api procedure for inspection of chemical cargo by inspectors

7/30/2019 API Procedure for Inspection of Chemical Cargo by Inspectors

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Ballot Version created 22nd

August 2007Page 1 of 31

API MPMS 17.12/HM51

Procedure for Bulk Liquid Chemical Cargo

Inspection By Cargo Inspectors

Ballot Draft 22nd August 2007

TABLE OF CONTENTS

TABLE OF CONTENTS .......................................................................................... 11. SCOPE.................................................................................................................. 3

1.1 GENERAL...................................................................................................... 3

1.2 MEASUREMENT STAGES...................................................................... 31.3 QUALITY CONTROL.............................................................................. 3

1.4 SUMMARY OF DATA TO BE REPORTED............................................ 3

2 DEFINITIONS.................................................................................................. 5

3. GENERAL PRINCIPLES.................................................................................. 9

3.1 THE PURPOSE OF A CARGO INSPECTION.......................................... 93.2 GENERAL RESPONSIBILITIES.............................................................. 9

4. SAFETY RECOMMENDATIONS ................................................................. 114.1 GENERAL .............................................................................................. 11

4.2 SAFETY ASPECTS OF EQUIPMENT ................................................... 11

4.3 SAFETY AT SAMPLING POINTS......................................................... 11

4.4 STATIC ELECTRICITY ......................................................................... 124.5 ENTRY INTO ENCLOSED SPACES ..................................................... 12

5. OPERATION PLANNING (Loading and Discharge) ...................................... 14

5.1 KEY MEETING .................................................................................... 14

5.2 INFORMATION TO BE DETERMINED BEFORE A LOADING ORDISCHARGE OPERATION COMMENCES...................................................... 14

6. MEASUREMENT AND SAMPLING PROCEDURES................................... 16

6.1 MEASUREMENT PROCEDURES - SHORE ......................................... 16

6.2 MEASUREMENT PROCEDURES - SHIP.............................................. 17

6.3 TEMPERATURE MEASUREMENT - Ship and Shore ........................... 18

6.4 SAMPLING............................................................................................. 18

6.4.1 Manual Sampling of Shore Tanks......................................................... 18

6.4.2 Sampling On Board Ship...................................................................... 18

6.5 CALCULATION OF QUANTITIES ....................................................... 19

6.6 USE OF VESSEL EXPERIENCE FACTORS ......................................... 196.7 BUNKER SURVEY ................................................................................ 19

7. CALCULATION OF QUANTITIES.................................................................. 20

7.1 GENERAL .............................................................................................. 20

7.2 CALCULATION METHODS ................................................................. 20

7.3 EXAMPLES OF SHORE TANK AND MARINE TANK

CALCULATIONS .............................................................................................. 21

7.3.2 Weight Calculations.................................................................................... 217.4 REPORTING........................................................................................... 22


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8. VESSEL EXPERIENCE FACTOR ............................................................. 24

9.0 PROCEDURES TO CONTROL PRODUCT QUALITY............................. 25

9.1 Acceptance Procedural Guidelines................................................................. 259.2 Tank Cleaning Information ...................................................................... 26

9.2.1 Tank cleaning operations...................................................................... 26

9.3 Tank Inspection Guidelines..................................................................... 279.3.1 Internal Inspection of Tank Surfaces .................................................... 27

9.3.2 Wall Wash Sampling and Testing......................................................... 27

9.4 First Foot Loading and Sampling ............................................................. 28

9.5 Cargo Tank Coating Suitability ................................................................ 29

9.6 Loading Shore Tank.............................................................................. 29

9.7 Pipelines .................................................................................................. 29

9.8 Discharge Port ......................................................................................... 309.9 Sample Retention................................................................................... 30

10. FINAL REPORT ........................................................................................ 31


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1. SCOPE1.1 GENERALThe purpose this document is to provide systematic cargo measurement procedures for use primarily bycargo inspectors and to specify procedures directed at minimising cargo contamination and losses, inthe absence of, or in conjunction with, specific client guidelines, the following document should be

considered a summary of best practices used within the industry.

Where the term measurement is used in a general sense, it should be taken to include all aspects of

cargo inspection including (but not limited to) tank suitability inspection, sampling, laboratory analysisand testing and other superintending activities, as required by the inspectors principals.

The points at which cargo inspectors are required to make their measurements are described anddefinitions of the terms used throughout this document are provided in Section 2. Whenever possibleterms approved by API, EI and ISO/TC28 have been adopted.

The document also considers the purpose of a cargo survey and summarises general responsibilitieswhich cargo inspectors will be held to accept when they are appointed.

Safety matters and related responsibilities are defined and emphasis is placed on the need for cargoinspectors to be continually conscious that safety requirements take precedence over all other

considerations.The document describes the detailed procedures which inspectors are required to follow and providesreferences to the analytical test methods and calculations. Reference is made to alternative methodssince the procedures recognise that within the industry opinions may vary regarding the use of test

methods, especially where different methods may be specified by parties and contractors.

1.2 MEASUREMENT STAGESThe organisation of the detailed procedures in this document are shown in Figure (1) and reflect thefact that when a chemical cargo is transported by vessel from one shore terminal to another,measurements are made for the purpose of establishing:(a) the quantity of cargo loaded (i.e. to confirm the quantity of cargo shown on the Bill of

Lading);

(b) the quantity of cargo loaded by the vessel;(c) the quantity of cargo discharged by the vessel;

(d) the quantity of cargo received by the receiving terminal;(e) the difference between the quantities established under (a) to (d) above.Note; for a particular voyage involving more than one loading port or discharge port, measurements

should be made at all such additional ports in order that a reliable comparison can be made between thequantities shown on the Bill of Lading, the cumulative outturn and ships figures.

1.3 QUALITY CONTROL

It is recognised that contamination may occur during the various transfer and transportation stages of

cargo movement.Procedures and recommendations for a testing schedule are given which will minimise such

contamination risk.

1.4 SUMMARY OF DATA TO BE REPORTED

Because it is recognised that cargo inspection companies and their clients each have their preferred wayof recording the data to be reported, particular forms are not prescribed by this standard. However, forinformation, a listing of the typical information sufficient to define a chemical cargo loading or

discharge operation is provided in Section 10. This listing represents a consensus of a number of cargoinspection companies and their clients. Additionally, a listing of typical forms sufficient for a completeanalysis of the inspection is given in Section 10. The detailed format of these forms should be agreed

with clients when contracts are being arranged.


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OVERALL ANALYSES OF OUTTURN

Supplier (B/Lading) Tanker after loading Tanker before discharging

(1) (2) (3)

OutturnLoss

(1 - 4) = (1 - 2) + (2 - 3) + (3 - 4)

TOTAL PHYSICAL AND APPARENT LOSSES (Incl. MEASUREMENT ERROR)

12 3

LOADING TERMINAL LOADING IN TRANSIT DISCHARTERMINAL(BILL OF LADING)


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2 DEFINITIONSThe following definitions apply in general to the measurement of bulk liquids and may not bespecifically applicable to chemicals. For the purposes of this document the following definitions applywhich incorporate terms which have been approved by ISO/TC28.

Clingage: Chemical residues which adhere to the surface of tank walls and structures on completion of

discharge.Correction Factors: Factors for correcting volumes back to the standard reference temperature and

pressure (15C; 1.01325bara). Please refer to Annex B for further breakdown on terminology.Critical zones: level range through which the floating roof or floating blanket is partially supported byits legs.

Note: The zone is usually clearly marked on tank capacity tables. Measurements for custodytransfer purposes should not be made within it. Floating roofs may on occasion be fixed at ahigh or low leg position and both zones will usually be marked on tank capacity tables.

