CODE OF PRACTICEF O R

FOSSIL-FUEL BOILERS

Boilers and PressureVessels AuthorityHong Kong2 0 0 2

(Issued under Section 18A of theBoilers and Pressure Vessels Ordinance)

CONTENTS

P a g e

I n t ro d u c t i o n

Chapter 1 General 1

Chapter 2 Essentials of Fossil-fuel Boilers 1 0

Chapter 3 Operation of Fossil-fuel Boilers 1 9

Chapter 4 E m e rgencies 2 7

Chapter 5 Maintenance 3 1

Chapter 6 F i re Precautions, Fire Fighting and Equipment 4 0

Chapter 7 Accidents and Defects 4 7

Appendix I Typical Fossil-fuel Boiler 4 9

Appendix II C e rtificate of Competency 5 4

Appendix III Blowing of Water Level Gauge 5 6

Appendix IV Basic Knowledge of Combustion 5 8

Appendix V Basic Knowledge of Electricity 6 1

Appendix VI Quoted References on Statutory Provisions 6 3

INTRODUCTION

I. The Boilers and Pressure Vessels Ordinance, Cap. 56, sets out the provisions relating to the control, use and operation of boilers and pressure vessels. Someof these provisions, and some other relevant statutory provisions, are highlightedor summarised in this Code of Practice (see Appendix VI). The statutoryprovisions referred to in this Code are provisions in force on 15 November 1994.

II. This Code of Practice is issued in pursuant to section 18A of theOrdinance for the purpose of ensuring acceptable standards in the design,manufacture, installation, maintenance, examination, testing and operationof all fossil-fuel boilers. The terminology used in this Code conforms tothe Boilers and Pressure Vessels Ordinance, Cap. 56, and its subsidiaryR e g u l a t i o n s .

III. Under section 18A(2) of the Ordinance, any person who fails to observethe provisions of this Code shall not render himself liable to criminalproceedings of any kind, but any such failure may, in any proceedingswhether civil or criminal and including proceedings for an offence underthe Boilers and Pressure Vessels Ordinance, be relied upon by any party tothe proceedings as tending to establish or to negative any liability which isin question in those proceedings. However, failure to observed statutoryprovisions, including the provisions of the Boilers and Pressure Ve s s e l sOrdinance, may be an offence under the relevant Ordinance orR e g u l a t i o n s .

I V. These steam boilers must be operated safely and dependably and remainserviceable for years, with cleaning and maintenance for the most partbeing undertaken during pre-planned maintenance periods. The safety anddependability built into modern boilers is by rigorous compliance of allmaker's instructions, relevant codes and standards for regulation design,fabrication and inspection of the boilers and their auxiliary equipment.

V. All references to the "Authority" in the Code refer to the "Boilers andPressure Vessels Authority".

VI. The Boilers and Pressure Vessels Authority, currently the Commissionerfor Labour, has delegated certain powers under the Ordinance to thePrincipal Surveyor of the Boilers and Pressure Vessels Division, LabourDepartment. Enquiries may, therefore, be directed to the PrincipalSurveyor or his staff .

Boilers and Pressure Vessels Authority

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CHAPTER 1

GENERAL

Current Legislation

1.1 Provisions are made in law to control the use and operation ofboilers and pressure vessels, to provide for the holding ofinquiries into accidents in or to boilers and pressure vessels and toprovide for all other connected matters. This is through:-

(a) Boilers and Pressure Vessels Ordinance, Cap. 56;

(b) Boilers and Pressure Vessels Regulations;

(c) Boilers and Pressure Vessels (Forms) Order; and

(d) Boilers and Pressure Vessels (Exemption) (Consolidation)Order.

Copies of the above can be purchased from any of theGovernment Publications Sales Centre.

Powers of the Authority and the Authorized Officers

1.2 The Authority may authorize any public officer to perform orexercise all or any of the functions, duties and powers which areimposed or conferred on the Authority or an authorized officer. Inthe discharge of the above legal responsibilities, the Authorityand the authorized officer shall have the following powers:-

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(a) at any time to enter any premises or place in which heknows or has reason to believe that there is a fossil-fuelb o i l e r ;

(b) at any time, to examine and test any fossil-fuel boiler andits auxiliary equipment;

(c) to require the production of any Certificate or Certificate ofFitness concerned with the fossil-fuel boiler and to makecopies of the same; and

(d) to make such examination and inquiry as may be necessary.

Registration of a Boiler

1.3 The owner of a new boiler shall, not less than 30 days before heintends to put the boiler into use, deliver to the Authority:-

(a) one copy of the maker's certificate and one copy ofthe certificate of inspection during construction issued inrespect of the fossil-fuel boiler by a recognized inspectionbody; or

(b) documentary evidence, to the satisfaction of theA u t h o r i t y, that the fossil-fuel boiler complies with arecognized engineering standard or code in respect of:-

(i) the welders employed and welding procedures usedin the construction and erection of and, if repairshave been carried out, in the repairs to, the fossil-fuelb o i l e r ;

(ii) heat treatment before and after welding;

(iii) tests and inspections carried out on the fossil-fuelb o i l e r ;

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(iv) kind and grade of material used in the pressure partsof the fossil-fuel boiler;

(v) any other relevant technical details that the Authoritym a y, by notice in writing, specify; or

(c) where the owner cannot deliver either thedocuments referred to in paragraph (a) or the documentsreferred to in paragraph (b), details of the design andmethods of construction, inspection and testing of thefossil-fuel boiler and its auxiliary equipment.

1.4 All above documents must be endorsed by a Boiler Inspector tothe effect that they relate to the equipment under registration. TheBoiler Inspector shall determine the maximum permissibleworking pressure for the equipment and state that in thedocuments accompanying the application of registration. Where adocument is not written in English or Chinese, it should beaccompanied by an English or Chinese translation. If thesedocuments are not produced or do not give the Authoritys u fficient information to enable him to assess the maximumpermissible working pressure, he may require the owner to havethe fossil-fuel boiler surveyed by a Boiler Inspector at Owner'sexpenses for collecting manufacturing and other details requiredin the preparation of documents for registration of the boiler.

1.5 On completion of the necessary formalities described in the aboveparagraphs the Authority will register the fossil-fuel boiler andallot a registration number which must be e n g r a v e d by the ownerin a conspicuous position on the equipment before it is put intou s e .

1.6 Forms of application for registration can be obtained free fromthe Boilers and Pressure Vessels Division of the LabourD e p a r t m e n t .

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C e rtificate of Competency

1.7 The Authority may, upon application in writing, together withdocumentary evidence or by passing an examination conducted bythe Authority and upon payment of a prescribed fee, issue aCertificate of Competency to any person who satisfies him of hissuitability to operate fossil-fuel boilers.

1.8 Incorrect operation of fossil-fuel boiler and its fittings can causeaccidents resulting in injury or loss of life.

1.9 The Ordinance requires that a Competent Person must be presentat all times to directly supervise the operation of the fossil-fuelboiler to ensure safety in its operation. An employer shouldarrange for additional persons to receive the necessary trainingand to obtain Certificate of Competency so that such persons canstand in as a relief person during the absence of the boilero p e r a t o r. In no circumstances whatsoever should a fossil-fuelboiler be operated without a competent boiler operator.

