable the master to prevent excessive stresses in the ship’s structure, the ship shall be provided with a booklet, which shall be written in a language with which the ship’s officers responsible for cargo operations are familiar. The booklet shall, as a minimum, include:

.1 stability data,

.2 ballasting and de-ballasting rates and capacities;

.3 maximum allowable load per unit surface area of the tank top plating;

.4 maximum allowable load per hold;

.5 general loading and unloading instructions with regard to the strength of the ship’s structure including any limitations on the most adverse operating conditions during loading, unloading, ballasting operations and the voyage;

.6 any special restrictions such as limitations on the most adverse operating conditions imposed by the Administration or organization recognized by it, if applicable; and

.7 where strength calculations are required, maximum permissible forces and moments on the ship’s hull during loading, unloading and the voyage.

Before a solid bulk cargo is loaded or unloaded, the master and the terminal representative shall agree on a plan* which shall ensure that the permissible forces and moments on the ship are not exceeded during loading or unloading, and shall include the sequence, quantity and rate of loading or unloading, taking into consideration the speed of loading or unloading, the number of pours and the de-ballasting or ballasting capability of the ship. The plan and any subsequent amendments thereto shall be lodged with the appropriate authority of the port State.

Bulk cargoes shall be loaded and trimmed reasonably level, as necessary, to the boundaries of the cargo space so as to minimize the risk of shifting and to ensure that adequate stability will be maintained throughout the voyage.

When bulk cargoes are carried in ‘tween-decks, the hatchways of such ‘tween-decks shall be closed in those cases where the loading information indicates an unacceptable level of stress of the bottom structure if the hatchways are left open. The cargo shall be trimmed reasonably level and shall either extend from side to side or be secured by additional longitudinal divisions of sufficient strength. The safe load-carrying capacity of the ‘tween-decks shall be observed to ensure that the deck-structure is not overloaded.

The master and terminal representative shall ensure that loading and unloading operations are conducted in accordance with the agreed plan.

If during loading or unloading any of the limits of the ship are exceeded or are likely to become so if the loading or unloading continues, the master has the right to suspend operation and the obligation to notify accordingly the appropriate authority of the port State with which the plan has been lodged. The master and the terminal representative shall ensure that corrective action is taken. When unloading cargo, the master and terminal

representative shall ensure that the unloading method does not damage the ship’s structure.

The master shall ensure that ship’s personnel continuously monitor cargo operations. Where possible, the ship’s draught shall be checked regularly during loading or unloading to confirm the tonnage figures supplied. Each draught and tonnage observation shall be recorded in a cargo logbook. If significant deviations from the agreed plan are detected, cargo or ballast operations or both shall be adjusted to ensure that the deviations are corrected.

At a moisture content above that of the transportable moisture limit, shift of cargo may occur as a result of liquefaction.

Many cargoes may appear to be relatively dry and granular when loaded, but may contain sufficient moisture as to become fluid under the stimulus of compaction and the vibration that occurs during a voyage.

In the resulting viscous fluid state, cargo may flow to one side of the ship when it rolls one way, but not completely return when it rolls the other. Thus, the ship way progressively reaches a dangerous heel and capsize.

Ships other than specialist suited ones shall carry only those cargoes having a moisture content that is not in excess of the transportable moisture limit as defined in this Code.

Specially suited ships

Specially suited ships may carry concentrates having a moisture content in excess of the transportable moisture limit if the ship possesses a valid document of approval from her administration, accompanied by such stability information as her administration may require. The document of

approval must clearly state “For carriage of concentrates having a moisture content in excess of the transportable moisture limit”.

When concentrates are loaded that have a moisture content in excess of the transportable moisture limit, the whole surface area of each cargo space shall be trimmed level.

Cargoes having a moisture content in excess of the flow moisture point shall not be carried in bulk.

Before loading, the shipper or his appointed agents shall provide to the master and the port warden, if requested, details, as appropriate, of the characteristics and properties of any material constituting bulk cargo, such as flow moisture point, stowage factor, moisture content, angle of repose, chemical hazards, etc. so that any necessary safety precautions can be put into effect.

To do this the shipper shall arrange, possibly in consultation with the producers, for the cargo to be properly sampled and tested. Furthermore, the shipper should provide the ship’s master and the port warden, if requested, with the appropriate certificates of test, as applicable for a given cargo.

Before and during loading, auxiliary check tests of the moisture content may be carried out using instruments designed specifically for that purpose, such as the “SPEEDY MOISTURE TESTER”. Tests conducted with this instrument indicate a precision of ±1% compared with the laboratory method, i.e., with a laboratory reading of 10%, the “SPEEDY” reading could range from, 9% to 11%. If the readings obtained by this method are consistently higher than those shown on the certificate, loading of the cargo should cease and a further laboratory test be conducted.

If the master has doubts as regards the appearance of condition of the cargo for safe shipment, the following auxiliary method may be used on board ship or at the dockside to perform a check test for approximately determining the possibility of flow:

Half fill a cylindrical can or similar container (0.5-1 litre capacity) with a sample of cargo. Take the can in one hand and bring it down sharply from a height of about 0.2m to strike a hard surface such as a solid table. Repeat the procedure twenty-five times at one or two second intervals. Examine the surface for free moisture or fluid conditions. If free moisture or a fluid condition appears, make arrangements to have additional laboratory tests on the cargo conducted before it is accepted for loading.

COAL is very liable to spontaneous heating.  If there is sufficient oxygen available, combustion is liable to take place. The amount of heating that takes place depends on the type of type coal and how much heat can be dispersed by ventilating the coal.  Ventilation can be a double-edged weapon as although it takes heat from the coal it also allows unwanted oxygen into the coal.  To keep the coal as cool as possible it should be stowed away from hot bulkheads.  To keep oxygen away from the coal only surface ventilation should be allowed. 

All spar ceiling or cargo battening should be removed as besides the liability of it to damage, it can give unwanted air pockets in the coal.  Unwanted air may also get into a cargo through a temporary wooden bulkhead. If such a bulkhead has been constructed all cracks should be sealed, preferably by pasting paper over both sides of the bulkhead.

Freshly mined coal absorbs oxygen, which, with extrinsic moisture, forms peroxides.  These in turn breakdown to form carbon monoxide and carbon dioxide.

Heat is produced by this exothermic reaction causing further oxidation and further heat.  If this heat is not dissipated ignition will occur.  This is called Spontaneous combustion.

As this is essentially a surface reaction the smaller the surface available for the absorption of oxygen the better. Every attempt should be made to prevent undue breakage of the coal whilst it is being loaded. It may be noted that 1 MT of coal in an unbroken cube has a surface area of about 3.72m2, whereas if it is broken up to pass through a 1.5mm mesh screen its surface area is nearly 4000m2. If a large amount of breakage occurs the small coal with the large surface area is found in the centre of the hold, whilst the large

coal will roll down the sides. This aggravates the situation, as the large coal gives a good path for air to flow to the smaller coal where the spontaneous heating is most liable to occur.

Most coal fires in cargo occur at about ‘tween deck level and this is the area where the greatest attention should be paid to temperature and the restriction of through ventilation.

The following are recommendations for the carriage of coal.

The ventilators to the lower holds should be so arranged that they might be opened or closed at will during the voyage.

As the critical temperature at which the process of spontaneous heating in coal becomes greatly accelerated is in some varieties of coal as low as 36˚C, and generally is not much higher, the need of keeping the exteriors surface

of the hull, and thereby the interior of the ‘tween decks and holds, as cool as possible is manifest.

The iron decks of ships carrying coal in the tropics can be covered with

dunnage to lessen heating.

Suitable means should be provided for ascertaining from time to time the temperature of the lower mass of coal, particularly below the hatchways, and this might be done by means of two pipes leading down to the bottom of the coal at each hatchway.

The temperature tubes should have closed ends to prevent admission of air into the cargo. The temperature of the coal at three heights should be taken daily.

Gas from the holds or ‘tween decks space may find its way into shaft, peaks, chain lockers or similar space unless the bulkheads and casings are maintained in gas tight conditions.

Naked lights should not be used in holds or other spaces in which gas may accumulate until the spaces have been well ventilated.

Full use should, when necessary, be made of the breathing apparatus or smoke helmet and the safety lamp, which form part of the ship’s statutory fire appliances.

The employment of the crew in chipping and painting below decks during the voyage should be avoided.  The danger from smoking should be realized and no oily waste, wood, old rope, sacking etc. should be left below where it can become ignited by spontaneous heating

On arrival at the port of discharge the hold ventilators should be unplugged and the lower hold well ventilated before commencing to work cargo.

Coal is frequently loaded from a single tip and earlier it was necessary to drift the vessel fore and aft so that all holds may be filled.  To keep these shifts to a minimum No.2 was first put under the tip.

After about one third the capacity of the hold was loaded the vessel was shifted so that No. 3 was loaded to about one third of its capacity.  Likewise the remaining after holds were loaded and then the tip was shifted astern to reach No. 1, half the capacity was put in, before shifting to No. 2, which was then filled. 

The other after holds were now filled in order excepting the aftermost. The aftermost hold and the No.1 were now worked so that the vessel would complete loading in a good trim.

Coal is sometimes graded, when this in so, care should be taken to prevent undue breakage.

Lowering the first few truckloads into the hold helps as do control of the rate of tipping down and chute.

Some ports have conveyor belts and an endless bucket system for loading; this is excellent for graded coal and also keeps the dust down with the ordinary coal.

Fortunately it is mainly the better coals, which are graded, and in generally these are not so friable.

Coal will need to be trimmed and its angle of repose is quite high, especially if large coal is loaded.

There is no danger for coal shifting unless it is the very small stuff known as mud coal, slurry or duff.

This is very fine coal, almost dust, and if the moisture content is high it behaves almost like a liquid.

Deck Cargo 

 

Cargo which are normally carried on deck include the following but are not

limited to these and many exceptional cargoes may be carried and also have

been carried in the past.

Dangerous cargo – IMDG cargo not permitted on deck

Large packages which due to any size restriction may have to be loaded on to the deck

The above includes engineering or construction equipment

Odd size package

Where the bulk volume far exceeds the weight of the cargo – knocked down bridges, port equipment – not easily liable to weather damage.

Occasionally livestock in limited numbers

Onions or other perishables – short voyages with the weather holding

Yachts – luxury boats.

Cast iron goods – man hole covers – pipes.

The list is endless and it all depends on the routes, the trading pattern and the weather.

The cargo whether on deck or under deck stow has to be stowed well and the cargo should be prevented from moving and gaining enough momentum to part lashings and damage the ship structure.

Deck cargo is liable to damage itself – fall overboard and thus be lost. However the misery does not stop here in the act of parting lashing and going overboard the deck cargo unleashes considerable damage to the ship structure as well as the crewmembers.

Small apparently insignificant items such as sounding pipes and air pipes are often torn out and this may endanger the ship from the resulting chances of flooding lower down compartments.

Crewmembers ordered to lash cargo where the lashings have parted have been seriously injured and some have lost lives combating the shifting cargo.

The point is to have a good solid stow – prevent the cargo from shifting and gaining momentum with the shift. Since this would part any strong lashing. The lashing undertaken should be for the worst sea condition that may be experienced.

Deck cargo loading on top of hatch covers should be carefully planned. All loading of under deck spaces should have been completed – lashing may continue with portable lights.

The hatch covers should be closed and battened down – all side wedges as well as cross wedges (centre wedges) should have been fitted. With the hatch cover sealed for sea, the space should then be given out for loading of deck cargo.

The permissible load density of the hatch covers should be checked and timbers laid to spread the weight of the cargo. The load density of the hatch covers are given for a new vessel and as the ship ages the load density would reduce due to fatigue of the metal as well as wear and tear. Thus the utmost need to spread the weight using timber.

Shoring and toming of the hatch cover from below deck is practically useless since the hatch cover moves/ slides somewhat with the motion of the ship.

The height of the cargo on the hatch covers as well as that on deck should not be so high that the view is obstructed from the Navigating Bridge.

 

Ice accumulation on hatch cover and on deck

 

 

The above photographs show the extent of the weight that Ice accumulation

can pose for a ship. The weight on deck may eventually lead a ship to

progress to a condition of ‘angle of loll’.

The weight of the ice may be in excess of a hundred tonnes, and thus the danger of a ship regarding stability.

As with the above any deck cargo for that matter would have a very high KG as such the GM (F) would be quite small. Especially in the case of GC vessels, which do not have a very large GM (F) the loading of deck cargo, is bound to lead to further loss of GM (F). If the ship loads the deck cargo with her own gear then the ship would during the loading operation have still further low GM (F) due to the KG of the load being at the top of the derrick/ crane for part of the loading sequence.

Containers on deck

Containers when they are loaded on deck are subject to the following consideration – barring stability, which would have been planned for.

The load density of the deck

Spreading the load of the container evenly

Chocking the container base to prevent shifting due to rolling or pitching

Lashing the container for the above as well to prevent the container from being bodily lifted.

Placing the containers in as close a group as possible

Safeguarding the sounding pipes and the air pipes within the periphery of the container space.

Keeping the fire hose boxes clear as well as the passage leading to them, the fire hydrants should similarly be kept clear.

No lashing should be taken which would damage or cause to be damaged the fire lines.

Checking that the leads for the lashing wires are adequate as well as that the chocking points are well supported

Keeping a passage for crew members to check the lashings during g voyage.