Density: mass of the substance divided by its volume.Note: When reporting the density, the unit of density used, together with the temperature,should be explicitly stated, for example kilograms per cubic metre at 15 degrees Celsius

(kg/m3

at 15C).In-transit loss: difference between the Total Calculated Volume on board a vessel after loading and

the Total Calculated Volume on board before discharge.

Inhibitors: A compound (usually organic) that retards, controls, or stops an undesired chemicalreaction, such as corrosion, oxidation, or polymerization.

Letter of Protest or a Notice of Apparent Discrepancy: a letter issued by any participant in a custody

transfer citing any condition in dispute. This serves as a written record that the particular action orfinding was questioned at the time of occurrence.Mass: An absolute measure of a particular quantity of matter. Mass is defined in terms of

a standard mass, and therefore the mass of an object is simply a multiple of the mass standard.The mass of an object remains constant regardless of its location. The metric unit ofmass is the kilogram (kg)

0.001kg = 1 gramme

1000kg = 1 metric tonne (tonne)

Outturn: quantity of a cargo discharged from a vessel, measured by a shore terminal.Outturn certificate: statement issued by a receiving terminal certifying the outturn.Outturn loss: difference in the weight or standard volumes of oil between the quantity shown on theBill of Lading and the quantity shown on the Outturn Certificate.

Remaining on board: abbreviated ROB: Refers to material remaining in a vessels cargotanks, void spaces, and/or pipelines after the cargo is discharged. ROB includes any combination

of water, oil, slops, oil residue, oil water emulsions, sludge, and sediment. Samples

All-levels sample: A sample obtained by submerging a stoppered beaker or bottle to a point as near aspossible to the draw-off level, then opening the sampler and raising it at a rate such that it isapproximately three-fourths full as it emerges from the liquid. An all-levels sample is not necessarily a

representative sample because the tank volume may not be proportional to the depth and because theoperator may not be able to raise the sampler at the variable rate required for proportional filling. Therate of filling is proportional to the square root of the depth of immersion

Bottom sample: spot sample taken from the product at or close to the bottom of a tank or container.

Clearance sample: spot sample taken at a specified distance below the bottom of the tank outlet.Composite sample (weighted): sample obtained by combining a number of spot samples in definedproportions so as to obtain a sample representative of the bulk of the product

Dead bottom sample: spot sample taken from a point on the tank bottom.Note: Such samples require the use of a device with a bottom opening, commonly used for

free water samples.

Drain sample: sample obtained from the water draw-off point on a storage tank.


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first foot sample: sample drawn from a vessel tank early during a cargo loading, when the depth ofproduct in the tank(s) is approximately 300 mm, (one foot).

Note: Regulations concerning the dissipation of static charge normally require the cessation ofpumping and a relaxation time of thirty minutes before first foot samples are drawn.

Lower sample: spot sample taken at a level of five-sixths of the depth of liquid below the top surface

Middle sample: spot sample taken at a level of one-half of the depth of liquid below the top surface

Multi-tank composite sample: a mixture of individual samples or composites of samples that have

been obtained from several tanks or ship/barge compartments containing the same grade of material

Running sample: sample obtained with an apparatus which accumulates the sample while passing in

both directions through the total liquid height, excluding any free waterNote: The apparatus passes through the liquid at such a rate that it is approximately 80% full

as it emerges from the liquid.

Single tank composite sample: blend prepared from the upper, middle and lower samples from a

single tank

Skim sample (surface sample): spot sample taken from the surface of the liquid.

Spot sample: sample taken at a specific location in a tank or from a pipeline.

Suction level sample (outlet sample): sample taken at the lowest level from which liquid hydrocarbon

is pumped from the tank.

Tap sample: A spot sample taken via a tap, typically located on the side of the shore tank.

Top sample: spot sample obtained 150 mm (6) below the top surface of the liquid

Upper sample: spot sample taken at a level of one-sixth of the depth of liquid below the top surface

Zone sample (core sample, flow through sample): sample taken as that part of the liquid column

which is contained within the whole height of the sampler when it is sealed at a single spot locationwithin a tank.

Slops: Are oil, oil/water/sediment, and emulsions contained in slop tanks or designated cargo tanks.The mixture usually results from tank stripping, tank washing, or dirty ballast phase preparation.

Volume Correction Factor (VCF) (Also termed Ctl in dynamic calculations): See Correction

Factors.

Volume meter: A device that when installed in a pipe in which liquid is flowing indicates the volumeof liquid that passes through it.

Volume Dynamic

Volume, gross: The indicated volume multiplied by the meter factor (MF) for the particular liquidand flow rate under which the meter was proved.

Volume, total observed; abbreviated TOV: The total measured volume of all petroleum liquids,sludges, sediment and water, and free water at observed temperature and pressure.

Volume, gross observed; abbreviated GOV: The total volume of all petroleum liquids and sedimentand water, excluding free water, at observed temperature and pressure.

Volume, gross standard; abbreviated GSV: (a) The total volume of all petroleum liquids andsediment and water, excluding free water, corrected by the appropriate volume correction factor (Ctl)for the observed temperature and API gravity, relative density or density to a standard temperature such

as 60F or 15C and also corrected by the applicable pressure correction factor (Cpl) and meter factor;


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(b) the gross volume at standard temperature corrected to standard pressure. Gross standard volume =closed meter reading - open meterreading xMFx Ctl, x Cpl.

Volume indicated: The change in meter reading that occurs during a receipt or delivery.Volume, net standard; abbreviated NSV: The total volume of all petroleum liquids, excludingsediment and water and free water, corrected by the appropriate volume correction factor (Ctl)for the

observed temperature and API gravity, relative density, or density to a standard temperature such as60F or 15C and also corrected by the applicable pressure correction factor (Cpl) and meter factor.

Volume, total calculated; abbreviated TCV: The total volume of all petroleum liquids and sedimentand water, corrected by the appropriate volume correction factor (Ctl) for the observed temperature and

APIgravity, relative density or density to a standard temperature such as 60F or 15C and also

corrected by the applicable pressure correction factor (Cpl) and meter factor, plus all free watermeasured at observed temperature and pressure (gross standard volume plus free water).

Volume Static

Volume, total observed; abbreviated TOV: The total measured volume of all petroleum liquids,sludges, sediment and water, and free water at observed temperature and pressure.

Volume, gross observed; abbreviated GOV: The total volume of all petroleum liquids and sedimentand water, excluding free water, at observed temperature and pressure.

Volume, gross standard; abbreviated GSV: The total volume of all petroleum liquids and sedimentand water, excluding free water, corrected by the appropriate volume correction factor (Ctl) for theobserved temperature and API gravity, relative density or density to a standard temperature such as60F or 15C.

Volume, net standard; abbreviated NSV: The total volume of all petroleum liquids, excludingsediment and water and free water, corrected by the appropriate volume correction factor (Ctl)for theobserved temperature and API gravity, relative density, or density to a standard temperature such as60F or 15C.

Volume, total calculated; abbreviated TCV: The total volume of all petroleum liquids and sedimentand water, corrected by the appropriate volume correction factor (Ctl) for the observed temperature and

APIgravity, relative density or density to a standard temperature such as 60F or 15C.

Vessel Experience Factor: Please refer to API 17.9 / HM 49.

Water:Dissolved water: water contained within the petroleum liquid forming a solution at the prevailingtemperature.

Suspended water: water within the petroleum liquid which is finely dispersed as small droplets. It

may, over a period of time, either collect as free water or become dissolved water, depending on theconditions of temperature and pressure prevailing.Free water (FW): the water that exists in a separate phase.Total water: sum of all the dissolved, suspended and free water in a cargo or parcel of petroleumliquid.Water cut or dip: The depth of free water in a container over and above the dip plate.