1 . 1 0 The Competent Person who operates or supervises the operationof fossil-fuel boilers must be in possession of a valid Certificateof Competency issued by the Authority. Appendix II lists theequipment which holders of different Certificates of Competencycan operate.

Periodic Examination

1 . 11 All fossil-fuel boilers must be properly maintained in accordancewith provisions laid down in the Ordinance and its SubsidiaryRegulations and must be examined periodically by a BoilerI n s p e c t o r. The interval between examinations for most fossil-fuelboilers is 14 months.

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C e rtificate of Fitness

1.12 If the Boiler Inspector is satisfied with the condition of thefossil-fuel boiler which he has examined, he should issue aCertificate of Fitness for the same on a prescribed form anddeliver two copies of this certificate to the owner. The ownermust then deliver the two copies of this certificate to theAuthority within 7 days. The original Certificate of Fitnessmust be kept in the premises where the fossil-fuel boiler isi n s t a l l e d .

1.13 An equipment can be operated only when its Certificate ofFitness is still valid.

C l o s u re Order

1.14 The Authority may, by notice in writing served upon theo w n e r, issue a closure order to prohibit further use of apressure equipment where it appears that:-

(a) a boiler or any of its auxiliary equipment is not, or maynot be, in safe working order;

(b) a boiler or any of its auxiliary equipment has not beenexamined or tested in accordance with this Ordinance;

(c) a boiler is being, or has been operated at a pressuregreater than its approved maximum permissible workingpressure; or

(d) the seal attached to a safety valve by a Boiler Inspectorhas been broken or the setting of a safety valve has beenaltered by a person who is not a Boiler Inspector.

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1.15 Upon receiving the closure order, the owner and the operator muststop using the boiler immediately and rectify the faults for whichthe closure order is issued. The owner should engage a BoilerInspector to thoroughly examine the equipment and issue a freshCertificate of Fitness. This Certificate of Fitness should beproduced to the Authority, who will permit the resumption of theuse of the equipment concerned.

Sale, Hire or Removal of Appliances

1.16 If a fossil-fuel boiler is hired or sold, the owner must notify theAuthority within 7 days of the name and address of the person towhom it has been hired or sold, and must report whether the saleor hiring involves removal.

1.17 Any fossil-fuel boiler which has been removed either to newpremises or to another part of the same premises must beexamined by a Boiler Inspector before it is put into use again. Theowner should also notify the Authority the new installationa d d r e s s .

1.18 The owner of a registered fossil-fuel boiler must notify theAuthority within 7 days if he changes his address.

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.15 Upon receiving the closure order, the owner and the operator muststop using the boiler immediately and rectify the faults for whichthe closure order is issued. The owner should engage a BoilerInspector to thoroughly examine the equipment and issue a freshCertificate of Fitness. This Certificate of Fitness should beproduced to the Authority, who will permit the resumption of theuse of the equipment concerned.

ale, Hire or Removal of Appliances

.16 If a fossil-fuel boiler is hired or sold the owner must notify theAuthority within 7 days of the name and address of the person towhom it has been hired or sold, and must report whether the saleor hiring involves removal.

.17 Any fossil-fuel boiler which has been removed either to newpremises or to another part of the same premises must beexamined by a Boiler Inspector before it is put into use again. Theowner should also notify the Authority the new installationaddress.

.18 The owner of a registered fossil-fuel boiler must notify theAuthority within 7 days if he changes his address.

Examination after Extensive Repairs

1.19 If extensive repairs have been carried out to a boiler or to itsauxiliary equipment, fittings and attachments, the boiler mustbe examined by a Boiler Inspector and issued with a Certificateof Fitness before being put back into use. Extensive repairsmean any repairs that affect or may affect the structure of theboiler and include alterations or welding repairs to thepressure parts of the boiler or its controls and safety devices.

Accidents

1.20 If an accident occurs to a boiler or its auxiliary equipment or ifthe owner becomes aware of any defect that is likely toendanger life or property, he must at once take the equipmentout of use and notify the Authority of the accident or defectwithin 24 hours. A copy of the latest Certificate of Fitness mustbe sent to the Authority at the same time together with detailedinformation about the equipment and the accident or defect.(See Chapter 7 of this Code).

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O ffences and Penalties

1.21 The Ordinance and the Regulations set forth penalties for variousbreaches as briefly summarized under.

Section 15AFailure to submit application for registration.Maximum fine:- $10,000 [ Level 3 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

Section 22Failure to ensure the proper maintenance of a boiler or a pressurevessel and its auxiliary equipment.Maximum fine:- $25,000 [ Level 4 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

Section 49(1)Operating boiler/pressure vessel not having been examined inaccordance with the Ordinance.Maximum fine:- $50,000 [ Level 5 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

Section 49(4)Operating boiler/pressure vessel at a pressure greater than itsmaximum permissible working pressure.Maximum fine:- $50,000 [ Level 5 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

Section 49(6)Failure to comply with prohibition order issued by the Authority.Maximum fine:- $50,000 [ Level 5 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

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Section 49(7)Operating boiler/steam receiver without the direct supervision ofcompetent persons.Maximum fine:- $50,000 [ Level 5 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

Section 55(1)Utters or makes use of any notice, form or document knowing thesame to be forged or false.Maximum fine:- $10,000 and imprisonment for 12 months.

Section 56Corruptly solicits or receives any advantage whatsoever as aninducement for certification of forbearing to make any report ornotification required to be made under the Ordinance.Maximum fine:- $50,000 and imprisonment for 5 years.

Regulation 4(1)(a)Steam receiver not fitted with suitable steam reducing valve.Maximum fine:- $10,000 [ Level 3 of Schedule 8 of CriminalProcedure (Amendment) (No. 2) Ordinance, 1994 ]

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CHAPTER 2

ESSENTIALS OF FOSSIL-FUEL BOILERS

Basic Principle

2.1 Generation of steam in a closed vessel causes an increase inpressure due to a large increase in volume following a liquid-to-gas phase change. This process accompanies an increase intemperature of the water and the generated steam.

2.2 Design pressure is maintained while maintaining designed waterlevel with a steam space above it, and controlling steam generationto balance steam flow from the boiler.

2.3 Water must be continuously supplied for the steam generation. Forall input conditions, water pressure and temperature at inlet remainnearly fixed. The heat input to the boiler is through the combustionof fossil fuel - coal, oil or gaseous fuel.

Types of Boiler

2.4 The demand for steam for power generation as well as industrialprocesses is continuously increasing. Steam boilers now cover awide range - from those required to run a laundry to the veryl a rge ones used in electric power generation. Some of the recentboilers installed in Hong Kong deliver approximately 2,000tonnes of steam per hour and consume 1.90 million tonnes ofcoal per year per unit. Steam pressures and temperatures can be ashigh as 163 kg/cm 2 (2,400 psi) and 538ºC (1,000ºF) respectively.