In general the close stow is difficult on GC vessels where the container is usually loaded between the hatch coaming and the bulwark. So the container should be loaded as close as possible to the hatch coaming, as well as close to the Mast House structure. If few containers are being loaded then the shelter offered by the Mast House structure should be kept in mind.

The load is spread by having the container loaded onto timbers at least 4” x 4”. The timbers should be extended to well beyond the shoe of the container in all directions to spread the load. Once this is done the chocking of the container is started. Again heavy timbers are used and the container is first secured to prevent any lateral and transverse shifting. While selecting chocking points all heavy framework should be selected. Bulwark stays are not strengthened enough to be used as chocking points. Hatch coamings may be used and as a last resort bulwark stays. After the chocking is completed the container is lashed. The lashing is further to prevent the longitudinal as well as the transverse shifting. For this the base shoes offer the best lashing points. To prevent the container being bodily shifted out the lashings are continued to the top shoes.

All lashing should be separate in the sense that a single lashing wire should not be passed over a few shoes and then lashed at the final point. Each lashing should have a turnbuckle or bottle screw incorporated and there should be at least 60% free thread in them after completion of lashing.

The bottom lashing and the top lashing should not be counted together fore the purpose of assessing the total number of lashings taken for the container.

The top lashings are for bodily rise and as such should be counted separately.

As a thumb rule, if the SWL of the lashing wire is 2T then to lash the top of a 20T container the number of lashings should be a minimum of 10 (all well positioned), similarly the bottom should have 10. The bottom lashings may be reduced depending upon the chocking of the container and the availability of the lashing point.

Note that a single strong point for lashing should not have more than 2 lashing wires – the preferred would be 1, however it is often impossible to find so many lashing points.

This shows a container ship lashing; note that the container is loaded onto the ship shoe slots which are strengthened, the rod lashings are only for the top of the containers.

Here the bottom shoes are not lashed since the ships sunken shoes and twist locks effectively chock and lash the bottom of the container.

Stowage and Lashing of Timber deck cargoes as laid down by IMO code of Safe Practice for Ships Carrying Timber Deck Cargoes

Purpose

The purpose of the Code is to make recommendations on stowage, securing and other operational safety measures designed to ensure the safe transport of mainly timber deck cargoes.

Application

This Code applies to all ships of 24 m or more in length engaged in the carriage of timber deck cargoes. Ships that are provided with and making use of their timber load line should also comply with the requirements of the applicable regulations of the Load Line Convention.

Timber means sawn wood or lumber, cants, logs, poles, pulpwood and all other type of timber in loose or packaged forms. The term does not include wood pulp or similar cargo.

Timber deck cargo means a cargo of timber carried on an uncovered part of a freeboard or superstructure deck. The term does not include wood pulp or similar cargo.

Timber load line means a special load line assigned to ships complying with certain conditions related to their construction set out in the International Convention on Load Lines and used when the cargo complies with the stowage and securing conditions of this Code.

Weather deck means the uppermost complete deck exposed to weather and sea.

The stability of the ship at all times, including during the process of loading and unloading timber deck cargo, should be positive and to a standard acceptable to the Administration. It should be calculated having regard to:

The increased weight of the timber deck cargo due to:

Absorption of water in dried or seasoned timber, and

Ice accretion, if applicable;

Variations in consumables;

The free surface effect of liquid in tanks; and

Weight of water trapped in broken spaces within the timber deck cargo and especially logs.

Safety precautions to be taken as far as stability of the ship is concerned

The master should:

Cease all loading operations if a list develops for which there is no satisfactory explanation and it would be imprudent to continue loading;

Before proceeding to sea, ensure that:

The ship is upright;

The ship has an adequate metacentric height; and

The ship meets the required stability criteria.

Ships carrying timber deck cargoes should operate, as far as possible, with a safe margin of stability and with a metacentric height which is consistent with safety requirements but such metacentric height should not be allowed to fall below the recommended minimum.

However, excessive initial stability should be avoided as it will result in rapid and violent motion in heavy seas which will impose large sliding and racking forces on the cargo causing high stresses on the lashings. Operational experience indicates that metacentric height should preferably not exceed 3% of the breadth in order to prevent excessive accelerations in rolling provided that the relevant stability criteria are satisfied.

This recommendation may not apply to all ships and the master should take into consideration the stability information obtained from the ship’s stability manual.

STOWAGE

General

Before timber deck cargo is loaded on any area of the weather deck:

Hatch covers and other openings to spaces below that area should be securely closed and battened down;

Air pipes and ventilators should be efficiently protected and check valves or similar devices should be examined to ascertain their effectiveness against the entry of water;

Accumulations of ice and snow on such area should be removed; and

It is normally preferable to have all deck lashings, uprights, etc., in position before loading on that specific area. This will be necessary should a preloading examination of securing equipment be required in the loading port.

The timber deck cargo should be so stowed that:

Safe and satisfactory access to the crew’s quarters, pilot boarding access, machinery spaces and all other areas regularly used in the necessary working of the ship is provided at all times;

Where relevant, openings that give access to the areas can be properly closed and secured against the entry of water;

Safety equipment, devices for remote operation of valves and sounding pipes are left accessible; and

It is compact and will not interfere in any way with the navigation and necessary working of the ship.

During loading, the timber deck cargo should be kept free of any accumulations of ice and snow.

Upon completion of loading, and before sailing, a thorough inspection of the ship should be carried out. Soundings should also be taken to verify that no structural damage has occurred causing an ingress of water.

On ships provided with, and making use of, their timber load line, the timber deck cargo should be stowed so as to extend:

.1 over the entire available length of the well or wells between superstructures and as close as practicable to end bulkheads;

.2 at least to the after end of the aftermost hatchway in the case where there is no limiting superstructure at the aft end;

.3 athwartships as close as possible to the ship sides, after making due allowance for obstructions such as guard rails, bulwark stays, uprights, pilot boarding access, etc., provided any area of broken stowage thus created at the side of the ship does not exceed a mean of 4% of the breadth; and

.4 to at least the standard height of a superstructure other than a raised quarterdeck.

The basic principle for the safe carriage of any timber deck cargo is a solid stowage during all stages of the deck loading. This can only be achieved by constant supervision by shipboard personnel during the loading process.

SECURING

General

Every lashing should pass over the timber deck cargo and be shackled to eye plates and adequate for the intended purpose and efficiently attached to the

deck stringer plate or other strengthened points. They should be installed in such a manner as to be, as far as practicable, in contact with the timber deck cargo throughout its full height.

All lashings and components used for securing should:

.1 possess a breaking strength of not less than 133 kN;

.2 after initial stressing, show an elongation of not more than 5% at 80% of their breaking strength; and

.3 show no permanent deformation after having been subjected to a proof load of not less than 40% of their original breaking strength.

Every lashing should be provided with a tightening device or system so placed that it can safely and efficiently operate when required. The load to be produced by the tightening device or system should not be less than:

.1 27 kN in the horizontal part; and

.2 16 kN in the vertical part.

NOTE: 1   Newton   equals 0.225 lbs. force or 0.1 kgf.

Upon completion and after the initial securing, the tightening device or system should be left with not less than half the threaded length of screw or of tightening capacity available for future use.

Every lashing should be provided with a device or an installation to permit the length of the lashing to be adjusted.

The spacing of the lashings should be such that the two lashings at each end of each length of continuous deck stow are positioned as close as practicable to the extreme end of the timber deck cargo.

If wire rope clips are used to make a joint in a wire lashing, the following conditions should be observed to avoid a significant reduction in strength:

.1 the number and size of rope clips utilized should be in proportion to the diameter of the wire rope and should not be less than four, each spaced at intervals of not less than 15 cm;

.2 the saddle portion of the clip should be applied to the live load segment and the U-bolt to the dead or shortened end segment;

.3 rope clips should be initially tightened so that they visibly penetrate into the wire rope and subsequently be retightened after the lashing has been stressed.

Greasing the threads of grips, clips, shackles and turnbuckles increases their holding capacity and prevents corrosion.

Uprights

Uprights should be fitted when required by the nature, height or character of the timber deck cargo.

When uprights are fitted, they should:

.1 be made of steel or other suitable material of adequate strength, taking into account the breadth of the deck cargo;

.2 be spaced at intervals not exceeding 3 m;

.3 be fixed to the deck by angles, metal sockets or equally sufficient means; and

.4 if deemed necessary, be further secured by a metal bracket to a strengthened point, i.e., bulwark, hatch coaming.

Loose or packaged sawn timber

The timber deck cargo should be secured throughout its length by independent lashings.

The maximum spacing of the lashings should be determined by the maximum height of the timber deck cargo in the vicinity of the lashings:

.1 for a height of 4 m and below, the spacing should be 3 m;

.2 for heights of above 4 m, the spacing should be 1.5 m.

The packages stowed at the upper outboard edge of the stow should be secured by at least two lashings each.

When the outboard stow of the timber deck cargo is in lengths of less than 3.6 m, the spacing of the lashings should be reduced as necessary or other suitable provisions made to suit the length of timber.

Rounded angle pieces of suitable material and design should be used along the upper outboard edge of the stow to bear the stress and permit free reeving of the lashings.

Logs, poles, cants or similar cargo

The timber deck cargo should be secured throughout its length by independent lashings spaced not more than 3 m apart.

If the timber deck cargo is stowed over the hatches and higher, it should, in addition be further secured by:

.1 a system of athwarthship lashings (hog lashings) joining each port and starboard pair of uprights near the top of the stow and at other appropriate levels as appropriate for the height of the stow; and

.2 a lashing system to tighten the stow whereby a dual continuous wire rope (wiggle wire) is passed from side to side over the cargo and held

continuously through a series of snatch blocks or other suitable device, held in place by foot wires.

The dual continuous wire rope should be led to a winch or other tensioning device to facilitate further tightening.

Testing, examination and certification

All lashings and components used for the securing of the timber deck cargo should be tested, marked and certified according to national regulations or an appropriate standard of an internationally recognized standards institute. Copies of the appropriate certificate should be kept on board.

No treatments, which could hide defects or reduce mechanical properties or strength, should be applied after testing.

A visual examination of lashings and components should be made at intervals not exceeding 12 months.

A visual examination of all securing points on the ship, including those on the uprights, if fitted, should be performed before loading the timber deck cargo. Any damage should be satisfactorily repaired.

Lashing plans

One or more lashing plans complying with the recommendations of this Code should be provided and maintained on board a ship carrying timber deck cargo.

Personnel Protection And Safety Devices

During the course of the voyage, if there is no convenient passage for the crew on or below the deck of the ship giving safe means of access from the accommodation to all parts used in the necessary working of the ship, guard

lines or rails, not more than 330 mm apart vertically, should be provided on each side of the deck cargo to a height of at least 1 m above the cargo. In addition, a lifeline, preferably wire rope, set up taut with a tightening device should be provided as near as practicable to the centreline of the ship. The stanchion supports to all guard rails or lifelines should be spaced so as to prevent undue sagging. Where the cargo is uneven, a safe walking surface of not less than 600 mm in width should be fitted over the cargo and effectively secured beneath, or adjacent to, the lifeline.

Where uprights are not fitted, a walkway of substantial construction should be provided having an even walking surface and consisting of two fore and aft sets of guard lines or rails about 1 m apart, each having a minimum of three courses of guard lines or rails to a height of not less than 1 m above the walking surface. Such guard lines or rails should be supported by rigid stanchions spaced not more than 3 m apart and lines should be set up taut by tightening device.

As an alternative a lifeline, preferably wire rope may be erected above the timber deck cargo such that a crewmember equipped with a fall protection system can hook onto and work about the timber deck cargo. The lifeline should be:

.1 erected about 2 m above the timber deck cargo as near as practicable to the centreline of the ship;

.2 stretched sufficiently taut with a tightening device to support a fallen crewmember without collapse or failure.

Properly constructed ladders, steps or ramps fitted with guard lines or handrails should be provided from the top of the cargo to the deck, and in

other cases where the cargo is stepped, in order to provide reasonable access.

Action To Be Taken During The Voyage

Tightening of lashings

It is of paramount importance that all lashings be carefully examined and tightened at the beginning of the voyage as the vibration and working of the ship will cause the cargo to settle and compact. They should be further examined at regular intervals during the voyage and tightened as necessary.

Entries of all examinations and adjustments to lashings should be made in the ship’s logbook.

Container Cargo 

 

Sea Containers were invented in the mid 1950s by Malcolm McLean, a North

Carolina trucking owner who grew tired of wasting his trucking company’s

time with trucks standing idle in line as ships were unloaded bit by bit by

dockworkers. 

McLean developed sealed truck trailers and the concept of loading and unloading the trailer interiors only at the points of origin and destination. 

The first ship modified to accept these “containers” on deck, sailed with 58 of them from New York to Houston in April 1956. This was the start of McLean’s company, the Sea-Land Corporation. 

The Matson Line (Hawaii) put the first fully containerized ship into service in 1960. 

The International Standards Organization (ISO) first established container standards in 1961.  The ISO standard is not prescriptive and instead simply stipulates tests that the containers must pass.

Modern container ships have only one problem – when the ship arrives in port, the object is to unload the containers quickly to get them on to their final destination and to get the container ships back out to sea fully loaded heading for the next port. 

To accomplish this, container ships are equipped with steel skeletons called “cell guides”.

A special lifting fixture is used with remote actuators, which engage the corner blocks on the top of the container. 