Wall wash test: the procedure for washing selected areas such as the interior bulkheads, tank bottomsand sumps of cargo tanks with an appropriate wash liquid and testing the wash liquid for the presence

of material which might contaminate cargo to be loaded.

Wall Wash Sample: sample obtained from a wall wash test.

Wedge formulaA mathematical means of approximating the small quantities of liquid and solid cargoand free water onboard before a vessel is loaded and after its cargo is discharged. The formula is basedon cargo compartment dimensions and vessel trim. The wedge formula shall be used only when a

wedge exists and when the liquid does not touch all bulkheads ofthe vessels tank.

Weight conversion factor (WCF): factor, dependent on the density, for converting volume to weight-in-air. Such factors should be obtained from the Petroleum Measurement Tables.


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Weight: abbreviated wt: The net force exerted on an objects mass compared with a referencestandard.

Weight-in-air: The weight in air of a substance is its weight in vacuum, reduced by its buoyancy (inair).Weight-in-vacuo: correctly termed mass.

Wipe test: the procedure of physically wiping any interior surface (bulkheads, steam coils, etc) withabsorbent white rags. This procedure is used to test the wiped surfaces for possible colour

contamination .


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3. GENERAL PRINCIPLES

3.1 THE PURPOSE OF A CARGO INSPECTIONThe main purposes of a cargo inspection of a bulk liquid chemical are:

When required, inspect the tanks prior to loading to determine if the tanks meet requirements

for cargo to be loaded. To advise and assist in minimising the extent to which procedural and/or measurement errors

before, during and after the loading or discharge or cargo transfer that could affect the quantity

and quality of product recorded on documents issued at the port or place of load or dischargeor cargo transfer.

To ensure during the loading or discharge or cargo transfer that all practicable steps are takenwhen bulk liquid chemicals are being transferred so that the bulk liquid chemical cargo isnot, and do not become, contaminate

When required verify the quality of the cargo to be discharged or loaded or transferred.

Upon completion of discharge verify cargo tank condition.

Maintain a detailed time log.

To identify to all concerned parties in a timely manner any matter that may be relevant to thehandling of the cargo.

To provide a detailed report that details the quantity and quality of each parcel at the point ofload or discharge or cargo transfer in a timely manner

3.2 GENERAL RESPONSIBILITIESTo achieve the purpose described above, the cargo inspector shall discharge a number of

responsibilities, some of a general nature and others of a highly specialised and clearly defined nature.The general responsibilities are described immediately below and the specialised responsibilities formthe subject matter of subsequent sections.

3.2.1The cargo inspection company shall ensure to the best of their ability and in order to minimisemisunderstandings, that clear, written instructions are received from the specific party for whom theinspection is being performed.3.2.2The cargo inspection company shall ensure briefed and trained inspection personnel make themselves

available on time as appropriate and as specifically required by the principal(s) for whom theinspection is being performed.

3.2.3Details of the tank inspection, measurement, sampling, site & laboratory analytical methods andcertification referred to in these procedures may be specified separately by different parties for whomthe inspection is being performed.

3.2.4A formal protest in writing should be submitted by the cargo inspectors to the terminal and/or thevessel(s) when:

Any occurrences conflict with the interests of the specific parties for whom the inspection is beingperformed.

Operational or other restrictions make it impossible for the cargo inspector to follow theprocedures detailed in this Standard or the specific requirements of any of the parties for whom theinspection is being performed.

A quality or measurement discrepancy occurs, or is suspected, between those determined by thecargo inspector and those determined by other involved parties.

Any of the contractual conditions governing the transfer of the cargo, which have been madeknown to the inspectors, are not met.

Such protests should be issued in writing when the occasion for protest is first observed and before the

vessel sails from the loading or discharge port.Any additional observations and comments supporting any of the events reported should be included in

the cargo inspectors report.

3.2.5Before any cargo operation commences the cargo inspector shall meet all key personnel concerned with

such operation to review and agree on the operational plan and procedures relating to the clean andaccurate custody transfer of the cargo (See section 5 for Key Meeting information).

3.2.6


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Any Inspection procedure to be performed either on board a vessel or in the shore terminal must beaccomplished with either the vessel(s) or the terminal representatives explicit approval and in thepresence of his nominee.

3.2.7The cargo inspector must comply with all applicable governmental, local port authority and terminalregulations in force at the port of loading or discharge.

3.2.8The inspector must also perform his required tasks in a safe manner in accordance with Section 4 of

this standard, and always in compliance with the inspection companys safety requirements andlocation specific safety requirements.

3.2.9Knowledge and experience of the visual inspection and estimation of cargo tank coatings and thedetermination of coating condition or integrity (% of total coating in place or % breakdown of thecoating in place) is required to ensure that the inspection result meets the requirements and expectation

of the parties for whom the inspection is being performed. (See Section 9.5 on tank coatings)

3.2.10Calibration documents shall be available at the location required for all measuring equipment.

3.2.11Measurement and sampling equipment must be clean, safe, and suitable for use and NOT BECOME a

source of cargo or sample contamination. The materials from which the probe, flex and samplingequipment are constructed must be proof against possible corrosive action by the chemical beingmeasured.

3.2.12Many vessels now operate under a closed or restricted loading or discharging system such that openhatch manual gauging and sampling of cargo tanks may not be possible and is often not permitted.Under such circumstances the use of a portable electronic gauging device (PEGD) is recommended as

these devices are designed for use in either closed or restricted gauging applications. Closed andrestricted gauging operations will generally require that the portable electronic gauging tape be used inconjunction with a compatible vapour lock valve.Note: In the event that permission for the specified operations to be performed is refused, or there areother reasons why manual measurements cannot be made, written letter of protests should be madewith the vessel(s) and/or Terminal Representative and the facts recorded in the cargo inspectors report.

3.2.13Cargo inspectors shall record each occasion when they are required to take measurements underconditions which are not conducive to custody transfer accuracy.

3.2.14The Inspection report issued on completion of custody transfer operations should follow the guidelinescontained in this Standard and also be in accordance with any specific reporting instructions given by

each specific party for whom the inspection is being performed.


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4. SAFETY RECOMMENDATIONS

4.1 GENERAL

4.1.1This section makes reference to a wide range of recommendations and requirements designed to enableinspectors to perform their duties in a safe manner. Operating conditions are often beyond the controlof attending inspectors. Inspector should decline to perform under unsafe conditions.Particular attention is drawn to the International Safety Guide for Oil Tankers and Terminals(I.S.G.O.T.T.) and inspectors should always refer to this guide. The precautions given below should be

taken whenever they do not conflict with local or national regulations which should, in any event,always be followed.

Careful consideration should be given to the nature and known hazards of the material being

handled.4.1.2Personnel should be made aware of the potential hazards and be given instructions in safety precautions

to be observed.

4.1.3All regulations covering entry into hazardous areas should be observed.4.1.4Suitable clothing, footwear, facial equipment and any other equipment used to provide protection

against all known hazards associated with the operations shall be worn.

4.2 SAFETY ASPECTS OF EQUIPMENT

4.2.1The inspector should use equipment, which complies with all safety codes. Portable equipment such as

mobile phones, pagers and computers, should not be operated except in designated areas.4.2.2

Sample receivers and containers should be designed to meet the requirements of cargo being sampled.Cleaning and leak testing as appropriate for sample containers should be performed at regular intervals.4.2.3

Lines and chains used for lowering sampling equipment should be electrically conductive and shouldnot be made from man made or synthetic fibres. Natural fibres such as manila, cotton, or sisal shouldbe used for this purpose.