2.5 In general, fossil-fuel boilers are of two main types:-

(a) The Fire-tube or Shell Boiler; and(b) The Wa t e r-tube Boiler.

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F e a t u res of Fire - Tube boiler

2.6 Fire-tube boilers are potentially dangerous as the steam pressuresare high and the volume of hot water and steam content is larg e .Features normally include:-

(a) water surrounds the tubes through which hot combustiongases pass before venting to atmosphere through gasu p t a k e s .

(b) water converted into high pressure steam by transfer of heatfrom the very high temperature combustion gases.

(c) hot combustion gases produced by burning diesel oil, towngas etc. in the furnace.

(d) designed for automatic control.

(e) essential mountings include safety valves, pressure switches,pressure gauges, water level gauges, valve fittings, low-water level cut-off and alarm devices etc.

2.7 There have been various designs and makes of the fire-tube boilere.g. Vertical Cross Tube Boiler, Cochran Boiler, Vertical Dry To pB o i l e r, Scotch Marine Boiler, Horizontal Return Tube Boiler andPackaged Boilers. Packaged Boilers are completely self-containedunits and are the latest development of the Scotch Marine Boiler.These boilers are factory assembled, tested and adjusted. Figure 1illustrates one of these units. Each unit has electrically driven feedand fuel pumps, forced draught fan, combustion equipment,operating and safety control equipment for manual or automatico p e r a t i o n .

Figure 2 indicates a typical feed water system and Figure 3 showsa typical fuel oil system commonly used for fire-tube boilers.These systems are also applicable to water-tube boilers with somevariation or extra auxiliary equipment/fitting.

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F e a t u res of Wa t e r- Tube Boiler

2.8 Wa t e r-tube boilers provide for better water circulation, moreheating surface and reduced explosion hazard. A basic water- t u b eboiler is illustrated in figure 4. Feature normally include:-

(a) hot combustion gases surround the tubes through whichwater/steam circulates.

(b) water is converted into high pressure steam, saturated orsuperheated, by transfer of heat from the very hightemperature combustion gases.

(c) hot combustion gases produced by burning coal, oil or gasin specially designed water cooled furnaces.

(d) designed for automatic control.

(e) essential mountings include safety valves, feedwaterc o n t r o l l e r, combustion control system, water levelc o n t r o l l e r, pressure and temperature controllers, and low-water level alarm and cut-off devices etc.

2.9 The water-tube boilers advanced considerably throughdevelopment of a design connecting the steam generating tubesdirectly to a steam separating drum and featuring the use of benttubes as against earlier straight tubes. Steam pressure and steamconditions also increased through adoption of steam reheating,regenerative feedwater heating and construction of larger boilersincorporating pulverized coal firing rather than the old fashionstokers that proved inadequate for modern highly forced boilers.The higher volumetric combustion rates and unit sizes ofpulverized coal firing units has been achieved through the use ofwater cooled furnaces. This technique eliminated the problem ofrapid deterioration of refractory walls due to slag, and reducedfouling of convection heating surfaces to manageable proportionsby lowering the temperature of the gases leaving the furnace.Figure 5 illustrates a modern water-tube boiler.

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We l d i n g

2.10 Fabrication of the pressure and non-pressure parts and theauxiliary equipment for modern units involves uniquemanufacturing methods and extensive use of diverse weldingtechniques. Welding is especially important in the construction ofboiler drums and pressure parts. Its development has facilitatedfabrication of pressure components of large size and greatfunctional capability. All pressure part welding performed onpower boilers and pressure components must be performed by"qualified welders" - persons qualified by competent authority orby a recognized inspection body in accordance with the qualifyingprocedure in a standard or code. Adherence to approvedprocedures through employing qualified personnel is fundamentalto safety and dependability. Another important means for ensuringquality of materials and fabrication is by means of non-destructiveexaminations e.g. radiography, ultrasonics, magnetic particle ordye penetrant...etc.

Fuel Burning Installation

2 . 11 The fuel burning installation consists of an air blower, a burnerand fuel supply. The air blower supplies air for combustion andp u rging before and after any combustion. The burner atomizes theoil fuel for ease of ignition and good combustion. The burner, ormore exactly nozzle, in a gas fired boiler does not atomize the gasbut provides a cone of flame of the designed length and angle foroptimum combustion.

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F i t t i n g s

2.12 Safety Va l v e

Every fossil-fuel boiler must have a spring loaded safety valveattached directly to the boiler separate from any stop valve andcapable of being sealed. The safety valve automatically preventsthe boiler from being operated in excess of i ts maximumpermissible working pressure and can give a visual/audible alarmto the operator should other alarm and automation systems fail.The capacity of the safety valve must be such as to be capable ofd i s c h a rging maximum boiler output with the stop valves shut andwithout causing any excessive increase in steam pressure.Permanent provision must be made for the hot effluent from thesafety valve to be d i s c h a rged safely when it blows.

2.13 Water Level Gauge

Every fossil-fuel boiler must be fitted with at least one water levelgauge of transparent material, or of such other type as theAuthority may approve, to show the water level in the boiler. Inthe case of glass tubular types, an efficient guard, for protection ofperson from injury by a burst glass gauge, shall be provided. Theguard should not obstruct reading of the gauge.

2.14 Low Water Level Alarm

This alarm shall give visual and/or audible warning signal in theevent of low water level in the boiler. The level at which the alarmis activated shall follow instruction by the maker or as advised bythe Boiler Inspector.

2.15 Stop Va l v e

Every fossil-fuel boiler must be fitted with a suitable stop valve.

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M i s c e l l a n e o u s

2.16 Air vent - should be fitted at the highest point of the boiler torelease air trapped inside the boiler during flashup or to preventcreation of vacuum during shutdown; and

2.17 Bottom blowdown or drain - should be fitted for blowdown duringoperation to remove precipitates or to empty the boiler for layup orwork to be carried out. Hot effluent from the blowdown should bed i s c h a rged safely.

Boiler Contro l

2.18 In manual control of a boiler, the operator must maintain a tediousconstant watch for the occurrence of any disturbance. Time isrequired for the boiler to respond to a correction, and this can leadto possible over-correction with further disturbance to the boiler.H o w e v e r, an automatic controller does not experience tedium and,once properly adjusted, will always make appropriate adjustmentsto minimise disturbances to the boiler and, therefore, willgenerally control the system more accurately and reliably.

2.19 Boiler control regulates the outlet conditions of steam flow,pressure, and temperature to their desired values. The quantities offuel, air and water are adjusted to obtain the desired outlet steamconditions. The control system has the function of "looking at" thedesired and actual values of the steam conditions and adjusting theamounts of fuel, air and water to make the outlet conditions matchtheir desired values. The controller can be manual with theoperator making the adjustments or it can be automatic using apneumatic or computerised system.

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Automatic Contro l s

2.20 Instruments and controls serve to assure safe, economic andreliable operation of the equipment. Boiler control systems forfossil-fuel boilers include:-

(a) boiler instrumentation.