A recent survey indicates that port crane operators can execute full crane cycles to remove and position containers at rates of between 30 and 60 boxes per hour.

 

Containers come in two basic sizes – 20 Footer and 40 Footer and are commonly known as TEU (Twenty Equivalent Units) and FEU (Forty Equivalent Units).

The external body of the container is made of corrugated sheet metal and is not capable of taking any load. The four corners have shoes and are strengthened to take in load.

The inside bottom has a wooden ceiling. There are weather-insulted vents provided to facilitate venting.

The weights marked on the containers are TARE weight and LADEN weight. TARE weight is the weight of the empty container and is usually 2200KGS for a TEU, while the LADEN weight may be anything from 20000KGS to 32000KGS (strengthened steel construction).

The container shoes fitted at the corners are hollow with 5 oval slots to

facilitate the fitting of container fittings as well as for lifting the container –

either by using conventional wire slings or by spreaders.

Since the containers are concentrated weights the loading of the same require special heavy dunnaging to spread the load evenly over the deck – if carried as deck cargo on conventional general cargo ships.

However the carriage of containers are primarily on container ships or on ships, which have been built to take in general cargo as well as containers to a limited extent.

Lashing of containers on purpose ships are supplied from reputed lashing makers and have been tested for the loads they are to lash. Various fittings are used and all of these are generally carried on board.

                    

Base stacker                             Twist Lock                                           Double Stacker

 

               

Corner Eye Pad                                                Side Stack Thrust                                 Bridge Fitting

        

Twist Lock                               Rod Lashing Bar                                               Spacer Stacker

A spacer stacker is used where there is a difference between adjacent containers as loaded in their heights, one being the 8ft and the other 8.5FT.

On normal ships where these fittings may not be available wire ropes are used however the number of ropes to be used would be decided by the weight of the container.

On GC ships with no provision for built in shoes only single height loads are carried.

However on container ships the hold stacks may extend to 7 high and on hatch top/ deck to 5 high.

The hold and the deck/ hatch top being strengthened.

The lashings to be done are specified in the container-lashing manual supplied to the ship from the building yard. This is not to be reduced since the stresses have been calculated and the number of lashings incorporated.

The containers are loaded onto a container ship in a specified manner. The ship is divided into BAYS or ROWS. Looking from the side the bays are marked from forward to aft.

The containers are stacked in tiers and are in general called the stacks.

This way ensures that any container can be located very easily – knowing the bay number and the row number isolates the location and the stack height give the exact position of the container.

On container ships the containers are lowered onto slots inside the holds, the holds bottom is provided with sunken shoes, twist locks/ stackers are fitted onto these and the container is lowered onto them.

Cell Guides on Deck – Open hatch concept:

Some containers are designed to carry refrigerated cargo, these special containers have their own cooling plant in built on one end of the container, and all that is required for the ship to provide is a power point for the electricity. The containers come with their own recording device and card, the ships officers has to renew the card on the expiry of the same, and is to see that the cooling plant does not stop functioning, manuals are provided whereby ships staff can do some minor repairs to the plant.

Today a variety of cargo which previously was thought could only be loaded onto a general cargo ship, is transported on container ships. An example is a tank, thus small parcels of liquid is carried on container ships.

Lashing of containers is very important since a typical container ship has a low GM(F), consequently the ship rolls quite a bit and the stresses developed by the cargo swaying is liable to break the lashings and put the containers into the sea.

             

All lashings are to be done following the ships lashing manual. In general the

following is a typical lashing system, others may also be accepted if

permitted by the manual.

The planning of loading of a container ship is normally undertaken ashore, but the officer in charge of the watch should keep an eye on the loading to detect errors in stowage which may occur. A particular watch should be kept for containers with dangerous goods placards to see that their stowage satisfies segregation requirements as laid down in the IMDG code.

Other things to watch for are that container marked for underdeck stowage do not end up on deck – this is serious since the container may be for second

port by rotation, also the heavier containers are generally loaded underdeck to increase the GM. Thus in addition to a loss of GM the ship would also have a mess up at the disport.

Refrigerated containers should be loaded where they can be connected to the ship’s power supply and the duty officer is to ensure the same. While loading a slight slackening of watch can become a liability since the gantries load very fast and to unload or to shift is expensive and time consuming – even if the fault actually is of the port.

Sometimes containers are loaded which due to the nature of the contents have to be overstowed, in this case the container is loaded and the container is then blocked off so that there would be no chance of any pilferage – such containers may carry – currency/ coins, drugs, and mail or other high value cargo.

Oil Tanker 

 

A tanker is a specialized ship intended for the carriage of bulk liquid cargo.

An Oil tanker again is further divided into 2 basic types, namely Crude Oil

Tanker and Product Oil Tanker.

For both of the above the cargo of oil is carried within the tanks similar to the holds of other ships, the difference being that the bulkheads are extra strengthened to take in the load, and the hatch or rather the tank openings are very small, the sole purpose of having them is for Man Entry and for small repair work in the dry docks.

The cargo of oil is loaded on to the ships tanks by pipelines, which are fixed on the ship (permanent structure), the shore pipelines are connected to the ships pipelines at the manifold on either side of the ship. Note that some special ships also have manifolds at the bow and at the stern.

The shore pipelines may be connected using flexible steel rimmed rubber hoses (small ports/ Ship to ship transfers/ SBM) – the flexible come in small lengths are connected to each other to make them long pieces.

The shore pipelines may also be connected with rigid loading arms – also called ‘chiksons’, which are remotely controlled and take in the roll of the ship to a certain extent but the fore and aft movement of the ship has to be kept to a minimum.

The combined pipeline system of the shore and the ship deliver the oil to the cargo oil tanks directly via the drop lines. These are as the name suggests pipelines, which drop to the bottom of the tanks vertically from the pipeline on deck – thus bypassing the pump room.

There are various cross- over valves, which are opened in order to load a group of tanks.

The shore system starts to pump/ delivers by gravity (some Persian Gulf ports) at a slow rate, so that any leakages can be detected and to check whether the right tank is receiving the oil or not, once the shore and the shipside are satisfied the pumping – loading of the cargo is increased. In case of any subsequent leakages that are detected the ship valves should not be shut abruptly, rather the shore has to be informed first and then only the ship valves are to shut, this to prevent pressure surge from bursting the pipelines.

To prevent this surge from affecting the pipelines the cargo valves have set times at which they close – this depends on the size of the valves – typically a 550mm valve would shut at about 24 seconds, whereas a 250mm valve would shut at 6-8 seconds.

After the ship completes her loading the stage is set for the unloading or discharging operation.

While loading the cargo had by passed the pump room, now however the cargo from the tanks is allowed to flow to the pump room through the bottom pipelines. Just within the pumproom and at the pumproom bulkhead are situated isolation valves known as ‘Bulkhead Master valves’, by opening the valves the oil is led to the pump suction valve and on opening that the oil flows to the centrifugal pumps. Turbines, which are situated in the Engine Room, commonly drive these pumps; the shaft penetrates the ER bulkhead and drives the pump situated at the bottom of the pumproom.

The pump accelerates the flow of the oil into the discharge pipeline and this oil is thus led on the deck pipelines and to the manifold from where it flow through the flexible pipeline or the hard loading arm to the shore pipeline system.

The Pump Room

This is a cofferdam kind of space – in fact it is accepted as a cofferdam, which begins on main deck and ends at the keel.

It may have more than 2 decks, however these decks are not normally solid decks but are partial decks made of expanded metal, so you are able to see right to the bottom.

There would be a companionway leading from the top to the next deck and so on right to the bottom.

At the lowermost deck are situated the Cargo Oil Pumps (COP’s). The numbers of pumps vary in number – for crude oil tankers it is normal to have 4 pumps, three being used at any one time.

For product oil tankers the number of pumps depend on the number of grade of oil that the ship is capable of carrying.

So if the ship can carry 4 grades of oil then she would be having 4 pumps.

Once the gravity flow to the COP’s is not possible the stripped pumps are started, these pumps are of the reciprocating type and have great capacity to create partial vacuum to suck out the remaining oil from the tanks. Again on a product oil tanker the number of stripped pumps would be equal to the number of grades of oil that it can carry.

Earlier on Crude oil carrier there would be stripper pumps of the reciprocating type however today largely eductors are used to remove the remaining oil from the tank. Generally 2 eductors are provided on each crude oil tanker. However 1 stripper pump is always provided to strip the cargo lines of any residual oil and to pump the same to the shore system.

The pumproom is a hazardous area as such the light fittings are gas tight and only tanker safety torches are used. The ventilation system is of the exhaust type and has intakes from all the levels with the intakes being fitted with closing devices so that if required only a certain level can be evacuated.

Hydrocarbon gases being heavier than air tend to settle at the bottom of the pumproom as such the main exhaust are always from the bottom level.

The pumproom lighting is devised in such a way that the lights do not come on unless the ventilation has been started and is kept on for 15 minutes.

AT the top of the pumproom a harness and lifting arrangement is provided to lift out a person from the lowermost deck, for this reason a clear passage is left vertically from the top to the bottom of the pumproom.

Fire man’s outfit are also placed at the top of the pumproom, the pumproom may have different types of fixed fire fighting appliances such as total flooding by CO2 or by foam applicators fitted in the bilges (below the floor plates under the lowermost deck).

Bilge alarms are fitted which give alarms when the bilges are filled – a high level and a low level alarm is fitted which gives indications in the Engine room as well as in the Cargo Control room.

Picture shows the main deck layout of a Product tanker (capable of carrying 4 grades of oil):

The same tanker – with the tank layout.

And part of the pump room layout of the same tanker.

The above shows the location of the drop valves; drop lines, line master, bulkhead master and the bottom lines.

Cargo Oil Pumps (COP)

A centrifugal pump, in the pumproom bottom platform. The dark green pipeline is the discharge line. The pump consists of an impeller which rotates within the casing. Due to this rotation which is generally about 1000 – 1700 rpm the oil is speeded up and this increase in velocity causes the oil to flow out at a great pressure. These pumps are capable of delivering a very high rate of discharge (up to 4000 m3/hr). With this type of pump the level of oil has to be above the pump – as such the pump is situated at the bottom of the pump room.

Another detail of the same centrifugal pump.

The earlier centrifugal pump situated in the pumproom is driven by a shaft which is connected to the steam turbine – situated in the ER. The shaft passes from the ER to the pumproom through the pumproom bulkhead via a gas and oil tight gasket.

The turbines are driven by superheated steam from the boiler in the ER.

Positive displacement pumps such as the reciprocating pump work on the principle of a hand pump – the movement of the piston creates a vacuum which sucks out the fluid. However the size of the pump is dependent on the size of the piston and the length of the strokes so for discharging at a high rate is practically impossible. In general these pumps are used to discharge small quantities of oil such as the strippings – the balance that the centrifugal pump cannot discharge due to the oil going below the level of the pump. The pump is used today on crude tankers to strip out the pipelines after discharging and then collecting these line content (small) and then pumping them to shore.

Eductors

Eductors work on the principles of Bernoulli’s Principle.

A driving fluid is pumped down the main line, with very high velocity, through a constriction, and past a relatively smaller opening, thus creating a vacuum.

When eductors are used for clean ballast, the driving fluid is seawater.

When used for stripping crude oil, the driving fluid is the cargo itself- delivered by means of a bypass from one of the main cargo pumps.

When used for stripping tank washings, the driving fluid is from the secondary slop tank and then re-circulated back to the primary slop tank. In the latter case the driving fluid is either crude oil or seawater, depending on the tank cleaning method.

 Eductors are simple and rugged, have no moving parts, and do not become air locked like other type of pumps. They are widely used on tankers of all types and sizes.

 

Tank layout of a crude oil tanker:

The Pipeline system:

Pipeline systems on tankers differ in their degree of sophistication, depending on employment of the tanker. 

ULCC’s and VLCC’s have relatively simple pipeline systems usually the direct line system.

Some product (parcel) tankers may have very sophisticated piping systems. This could be the ring main system or in case of a chemical product tanker it could mean an individual pipeline and an individual pump for every tank on board.

Basically there are three systems of pipelines found on tankers, and the fourth system being the free flow system found on large crude carriers

Ring Main System

Direct line system

Single line to Single tank system (Chemical/Product ship)

Free Flow system

Ring Main System:

It is generally of a square or circular layout.

It is used mostly on product tankers, as segregation of cargo is required.

Though the system is expensive, as more piping, and extra number valves are used.

However if the vessel is carrying many grades of cargo, the advantages compensate for the extra cost of the original outlay.

Direct Line System:

This system is mainly found on crude oil carriers where up to 3 grades of cargo can be carried as most of the direct pipeline systems is fitted with three direct lines.

This system is cheaper to construct. The disadvantages over the ring main system, is that line washing is more difficult, the system has fewer valves which make pipeline leaks difficult to control, as the system lacks versatility there is problem with line and valve segregation.

This system provides the vessel to carry as many grades as there are tanks.

The disadvantage is the cost factor having a multitude of pumps on board.        

Free flow Tanker:

This system is usually found on large crude carriers, where the cargo piping is not used for the discharge of cargo.

Instead, gate valves are provided on the bulkheads of the tanks which when opened; allow the oil to flow freely in the aft most tank and into the COP.

The advantages of this system are primarily the cost factor, it allows for fast drainage and efficient means of pumping the cargo tanks. Disadvantages are of single crude being shipped.

Independent System:

This layout is not very common in the tanker trade.