4.2.4Lamps, flashlights, and other equipment such as portable electronic thermo probes (PETs) should beintrinsically safe and of an approved type suitable for the electrical classification of the area.

4.3 SAFETY AT SAMPLING POINTS

4.3.1Sampling points should be provided which enable samples to be taken in a safe manner.

4.3.2It is the terminal and/or the vessel's responsibility to ensure that safe access ladders, stairways,platforms and handrails are adequately lit and have been maintained in a structurally safe and clean

condition (i.e. free of cargo residues to prevent slipping hazards).4.33Adequate and safe containment for all draining and flushing requirements should be provided by

vessel(s) and/or the terminal.4.3.4Any spillages or defects in equipment should be reported immediately.

4.3.5.All equipment and material used by the cargo inspector, especially waste or rags should be removed on

completion of the operation.


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4.4 STATIC ELECTRICITY

4.4.1

The following precautions should be taken to avoid danger from static electricity when sampling tankscontaining flammable atmosphere.4.4.2

The contents of storage or ships tanks should not be sampled or measured with portable equipmentduring filling. An adequate relaxation time period after completion of transfer or loading into each tank

should be allowed before introducing any portable or external sampling or measuring equipment intothe tank or container.4.4.3

When sampling and measuring, the sampling lines and measurement tapes should be kept earthed(grounded) at all times, either by earth (ground) connection or by firm contact with the dip hatch, toprevent sparking.

4.4.4In order to earth (ground) any static charges on the person, an inspector should touch some part of thetank structure immediately before carrying out any measurement or sampling operation.

4.4.5Measurement and sampling should not be carried out during periods of atmospheric electric

disturbance or hail storms.

4.5 ENTRY INTO ENCLOSED SPACES

Because of the possibility of oxygen deficiency as well as the presence of hydrocarbon or toxic gas in apump room, cargo tank, cofferdam, double bottom tank or any enclosed space, it is the vessel(s) andterminal responsibility to identify such spaces and to establish procedures for safe entry.

Inspectors should consult the responsible vessel officer or terminal operator to determine whether entryinto such enclosed spaces is permitted and ONLY after the vessel officer or the terminal operator ortheir designated and exit last representatives have enter the tank first. Inspector shall be accompaniedby a representative of the vessel and/or the terminal, as appropriate, at all times.

4.5.1

No-one should enter an enclosed space unless an entry permit has been issued by a responsible vesselofficer or terminal operator who has ascertained immediately before entry that the tank atmosphere isin all respects safe for entry. Before issuing an entry permit, the responsible vessel officer or terminal

operator should at least ensure that:

The appropriate atmosphere checks have been carried out.

Effective ventilation will be maintained continuously while men are in the enclosed space.

Lifelines and harnesses are ready for immediate use. Where possible, pump room lifelines shouldbe already rigged and an unobstructed direct lift provided.

Approved breathing apparatus and resuscitation equipment should be available in an accessiblelocation.

Proper personnel protective equipment is being worn.

A responsible member of the crew or terminal operations is in constant attendance outside theenclosed space in the immediate vicinity of the entrance and in immediate contact with aresponsible vessel officer or terminal operator.

A means of communication between persons inside enclosed spaces and those outside should beestablished and frequently tested.

It is recommended that the foregoing is complied with at all times and upon all occasions.In the event of an emergency, under no circumstances should the attending crew member or terminal

operator enter the enclosed space before help has arrived. The lines of communication for dealing withemergencies should be clearly established and understood by all concerned.

4.5.3Pump rooms, by virtue of their location, design and operation, constitute a particular hazard and

therefore necessitate special precautions. No-one should enter a pump room at any time without firstobtaining the permission of a responsible vessel officer or terminal operations.


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4.5.4It is the duty of the responsible officer in charge of cargo operations to ensure that adequate ventilationof the pump room has been accomplished and that the atmosphere is suitable for entry. Approved

breathing apparatus and resuscitation apparatus should be available in an accessible location.At no time should a cargo inspector enter a pump room unless accompanied by a responsible memberof the ships staff or terminal operations.


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5. OPERATION PLANNING (Loading and Discharge)

5.1 KEY MEETINGExperience shows that chemical transfers are especially liable to involve problems relating to productquality. It is therefore important that before chemicals are transferred, the inspector, shore terminal andvessel personnel should meet to discuss and agree the procedures to be applied for cargo measurementand cargo quality assurance to ensure that:

The chemical does not become contaminated.

Handling losses are minimised.

The operation proceeds with a minimum of delay.

5.2 INFORMATION TO BE DETERMINED BEFORE A LOADING OR DISCHARGE

OPERATION COMMENCES

The following table gives the type of questions to be asked and the minimum information that should

be obtained by the cargo inspector from the vessel and terminal staff prior to carrying out physicalchecks.

LOAD DISCHARGE

Shore Ship Shore Ship

1. That ship/shore/inspection company are agreed on the

quantity/ of cargo to be transferred.

2. That the advised quantity is available.

3. (a) Identify the tanks involved, and the approximate

quantity to be transferred from/into each.(b) That the tank capacity being made available will be

sufficient to contain the cargo.(c) The proposed order that the tanks will be loaded/discharged.

4. Whether any tanks contain previous cargoes or residues.

5. Was there any in-transit movement of cargo?

6. The nature of the tank histories(a) Previous 5 (vessel) cargoes if available, minimum of 3(b) Last and current product (shore tank)

7. The planned loading/discharge rate.

8. Tank and line preparation and cleaning procedures, if any,that have been carried out.

9. The materials used for any tank coating and itscondition.

10. When the ship cargo tanks are subject to inert gas:

(a) What facilities exist for measurement and sampling ofcargo tanks?

(b) Whether cargo tanks can be separately inerted/depressurised.

(c) What is the quality of inert gas system (for examplenitrogen purity)

11. When carrying multi-grade cargoes, are the venting systemsof the different grades positively separated?

12. Whether any cargo tanks contain recovered washings


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(slops) which are to be discharged before, during or after

the transfer of cargo. If so:

(a) What is the nature and quantity of slops involved?

(b) Can the shore accept the material?

(c) What tank/line cleaning procedures are to be appliedafter tank washings have been discharged?

13. Whether the shoreline cargo system to be used for thetransfer connects with any other shoreline system. If so:

The status of the shoreline, whether full or empty, andmethod available for verification.

14. For ship and shore lines, Identify:(a) The points were they may be checked.(b) Are the transfer lines empty(c) The previous product through the line system and

whether any cleaning and/or pigging was carried out.

(d) Identify which line system is to be used.

15. In the case of multi-product cargo transfer:(a) Whether a common line system will be used.(b) Whether blinds or two-valve separation are available

for segregation.(c) The order of loading/discharge.(d) Whether simultaneous loading/discharge of two or

more product cargos.

16. The location of measurement and sampling points.

17. Whether consignees loading samples are on board.

18. Product and Correction factors

19. Actual Cargo temperature to determine suitability of cargotank

20. Cargo heating instructions(Does coil need to be tested or checked)

21. Any chemical additives or inhibitors to be added


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6. MEASUREMENT AND SAMPLING PROCEDURES

A number of similar measurement and sampling procedures may be applied several times during the

cargo loading-transportation-discharge cycle. Accordingly, to avoid repetition in these guidelines,these procedures are described in detail in this chapter only. Brief references to them are then made, as

necessary, in the subsequent chapters which detail the sequence of procedures to be applied at loadingand discharge.

* Warning! Refer to section 4.4 Static Electricity before commencing any measurement activity.