(b) combustion control.

(c) steam temperature control.

(d) water level control.

(e) b u r n e r- s e q u e n c e - c o n t r o l .

Instrumentation System

2.21 Instruments and methods for measuring pressure, temperature,flow and the quality and purity of steam are essential in theoperation of a boiler. They range from the simplest manual devicesto the more complex measuring devices used to actuate theautomatic control of boilers and their auxiliaries.

2.22 The use of a pressure gauge for determining steam drum pressureis a statutory requirement. It has to be easily readable, calibrated inpascals or multiples of it, and have the approved maximumpermissible working pressure clearly marked in red.

2.23 In steam boiler practice, it is frequently desirable to knowaccurately the metal temperature of tubes in e.g. furnace walls,economizers, superheaters etc. Such measurements may be fordetermining safety of pressure parts or other causes and the use ofthermocouples is a very practical and reliable method of

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temperature measurement, which is used extensively.Thermocouples are particularly well suited for the measurement oftemperature at interfaces between successive layers of insulationor at other points inside the insulation.

2.24 Steam purity or quality, which depends on the application and is ofparticular importance to high pressure boilers, can be tested onsteam, condensate or boiler water using some or all of followingm e t h o d s : -

(a) Sodium tracer (flame photometry).

(b) Electrical conductivity (for dissolved solids).

(c) Throttling calorimeter (for quality).

(d) Gravimetric method (for total solids).

2.25 The facilities available at site should be checked and the relevantinstructions for the use of the equipment strictly complied with.

Automatic Sequence Contro l

2.26 This control permits start-up of burner equipment from a singlepush button or switch control. Burner control systems of varioustypes are now applied to almost all boilers to prevent continuedoperation of a boiler where a hazardous furnace condition couldexist and to assist the boiler operator in starting and stopping ofburners and fuel equipment. The most important burner- c o n t r o lfunction is to prevent a furnace or pulverizer explosion, whichcould threaten the safety of operating personnel and possiblydamage the boiler. The capabilities of burner-control systems mustbe clearly understood by all personnel connected with the boilero p e r a t i o n .

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Flame Detection

2.27 A burner-control system must incorporate means of assuring thepresence or absence of flame on each individual burner regardlessof the type of fuel being burned. Ultraviolet (UV) flame detectorshave been successfully applied for all types of fuels. Flamemonitoring devices in current use are designed for on-off type ofoperation based on the presence or absence of the flame. Someplants today are using closed-circuit television to provide a meansof continuous furnace observation by the control room, and moreapplications are expected in future.

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CHAPTER 3

OPERATION OF FOSSIL-FUEL BOILERS

General

3.1 The safety and dependability of boilers and their auxiliary equipmentrequires that they receive proper attention not only while they werebeing designed, manufactured and erected, but also, of equalimportance, while they are in service.

3.2 Good operation begins before equipment installation is complete. Itincludes the training of the operators as well as preparation for thestartup of the equipment.

3.3 The ideal time to become familiar with new equipment is during thepre-operational phase when the equipment is being installed andcommissioned and when the boiler has been shut down and openedfor periodic examination. All preliminary operations for testing fans,pumps, fuel burning equipment, or for cleaning, drying, boiling outand blowing steam lines should be performed by experiencedoperators, working under the supervision of an appointed BoilerInspector or a person authorized/approved by the Authority. Suchpersonnel have the knowledge and experience to ensure the safeoperation of equipment by correct adjustments of controls, interlocks,fuel burning equipment and operating procedures.

3.3A All operational data during the running and operational period of afossil-fuel boiler should be recorded for reference. These recordbooks should be kept by a responsible person for as long aspracticable, otherwise be kept for a continuous period of the recent 3years or since registration and put to use.

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Preparation for Startup

3 . 4 Every new boiler or any boiler that has undergone major repairs oralterations must be prepared for putting back into service throughvarious steps, such as inspection, cleaning, hydrostatic testing, pre-calibration of instruments and controls, auxiliary equipmentpreparation, refractory conditioning, chemical cleaning, steam linecleaning (blowing), safety valve testing and setting, and initialoperation for adjustments and testing.

Inspection

3.5 An inspection of the boiler and auxiliary equipment serves twop u r p o s e s : -

(a) it verifies the conditions of the equipment and

(b) it familiarizes the operator with the equipment.

3.6 The inspection should begin sometime during the construction orperiodic examination phase and continue until all items arecompleted. One item which shall not be overlooked during inspectionis the provision for expansion of steam lines, flues and ducts, sootblower piping, and drain piping. Temporary braces, hangers or tiesused during construction or examination must be removed.

Cleaning

3.7 Debris and foreign material which accumulate during shipment,erection, or repair should be removed. Debris on the waterside canrestrict circulation or block drain lines. Debris on the gas side canalter gas or air flows. Combustible material on the gas side can ignite

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Preparation for Startup

.4 Every new boiler or any boiler that has undergone major repairs oralterations must be prepared for putting back into service throughvarious steps, such as inspection, cleaning, hydrostatic testing, pre-calibration of instruments and controls, auxiliary equipmentpreparation, refractory conditioning, chemical cleaning, steam linecleaning (blowing), safety valve testing and setting, and initialoperation for adjustments and testing.

nspection

.5 An inspection of the boiler and auxiliary equipment serves twopurposes:-

(a) it verifies the conditions of the equipment and

(b) it familiarizes the operator with the equipment.

.6 The inspection should begin sometime during the construction orperiodic examination phase and continue until all items arecompleted. One item which shall not be overlooked during inspectionis the provision for expansion of steam lines, flues and ducts, sootblower piping, and drain piping. Temporary braces, hangers or tiesused during construction or examination must be removed.

Cleaning

.7 Debris and foreign material which accumulate during shipment,erection, or repair should be removed. Debris on the waterside canrestrict circulation or block drain lines. Debris on the gas side canalter gas or air flows. Combustible material on the gas side can ignite

and burn at uncontrollable rates and cause considerable damage.Glowing embers can be the source of ignition at times when ignitionis not desired. Fuel lines should be cleaned to prevent subsequentdamage to valves and the blocking of burner parts. Atomising steamand atomising air lines should be cleaned.

Startup from Cold

3.8 The following procedures should be followed when starting a fossil-fuel boiler from cold condition:-

(a) Read and be fully conversant with the detailed operatinginstruction for the boiler and its auxiliaries.

(b) Check the Certificate of Fitness (CF) for the boiler to ensurethat it has not expired and that the approved maximumpermissible working pressure (MPWP) is indicated on thepressure gauge by a red line.

(c) Shut the steam outlet stop valve and the blowdown/drainvalve.

(d) Open the air vent.

(e) Set the water level gauge valves/cocks to the normal operatingpositions (see Appendix III for reference).

(f) Feed water into the boiler as appropriate until the water levelis just below the half-gauge level.

(g) Check that the fuel supply is securely connected and there isno visual loose connection or fuel leakage.