This system is quite normal on chemical ships.

There are some Product Tankers that have this system fitted on the ships.

This is a single line servicing an individual tank through an independent pump that could be either a submersible pump or a deep well pump.

Enclosed Space Entry

An enclosed space is one with restricted access that is not subject to continuous ventilation and in which the atmosphere may be hazardous due to the presence of hydrocarbon gas, toxic gases, inert gas or oxygen deficiency. This definition includes cargo tanks, ballast tanks, fuel tanks, water tanks, lubricating oil tanks, slop and waste oil tanks, sewage tanks, cofferdams, duct keels, void spaces and trunkings, pipelines or fittings connected to any of these. It also includes inert gas scrubbers and water seals and any other item of machinery or equipment that is not routinely ventilated and entered, such as boilers and main engine crankcases.

Many of the fatalities in enclosed spaces on oil tankers have resulted from entering the space without proper supervision or adherence to agreed procedures. In almost every case the fatality would have been avoided if the simple guidance in this chapter had been followed. The rapid rescue of personnel who have collapsed in an enclosed space presents particular risk. It is a human reaction to go to the aid of a colleague in difficulties, but far too many additional and unnecessary deaths have occurred from impulsive and ill-prepared rescue attempts.

Respiratory hazards from a number of sources could be present in an enclosed space. These could include one or more of the following:

Respiratory contaminants associated with organic vapours including those from aromatic hydrocarbons, benzene, toluene, etc.; gases such as hydrogen sulphide; residues from inert gas and particulates such as those from asbestos, welding operations and paint mists.

Oxygen deficiency caused by, for example, oxidation (rusting) of bare steel surfaces, the presence of inert gas or microbial activity.

Hydrocarbon Vapours

During the carriage and after the discharge of hydrocarbons, the presence of hydrocarbon vapour should always be suspected in enclosed spaces for the following reasons:

Cargo may have leaked into compartments, including pumprooms, cofferdams, permanent ballast tanks and tanks adjacent to those that have carried cargo.

Cargo residues may remain on the internal surfaces of tanks, even after cleaning and ventilation.

Sludge and scale in a tank which has been declared gas free may give off further hydrocarbon vapour if disturbed or subjected to a rise in temperature.

Residues may remain in cargo or ballast pipelines and pumps.

The presence of gas should also be suspected in empty tanks or compartments if non-volatile cargoes have been loaded into non-gas free tanks or if there is a common ventilation system which could allow the free passage of vapours from one tank to another.

Oxygen Deficiency

Lack of oxygen should always be suspected in all enclosed spaces, particularly if they have contained water, have been subjected to damp or humid conditions, have contained inert gas or are adjacent to, or connected with, other inerted tanks.

Other Atmospheric Hazards

These include toxic contaminants such as benzene or hydrogen sulphide, which could remain in the space as residues from previous cargoes.

ATMOSPHERE TESTS PRIOR TO ENTRY

General

Any decision to enter an enclosed space should only be taken after the

atmosphere within the space has been comprehensively tested from outside

the space with test equipment that has recently been calibrated and checked

for correct operation.

It is essential that all atmosphere testing equipment used is:

Suitable for the test required;

Of an approved type;

Correctly maintained;

Frequently checked against standard samples.

A record should be kept of all maintenance work and calibration tests carried out and of the period of their validity. Testing should only be carried out by personnel who have been trained in the use of the equipment and who are competent to interpret the results correctly.

Care should be taken to obtain a representative cross-section of the compartment by sampling at several depths and through as many deck openings as practicable. When tests are being carried out from deck level, ventilation should be stopped and a minimum period of about 10 minutes should be allowed to elapse before readings are taken.

Even when tests have shown a tank or compartment to be safe for entry, pockets of gas should always be suspected. Hence, when descending to the lower part of a tank or compartment, further atmosphere tests should be made. Regeneration of hydrocarbon gas should always be considered possible, even after loose scale has been removed. The use of personal detectors capable of continuously monitoring the oxygen content of the atmosphere, the presence of hydrocarbon vapour and, if appropriate, toxic vapour is strongly recommended. These instruments will detect any deterioration in the quality of the atmosphere and can provide an audible alarm to warn of the change in conditions.

While personnel remain in a tank or compartment, ventilation should be continuous and frequent atmosphere tests should be undertaken. In particular, tests should always be made before each daily commencement of work or after any interruption or break in the work.

Sufficient samples should be drawn to ensure that the resulting readings are representative of the condition of the entire space.

Hydrocarbon Vapours

To be considered safe for entry, whether for inspection, cold work or hot work, a reading of not more than 1% LFL must be obtained on suitable monitoring equipment.

Benzene

Checks for benzene vapour should be made prior to entering any compartment in which a cargo that may have contained benzene has recently been carried. Entry should not be permitted without appropriate personal protective equipment if statutory or recommended Permissible

Exposure Limits (PEL’s) are likely to be exceeded. Tests for benzene vapours can only be undertaken using appropriate detector equipment, such as that utilizing detector tubes. (Benzene causes cancer, and has a delayed action which may be up to 20years)

Detector equipment should be provided on board all vessels likely to carry cargoes in which benzene may be present.

Hydrogen Sulphide

Although a tank which has contained sour crude or sour products will contain hydrogen sulphide, general practice and experience indicates that, if the tank is thoroughly washed, the hydrogen sulphide should be eliminated. However, the atmosphere should be checked for hydrogen sulphide content prior to entry and entry should be prohibited in the event of any hydrogen sulphide being detected. Hydrogen sulphide may also be encountered in pumprooms and appropriate precautions should therefore be taken.

Oxygen Deficiency

Before initial entry is allowed into any enclosed space, which is not in daily use, the atmosphere should be tested with an oxygen analyzer to check that the normal oxygen level in air of 21% by volume is present. This is of particular importance when considering entry into any space, tank or compartment that has previously been inerted.

Generally nearly all substances have been assigned Permissible Exposure Limits (PEL) and /or Threshold Limit Values (TLVs). The term Threshold Limit Value (TLV) is often expressed as a time weighted Average (TWA).  The use of the term Permissible Exposure Limit refers to the maximum exposure to a toxic substance that is allowed by an appropriate regulatory body.

The PEL is usually expressed as a Time Weighted Average, normally averaged over an eight-hour period.

Short Term Exposure Limit (STEL), is normally expressed as a maximum airborne concentration averaged over a 15-minute period.

The values are expressed as parts per million (PPM) by volume of gas in air. Toxicity can be greatly influenced by the presence of some minor components such as aromatic hydrocarbons (e.g. benzene) and hydrogen sulphide. A TLV of 300PPM, corresponding to about 2%LEL, is established for gasoline vapours.

Entry Procedures

General

A responsible officer prior to personnel entering an enclosed space should issue an entry permit. An example of an Enclosed Space Entry Permit is provided in ISGOTT.

Suitable notices should be prominently displayed to inform personnel of the precautions to be taken when entering tanks or other enclosed spaces and of any restrictions placed upon the work permitted therein.

The entry permit should be rendered invalid if ventilation of the space stops or if any of the conditions noted in the checklist change.

No one should enter any cargo tank, cofferdam, double bottom or other enclosed space unless an entry permit has been issued by a responsible officer who has ascertained immediately before entry that the atmosphere within the space is in all respects safe for entry. Before issuing an entry permit, the responsible officer should ensure that:

The appropriate atmosphere checks have been carried out, namely oxygen content is 21% by volume, hydrocarbon vapour concentration is not more than 1% LFL and no toxic or other contaminants are present.

Effective ventilation will be maintained continuously while the enclosed space is occupied.

Lifelines and harnesses are ready for immediate use at the entrance to the space.

Approved positive pressure breathing apparatus and resuscitation equipment are ready for use at the entrance to the space.

Where possible, a separate means of access is available for use as an alternative means of escape in an emergency.

A responsible member of the crew is in constant attendance outside the enclosed space in the immediate vicinity of the entrance and in direct contact with a responsible officer. The lines of communications for dealing with emergencies should be clearly established and understood by all concerned.

In the event of an emergency, under no circumstances should the attending crew member enter the tank before help has arrived and the situation has been evaluated to ensure the safety of those entering the tank to undertake rescue operations.

Regular atmosphere checks should be carried out all the time personnel are within the space and a full range of tests should be undertaken prior to re-entry into the tank after any break.

The use of personal detectors and carriage of emergency escape breathing apparatus are recommended.

Reference should be made to ISGOTT for additional guidance on entry into pumprooms.

 

Cargo Measurement 

Tank quantities are measured by noting the level of the fluid in the tank and then referring to the tank calibration tables and noting down the quantity specified against that level.

Thus we take the sounding of a tank – water and fuel on all type of ships and then follow the above practice. Note that prior to referring to the tables the tank level has to be corrected for error due to trim and list. These corrections are generally given in the tank calibration tables.

The above method though fine by all are turned upside down on a tanker. A tanker loads oil and it is not feasible to take a sounding every now and then – besides it is very messy. On tankers therefore instead of sounding the reverse is measured – that is the vacant level to reach the top of the tank – or the ullage.

Thus ullage tables are nothing but the sounding table reversed.

Note the following:

The maximum sounding of a tank is 24.35m the maximum ullage is also 24.35m.

When the sounding is 10m the ullage would be 24.35 – 10 = 14.35m

Thus when a tank is filling up the sounding increases, whereas the ullage reduces.

Once the liquid level is obtained the same is seen for the quantity (Volume) in the calibration book.

This is the Gross volume at Natural Temperature GVn (observed temperature being taken of the liquid at three levels and then averaged)

The sounding of any water which may be present in the tanks is now taken (some water is usually present in crude oil and also sometimes in product oil). The calibration tables are again referred and the volume of Free Water is obtained.

Thus the Net Volume at Natural (NVn) is found by subtracting the water form the GVn.

This NVn is now converted to a volume at 15˚C by looking up the correction in the ASTM tables – a factor is found, which converts the Volume at Natural temperature to a volume at 15˚C.

This would then be the Net volume of oil loaded.

The conversion is required since the loading temperature may be 40˚C whereas the temperature of the oil after a voyage of 30 days would drop to about 30˚C or so. Obviously the volume would then contract, so a standard temperature correction is done to 15˚C at both the load as well as the disport.

For weight calculations the volume at 15˚C is taken and this is multiplied by the density at 15˚C of the oil (actually a factor which is 0.0011 less than the density at 15˚C is used)

Bale Capacity:

This is the cubic capacity of a space when the breadth is taken from the inside of the cargo battens, the depth from the wooden ceiling to the underside of the deck beams and the length from the inside of the bulkhead stiffeners or sparring where fitted.

Grain Capacity:

This is the cubic capacity of a space when the lengths, breadths and the depths are taken right to the ships side plating. An allowance is usually made for the volume occupied by frames and beams.

Stowage Factor:

This is the volume occupied by unit weight of cargo. Usually expressed as cubic metres/ tonne. It does not take into account space, which may be lost due to broken stowage. However it obtained by multiplying the greatest length by the greatest breadth with the greatest height.

Example:

A bale of Hessian has the following dimensions: L – 1.2 M, B – 1.2 M and H – 1.5 M. The bale weighs 800 KGS.

The SF then would be obtained by:

Volume: L x B x H = 1.2 x 1.2 x 1.5 = 2.16 CBM

So, 2.16 CBM would weigh 0.8 MT

Or 1 MT of the cargo in bales would occupy 2.7 CBM

 

Broken Stowage:

The space between packages which remains unutilized. This is generally expressed as a percentage and the amount that is to be allowed varies with differ rent cargo and the shape of the hold. It is greatest when large cases have to be loaded in a n end hold, where the after end narrows down considerably.

BS is generally not given in any of the booking lists, but is a ship/ hold experience factor or a sister ship experience factor for that particular cargo. The most commonly accepted figure is about 10%, thus with a BS of 10% the available cargo space that may be loaded would be 90%.

Example: Given to load a quantity of light packaged cargo having a SF at 2.7 CBM/MT, the hold space (bale capacity) is given as 885 CBM. To find the amount of cargo that may be loaded in the hold.

The bale capacity is 885 CBM but since the BS is 10% the available space would be 885 x 90% Or 796.5 CBM Thus the cargo that can be loaded would be 796.5/ 2.7 = 295 MT (about).  However this BS that is given is for a proper stow as per earlier estimates, the final stow should also be a good stow or the BS that would be obtained on final completion would vary.

Thus on final completion of loading if the ‘tween deck was loaded with only 275 MT then the BS that was obtained would be:

Full capacity 885 CBM at 2.7 CBM/ MT could take in 885/ 2.7 = 328 MT

But it finally took in only 275 MT thus had a shortfall was 53 MT which was due to BS.

Thus,

328 MT – 275 MT = 53

And 53  / 328 = 0.16

Expressed as a percentage = 16% was lost due to BS instead of the earlier estimated figure of 10%.