Chemical cargos may be static accumulating. Take precautions accordingly. *

6.1 MEASUREMENT PROCEDURES - SHORE

6.1.1

Prior to gauging, ascertain whether the shore lines, if any non-dedicated lines involved in the operation,contain product and, if so, what product. A record of what steps were taken to determine that the shore

lines were full or empty. In most modern chemical installations there are dedicated lines from tank tojetty, or even to the jetty-head ship-shore connection.6.1.2A sample of the shore pipeline contents before load or discharge, where permissible, should always be

taken and retained.6.1.3Where relevant, the inspector and the terminal shall by mutual agreement arrange for lines and valves

to be set so as to prevent the possibility of contamination or loss through other lines or tanks, and anysuch settings should be visually checked and verified before commencement of operations.6.1.4In the event that an apparent shortage is established after loading or discharge has been completed, theinspector and the terminal shall confirm that there have been no changes in the volumes of any statictankage that could have been inadvertently connected to the system in use.

6.1.5If the shore tank nominated for use has been in service or mixed recently, wait for at least half an hourfor the liquid level to become constant before commencing gauging. A minimum of two consistent

gauges must be recorded.6.1.6By mutual agreement between the parties concerned and subject to acceptance by the local Customs

Authorities, automatic tank level gauging and temperature measurement systems may be used forcustody transfer.6.1.7If automatic systems are used, reference to the terminals gauge proving records should be made andthe completeness or otherwise of these records indicated in the general comments section.6.1.8

Wherever possible, the inspector should take his own measurements.

6.1.9

If floating roof tanks are nominated for bulk chemical operations, check and record whether or not thetank roof is free of excessive quantities of water and debris. Where appropriate, i.e. after loading andbefore discharge, confirm that the roof is not grounded or in the critical zone, and has undergone no

significant change in condition since operations began.

6.1.10

Report the reference heights of the shore tanks recorded in the tank calibration tables. Confirm thereference height by direct, manual measurement and attempt to establish whether the gauging pipe (iffitted) is / is not perforated (slotted).

6.1.11Ascertain the last time the tank was strapped or calibrated, when the tank was last cleaned or inspected

and when any repairs were made to the tank.6.1.12


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Water cuts, where appropriate, should be obtained using a portable electronic gauging device (PEGD).Where water is present, either as an extraneous and measurable layer or as contaminating suspension orsolution with the material such that its presence will affect the calculation of the final quantity of cargo,

then it should be dealt with as per HM-1 Calculation of quantities.

Except in the case of aqueous solutions such as caustic soda and urea ammonia, chemicals are, in

most cases, shipped as a pure material. Accordingly water measurements are not normally taken orincluded in the calculation of the final quantity.

6.1.13

Ullage measurements, if utilised for any reason, should always be related to the gauging reference pointspecified in the tank calibration tables.

6.1.14Manual gauging shall require obtaining either two consecutive gauge readings to be identical, or threeconsecutive readings within a range of 3 mm (1/8 in.). If the first two readings are identical, this reading

shall be reported to the nearest 1 mm if metric tapes are used, or to the nearest 1/8 in. if customary tapesare used. When three readings are taken, all three readings shall be within the 3 mm (1/8 in.) range andreadings averaged to the nearest 1 mm for metric tapes and 1/8 in. for customary tapes.

6.1.15Inspectors measurements are to be compared with those recorded by the automatic gauge system as

shown in 6.1.15. Some terminals do not allow inspectors to take their own measurements. Where thisis the case, inspectors should satisfy themselves from the terminals gauge proving records that thegauges are satisfactory, making an appropriate note in the general comments of their report. In cases

where inspectors are prevented from conducting a full manual gauging exercise, wherever possible areading from a local tank read out should be taken.

6.1.16Provided that auto gauges satisfy the following criteria, readings may be used as the basis for

calculating quantities. The difference between the change in the tank level during the transfer measuredby automatic level gauge and by manual gauge should be in line with local terminal practice. Wheredifferences are greater than the local terminal practice, manual determinations are recommended.

6.1.17The materials from which the probe, flex and sampling equipment are constructed must be proofagainst possible corrosive action by the chemical being measured.

6.2 MEASUREMENT PROCEDURES - SHIP

6.2.1Where it is safe and physically possible to do so, every effort should be made to read and record the

vessels fore, aft and mid-ship port and starboard draft marks, prior to cargo measurement.6.2.2

For all measurements where vapour locks have been retrofitted, reference should be made to theappropriate documentation issued by the competent authority confirming no physical differences existbetween documented and actual reference heights.6.2.3

Where supplementary tables have been issued following retrofitting, these should be used. If anydiscrepancies are identified then these should be taken into consideration when making calculations6.2.4If automatic level gauges are utilised, check the actual stowed readings against the documented figures,requesting and recording from the vessels personnel, any variances found. If there are no differencesin stowed automatic level gauge readings, then automatic gauges may be used for ullages.

6.2.5Where any form of electronic gauge is used, a means should be sought to verify the accuracy ofreadings. This should include review and consideration of the vessels calibration records.

6.2.6Where it is not possible to conduct manual measurements for purposes of verification, then a protestshould be issued.


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6.2.7Local port/terminal and vessel operational requirements with regard to vapour control emissions shouldbe adhered to.

6.2.8A portable electronic gauging device (PEGD) should be used for all manual liquid measurements,ensuring the correct safety procedures in accordance with ISGOTT are in force.

6.2.9Whatever method is used; the ullages should be taken and recorded to the nearest graduation (1mm) of

the measurement tape/equipment.6.2.10Where applicable, water cuts should be obtained from all ship cargo tanks using a portable electronic

gauging device (PEGD). If the vessel has any trim, this must be allowed for in the calculations.6.2.11In the event that an apparent shortage is established after loading or discharge has been completed, the

inspector, vessel, and the terminal shall confirm that there have been no changes in the volumes of anystatic tankage that could have been inadvertently connected to the system in use.

6.3 TEMPERATURE MEASUREMENT - Ship and Shore

6.3.1It is recommended that a portable electronic thermometer, with a performance traceable to a standardreference thermometer over a suitable temperature range, be used for all temperature measurements. It

is further recommended that its accuracy be checked before and after use, (mercury in glassthermometersare a satisfactory as back- up). For depths of 3.5m (10ft) or greater, readings should betaken at three levels. These readings should be taken at Upper, Middle and Lower cargo levels. When

cargo depths are less than 3.5m (10 ft), readings should be taken from one level, at the cargo middle

level. All temperature readings should be recorded to the nearest 0.1C (0.1F) and averaged.If the inspector is of the opinion that temperature layering is present, then a temperature profile shouldbe obtained by taking temperatures at 1m intervals or less and averaging the results.

6.4 SAMPLING

The inspector is responsible for ensuring that sufficient representative samples are drawn at all

appropriate stages for subsequent testing, compositing or retention. Such samples may be retained atthe terminal or despatched, often via the vessel, to the receiver, and in all cases shall be distributed inaccordance with appointing clients instructions. They should be clearly labelled to identify sample. If

the test procedures call for sample handling techniques which could alter composition of the samplesufficiently to affect the results of other tests or if the test method calls for special sample containers,separate samples for these tests should be drawn, and care must be taken to ensure that the correct type

of sample container is utilised (e.g. some chemicals are light sensitive).

6.4.1 Manual Sampling of Shore TanksEach shore tank to be used in the transfer should be sampled in such a manner as to meet therequirements of interested parties and regulatory agencies.

Tank samples drawn before commencement or on completion of operations should be analysedaccording to clients instructions. Samples at various levels may be necessary for products which aresuspected of being non-homogeneous.