(h) Set the heating at low firing rate.

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(i) Switch on the blower to purge the furnace for the periodrecommended by the maker or for at least 15 minutes. Theoperator should observe the uptake flap to ensure that adraught for purging, has been established in the furnace. Ifsuch flap is not provided, the operator should make use of theparticular boiler design to ensure that draught has beene s t a b l i s h e d .

(j) Switch on the oil fuel pump or the main gas supply and seethat fuel pressure is built up and the oil fuel is circulating (nocirculation is necessary for gas fuel). Confirm that there is nofuel leakage. If there is any leakage, shut down the boiler andarrange the repair before proceeding.

(k) Now the boiler ignition system may be switched to establish aflame inside the furnace, for raising steam at a low firing rate.The operator may choose to a use continuous firing method orintermittent firing method depending on the design and thepast operating experience of the boiler. Intermittent firing issafer but takes a longer time to raise steam. In many practices,intermittent firing is typically 10 minutes fire in every 20minutes, until steam is generated.

(l) If the ignition fails, repeat from step (i). However, if it fails toignite for several times, stop the fuel supply and purge thefurnace for the period recommended by the maker or for atleast 10 minutes. Examine the burner, the flame detector andthe fuel system such as fuel quality (e.g. is there watercontamination in the oil fuel). When everything is found ino r d e r, repeat from step (i).

(m) The boiler should be heated gradually to raise steam. Aftersteam has been coming out from the air vent for 3-5 minutes,shut the air vent. This waiting period is to ensure that all airtrapped inside the boiler has been driven out.

(n) The boiler may now be switched to high firing rate to bring the

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steam pressure to the working pressure which shall be lessthan the MPWP.

(o) Blow the water level gauge (see Appendix III for blowingprocedures) to see that the gauge is in proper working order.

(p) When the steam pressure has reached the working pressure,open the steam outlet stop valve gradually and cautiously. Ifhammering or any abnormal noise is heard along the steampipeline, do not open the stop valve any further. Instead, thestop valve should be closed to a 'cracked open' position (about1/2 turn open) to warm the pipeline. If possible, the pipelineshould be drained during this procedure. After warming thepipeline for a few minutes, the stop valve can be openedgradually and cautiously again until fully opened.

(q) The steam outlet stop valve should be fully open at all timesduring operation. Do not throttle the stop valve.

Duties of Competent Person

3.9 Boiler steam pressure must be maintained within close limits of theworking pressure. For a manual boiler, it is done by adjusting thefiring rate. For an automatic boiler, the operator should see that thefire is automatically switched ON or OFF at the prescribed pressure.In no case shall the MPWP be exceeded.

3.10 Boiler water level must be properly maintained. For a manual boiler,water is fed into the boiler from time to time to maintain the level atabout half-gauge. Too high or too low a water level must be avoided.For an automatic boiler, the operator shall see that water is being fedinto the boiler automatically at prescribed levels.

3 . 11 The operator should ensure a good reserve or a reliable water supply.The boiler must be shutdown in case of interruption in water supply.

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3.12 The water level gauge must be under continuous observation. When alow water level alarm or, in the case of automatic boiler, a low waterlevel cut-off is fitted, the operator must never rely solely on thesedevices. It may be too late if the operator takes action only when suchalarm devices are activated, not to mention if they are notfunctioning. The water level gauge should be tested by blowingthrough the cocks at least once in a watch. Appendix III contains thecorrect procedures for blowing a water level gauge.

3.13 The safety valve is an important safety device to prevent the boileroperating at an excess pressure and causing explosion. The safetyvalve can get jammed or stuck at times and should therefore be liftedto blow periodically by the easing gear, if fitted. This will ensure thatit remains free to operate.

3.14 The low water level alarm and the extra-low level cut-off deviceshould be tested periodically to ensure that it is functioning. This testcan be done, while the boiler is firing and before it takes up thenormal load, as follows:-

(a) switch off the feed water supply;

(b) isolate the water level float chamber and open its drain tolower the water level inside it;

(c) the alarm should operate and the cut-off device, if fitted,should switch off the fire;

(d) if the devices do not work at the prescribed water level, theboiler is to be shutdown and the devices to be repaired oradjusted; and

(e) when the devices have been functioning properly, bring thefloat chamber to normal, switch on the feed water supply andreset the boiler to resume normal operation.

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Water Treatment

3.15 The Competent Person must use the recommended sampling systemfor testing the boiler water quality. The correct dosage of watertreatment chemicals should be used as recommended by the boilermanufacturer or the supplier of the chemicals for the boiler watert r e a t m e n t .

The limits generally recommended for low pressure boilers of usualoperating pressure in the range between 0-15 bar are:-

Alkalinity to Phenolphthalein 50-300 ppm CaCO3

Chloride max. 300 ppm CaCO3

Phosphate 30-70 ppm CaCO3

Dissolved solids max. 1500 ppm

3.16 Boiler water and condensate should be regularly tested usingappropriate testing kit and following appropriate testing instructionsand procedures in accordance with maker's or chemical supplier'srecommendation. The test result records should be kept by aresponsible person for as long as practicable for reference, otherwisebe kept for a continuous period of the recent 3 years or sinceregistration and put to use.

3.17 The Competent Person must exercise extreme care when handlingchemicals for boiler water treatment since most of them are corrosiveand/or poisonous.

Fuel Burning Installation

3.18 The operator must ensure that there is no fuel leakage. Oil fuelleakage is detected easily. For gas fired installation, the operatorshould examine the joints for any gas leakage by applying soapsolution to the joints. The bubbles formed indicate gas leakage.Portable gas leakage detector of appropriate type should be used asfar as practicable.

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3.19 Fuel burner, filters and oil fuel pumps must be kept free of leakageand the detector, if fitted, should be cleaned periodically to avoidpossible false alarms and false cut-off .

Shutdown

3.20 The following procedures should be followed in a normal shutdowno p e r a t i o n : -

(a) Switch off the oil fuel pump or the main gas supply and isolatethe fuel supply.

(b) P u rge the furnace to drive away any residual combustiblevapour or gas.

(c) Shut the steam outlet stop-valve.

(d) Stop the feed water supply and shut off the feed water valves.

(e) Let the boiler cool down slowly. The operator should not drainall the hot water inside the boiler or feed in cold water in orderto accelerate cooling as undue thermal stress is created.

(f) When the boiler pressure has dropped to about 20 kPa oncooling, open the air vent carefully. It will prevent vacuumbeing created when steam inside the boiler condenses.

(g) The water remaining in the boiler may then be drained if theboiler is to be laid up for a considerable long time, say fewweeks. Care must be taken to discharge the hot water safely.

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CHAPTER 4

EMERGENCIES

General

4.1 Some common emergencies are discussed here. The most appropriateaction is through correct appreciation of the situation and usingoperator's knowledge of the boiler installation and its environment.