Example-101

Given to load No. 1 Lower Hold

Bale capacity – 962 m3

Max Height – 11.945m

Permissible Load – 9.2 t/ m2

Forward Breadth – 4.5m

After Breadth – 11.5m

Mean Breadth – 8m

Length – 10.5m

 

Area of the hold – Length x Mean Breadth

A = 11 x 8 = 88m2

Permissible Load density – 9.2 t/m2

Therefore the load if evenly spread all over the hold would enable the hold to be loaded with:

88 x 9.2 = 809.6 MT

Example-102

Given to load No. 1 Lower Hold

Bale capacity – 962 m3

Max Height – 11.945m

Permissible Load – 9.2 t/ m2

Forward Breadth – 4.5m

After Breadth – 11.5m

Mean Breadth – 8m

Length – 10.5m

Cargo – SF 2.7 m3/t

Volume – 962 m3

Cargo can load – Volume/ SF

Cargo to load – 962/ 2.7

Cargo to load – 356 MT

 

Example-103

Given to load No. 1 Lower Hold

Bale capacity – 962 m3

Max Height – 11.945m

Permissible Load – 9.2 t/ m2

Forward Breadth – 4.5m

After Breadth – 11.5m

Mean Breadth – 8m

Length – 10.5m

Cargo – 150 MT, SF 2.7 m3/t to load only in after half of the hatch space

After breadth – 11.5m

Mid Breadth – 8m

Mean breadth – 9.75m

½ Length – 5.25m

Area of ½ hold as above – 51.2 m2

Volume of above – 611 m3

Max permissible load on 51.2 m2 – 9.2 x 51.2 = 471 MT

Since the cargo has a SF of 2.7 m3/t the volume occupied by the cargo would be:

Volume/ SF

611/ 2.7 = 226 MT

So the after half of the hold would take in 226 MT of the cargo and would remain within the permissible load density.

Let us now fill up the forward half of the hold with a cargo having a SF of 0.8 m3/t (heavy cargo)

Cargo – ?? MT, SF 0.8 m3/t to load in forward half of the hatch space

After breadth – 4.5m

Mid Breadth – 8m

Mean breadth – 6.25m

½ Length – 5.25m

Area of ½ hold as above – 32.8 m2

Volume of above – 392 m3

Permissible load would be: 32.8 m2 x 9.2 (SF) = 302 MT

Cargo that could be loaded as per SF – Volume/ SF = 392/ 0.8 = 490 MT

But the permissible load is – 302 MT, so the cargo could not be loaded right up to the top of the hold. So there would be a height restriction.

First we find the Volume as required for the permissible load of 302 MT

Load 302 = Volume/ 0.8

Or Volume = 302 x 0.8 = 242 m3

Since we know the area as 32.8 m2 we can find the height,

Volume/ Area or 242/ 32.8 = 7.4 m

Thus the cargo of 302 MT could be loaded only up to a height of 7.4m.

Cargo Handling Safety 

Safety while working with cargo gear

Derricks are long hollow steel booms rotating on swivels (heel), they each have a part rope guy and a steel pendant which is used for heaving and positioning the derrick and also to keep the derrick in place. The rope is used in a tackle and can absorb sudden shocks, which come on the derrick while in operation. On the opposite side to the cargo being worked a preventer guy made of wire rope is fitted which is kept slightly slack than the rope guy, This enables the rope guy to stretch before any load comes on the preventer guy. This preventer is the last shock and strain absorber, if the preventer is weak or is damaged it can part with disastrous consequences. So maintaining the preventer and fixing it right is of utmost importance.

When the two derricks are used together such that one derrick is positioned just above the loading area on the jetty and the other is positioned above the un loading area within the hold, and the gynfall (load lifting) wires are joined together, the arrangement is called a UNION PURCHASE. This is the fastest method of working cargo, however the loads that this arrangement can lift are less than the individual SWL of the derrick. Additionally there is a risk of the angle subtended at the hook point between the two-gynfall wires going beyond 120degrees when the gynfall wires together act as a pulling force on the derricks laterally and can part the rope guys and or the preventer wire.

Thus while the Union Purchase may be the fastest method it requires careful rigging of the derricks as well as experienced winch men to handle the

operation together with the duty officer keeping an alert watch on the working of the same.

Cargo blocks are maintained during the voyage, but due to various reasons especially with bush bearings sheaves, the bearing may burn out. Prior breakdown however the block would give an indication by a shrill metallic sound, the crew and duty officer on deck is to be alert on deck and the moment a noise is heard the cargo work is to be stopped and the cause investigated.

After each shift of cargo handling – when the stevedores take a break all the cargo gear is to be examined for any wear and tear, if required the defective items are to be replaced. If new blocks are being put to use, they should be greased before fitting them. The test certificates and the cargo-rigging plan should be checked to see that the correct item is being fitted. Often a cargo

block breaks down and on examining it is seen that it had a SWL 5T marked on it. Instantly a 5T block is brought from the store and fitted, it could be that the block that had been fitted earlier was of a lesser SWL – so it is always better to check the rigging plan.

The handling of the cargo gear also needs to be supervised and any extreme rough handling should be stopped. Where the gyn fall wire rubs against the hatch coaming or gunwale suitable padding should be place.

The derricks should be properly rigged and the preventer wire should, if it has been rigged properly, stretch when the load is in between the two derricks (in case of union purchase). With no load the preventer should be with some slack.

The cargo hook should have a locking clip to prevent the sling from slipping out of the hook.

Cargo handling areas should be cordoned off so that no person is found walking or standing under a cargo load. Free passage may be used of the non-working side of the cargo hatch.

A helmet is no safety for a load if it falls – helmets are satisfactory if some loose small objects fall.

For heavy individual loads a swinging derrick is often used either a single derrick is used where the guy ropes are removed and other winch wires (also called steam guys) are used to control the movement of the derrick.

A number of other types of rigging have over the years been tried out some with great success and some with little.

Jumbo derricks were derricks attached to a Mast and could lift as the name suggests heavy loads, the forward Jumbo derrick was generally for extra

heavy loads while the aft derrick was for slightly lesser loads. In preparing for operation the Jumbo derricks required four winches – 1 for topping the derrick, one for lifting the load and two for swinging the derrick. As such prior using the Jumbo derrick was rigged and the lashings were then removed. The rigging entailed that four light derricks were inoperable since their winches were requisitioned, so efficient planning on the part of the chief officer was required.

Stulken derricks had a single boom but the rigging was such that a single operator could control the movement of the derrick, another advantage was that these derricks could service two adjacent holds by being capable of being plumbed for either hold.

Velle derricks (with Thomson rig) were also very popular for ships, which often loaded heavy loads such as containers; in this the control again was unified into a single man operation.

The above derricks were however very difficult to rig if the wire had to be changed, and often the crew would spend an entire day rigging one derrick.

Cargo cranes are used on many ships and especially on bulk cargo carriers. These may be light cranes for general cargo ships or heavy-duty cranes for lifting huge grabs or containers.

Ships, which have slots for containers but also load general cargo, are often fitted with cranes with SWL up to 40 tonnes. If a single crane is incapable of being used to lift such heavy containers then two cranes are ‘twinned’ to handle the load. The control is unified and both the cranes work in tandem.

Hatch Covers

Hatch covers especially the Macgregor rolling hath covers should be opened by a responsible person and after opening the hatch covers should be locked to prevent their rolling and closing on their own due to excessive trim.

Partially opening of hatch covers should be avoided unless there is a means of locking them into place.

Prior opening a hatch cover the eccentric wheels should be examined to see whether any have not been made upright for opening. All loose gear on top of the hatch cover should be removed. Under no circumstances should a hatch cover be opened with a load on it. Also the hatch cover recess should be physically checked to see that not obstruction is present and that no stevedore is napping in the recess.

Similarly a hatch cover should not be closed with load on it and any deck cargo loaded onto hatch cover should be done only after the hatch cover has be battened down (eccentric wheels turned down, cleats and wedges locked.

Prior closing it should also be ensured that the track way is clear of all ropes, portable light wires and any other obstruction and that the locking has been removed.

Tween deck hatch covers once they are opened are to be fenced off, generally stanchions (Height – 1.2m) are provided which have to be rigged and the wire/ chains fitted. Nobody is to be allowed to work unless these are rigged.

Cargo Lighting

Portable lights are required to be rigged in holds where there is no provision for fixed lighting system.

These lights are commonly called cargo cluster lights and have 4 or more light bulbs fixed to a common pan shaped metal holder. A wire mesh covers the front of the ‘pan’ and the inside of the ‘pan’ is painted white to reflect the light.

The light is attached to a short length of small dia rope to facilitate its being fixed at the coaming.

The lights are to be checked in the afternoon and should be rigged and in place by sunset. The lights should be switched when there is adequate light in the hold in the morning and should be un-rigged and stored neatly.

They should be switched on only after the gangs come for the work and should be promptly switched off once all have left the hold. Often the cargo lights are not removed and the hatch covers are closed especially when closing due to rain. This is fraught with danger, for the lead is cut and the cluster light falls into the hold, the bulbs are hot and may cause a fire, also the cut lead has power in it and may cause a short circuit for the system or may electrocute any person close by.

An experienced crew should supervise the rigging of cargo lights since if loading jute or other flammable cargo the distance off from the cargo should be maintained. Also the shore people may tend to drag a light inside the hold to facilitate loading, this should be supervised.

The electric cord should never lift the lights rather the ropes attached for the same should be used.

In holds where fixed lighting is available the light fittings should be inspected prior switching on and then only the lights are to be switched on. Water

seepage especially during rain may cause short circuits and may eventually lead to fires.

All lights should be switched off when no longer required.

Cargo Handling Equipment 

Care and Maintenance of Steel Wire Rope

Wire ropes have a lubricant incorporated during manufacture.  This serves a

dual purpose; it provides corrosion protection and also minimises internal

friction.  The protection provided by this manufacturing lubricant is normally

adequate to prevent deterioration due, to corrosion during the early part of a

rope’s life.  However, the lubricant applied during manufacture must be

supplemented by lubrication in service.  This service lubricant is termed the

‘dressing’ the kind of dressing used and the frequency of application varies

with the type of rope and its usage.  Details of the maintenance of steel wire

rope carried, or fitted in, ships is laid down in the Maintenance Manual of the

Company or the Planned Maintenance Schedule (PMS) of the item.  Wire

hawsers should be stowed on reels under a fitted cover whenever

possible.  When being reeled in or otherwise stowed, the surface of a wire

hawser should be washed with fresh water to free it from salt, then dried

with cloths and lightly smeared with the appropriate lubricant.

Inspecting Steel Wire Rope

Steel wire ropes carried or fitted in ships must be inspected periodically in accordance with the PMS.  When inspecting, the indications described below should be sought:

Distortion of Strands:  This is the result of damage by kinking, crushing, serious crippling round a bad nip, or other mistreatment.  If likely to cause the strands to bear unequal stresses they must be considered as reducing the strength of the rope by 30%; and should they be sufficiently serious to cause the heart to protrude, the rope must be discarded.  A crushed rope may be restored to some extent by the careful use of a mallet.

Flattening of Some of the Outer Wires by Abrasion:  These flat’s are easily seen because the abrasion gives the flattened wires a bright and polished appearance, but they do not affect the strength of the rope unless they are very pronounced.  Flats, which extend to three-quarters of the diameter of the wires will reduce their cross-sections - and therefore their individual strengths - by 10%, and as only a limited number of wires will be affected the loss in strength of the whole rope will be very small. (These flats must not be confused with flattening of the whole rope, which indicates distortion of the strands and is therefore much more serious).

Broken Wires: These are usually the result of fatigue and wear, and mostly occur in crane wires.  It is generally accepted that a wire rope is coming to the end of its useful life when one wire of any strand breaks.  To deal with a broken wire, grip with a pair of pliers the broken end and bend the wire

backwards and forwards until the wire breaks inside the rope between the strands, where it can do no harm.  A rope should be discarded if more than 5% of its wires are broken in a length equal to 10 times the diameter of the rope; for example a 24mm diameter, 6X24 wire rope should be discarded if seven broken wires are found in a length of 240mm.  Because of the danger to handlers, berthing wires should be discarded if any broken wires are discovered.

Corrosion:

Wire rope can be corroded by:

The action of damp on the wires from which the gaivanising has worn off, if this occurs to the inner wires first it causes rust to fall out of the rope and is therefore easily detected;

The action of fumes and funnel gases, which attack the outside wires, the effect then becomes visible on inspection;

Contact with acid, which soaks into the heart and attacks the inside wires; this is not necessarily noticeable on the outside of the rope, and can be the cause of parting without warning.

Lack of lubrication is a frequent cause of corrosion.  When a wire rope is under tension it stretches and becomes thinner, and during this process the individual wires are compressed and friction is set up; the fibre heart and cores are also compressed, releasing oil to overcome the friction.  A wire rope of outwardly good appearance, but with a dry powdery heart or core, has -not been properly maintained and should be treated with caution.

Effect of Extreme Cold:

When subjected to extreme cold a wire rope may become brittle and lose its flexibility, and an apparently sound rope may part without warning.  The brittleness is not permanent and the rope will regain its resilience in a normal temperature, but the potential danger should be remembered when working wires in very cold climates.

Testing of Steel Wire Rope

The wire from which the rope is to be made is tested before manufacture of the rope to ensure it complies with the relevant Standards with regard to tensile strength, torsion and galvanising properties.  After manufacture of each production length of rope, test samples are cut from the finished rope and strand.  These samples are used for a tensile test to destruction, tests of preforming of the rope, and tests on a mixture of the individual wires with regard to diameter, tensile strength, torsion and quality of galvanising.  Each coil of wire is accompanied by a certificate of conformity and a test certificate showing the guaranteed minimum breaking strength of the wire. (WHEN NEW.)