6.4.2 Sampling On Board ShipAt the commencement of a loading take a spot sample from a convenient sample point as near aspossible to the vessels manifold. After the time necessary to displace the line content completely, take

another sample from the vessels tank floor this is often called a first foot sample. If discrepanciesobserved, notify all relevant parties and retain samples. Sampling and testing requirements aregenerally specified by interested parties.On completion of loading take representative samples from each of the vessel tanks so that, if required,composite sample representative of the total cargo may be prepared in the laboratory for appropriate

testing. Such composite samples will be prepared by combining the individual vessel tank samples in

proportion to the volumes contained in the respective tanks.If free water is present during gauging then a free water sample should be obtained.


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Sufficient samples should be obtained and retained to meet the requirements of interested parties andregulatory agencies.

6.5 CALCULATION OF QUANTITIES

Calculate the quantities loaded/discharged in each tank according to normal chemical quantity

calculation procedures noted in section 6.7.

6.6 USE OF VESSEL EXPERIENCE FACTORSRefer to API document (API 17.9 / HM 49) on VEF for single grade cargoes where appropriate.Although vessels experience factors are not normally used for small parcel, multi tank vessels, if

applicable then reference to the API document on VEF should be followed.

6.7 BUNKER SURVEY

Bunker surveys should not be a part of the chemical cargo inspection of a chemical tanker. However, itis possible that a client may require a Bunker Survey as part of the inspection.


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7. CALCULATION OF QUANTITIES

7.1 GENERAL

7.1.1

This section only refers to the calculation of liquid chemical quantities, and not the calculation ofquantities of chemical gases, animal or vegetable oil or molasses.

7.2 CALCULATION METHODS

7.2.1

Systems used utilise two broadly similar methods:

a) Correct the volume at the observed temperature to the volume at the standard temperature byapplying a VCF after which the weight/mass is obtained by multiplying the standard volume with the

density at standard temperature.

b) Correct the density/SG at standard temperature with the thermal expansion coefficient to the

observed temperature, and multiply this by the volume at observed temperature to obtain mass/weight.(Density/SG refers to vacuum/air - mass/weight).

7.2.2

It is sometimes the case that the quantity of cargo loaded (or discharged) is obtained by other methods,such as road/rail cars over weighbridges. The inspectors report should include full details of the grossand tare weights of all individual units in their report.

7.2.3Within the above two approaches are various sub-divisions, including, but not limited to:

7.2.3.1 Correction of observed volume using a VCF. A VCF is that factor which a volume ofproduct at one temperature, must be multiplied by to obtain the volume at a standardtemperature. These factors can be obtained from;A) API-ASTM-EI Petroleum Measurement Tables (B, C or D)B) ASTM D1555 and 1555M (Metric edition), which tabulates VCFs for various

aromatics.C) A volume correction factor, per degree difference in observed temperature.D) Product specific tables of VCF, showing the VCF at observed temperatures,

which must be applied to obtain the volume at standard temperature.7.234.2 Correction to the density at standard temperature using;

A) Product specific tables of density at various temperatures.B) A density correction factor, per degree difference in observed temperature.7.2.4

Because of the above, the following rules should be applied;

A) The origin of the density used in the calculation should be clearly stated.

B) Standard temperatures are 15oC, 20

oC or 60

oF. However other temperatures may be used

if mutually agreed.C) Unless there are local requirements stating that quantities should be expressed as a mass

(i.e. in vacuo), then it is preferable that they are expressed as a weight (i.e. in air). Theinspection report should ensure that they clearly state whether such quantity is in air orvacuo.


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7.3 EXAMPLES OF SHORE TANK AND MARINE TANK CALCULATIONS

7.3.1 Volumetric Calculation

Example 1 What is the volume at 60F and weight of a cargo of p-xylene using ASTM D1555

Measured Volume 9280 gallons

Measured temperature 88.7F

VCF by D1555 0.98414

Volume at 60F 9280 x 0.98414 = 9132.8 gallons

Density at 60F

Density at 60F (from Table in Annex A) 7.2086 lbs/gal

Weight9132.8 * 7.2086 = 65834.7 lb (air)

Example 2 What is the volume at 15 C and weight of a cargo of p-xylene using ASTM D1555M

Measured Volume 1289561 litresMeasured temperature 22.3C

VCF by D1555M 0.99278

Volume at 15C 1289561 x 0.99278 = 1280250

Density at 15C kg/l (ait) 0.8643 kg/l

Weight 1280250 litres * 0.8643 kg/l= 1106520 kg

Example 3 What is the volume at 15C of a cargo of MTBE using ASTM D1250 C

Measured Volume 1289561 litresMeasured temperature 22.5C

Coefficient of thermal expansion 0.0014202 alpha 15 per CVCF by D1250 table 54C 0.99360

Volume at 15C 1281308 litres

Density at 15C 0.7440 kg/l (vac) 0.7429 kg/l (air)

Mass 953293 kg, 953.293 tonnes (vac)

Weight 951884 kg, 951.884 tonnes (air)

7.3.2 Weight Calculations


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Example 4 What is the weight of a cargo of Benzene using density correction coefficients.

The Density at standard temperature is converted to Density at Measured temperature. Density at

measured temperature is applied to measured volume to give weight.

)( Cstst

+=

Where:

=t

density at measured temperature

s

= density at standard temperature

t= difference in temperature (standard - measured)

Cs = density correction coefficient

Measured Volume 1289561 litres

Measured temperature 22.5C

Density coefficient 0.00100 kg/l per C

Density at 15C 0.8831 kg/l (air)

Density at 22.5C 0.8756 kg/l (air)

Weight 0.8756 kg/l * 1289561 l = 1129140 kg

Litres at 15C weight / Density at 15C (air)

1129140 litres /0.8831 = 1278609 litres

7.4 REPORTING

7.4.1

When compiling an inspection report, the raw data from which the report is derived should berecorded, including the following information:

A) The terminal or tank vessel where the measurements were taken

B) Tank number (s), product description, date and time

Dip or ullage measurement, together with details of any correction to be applied and also the

reference heights obtained.

The representative product temperature and how temperature was taken (i.e. upper middle lower,electronic hand held or fixed probe, etc.)

E) All measurement equipment used by the inspector should be properly calibrated and therelevant references are available on request.

F) The density used and the reference temperature at which it applies.

G) The factor used to correct either volume or density and the temperature scale to which itapplies (

oC or

oF).

H) The condition of the pipelines before and after measurement, and if it is incorporated into thecalculations.

I) Any quantity of the pipeline flushing, which is passed into slops, should be recorded.


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J) The total quantity of product supplied or received and the units used should be clearly shown.


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8. VESSEL EXPERIENCE FACTOR

Refer to Section 6.6


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9.0 PROCEDURES TO CONTROL PRODUCT QUALITY

Introduction

The following procedures provide a summary of chemical cargo loading and discharge operations that

inspectors should follow.

Under normal operating conditions, vessels will have prepared their tanks for loading during thepreceding voyage and, where appropriate, will have followed specific recommendations given to the

Master in his voyage instructions or made use of Tank Cleaning Guidance Manuals made available onboard by the vessels owners. Any such guidance manuals will also be considered by the Master inconjunction with any restrictions required by the tank coating manufacturers.

Vessels will present in what they consider to be a ready-to-load condition and inspectors at a load portwill be required to either accept or reject the vessels cargo tanks and associated pumps and lines.

Inspectors should be aware that they are not responsible for any cleaning or tank washing proceduresaboard the vessel and they should not offer any advice or instruction to the Master in the event that

their initial tank inspection results in a rejection requiring further cleaning.Note: There may be an exception to the foregoing where an inspection company might be asked by the

vessel owner or charterer, to provide a specialist tank cleaning expert or supercargo to assist the

Master. This is a specialised service and no further reference will be made in these guidance notes to

that activity.