Electric Shock

4.2 Electric shock victims may be treated as follows:-

(a) DO NOT touch the victim;

(b) switch off the main power supply immediately;

(c) use an insulator e.g. dry plastic rod or dry stick, to removevictim's contact with the electrical live part. A pair of glovessuitable for electric work should be readily available for suchan emerg e n c y ;

(d) make the victim lie in a comfortable position;

(e) dial emergency service hotline 999;

(f) loosen the victim's clothing to ease breathing;

(g) cover the victim with blanket to keep him warm;

(h) if the victim shows any sign to vomit, help him to do so andclean him afterwards;

(i) it is not advisable to give the victim any kind of medicine butwait for the medical aid.

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4.3 Shutdown the boiler and report the incident to the Boilers andPressure Vessels Division of Labour Department. The boiler must notbe put into use again until instructed by the Authority.

Flame Failure

4.4 Any abnormal flame failure shall be dealt with as follows:-

(a) Never try to re-ignite the flame using the furnace heat andinjecting fuel into the furnace.

(b) P u rge the furnace for the period recommended by the maker orfor at least 5 minutes.

(c) Switch on the flame ignition system.(d) If the flame fails to establish, repeat from step (b).(e) On repeated failure to re-ignite the flame, secure the fuel

burning installation and, if necessary, the boiler.(f) Examine the burner, the flame detector and the fuel supply for

fuel quality etc. When everything is found in order, start fromstep (b) to ignite the flame.

Low Water Level and Extra-Low Water Level

4.5 Whenever low water level or extra-low water level is observed,switch off the power supply to the boiler i m m e d i a t e l y. Shut thesteam outlet stop valve and allow the boiler to cool. DO NOTimmediately feed water into the boiler to restore water level. Thecold water fed in may cause damage to the hot boiler or even anexplosion. Never rely solely on the low water level alarm or theextra-low water level trip. Blow the water level gauge to confirm thewater level. If the level observed was faulty and the true level isnormal, bring the boiler back to operation carefully. Otherwise, shutdown the boiler and inspect the boiler internally for any damage.Check the feed water system and repair as appropriate. Start up theboiler only after a satisfactory thorough examination of the boiler. Ifin doubt, call a Boiler Inspector to inspect the boiler.

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Excess Pressure

4.6 Boiler steam pressure must never exceed the approved maximumpermissible working pressure. If such a situation occurs, switch offthe fire immediately. If the safety valve has failed to blowa u t o m a t i c a l l y, lift the safety valve by means of the easing gear, iffitted, to release the pressure inside the boiler. Shut off the steamoutlet stop valve to prevent damage to the system by the excessivep r e s s u r e .

4.7 In the situation where the safety valve had failed to functiona u t o m a t i c a l l y, the boiler shall not be brought back to service againu n l e s s :

(a) the defect causing excessive pressure in the boiler is identifiedand rectified;

(b) the boiler shows no signs of leakage, structural damage ord i s t o r t i o n ;

(c) the system has been thoroughly checked; and

(d) the safety valve has been tested and reset correctly by a BoilerInspector and a new Certificate of Fitness issued.

4.8 The safety valve prevents the boiler from generating excess pressure.The operator must not rely soley on the safety valve but mustobserve the steam pressure continuously and take corrective action asn e c e s s a r y.

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Power Failure

4.9 In case the power supply to an individual boiler fails, the boiler mustbe shut down and a registered electrical worker called to trace thefault and repair the electric circuit. The operator shall not, unless heis also a registered electrical worker, attempt to repair the electricc i r c u i t .

4.10 The automatic control circuits should be checked from time to timeby a duly authorized person to confirm that they are functioningc o r r e c t l y.

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CHAPTER 5

MAINTENANCE

Preventive Maintenance of a Boiler

5.1 The capability of a boiler to operate safely is important and is bestachieved through "preventive maintenance" procedures. Preventivemaintenance includes a policy of operating a boiler installationproperly and within its designed range. It includes maintaining theinstallation in a clean and good engineering condition. Preventivemaintenance also provides for regularly scheduled shutdowns tomake the statutory and other examinations which are not possibleduring operation, and to enable the carrying out of necessary repairs.Preventive maintenance is more cost effective when comparingpossible alternative such as an unexpected breakdown or a seriousa c c i d e n t .

5.1A All maintenance and general repairs carried out on a fossil-fuel boilershould be recorded. These record books should be kept by aresponsible person for as long as practicable for reference, otherwisebe kept for a continuous period of the recent 3 years or sinceregistration and put to use.

5.1B All modifications, extensive repairs and repairs involved withpressure parts other than those involved with part replacement,carried out on a fossil-fuel boiler should be recorded and reported.These record books and reports should be kept by a responsibleperson for as long as practicable since the equipment was registeredand put to use.

In-service Maintenance

5.2 The first emphasis is on safe operation, the avoidance of conditionsthat could result in explosive mixtures of fuel in the furnace and theprotection of pressure parts to prevent excessive thermal stresses oroverheating, resulting in failure.

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Furnace

5.3 The prevention of a furnace explosion accords top priority because ofthe potential for personnel injury, the high cost of repairs and otheradverse economic consequences. Four items are of major importancein prevention of furnace explosions:-

(a) optimum operating procedures and OPERATOR TRAINING;

(b) optimum burner observation with prompt detection of flamef a i l u r e ;

(c) detection of unburnt combustibles in flue gases; and

(d) positive, immediate indication of the fuel-air relation at theb u r n e r s .

5.4 It is imperative that procedures and basic principles for safeoperation are clearly understood by the operators, even though fullyautomatic control may be used. The majority of furnace explosionsresult from failure to detect a loss of ignition, even though otherindicators, such as dropping boiler pressure, steam temperature, exit-gas temperature, show that fuel is either not being burned or is beingburned incompletely. This emphasizes the fact that nothing takes theplace of seeing the fire.

5.5 A "combustibles alarm" to indicate the presence of unburnedcombustibles in the flue gas is considered as a good back up forflame observation. The differential air pressure, between burnerwindbox and furnace, is an essential aid in purging the furnace andigniting the flame, and normal operation. It is an excellent guide inthe establishment of correct fuel-air relationship to prevent loss ofignition or the accumulation of unburned combustibles in and aroundthe furnace.

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Pressure Parts

5.6 A very important item of safety equipment is the boiler safety valve.Modern safety valves are highly dependable when properly installed,and their installation checked by a Boiler Inspector.

5.7 Next on the list of safety equipment is a reliable means to determinethat the boiler is filled with water to the correct level. Monitoring offeed water and boiler water conditions, as well as steam purity, areessential for any boiler operation. Thermocouples installed in thefurnace are an excellent guide to internal cleanliness of the boiler andcan be used as an indicator of the need for chemical cleaning.Reliable measurement of metal temperatures, gas temperatures andtemperatures of steam and water are necessary for safe operation andreasonable maintenance of the boiler installation.

Safety Valves

5.8 Safety valves on drum-type boilers are normally tested both for setpoint pressure and for the closing pressure. This requires that theboiler pressure be raised until the valve opens and relieves suff i c i e n tpressure for the valves to close.