General Remarks on Steel Wire Rope

How to Measure the Size of a Rope

The size of a wire rope is the diameter in millimetres of a true circle, which will just enclose all the strands.  Measure at each of three places at least 2m apart.  The average of these measurements is to be taken as the diameter of the rope.

Sheaves for Wire Rope

Size of Sheave Required for a Wire Rope Hoist. The diameter of sheave required for each type of six-strand wire rope supplied should be at least

twenty times the diameter of the wire.  The diameter of a sheave used for any wire rope will considerably affect the life of that rope.  As the rope bends round a sheave the strands and wires farthest from the centre of curvature move apart and those nearest the centre of curvature move closer together.  This results in the generation of considerable friction between these wires and strands, and the smaller the sheave the greater will be the friction.  Friction also increases rapidly with the speed at which the rope is moving.  While the rope is bent round a sheave the outer wires are also subjected to a marked additional stress, and the smaller the diameter of the sheave the greater will be the stress.  For these reasons the minimum diameters of sheaves recommended from practical experience for various types of ropes at speeds not exceeding 60m per minute are 20 times the diameters of the ropes.  For each increase in speed of 30m per minute, 5% must be added to these figures; this will give a rope a reasonable life, but it is emphasized that its life will be greatly increased if still larger sheaves are used.  Similarly, if a smaller sheave than that recommended has to be accepted it will shorten the life of the rope, and on no account should a sheave be used that is more than 20% smaller than that determined by reference to the above criteria.

Use of Correct Sheave:

 The life of a rope used for hoisting can also be considerably shortened by using the wrong type of sheave.  The groove in the sheave must fit and support the rope as it travels round the sheave, otherwise there will be increased internal friction and external wear.  Figure below shows a sheave with too wide a groove, which results in a flattening of the rope and considerable distortion and internal friction. 

Figure below shows a sheave with too narrow a groove, which results in the rope not being supported, the wires of the strands being subjected to considerable wear, and friction being set up between the rope and the sides of the groove. 

The groove of the correct sheave should be shaped in cross-section to the true arc of a circle for a distance equal to one-third of the circumference of the rope, and the radius of the groove should be between 5 and 10% greater than the specified radius of the rope.

Cargo Blocks

Rigging of cargo blocks:

Union Purchase – derricks with 2 sets of individual side guys.

Union Purchase – derricks with 1 set of individual side guys and a centre guy.

Rigging for a Gun Tackle:

Using one of a set of derricks to load heavy loads, this uses the gynfall wire of the other derrick as a steam (power) guy and also uses the gynfall wire of another derrick as the other steam guy.

The derrick head block is connected to a floating block and the gun tackle set up as shown below.

 

Working with Derricks:

While topping/ lowering derricks the following are to be ensured:

Both side guys are to be rigged and attended to.

As the derrick is being lowered or topped the guys are to be heaved up or slackened.

The gynfall wire is to be slackened when topping up the derrick

The person attending to the lock should be attentive and at the slightest doubt about the speed or range of topping/ lowering he has to release the lock. So that the derrick is prevented from having a free fall.

Lowering of the derrick should be within limits as set out in the derrick rigging plan

While parking the derrick, the control over the side guys should be especially good since with a slight swing the boom is liable to damage other structures.

The derricks should not be lowered or topped if the ship is rolling as this would make controlling the derrick very difficult.

The end rope of the controlling side guys should be held after a full turn on the rams horn and there should be adequate clear slack. In case of an emergency the next turns should be put on quickly

If a ram’s horn is not available then other suitable points may be used, however railing are not to be used.

Derricks are secured either on a horizontal crutch (light derricks) or vertically with clamping to the mast.

Prior to lowering the derrick the following are to be inspected and if any are found wanting they are to be made good:

The crutch post and the bracket at the base are to be inspected

The grommet attached to the eye pad (for the gynfall wire) is to be inspected

The crutch wood sheathing is to be checked if damaged then a canvas packing may be made in lieu

After the derrick is parked, the crutch clamp is to be fitted and the locking arrangement fixed. There should be no play.

The side guys are to be tightened and fixed on either side, the extra rope of the guys being neatly coiled onto pallets or slung on railings and tied as a whole – the rope should be covered by a canvas cover

The gynfall wire hook is to be hooked to the grommet and the wire tightened (just).

The topping wire should not have any weight, but neither should it be slack

The heel of the derrick should be covered with canvas and so should be the gynfall and the heel block

The preventer wire should be coiled and placed on a pallet

Types of Slings in common use:

Beside those mentioned there are various other slings in use.

Plate sling: Normally the hinges clamp hangs loose, but once fitted on to the plate and the wire pulled up, the clamps hold the plate very firmly.

Open rope sling: This is used for various types of delicate cargo. Not good for heavy weights.

Canvas sling: Used for lifting small bags of rice and other cereals, the canvas

is useful for collecting any spillage that may be caused.

 

Snotter: This is used for various cargos. It is the most versatile form of sling. Has been used even for container loading, by attaching hook/ shackles to one end and using for such snotters.

Pallet:

This is unitized cargo on a wooden pallet (the bottom double tier of wood). Such cargo may be handles using wore slings but the more safe and common is to use nylon straps or rope slings.

If the cargo is loaded on to the ship and the pallet retains the nylon strap then it is termed as pre-slung cargo. The strap is returned to the ship after discharging the cargo.

Hook Handling:

Bales are soft cargo and they liable to be damaged by hooks, which penetrate the surface and go deep inside.

Bales especially of hessian, bagged cargo and other such cargo are rendered useless if the hooks punch holes into them.

Such cargo have a label saying use no hooks.

However many port workers use the same hooks to handle these cargo

The preferred hooks for such cargoes are shown below.

These contain about 3 rows of small raised metal pieces that good at gripping but do not damage the cargo.

Some bagged cargo come with ‘ears’ protruding from the four corners of the bags, these ‘ears’ are material of the bag and facilitate the handling of the cargo.

Unitized cargo and Pre-slung cargo

Unitized cargo are cargo such as tea or bagged sugar/ asbestos which are placed on top of a wooden pallet and are strapped together into a unit.

The advantages of this is that the pallet (now referred to the whole) is easily moved and stored by forklifts.

Much manual labour is not required. These types of pallets may be stacked more than one high, though genially 2 high.

Ease of lashing and faster loading is the essential advantages. However a lot of broken stowage occurs if the hold dimensions are not square. Thus these type of cargo were unsuitable in old ships which had a tunnel in the after holds and the bilges were rounded.

Since these cargo came with their own wooden pallets the dunnaging cost was also saved.

After the development of unitized cargo, to speed up further the handling process the cargo pallets were pre-slung with nylon straps.

Thus a trailer arriving on the jetty had the pallets neatly arranged and with their own slings. All it took from the shore labour was for a person to hook on the slings. Once on board the slings were not returned but the pallets was stowed with the sling. At the discharging port the forklift brought the pallet top the hatch square and aging the pallet was lifted out with the same sling. On completion of discharge if no cargo was being loaded on the ship the slings were brought back on the ship. The slings were the property of the ship and a strict tally was maintained. The slings were made of nylon straps in various colours and were certified as to the SWL.

With the advent and popularization of containers pre-slung cargo system died out. Unitized cargo is still existent and containers are loaded with unitized cargo.

Cranes versus Derricks

Using various cargo gear for handling of cargo.

Until the early ‘80’s the primary gear was the derrick. A ship would have a set 0of derricks for each hatch, sometimes if the hatch was big the two sets of derricks. One for the fore part and the other for the after part. The advantages of the derricks is that the boom never moved after it was rigged into position. The only moving parts are the sheaves of the blocks and the wires. As such it was and still is the fastest means of discharging cargo.

The advantages of discharging with derricks are:

Very few moving parts

Time to discharge the least

Not much skill required to operate the derricks

Breakdown rate low

Easy to maintain and to repair on board

Spares are easily obtained from even small workshops

Spares are cheap

The disadvantages are:

Cannot discharge large and heavy packages

To be effective the derrick plumbing position has to be properly judged.

Has to be re-rigged every time the discharge area or loading square changes

Requires forklifts to feed the loading area

Cranes are used to handle heavy and large packages including grabs on bulk carriers.

The advantages of the cranes are:

Can discharge from 360˚ angle

Can handle cargo from anywhere in the hatch square

Depending on the SWL of the crane can handle very heavy packages

Sophisticated and has various safety cut outs to prevent damage and accident.

The disadvantages are:

Is slow

Requires skilled person to operate

With unskilled labour requires frequent resetting of the safety cut outs.

Maintenance difficult and time consuming

The good service provided by a crane is dependent on the maintenance

Repairs even more difficult and time consuming

Spares are to be ordered in advance from the manufacturer

Wires are of special construction and are very expensive.

Rigging other derricks:

Velle Derrick Rigging

 

 

The above is a Velle derrick. This type of derrick is a swinging derrick and is capable of lifting heavy weight and may be found on container-oriented vessels (GC as well as container cargo).

The rig is one of the most complicated. On a ship the crew has to be very well experienced to rig up this derrick. The length of the wire is also of special length and may be of 250 – 280 metres.

There are 3 winches in operation; the 2 extreme winches have separate barrels, which turn in the opposite direction. The extreme winches share 2 wires, 1 wire starts at 1 winch and ends on the other. The same is for the other wire.

The gynfall wire is on a single centre winch. The controls are usually joystick control – 1 for the swinging and the other for the lifting. Thus the extreme winches control the swinging as well as the topping/ lowering action and are controlled by a single control joystick.

This is a rare rigging plan and the author has taken great pains to personally draw it out while serving on a ship rigged with 22T Velle derricks.

Use of Forklifts:

The precautions prior lowering and using forklifts inside the holds:

The forklift should not have any oil leakages

The height of the hold should be considered while lowering a tall forklift

The weight of the forklift together with the cargo should not exceed the load density of the hold

The forklift should not be emitting profuse quantities of smoke

Adequate fire fighting arrangements should be inside the hold for any fire of the forklift

Jute and other flammable cargo should be kept away from any ingress of oil from any leaking forklift

The driver should not drive the forklift rashly

Adequate lighting should be ensured

Saw dust and sand should be kept stand by for any unforeseen oil leaks.

Cargo Care  

Inspection of Holds prior Loading:

All holds should be inspected prior commencing loading this may be done while the ship is enroute or just after completion of discharging and prior loading at the same port.

A thorough cleaning of the hold is undertaken; the bilges are cleaned and tried out with an amount of water. If required the hold is hosed down and the water pumped to holding tanks.

This ensures that there is no refuse lying within the holds and that the bilges after loading would if necessary be capable of being pumped out.

The bilges if with offensive smell have to be sweetened.

This is again a necessity to prevent any food cargo from being tainted.

All other lines in the hold are to be pressed up and checked for leaks. Air pipes and sounding pipes passing through the hold spaces are to be checked up with a head of water.

The above ensures that ingress of water into the hold is minimized.

The hold bottom has to be inspected for any dents in the plating.

Some DB’s may be dedicated for fuel oil/ ballast as such this would give a fair idea if the plates have set in or if their appears to be a deep indentation/

All spar dunnage at the ship sides are to be fitted and the frames at the sides have to be inspected.

This is done so that if bale cargo is loaded the shipside steel does not come in contact with the cargo.

The used lashing material has to be removed including all temporary eyes, which had been made.

And if this is not done then the same eyes may be inadvertently be used for new lashing – lashing wires are for one use only and the risk of parted lashing arises by using old lashings.

Use of Dunnage

There are basically a few reasons why dunnage is so necessary on general cargo ships while loading general cargo.

Of prime importance is to keep the cargo away from the steel bottom of the hold. The steel bottom condenses the moisture in the air and these droplets of moisture over a period of time can damage cargo. This is known as ship sweat. And only by dunnage can the cargo be safeguarded against this. Good ventilation certainly helps but some amount of sweat is ever present.

The second reason why dunnage is spread about on the holds is to bring about some amount of frictional resistance between the cargo and the steel bottom. Thus lashing becomes easier. Another factor is the dunnage helps in spreading the cargo weight evenly.

In the event of small ingress of water the dunnage helps in channeling the water into the bilge wells, if this were not prevented then any accidental ingress of water would be absorbed or retained in pools by the cargo.

If the hold bottom is dirty due to stain and hard coating of earlier cargo and hosing down is not possible then a double layer of dunnage would prevent the cargo in coming into contact with the stain.

In general holds are laid with double dunnage while tween decks are layered with single dunnage.

The size of the dunnage may vary but usually they are about 6” X 1” X 6 feet. These are laid about 6” to 10” apart, though the gaps may again vary depending upon the nature of the cargo. The bottom tier of the hold dunnaging may be laid in the fore and aft direction and the top tier in the athwart ship direction. At the aft of the hold a clearing of two feet is laid with the bottom tier in the athwart ship direction. This helps in the water/ condensation from trickling to aft and then subsequently finding the bilge well.

Tween deck dunnaging is of one tier – exceptionally may be two tiers and it really doesn’t make much difference if the dunnage is laid out in the fore and aft direction or in the athwart ship direction.

For heavy cargo where spreading the weight takes precedence over other hazards, the dunnage or timber used is generally 4” X 4” X 6 feet (they may be also of stouter variety).

These heavy timbers are laid out in the fore and aft direction in order that the load is spread on as many frame spaces as possible.

Dunnaging also forms a very important factor when ventilation is of primary concern especially when loading a consignment of Rice. Extra channels are created within the bagged cargo to allow good ventilation. Together with double dunnaging being provided between stacks of 4-6 bags. If this is not done then the cargo sweat that may be generated is not removed and condenses on the cargo itself allowing the cargo to rot.