9.1 Acceptance Procedural Guidelines

There are many hundreds of chemicals carried by sea-going vessels and it is not possible in a manualsuch as this to consider each and every product so far as its particular tolerance to other materials isconcerned. In general, petrochemicals are pure substances and tolerance levels for contamination areextremely low.

It is the inspectors responsibility to ensure, so far as it is possible to do so, that the vessel is ready toload without risk of contamination.

The possible sources of potential contamination include the following:

Cargo lines from the loading manifold to the tank bottom including drop lines and strippinglines.

Prior cargos

Cleaning material residues Pump suctions including deep well pump cofferdams.

Vent and inert gas lines.

Unbroken blisters in epoxy coated tanks Flaking or broken blisters of the coating

Discolouration of tank coating

Sea water residues

Polymerised materials

The above list is not exhaustive and, in particular, epoxy coated tanks have the propensity to absorbcargo during a loaded passage. Depending on the previous cargo, subsequent desorption may takeweeks or months to desorbed or be extracted by a subsequent solvent cargo and the potential forcontamination remains. As examples, both styrene monomer and ethylene dichloride are known to be

slow to be desorbed from epoxy coated tanks. This phenomenon has been well documented duringrecent years and avoidance of risk depends on proper cargo sequencing and is outside the remit of the

cargo inspector. It is commented on in this section for information only.


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9.2 Tank Cleaning Information

Cargo inspectors are not responsible for the preparation and cleaning of cargo tanks prior to loading.

This is entirely the responsibility of the vessels owners and crew. Inspectors should not offer advice tothe crew in the event that cargo tanks are not ready to load, other than to give reasons why the tank hasbeen rejected.

Cargo inspectors are responsible for inspecting cargo tanks for visual cleanliness and for chemical

cleanliness in cases where final acceptance is subject to wall wash testing. These guidance notes maytherefore assist the inspector in forming a judgement.

Chemical cargoes have a low tolerance to contamination and it is common for various tank cleaningchemicals / detergents to be used during tank washing. Chemicals and cleaning agents may have anaffect on the cargo to be loaded.

9.2.1 Tank cleaning operations

In common with all other bulk liquids, the most common tank washing material is sea water.Depending on the previous cargo, the water may have to be applied at elevated temperatures. The crew

will take note of any restrictions recommended by the tank coating manufacturers and, in some cases,notably volatile water miscible chemicals water washing cannot be started until the tank has beenventilated to a visible dry state. This may take several days and is necessary because the reaction ofwater to certain chemicals will result in the formation of acidic compounds.

Some of the more commonly carried chemicals (e.g. methanol and ethylene glycol) cannot tolerate thepresence of chlorides therefore all salt water washing must be followed by a fresh water wash. Indeed,

the quality of fresh water in sufficient quantities for tank cleaning varies at different locations and it isusually the case that ordinary fresh water alone will not be sufficient to render the tank chloride free.Washing with de-ionised water will usually be required.

Following water washing, it is likely that a range of chemical additives will be used depending on theprevious cargo. Inspectors are reminded that chemical tankers, particularly those in the parcel tanker

trade, are likely to have carried other products such as animal and vegetable oils, caustic soda solutionand molasses as previous cargoes. The following list of generic chemicals is noted.

(a) Degreasing solvents used when previous cargo is a lube oil additive or other petroleum basedproduct.

(b) Alkaline detergents used to help removal of animal and vegetable oil residues.(c) Diluted phosphoric acid used to improve the appearance of organic coatings. This is of

cosmetic value only and will help to remove visual rust stains caused by pitting or mechanicaldamage.

(d) Hydrocarbon free additives. This may be used when, for example, the next cargo is one thatwill not tolerate hydrocarbons at any level such as methanol.

(e) Strong alkaline products used when hard to remove drying oils were previously carried.(f) Bleach Solutions (Sodium Hypochlorite). Diluted solutions are used to remove odour and will

assist in removal of colour staining. This is sometimes present when the vessel has carried acargo of dyed petroleum products. It also assists in neutralising oxidising agents that may

originate from an earlier cargo.(g) Chlorinated solvents. These are used following some noxious or poisonous cargoes such as

iso-cyanates.

(h) Spraying with MEK or Acetone. Used mainly to get rid of hydrocarbon traces.

Application of most of the above is either by circulation through the tank washing or butterworth linesor by spraying with a barrel pump.

Inspectors are advised that most tank cleaning chemicals, except mild detergents, will cause cargo

tanks to be unsafe for entry without the necessary respiratory masks and all tanks will require thoroughremoval with fresh water and/or deionised water following use.

Inspectors should avoid tank entry unless tanks have been gas freed (See enclosed space Section 4.5)


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It is common for chemical tankers to be equipped with deep well pumps and it is normal practice forthe cofferdams around the pump suctions to be purged with air or inert gas immediately prior toloading. This purging operation may reveal the presence of hydraulic oil or previous cargo and

inspectors should witness or confirm this operation has been undertaken.

9.3 Tank Inspection Guidelines

Reference has been previously made to the low level of contamination tolerance of petrochemicals toother materials that may have been carried aboard a vessel. Tank inspections by the cargo inspectortherefore require a considerably enhanced level of scrutiny than would be the case with, for example,

clean petroleum products and tank entry is most often needed.

Prior to inspecting tanks, inspectors should obtain details of, at least, the previous three cargoes (or

preferably five cargoes) carried in each cargo tank and full details of the cleaning methods employedby the crew following each cargo discharge. These details should be included in the inspectors final

report.

There are three main aspects to a pre-loading cargo tank inspection and these are discussed as follows.

9.3.1 Internal Inspection of Tank Surfaces

Chemical tankers will clean the cargo tanks and associated pipeline systems prior to arrival at the loadberth.

Special attention should be paid to the condition of the tank coating in the case of epoxy coated tanksand, in particular, to the presence of blisters and flaking of the coating. Unbroken blisters may containresidues from an earlier cargo as will loose or flaking coating. Depending on the charterer or shipper

requirements, the inspector may be asked to estimate the percentage of coating missing or damaged.Reference to the vessels previous cargoes can have a bearing on the further action required from thecrew when determining the likely effect the condition of the coating might have on the cargo to be

loaded.

Attention should also be paid to the cargo tank, pipes, drop lines, pump casings, suction wells and

heating coils. These items can form shadow areas and often receive less than adequate attention duringtank washing.

Inspectors cannot, of course, visually inspect the internal condition of pipelines for their full length andthe inspection report should clearly state the applicable limitations. Vent and inert gas lines are usuallyvisible at the tank entry point and could contain prior cargos, polymerised material, or washing

residues, that if present, could contribute to contamination. Deck lines will have drain points and these

should be opened in case residues from tank washing operations or prior cargos are present.

9.3.2 Wall Wash Sampling and Testing

Chemical Tankers operate normally subject to switch loading between a very large number of highpurity cargoes have no tolerance to contamination from earlier (prior) cargoes.

Because of the sensitive nature of certain chemical cargoes, the standard visual tank inspection of thesurfaces may not be sufficient to ensure freedom from risk of contamination and acceptance proceduresmay require further testing of wall wash samples.

Wall wash techniques require random washing of tank surfaces over small areas (usually about 1

sq.mtr), either with a sample of the cargo to be loaded or, more commonly, with a laboratory grademethanol (similar solvent) sample.