5.9 The set point on each safety valve is normally checked, and adjustedif necessary, immediately after reaching full operating pressure.Safety valve seats are susceptible to damage from wet steam or grit.Cleaning of the boiler and blowing out the superheater and steamlines before testing safety valves is necessary.

5.10 High pressure safety valves are tested without permitting them toopen fully by:-

(a) using special gags to restrict valve lift and to close the valve assoon as it starts to simmer; and

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(b) using special calibrated hydraulic jacks or air operated motorsto open the valves while the boiler is operating at normaltemperature and pressure. The popping pressure is determinedby adding the effective jack pressure to the boiler pressure.

5 . 11 Testing of safety valves always requires caution. Safety valveexhaust piping and vent piping should not exert any excessive forceson the safety valve. High pressure safety valves cannot seal if theyhave damaged seats.

Hydrostatic Test

5.12 After the pressure parts are assembled but before the refractory andcasing are installed, a hydrostatic test at 1-1/2 times the boilerapproved maximum permissible working pressure is applied to allnew boilers and maintained for a sufficient time for the detection ofany leaks. Gags are used to prevent safety valve opening during thistest even when the valves are equipped with the special internal plugsoften supplied with high pressure welded valves. Blanks are ofteninstalled in flanged valves.

5.13 High quality water should be used for the hydrostatic test to preventinternal fouling and corrosion. Demineralized water or condensatetreated with 10 ppm of ammonia for control of acidity/alkalinity (pHvalue) and 500 ppm of hydrazine for control of oxygen should beused for all non-drainable superheaters and reheaters. A clear, filteredw a t e r, on the other hand, is suitable for components that will bedrained immediately after the hydrostatic test.

5.14 After the boiler is filled, hydrostatic pressure is applied usually by apump made specially for testing purposes. While water is beingpumped into the boiler and pressure gradually increased, continuousinspection is made to observe any leakage conditions that might needrepair or become dangerous. During hydrostatic testing, safetyprecautions must be observed and non-essential personnel kept fromthe test area.

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5.15 Test pressure must be held long enough, at least one hour, to allowminute leaks to be observed. Following this holding period, pressureis retained for an inspection period. Following inspection of the unitit is drained. The refractory, insulation and casing work arecompleted in areas left open for test inspection.

5.16 A final overall inspection should be made after completion of theabove work and before operation. Externally all components of theboiler must be checked for explosion clearances e.g. at platforms andwalkways constructed adjacent to external members that move withthe unit. Obscure corners must be examined for any blocking orloose items. Remove any combustible materials to eliminateexplosion hazard during initial firing. Clean all internal cavities ofdebris etc. and check all tubes for alignment, particularly tubes whichmight interfere with soot-blower operation.

5.17 Temperature plays an important part in hydrostatic testing. First, themetal temperatures and, therefore, water temperature should beabove the dew point temperature of the surrounding air to prevent theformation of condensate on the parts being tested. Condensateobscures and practically prevents the detection of small leaks.Second, the water temperature should be kept low enough so thatpressure parts can be touched and close inspections made. It shouldnot be so high that water escaping small leaks evaporatesimmediately or flashes to steam. Finally, no air should be trapped inthe unit during the hydrostatic test. As the unit is being filled, eachavailable vent should be open until water appears.

5.18 Any blanks, gags and plugs used during the hydrostatic test areremoved when the test is completed. Gags used with or without thehydrostatic plugs should not be applied until 80 to 90% of the setpoint pressure is obtained. Conversely, the gags are removed whenthe boiler pressure has been reduced to 80 to 90% of the set pointpressure. This procedure protects the seating surfaces of the valveand prevents excessive pressure on the valve stem.

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Periodic Examination

5.19 Every fossil-fuel boiler must be opened for statutory periodicexamination before expiry of its Certificate of Fitness. The boilershould be cleaned, defects should be repaired and all valves shouldbe stripped for inspection and overhauled. Safety valves, water levelgauges, low water level alarm and other automatic control devicesshall be tested in a test run in the presence of the Boiler Inspectorprior to the issue of Certificate of Fitness. The operator or the ownershould organize the overhaul work of the boiler for examination bythe Boiler Inspector.

Waterside Scale

5.20 Water contains different kinds of dissolved salts. Some salts formhard scale. Chemical treatment can largely reduce formation of hardscale but it is difficult to totally eliminate those hard scale formingsalts. Hard scale formed on the boiler interior surfaces and theheating element surface will not only reduce the heating eff i c i e n c ybut may also cause overheating of the boiler and choking of smalldiameter pipes/valves.

5.21 The operator should cause the boiler to be shutdown periodically forcleaning of the scale. The period should be in accordance with theboiler manufacturer's recommendation or after six months operation.

5.22 Scale formation can be minimized by adding chemicals into the feedwater to turn the heavy scale salt into non-adhering sludge. Thesludge is subsequently blown out. However, chemical methods maynot prove to be cost effective in small capacity fossil-fuel boilers.The operator must exercise extreme care when chemicals are handledsince most of them are either corrosive or toxic. The instructions bythe chemical manufacturer must be strictly followed. The operatorshould use appropriate types of chemical, in accordance with theboiler manufacturer's instruction.

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Chemical Cleaning

5.23 Waterside impurities can lead to boiler tube failures or to carry overof solids in the steam, resulting in superheater tube failure or turbineblade deposits. Oil, grease and paint will bake on boiler tubes andform heat transfer barriers, causing the tubes to overheat and fail. Innatural circulation boilers, oil can cause foaming, resulting incarryover and a false indication of water level. Silica can also formheat transfer barriers and, at the higher saturation temperatures, willvolatilize and carry over with the steam to form deposits on turbineb l a d e s .

5.24 To remove accumulations of oil, grease and paint, the naturalcirculation boiler is given a caustic and phosphate boil-out after thefeedwater system has been given a phosphate flush. This boiling outand/or flushing should be accomplished before operation. Afterboiling out and flushing are completed, products of corrosion stillremain in the feedwater system and boiler in the form of iron oxideand millscale. It is recommended that acid cleaning for the removalof this millscale and iron oxide be delayed until operations at fairlyhigh capacities have carried all loose scale and oxides fromfeedwater system to the boiler and results in a cleaner boiler.

Water Side Corrosion

5.25 Corrosion includes, for the purpose of this code, rusting, localizedpitting and erosion of metal parts of the boiler. Corrosion causeswastage of metal which will weaken structural parts of the boilerrendering it liable to structural failure.

5.26 Removing scale is a good means to minimize corrosion. The operatorshould take the opportunity of shutdown to inspect the boiler for anyserious corrosion, especially localized corrosion, during scaler e m o v a l .

5.27 When serious corrosion is observed, the operator or the owner shallcause the boiler be inspected by a Boiler Inspector and be suitablyr e p a i r e d .

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Fireside

5.28 Overheating of the furnace will cause change in the microstructure ofthe metal parts resulting in reduction of strength. The furnace orfiretubes may deform and even collapse.