Dunnage is used primarily for the protection of the cargo from sweat related damage and consequently it is used so that the cargo does not get too closely packed thereby obstructing to the flow of air.

Special cargoes use more dunnage where air channels have to be kept so that the airflow is not hampered. Rice is one such cargo.

Advantage of dunnaging is also from the fact that it spreads the weight of the cargo evenly all across the tank top or tween deck top, but this advantage is a side benefit, the main reason is protection from sweat. And to some extent from heat from the boiler spaces in the engine room.

Dunnage is thus primarily for the prevention of sweat damage to cargo.

The structure of the ship is made of steel, this steel being a good conductor of heat cools down faster than wood as such the temperature of the steel may fall below the dew point of the air within the compartment leading to sweat. However if this steel can be prevented from coming into contact with the cargo by a layer of wood, which being a poor conductor of heat does not cool down so drastically, then the effect of the sweat coming into contact with the cargo and thus damaging the same may be limited.

If despite precautions being taken, sweating does occur, the damage caused may be minimized by adequate dunnaging of the boundaries of the compartment.

The permanent dunnage of the ships side is known as SPAR Ceiling or CARGO BATTENS. It consists of timber about 150mm x 50mm fitted over the side frames.  It is usually fitted horizontally into cleats on the frames. There is a vertical distance of not more than 230mm between the battens. On some ships the spars are fitted vertically and this gives better protection to the cargo as well as it suffers less damage and is thus more long lasting. Spar ceiling may also be fitted on the bulkheads at the ends of the compartment; this is especially the case where the bulkhead is the engine room bulkhead.

The tank top should be covered with a double layer of dunnage.  The bottom layer is usually 100mm x 50mm or 150mm x 50mm spaced about 300mm apart and laid athwart ships to ensure free drainage to the bilges. If the ship has only bilge wells then it is preferable to lay the dunnage in the fore and aft direction.

The upper layer consists of 25mm boards about 150mm in width laid at right angles to the bottom layer, about 150mm - 300mm apart.

Occasionally burlap/Hessian is laid over the dunnage - this improves the appearance of the hold but restricts air circulation through the cargo,

A permanent wooden ceiling more than 65mm thick is often laid on the tank top in the square of the hatch; this is to protect the tank top and does not replace the dunnaging.

A similar arrangement of dunnage will be found in the tween decks, although double dunnaging is not so commonly found here.  Care should be taken to have a good layer of dunnage at the ship’s side over the stringer plate, as water tends to accumulate there.

Secondhand timber is frequently used for dunnage.  It should always be inspected to ensure that it is free of stains, odour, nails and large splinters. New timber also has its drawbacks; it should be free of resin and should not have a strong smell of new wood.

The top of the cargo is protected by a covering (especially under the stringer

plate) by matting, wood dunnage or some sort of waterproof paper, or plastic

sheets.

Single Fore and Aft dunnaging the most common dunnaging:

The second Layer

Contamination of Cargo

Cargoes -which taint easily, e.g. tea, flour, sugar, should be kept well away from strong smells.  If a pungent (strong smelling) cargo e.g. cloves, cinnamon has been carried previously, deodorizing of the compartment will be necessary.

Dirty Cargoes should never be carried in the same compartment as “clean” cargoes.

A very general classification for “dirty” cargoes could include paints and oils, steelwork, animal products other than foodstuffs.  Similarly a general classification of clean cargo could include food products and manufactured vegetable products e.g. clothing.  Naturally there will be exceptions to both of the above groups.

Reasons for a general inspection of holds

All holds should be inspected prior commencing loading this may be done while the ship is enroute or just after completion of discharging and prior loading at the same port.

A thorough cleaning of the hold is undertaken; the bilges are cleaned and tried out with an amount of water. If required the hold is hosed down and the water pumped to holding tanks.

This ensures that there is no refuse lying within the holds and that the bilges after loading would if necessary be capable of being pumped out.

The bilges if with offensive smell have to be sweetened.

This is again a necessity to prevent any food cargo from being tainted.

All other lines in the hold are to be pressed up and checked for leaks. Air pipes and sounding pipes passing through the hold spaces are to be checked up with a head of water.

The above ensures that ingress of water into the hold is minimized.

The hold bottom has to be inspected for any dents in the plating.

Some DB’s may be dedicated for fuel oil/ ballast as such this inspection would give a fair idea if the plates have set in or if their appears to be a deep indentation.

All spar dunnage at the ship sides are to be fitted and the frames at the sides have to be inspected.

This is done so that if bale cargo is loaded the shipside steel does not come in contact with the cargo.

The used lashing material has to be removed including all temporary eyes, which had been made.

And if this is not done then the same eyes may be inadvertently be used for new lashing - lashing wires are for one use only and the risk of parted lashing arises by using old lashings.

Bilge and Suction Wells

Bilges and bilge wells should be thoroughly cleaned prior loading any cargo and especially if the previous cargo was oil cakes or such other cargo.

Bilges should be cleaned, the suctions tried out and then the bilges should be sweetened with pine oil or such. The bilges should be finally dried.

Prior loading of cargo all bilge wells should be cleaned and then filled with water and the water then pumped out.

Timings for pumping out the water should be noted and compared with the pump efficiency.

While filling the bilge well the sounding as measured by the sounding rod should be checked against the actual as observed inside the bilge well.

The sounding pipe should be checked for any blockage.

The striker plate underneath the sounding pipe also should be checked for wear down.

Deep Tanks

Deep tanks are tanks on general cargo ships, which are accessible from the hold. The lines leading to such tanks are to be blanked off since a slight leakage in such lines can damage cargo in the holds. The man holes to these tanks also has to be ensured that they are water tight. If any liquid is loaded then the thermometer conduits should be checked for any leakage as well the heating coils have to be tested prior loading. The pumping out arrangement has to be tried out before hand.

Covering of Bilge Wells

These suction filters are very easily taken care of. Hessian is used to form a pad comprising of a double layer and this is wrapped around the loose filter covers of the drain wells. The pad should not be so thick that it would absorb water and prevent the water from draining into the wells.

For limber boards the same pads are nailed down between the adjacent boards. And they then serve the same purpose, that is prevent any debris from clogging up the suctions.

Care of Ballast Lines

This is very important, since the inadvertent ballasting of the deep tanks would damage cargo loaded in the deep tanks.

There are many instances of the above happening, bulk carriers of yesteryears often had a hold dedicated as a water ballast tank, in 1978 a new ship off the building yard in Gothenburg had not blanked off the ballast lines since the line had a double segregation. The vessel proceeded to load grain in a US port and on arriving at a UK port for discharging her cargo, it

was found that a substantial amount of cargo in the mentioned hold had become damaged due to leakage of water from the ballast lines.

Separation Of Cargo

Separation of cargo for the above cases is required to prevent claims arising due to short landing and later complications with port authorities and customs for cargo left behind on a ship for which duty is payable

There may be numerous ways of separating cargoes bound for different ports or for same port and different consignees. In general though not all are any hard and fast rule the principle is to ensure that cargoes destined for a particular port or consignee is delivered accordingly.

Failure to do this at the time of loading would create chaos at the discharging port, with short landings – residual cargo, since the excess cargo that would remain would not be permitted to be discharged in a subsequent port without creating more paperwork and expenditure. In fact cases have arisen where ships have been arrested for landing cargo not destined for that port – customs take a very strict view of this in many parts of the world.

Thus it is of paramount importance to ensure that cargoes are efficiently separated and marked so that to an un-initiated the cargo discharge may proceed smoothly.

Port markings may be made by different means for different cargoes, the following are some of the few:

Hessian separation strips, in various colours – used to encircle the parcel

Shoring, blocking and securing the later port cargo, since this would have to be done in any case at the discharging port.

Paper sheets

Lashing ropes with coloured strips of cloth wrapped around the joints-turnbuckles/ shackles/ bulldog clips.

Different cargo used as a separation between two similar cargoes.

Water based colours used as port marking or consignee marking – this method though is used more often for consignee marking.

Where bare steel cargo is loaded oil based paint is also sometimes used, since the others may not be suitable due to partial rusting of the plates as well that hessian strips are in-efficient for these cargoes.

Valuable Cargo

Valuable cargo such as Banknotes or mail earlier used to be carried on general cargo ships in special lockers. If such lockers were not available then some dedicated space, which could be effectively secured, was made available. Newer ships do not have such allotted spaces and today most cargoes of such nature is shipped in containers.

Personal effects are also shipped and unless stated as very valuable is loaded in ordinary holds and are quickly over stowed with other cargo. As long as the over stowage is incomplete the hold is strictly watched and the watchman is done away with once the cargo is over stowed and the entrance to the hold is locked.

All mail and personal effects are tallied on board – by shore staff as well by a ships staff, the results are then verified. In case of any dispute the authorities are informed before a general protest is made.

Ventilation

On general cargo ships one of the largest number of cargo claims is made for goods, which, have been damaged in transit.  Barring breakages and handling damage the most common damage is caused by sweat.

SWEAT is formed when the water vapour in the air condenses out into water droplets when the air is cooled below its dew point. 

The water droplets may be deposited onto the ship’s structure known as “ship’s sweat” or on to the cargo known as “cargo sweat”. 

Ship’s sweat may run down, and may also drip onto the cargo. 

Cargo sweat occurs when the cargo is cold and the incoming air is warm. Cargo sweat that is formed may be absorbed by the cargo or if steel may run down after rusting the cargo.

To avoid sweat and its effects it is imperative that wet and dry bulb temperatures of the air entering and the air contained in the cargo compartment are taken at frequent intervals (once a watch).

If the temperature of the outside air is less than the dew point of the air already in the compartment, sweating will occur.

This gives rise to ship sweat and is most usually found on voyages from warm places to colder places. Especially in winter, on voyages from Singapore to Northern China.

Similarly if the temperature of the air in the compartment (or the cargo) is lower than the dew point of the incoming air sweating will again occur.

This gives rise to cargo sweat and usually occurs on voyage from cold to warmer places. Especially in winter, on voyages from Northern China to Singapore.

If the latter of the foregoing conditions is encountered ventilation from the outside air should be stopped until more favourable conditions obtain.

It should be noted that indiscriminate ventilation often does more harm than no ventilation whatsoever.

It should also be noted that variation in the angles of the ventilators from the wind cause very different rates of airflow within the compartment.

The angle, which the ship’s course makes with the wind, also affects the flow of air.

In general the greatest airflow occurs when the lee ventilators are trimmed on the wind and the weather ventilators are trimmed away from the wind.

Showing air circulation with lee vents on the wind and weather vents off.

This is THROUGH VENTILATION.

If the dew point temperature of the air in the hold can be kept below the temperature of the ship’s structure (decks, sides and bulkheads) and the cargo, there will be no danger of sweat forming.

This condition cannot always be achieved without some means of mechanically circulating and drying the air in the hold. 

With mechanical ventilation baffle plates are fitted in the hold and tween deck ventilators, so that air can be prevented from the outside when conditions are unfavourable.  At these times the air in the hold is re-circulated and, if necessary, it can be dried by passing it through a de- humidifying unit.

It must be emphasized that the best results can only be obtained from these systems when air temperatures and dew points are carefully observed and the maker’s instructions followed implicitly.

The adequate ventilation of container cargoes poses many problems and experiments have been made with portable ventilation units fitted into the individual containers.  However, it would appear the most common practice is to give through ventilation for the container compartments and hope that the ventilator grilles on the side of the containers give the correct flow air over the contents.  It may be pointed out that vastly different types of cargo may be loaded in adjacent containers in the ‘cell’ stowage and in most cases the ship’s personnel are unaware of the contents of individual containers.

Refrigerated cargo

The cleanliness of cargo compartments for the transport of refrigerated foodstuffs is more important than for any other cargoes. Failure to clean properly can result in mould growth and rotting of fruit and vegetables. Spaces are swept down and all loose dirt removed. Any remaining residues of previous cargoes will have to be scraped or washed off. After cleaning, the spaces are sprayed with a mild disinfectant such as weak sodium hypochlorite solution, which also helps to remove odours. Alternatively, an ozoniser may be used for the same purpose, especially after the carriage of a strong-smelling cargo like oranges.

Holds and lockers are then cooled to carriage temperature. It is essential that any dunnage to be used is placed in the space before pre-cooling, since the use of warm dunnage could cause considerable damage. It is common practice to have holds and refrigerating machinery inspected by an independent surveyor to certify that the ship is in a fit condition for the carriage of the intended cargo.

The cargo should be inspected ashore by the ship’s officers before loading to see that it is in good condition and has been properly pre-cooled where that is required. A sample of the cargo should be thoroughly inspected for signs of mould or other damage and its temperature checked by inserting a steel-tipped thermometer into the product. A record of the inspection and temperatures recorded should be kept. Similar random inspections of the cargo should be made during the loading. Any damaged products or carcasses which have thawed should be rejected or loaded separately. They could cause spoiling of the remainder of the cargo which was in good condition.

The carriage temperatures are stipulated by the shipper of the goods and should be adhered to as closely as possible. Temperatures are taken and recorded at frequent regular intervals and entered in a log-book. Many ships are also equipped with thermographs, which provide a continuous record of compartment temperatures. In the event of claims for cargo damage, the records and thermograph charts will be required as evidence that the correct temperatures were maintained.