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The purpose of washing small, but representative areas of the tank walls is to identify by chemicalanalysis, trace amounts of materials that may be detrimental to the cargo. Such contaminants (if any),

may have originated from the immediately tank cleaning materials or previous cargo or may havesurvived through additional intermediate cargoes. This is particularly the case where cargo tanks areepoxy coated.

The further purpose of taking and analysing wall wash samples is to allow cargo inspectors, their

principals and cargo interests, to make a reasoned judgement of the likely effects of any contaminantsdetected in the sample on the total quantity of cargo to be loaded in the tank. Refer to API/MPNS

17.8

The most common method of taking a sample is to choose an area(s) of the tank wall about 1 metrewide and about 2 metres from the bottom of each tank. A sample of laboratory grade methanol or, in

some cases, of the cargo to be loaded is cascaded over the surface of the tank either directly from abottle or from a spray bottle where it is allowed to run down the surface. The run down is thencollected in a bottle held at a about 1 metre below by use of a flat sided funnel. An alternative method

is to allow the cascaded liquid to run over and be absorbed by filter papers. The filter papers are thentransferred to a bottle before being tested. Wall wash sampling is easier if there are two inspectors

available.

Current recommendations for sampling are noted under:

Tank surfaces must be dry.

Discoloured or broken coating sections on tank walls should be sampled as follows: (a)Where such areas are less than 20% of total surface area (excluding deckheads), the washingsshould be included with those of the rest of the tank.

Non typical areas should be sampled and tested separately.

Samples should be tested in a shore based laboratory. The minimum number of areas to wall wash depends on the tank capacity.

Tank capacity less than 500 cubic metres 5 areas

Tank capacity 500/1000 cubic metres 7 areasTank capacity greater that 1000 cubic metres 9 areas

Inspectors should be aware that wall wash sampling procedures may cause a previously gas free tank todevelop an unsafe atmosphere and personal protective gear should always be worn and breathing

apparatus may be required.

9.4 First Foot Loading and Sampling

There are limitations on the extent to which inspectors can visually inspect all parts of the loading

system, vessel and shore, and should inquire about the steps taken by the vessel and the terminal toavoid or reduce the risk of contamination.

Loading/discharge manifolds, vents, and inert gas lines can only be inspected where visuallyaccessible. Extensive areas of the pump and piping systems can only be assessed on the basis ofinformation obtained from the Chief Officer in respect of tank cleaning operations and previous

cargoes.

Prior to loading first foots, an initial shore line sample should be drawn and visually examined to

ensure the cargo is clean and bright and free of suspended matter.

Subject to wall wash tests (where applicable) and receiving laboratory clearance, the vessel will then be

able to start loading first foots.

First Foot samples are required to determine whether any contaminants within the vessels loading

systems have survived cleaning regimes that might have a detrimental effect on the cargo to be loaded.


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9.5 Cargo Tank Coating Suitability

The following notes are provided to assist cargo inspectors in understanding potential contaminationproblems that may arise with chemical cargoes.

Zinc silicate, phenolic epoxies and pure epoxies are the most commonly used generic coatingsystems in cargo tanks for the carriage of chemicals.

They vary in their resistance to cargoes and all have limitations in carriage.

The principal limitation in the use of zinc silicates is that they are only suitable in a narrow pHrange of approximately 5.0 to 9.0.

Phenolic epoxies are generally able to carry a wider range of low molecular weight cargoes andhave a higher free fatty acid resistance

The cargo resistance of coatings of the same generic type can vary between manufacturers and,hence, the manufacturers Resistance Lists usually available aboard the vessel should be consulted

should there be any doubts as to suitability of any particular cargo.

Some coatings are temperature sensitive. Cargo carriage requirements may require heating, andtemperature control should match the coating operability range.

Organic epoxy coatings have the propensity to absorb cargoes during a loaded passage. Thecontamination potential to a subsequent cargo is therefore considerable as:

large quantities can be retained the amount retained after different time periods is not well defined

variable absorption/desorption characteristics are found between different coating types

variable absorption/desorption characteristics are found within the same generic types from

different manufacturers. Different rates of absorption/desorption are found between different cargoes

Factors such as coating thickness, temperature and tank cleaning also have an influence onabsorption and desorption.

With some chemical cargoes, absorbed material can survive both further intermediate cargoesas well as extensive tank cleaning operations

9.6 Loading Shore Tank

9.6.1 Prior to attendance at a loading terminal, inspectors should familiarise themselves with allavailable information on the product to be loaded. Such information should be available

in the form of a Material Safety Data Sheet

9.6.2 Before loading from a shore tank, representative samples should be drawn and, whereinstructed to do so by the principle, tested against specification.

9.7 Pipelines

Owing to the very large number of chemicals shipped, use of dedicated and/or non-dedicated pipelines,

it is not possible to provide specific quality control loading procedures in this section for each product.The level of quality control is dictated by end use requirements and inspectors should be guided byprocedures at a loading terminal and any special instructions from their principals/clients. To ensure the

product is transferred without contamination to the ships tanks, it is recommended that samples aredrawn from key points along the pipeline system and, in particular, at the point of custody transfer(normally ships manifold).


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Although there may be some exceptions, chemical tankers will normally be equipped with deep wellpumps and each tank will have its own pump. Barges maybe equipped with deep well pumps or deckmounted pumps.

To ensure the product is received without contamination it is recommended that samples are drawnfrom key locations from the vessel hoses, lines, and accessorial equipment at points in loading process

such as first foot samples.

In the event of any sample not meeting the specification, the principles should be contactedimmediately.

9.8 Discharge Port

9.8.1 The procedures described in the foregoing sections for the load port will, to a large extent, bemirrored at the discharge port and are therefore only summarised here. The contents of all shore tanks

and associated piping nominated to receive the cargo should be sampled and may be tested perrequirements of the principal/clients specifications.

9.8.2 Samples from each ships tank should be drawn and may be submitted for testing. Samplesfrom the load port should be collected and retained by the inspector , an authorised representative of thereceiver, or a set of samples reserved for the consignee left on board the vessel. Details of load port

samples should be recorded by the inspector including the location where they are stored.

9.8.3 In some instances a line flushing exercise may be undertaken at the dock side and / or tank

side, samples drawn and analysed. In all cases, a sample should be drawn at the dock manifoldimmediately after the start of discharge.

9.8.4 In the event that discharge takes place to barges or other lightering vessels, proceduressections 9.0 are to be followed.

9.9 Sample Retention

All samples drawn or collected should be retained in a suitable storage in line with principalsrequirements.


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10. FINAL REPORT

On completion of a cargo inspection, a final report should be compiled. The format of this report

depends upon any agreement reached between the various interested parties. In any event, it isrecommended that a summary sheet is prepared which should include full details of ship and shore

cargo quantities. Notwithstanding the extent of the final report, it is recommended that a copy of alldocumentation completed and retrieved during the inspection be retained on file for further reference.For the sake of consistency in reporting, it is suggested that a final report may contain the followinginformation.

a) Summary report: including Bill of Ladingquantity, outturn difference, ship/shore differences(including adjustments by VEF), in-transit variation, change in OBQ/ROB, free water, etc.

b) Time log.c) Quantity report (including reference height report).d) Analysis report

e) Vessels ullage report.f) Vessels OBQ/ROB report.g) VEF report

h) Slops Report.i) Ballast/void space report

j) Bunker reportk) Sample reportl) Meter proving report

m) Auto Sampler Performance Reportn) Line verification (API 17.6)

Copies of Letters of Protest, Notices of Apparent Discrepancy and salient supplementary

documentation should be attached to the report.A General Note on Operations highlighting any special operational problems that may have beenobserved either aboard the vessel or ashore.

api procedure for inspection of chemical cargo by inspectors

Documents