In general cargo ships with a limited amount of refrigerated space it is usual to arrange, as far as possible, for the refrigerated cargo to be loaded last and at its destination to be discharged first.

When refrigerated cargo is to be, carried, specially insulated compartments must be provided.  The insulation on the sides, top and bottom of the compartment may be of cork, fiberglass wool or polyurethane rigid foam. It will be retained in position by galvanised sheeting.

The cooling may be effected by either circulating cold brine (relative density 1.047) through pipes on the sides and deck head, or by blowing cold air through the compartment.

The compartment must be scrupulously clean when loading meat and dairy products. It is recommended that after sweeping out, the compartment is wiped down with cloths wrung out in a cleansing fluid; this will prevent the formation of mould on woodwork.  If a fruit or other strong smelling cargo has been carried in the compartment previously, it will also be necessary to deodorize it. Spaces are swept down and all loose dirt removed. Any remaining residues of previous cargoes will have to be scraped or washed off. After cleaning, the spaces are sprayed with a mild disinfectant such as weak sodium hypochlorite solution, which also helps to remove odours.

Alternatively, an ozoniser may be used for the same purpose, especially after the carriage of a strong-smelling cargo like oranges.

The bilges should be cleaned and sweetened and their suctions tested.  The brine traps should be cleaned out, refilled and tested.  This also applies to those in the ‘tween deck.

The brine traps serve a dual purpose they prevent the cold air from reaching the bilges and thus freezing out the water in the pipes and also they prevent the bad odour from the bilges reaching the cold chambers.

If the vessel is fitted with brine-pipes the side baffle boards (which keep the cargo clear of the pipes) should be removed and the pipes wiped clean.  If fitted with the cold air circulation system, air ducts should be cleaned, this is particularly important if a dusty cargo has been carried previously.

Any fat or grease spots on the deck should be scraped up.

The insulation should be inspected and any repairs necessary to it or to the sparring, which is attached to it, must be effected.

Thermometers should, be made ready and, where fitted, thermometer pipes should be erected.

Any ventilators leading to the compartment must be plugged.  Air change plugs should also be in position.

Dunnage must be pre-cooled before use.  In most-trades the dunnage will be laid before the loading commences.

If the compartment is fitted with gratings, these will have been scrubbed before being laid down.

When chilled meat is to be carried, the requisite number of meat bars, hooks and chain will have to be placed in the compartment for pre-cooling.

The hook and chains should be sterilized (this is usually done ashore).

When the compartment has been prepared it will be cooled to the loading temperature.  It will then be ready for the surveyor to carry out a loading port survey.  In most cases this is in essential before any cargo is loaded.

When the cargo has been loaded the portable brine-pipes will be fitted in the. square of the hatch. Afterwards the insulated plug hatches must be shipped and fitted as tightly as possible.

It is frequently necessary to paste paper over the joints to keep the hatch as airtight as possible.  In extreme cases the joints may have to be caulked and pitched.  In the latter case, the greatest. care must be taken when opening up as pitch and oakum falling onto carcass meat can stain it.

When general cargo or frozen cargo at a different temperature is being carried in the deck above, a layer of sawdust is often put over the hatches and deck to absorb any condensation.

Occasionally it may be necessary to load cargo through a ‘tween deck which contains refrigerated cargo. The refrigeration should be stopped whilst the hatches are open, otherwise an undue amount of frost may form.  If this forms on brine pipes it will act as insulation and prevent further cooling.

Refrigerated containers with their own built in cooling units are to be inspected as thoroughly as for chambers above – that is if they are being stuffed on board, this is extremely rare. In general the containers are pre-cooled ashore and then are stuffed at the providers place or in the dock from refrigerated trucks. The inspections are done by shore surveyors.

Prior loading all the ships power points for these containers are to be tested and logged down.

While receiving the containers the containers are to be inspected for any dents or gashes on the body and the temperature card (circular) is to be noted.

The temperature is to be noted, however the temperature may a bit high on loading and it comes down after the ships power is switched on. The temperature graph is to be monitored and any sign of heating up is to be prevented. Some units have drawings to do some sort of emergency arrangements if the unit fails during the voyage.

The graph card needs to be renewed once the time scale gets over and these are kept as spare on board and are to be replaced by fresh cards, the filled in cards are to be kept with the cargo/ chief officer for handing them ashore prior discharging.

Temperature records are vital in both the methods of carriage. Temperatures are to be recorded at least three times a day and all the points provided and the same is to be recorded, if automatic recorders are provided then the visual sightings also should be used for checking.

For containers too the same procedure is to be followed, visual sightings are recorded together with the automatic recording.

All records are to be kept safely are to be handed over (copies) to the shore authorities after discharging. These records are vital in case there are claims about the cargo and the temperature records are the only proof the ship has to refute the claims.

Prior loading the cargo in pallets are to be inspected (non containerized) by ships officer together with the surveyor. Often the cargo is brought to the jetty and the packages may show signs of softening (thaw) these are to be rejected. Also depending on the shippers agreeing the temperature probes (which may puncture the cases) may be inserted to note the temperature, this however may not be allowed since they apparently damage the cases (paper hardboard). Any staining of the cases again is to be investigated and rejected if necessary. Reefer cargo is loaded last and discharged first. All cargo is tallied on board and ashore since some are liable for pilferage – shrimps as such.

 

 

 

Enclosed Space Entry 

An enclosed space is one with restricted access that is not subject to continuous ventilation and in which the atmosphere may be hazardous due to the presence of hydrocarbon gas, toxic gases, inert gas or oxygen deficiency. This definition includes cargo tanks, ballast tanks, fuel tanks, water tanks, lubricating oil tanks, slop and waste oil tanks, sewage tanks, cofferdams, duct keels, void spaces and trunkings, pipelines or fittings connected to any of these. It also includes inert gas scrubbers and water seals and any other item of machinery or equipment that is not routinely ventilated and entered, such as boilers and main engine crankcases.

Many of the fatalities in enclosed spaces on oil tankers have resulted from entering the space without proper supervision or adherence to agreed procedures. In almost every case the fatality would have been avoided if the simple guidance in this chapter had been followed. The rapid rescue of personnel who have collapsed in an enclosed space presents particular risk. It is a human reaction to go to the aid of a colleague in difficulties, but far too many additional and unnecessary deaths have occurred from impulsive and ill-prepared rescue attempts.

Respiratory hazards from a number of sources could be present in an enclosed space. These could include one or more of the following:

Respiratory contaminants associated with organic vapours including those from aromatic hydrocarbons, benzene, toluene, etc.; gases such as hydrogen sulphide; residues from inert gas and particulates such as those from asbestos, welding operations and paint mists.

Oxygen deficiency caused by, for example, oxidation (rusting) of bare steel surfaces, the presence of inert gas or microbial activity.

Hydrocarbon Vapours

During the carriage and after the discharge of hydrocarbons, the presence of hydrocarbon vapour should always be suspected in enclosed spaces for the following reasons:

Cargo may have leaked into compartments, including pumprooms, cofferdams, permanent ballast tanks and tanks adjacent to those that have carried cargo.

Cargo residues may remain on the internal surfaces of tanks, even after cleaning and ventilation.

Sludge and scale in a tank which has been declared gas free may give off further hydrocarbon vapour if disturbed or subjected to a rise in temperature.

Residues may remain in cargo or ballast pipelines and pumps.

The presence of gas should also be suspected in empty tanks or compartments if non-volatile cargoes have been loaded into non-gas free tanks or if there is a common ventilation system which could allow the free passage of vapours from one tank to another.

Oxygen Deficiency

Lack of oxygen should always be suspected in all enclosed spaces, particularly if they have contained water, have been subjected to damp or humid conditions, have contained inert gas or are adjacent to, or connected with, other inerted tanks.

Other Atmospheric Hazards

These include toxic contaminants such as benzene or hydrogen sulphide, which could remain in the space as residues from previous cargoes.

ATMOSPHERE TESTS PRIOR TO ENTRY

General

Any decision to enter an enclosed space should only be taken after the atmosphere within the space has been comprehensively tested from outside the space with test equipment that has recently been calibrated and checked for correct operation.

It is essential that all atmosphere testing equipment used is:

Suitable for the test required;

Of an approved type;

Correctly maintained;

Frequently checked against standard samples.

A record should be kept of all maintenance work and calibration tests carried out and of the period of their validity. Testing should only be carried out by personnel who have been trained in the use of the equipment and who are competent to interpret the results correctly.

Care should be taken to obtain a representative cross-section of the compartment by sampling at several depths and through as many deck openings as practicable. When tests are being carried out from deck level, ventilation should be stopped and a minimum period of about 10 minutes should be allowed to elapse before readings are taken.

Even when tests have shown a tank or compartment to be safe for entry, pockets of gas should always be suspected. Hence, when descending to the lower part of a tank or compartment, further atmosphere tests should be made. Regeneration of hydrocarbon gas should always be considered possible, even after loose scale has been removed. The use of personal detectors capable of continuously monitoring the oxygen content of the atmosphere, the presence of hydrocarbon vapour and, if appropriate, toxic vapour is strongly recommended. These instruments will detect any deterioration in the quality of the atmosphere and can provide an audible alarm to warn of the change in conditions.

While personnel remain in a tank or compartment, ventilation should be continuous and frequent atmosphere tests should be undertaken. In particular, tests should always be made before each daily commencement of work or after any interruption or break in the work.

Sufficient samples should be drawn to ensure that the resulting readings are representative of the condition of the entire space.

Hydrocarbon Vapours

To be considered safe for entry, whether for inspection, cold work or hot work, a reading of not more than 1% LFL must be obtained on suitable monitoring equipment.

Benzene

Checks for benzene vapour should be made prior to entering any compartment in which a cargo that may have contained benzene has recently been carried. Entry should not be permitted without appropriate personal protective equipment if statutory or recommended Permissible Exposure Limits (PEL’s) are likely to be exceeded. Tests for benzene vapours can only be undertaken using appropriate detector equipment, such as that utilizing detector tubes.

Detector equipment should be provided on board all vessels likely to carry cargoes in which benzene may be present.

Hydrogen Sulphide

Although a tank which has contained sour crude or sour products will contain hydrogen sulphide, general practice and experience indicates that, if the tank is thoroughly washed, the hydrogen sulphide should be eliminated. However, the atmosphere should be checked for hydrogen sulphide content

prior to entry and entry should be prohibited in the event of any hydrogen sulphide being detected. Hydrogen sulphide may also be encountered in pumprooms and appropriate precautions should therefore be taken.

Oxygen Deficiency

Before initial entry is allowed into any enclosed space, which is not in daily use, the atmosphere should be tested with an oxygen analyzer to check that the normal oxygen level in air of 21% by volume is present. This is of particular importance when considering entry into any space, tank or compartment that has previously been inerted.

Generally nearly all substances have been assigned Permissible Exposure Limits (PEL) and /or Threshold Limit Values (TLVs). The term Threshold Limit Value (TLV) is often expressed as a time weighted Average (TWA).  The use of the term Permissible Exposure Limit refers to the maximum exposure to a toxic substance that is allowed by an appropriate regulatory body.

The PEL is usually expressed as a Time Weighted Average, normally averaged over an eight-hour period.

Short Term Exposure Limit (STEL), is normally expressed as a maximum airborne concentration averaged over a 15-minute period.

The values are expressed as parts per million (PPM) by volume of gas in air. Toxicity can be greatly influenced by the presence of some minor components such as aromatic hydrocarbons (e.g. benzene) and hydrogen sulphide. A TLV of 300PPM, corresponding to about 2%LEL, is established for gasoline vapours.

Entry Procedures

General

An entry permit should be issued by a responsible officer prior to personnel entering an

enclosed space. An example of an Enclosed Space Entry Permit is provided in ISGOTT.

Suitable notices should be prominently displayed to inform personnel of the precautions to be taken when entering tanks or other enclosed spaces and of any restrictions placed upon the work permitted therein.

The entry permit should be rendered invalid if ventilation of the space stops or if any of the conditions noted in the checklist change.

No one should enter any cargo tank, cofferdam, double bottom or other enclosed space unless an entry permit has been issued by a responsible officer who has ascertained immediately before entry that the atmosphere within the space is in all respects safe for entry. Before issuing an entry permit, the responsible officer should ensure that:

The appropriate atmosphere checks have been carried out, namely oxygen content is 21% by volume, hydrocarbon vapour concentration is not more than 1% LFL and no toxic or other contaminants are present.

Effective ventilation will be maintained continuously while the enclosed space is occupied.

Lifelines and harnesses are ready for immediate use at the entrance to the space.

Approved positive pressure breathing apparatus and resuscitation equipment are ready for use at the entrance to the space.

Where possible, a separate means of access is available for use as an alternative means of escape in an emergency.

A responsible member of the crew is in constant attendance outside the enclosed space in the immediate vicinity of the entrance and in direct contact with a responsible officer. The lines of communications for dealing with emergencies should be clearly established and understood by all concerned.

In the event of an emergency, under no circumstances should the attending crew member enter the tank before help has arrived and the situation has been evaluated to ensure the safety of those entering the tank to undertake rescue operations.

Regular atmosphere checks should be carried out all the time personnel are within the space and a full range of tests should be undertaken prior to re-entry into the tank after any break.

The use of personal detectors and carriage of emergency escape breathing apparatus are recommended.

Reference should be made to ISGOTT for additional guidance on entry into pumprooms.