5.29 The operator should ensure that the water level inside the boilers isalways normal to avoid overheating. Also, the operator should adjustfuel pressure or even change for a more suitable burner in order toprevent the flame from impinging on any part of the furnace.

Gas Side Corrosion

5.30 Fuel invariably contains impurities which are corrosive. Gas fuel isless corrosive but oil fuel contains sulphur which on combustioncombines with oxygen producing sulphur dioxide and sulphurtrioxide. Both sulphur oxides form acid with water vapour. Acid isextremely corrosive to the metal part of the fireside.

5.31 The operator should ensure that the fuel used is not contaminatedwith water. Water contamination may not only extinguish the flamebut also cause acid formation. The operator should use a low sulphurcontent fuel and maintain the exhaust flue gas temperature at boilerexit to the uptake above acid dew point, namely, 120ºC to preventwater vapour condensation inside the fireside.

Debris

5.32 Ash, soot and incombustible impurities can remain and deposit onthe furnace and fuel gas passages. The problem is more aggravatedwith oil fuel. Such debris will not only impede heat transfer but alsocause choking of the fuel gas passages. The efficiency of the boilerwill be reduced. In serious cases, the boiler may be choked allowingaccumulation of dangerous combustible vapour or gas as a result ofpoor purg i n g .

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5.33 The operator should periodically clean the fireside of any debris. Heshould always maintain the correct fuel to air ratio to prevent sootysmoke and to ensure complete combustion.

Salt Water Contamination of Oil Fuel

5.34 Salt water contamination of oil fuel has very serious consequence forthe boiler. Besides reducing the combustion efficiency andextinguishing the flame, sodium salt in the salt water will formglassy slag on the furnace surface. In many cases, the sodium slagpromotes high temperature formation of very corrosive vanadiumcompounds. The effect of the slag is not only to reduce heat transferor efficiency of the boiler but also to corrode the metal surface at fires i d e .

5.35 The operator must remove water in the oil fuel. He should allow theoil fuel to settle in the storage tank, especially on a fresh charge offuel, and to drain away the settled water at the bottom. If larg eamounts of water are found, the operator should stop using the fueland check with the fuel supplier. The contaminated fuel must beremoved and the storage tank be cleaned to remove any traces of waterand salt that may exist. The drained oil/water mixture should bedisposed properly and under no circumstances should the mixture bedisposed into the public sewer.

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CHAPTER 6

FIRE PRECAUTIONS, FIRE FIGHTING AND EQUIPMENT

Liquid Fuels

6.1 Liquid fuels evaporate at rates varying with the temperature. Themore volatile fuels are those which give off vapour more readily atlower temperatures. With appropriate quantities of air, these vapourscan form mixtures which will flash or explode if ignited. If ignitiontakes place inside a compartment there will be an explosion withdestructive results. The destructive ability of vapour mixtures canexceed that of many solid explosives; a cupful of gasoline has thepotential explosive power of 2.26 kg (5 lb) of dynamite.

Precautions

6.2 Precautions relating to the storage of liquid fuel generally aim ata c h i e v i n g : -

(a) The elimination of either liquid or vapour accumulationsoutside the oil fuel tank or pipe system in use.

(a) The exclusion of all sources of ignition from theneighbourhood of any position where vapour-air mixturesm a y.

6.3 Air vent pipes to oil fuel tanks should be fitted with flame arrestersconsisting of double wire gauze of fine mesh. They must be keptclean, especially from paint, to allow them to fulfil their purpose. Inthe boiler room no oil should be allowed to accumulate in the airboxes, furnace bottoms, or on the boiler room floor. If leakage from

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the oil fuel system to the boiler room occurs at any time, the oilsupply to that part of the system should be shut off immediately. Oil-tight trays should be placed under all fittings from which liquid fuelmay spill when the fitting is opened. Savealls should be frequentlyexamined for the presence of oil. A box filled with sand should bekept in a readily accessible place in the boiler room to facilitate theextinguishing of any fire.

6.4 Oily waste can ignite without any external application of heat (suchas from a flame or spark), this is called spontaneous ignition. Oilwaste should therefore be kept in a metal receptacle partially filledwith water to prevent spontaneous ignition. The waste should bedisposed of, as soon as possible.

6.5 In general, the best safeguard against fire is a proper attitude towardscleanliness, the disposal of flammable refuse in all its forms, and anintelligent regard for possible danger. Many explosion have occurredwhen operating boilers merely because of lack of care andknowledge of potential danger.

Fire Fighting

6.6 In case of a fire in the boiler room, the competent boiler operators h o u l d : -

(a) Raise the alarm.(b) Call the fire service.(c) Restrict the air supply to the boiler room by closing windows

and doors.(d) Shut off the fuel supply to the burners.(e) Attack the fire using fire extinguishers.

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6.7 Oil fires - If water is used in fighting an oil fire, it should be sprayedon the oil using a special spray nozzle. Water has the effect oflowering the temperature of the oil below its fire point, and the firewill therefore go out. However, care should be taken not to allow toomuch water to accumulate, as oil being lighter than water will floaton top of the water, and may cause what started as a small local fireto become a large general one. Foam is a better fire extinguishingagent to use in the case of oil fires and at least one 9 litres (2 gallons)foam extinguisher is normally provided in each boiler room. Foamfloats on the surface of the oil and acts as a blanket thereby starvingthe fire of the oxygen necessary for combustion. Dry sand may beused as a means of confining the oil to a small area, thus preventingthe oil from spreading. The oil fuel supply to the burners should beshut off, and for this purpose, a master shut-off valve is usually fittedin the oil fuel supply line and located outside the boiler room.

6.8 Electrical fires - In the case of electrical fires or fires in the closevicinity of electrical appliances, a fire extinguishing medium whichis a non-conductor of electricity should be used, otherwise, the firefighter may experience electric shock. Dry powder extinguishers andcarbon dioxide (CO

2) extinguishers are suitable for use on electrical

fires. All fuses, switches, etc. that can isolate the affected sectionfrom the source of electrical supply should be withdrawn or opened.

Fire Fighting Equipment

6.9 Some commonly encountered types of portable fire extinguishersused in combating oil and electrical fires are described in thefollowing paragraphs.

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Foam Extinguishers

6.10 Usually consist of two parts, an inner container and an outer casing.The outer casing is of lead-coated steel. The inner container is madeof copper. The foam making contents are a solution of aluminiumsulphate in the inner container and bicarbonate of soda in the outerc o n t a i n e r. The extinguisher is operated by merely turning it upsidedown. Other similar models may have double sealing valves whichare released by a T-handle or level before the extinguisher isi n v e r t e d .

6 . 11 Foam is emitted to a distance of from 6 m (20 ft) to 9.1 m (30 ft), andonce started the extinguisher will empty and eject about 90 litres (20gallons) of foam. The foam should be directed to fall upon the fire-ifneed be, by deflecting it from another surface.

6.12 Foam extinguishers are suitable for oil fires. They should not be usedin fires involving electrical equipment as electric shock, which couldprove fatal, might be experienced.

Dry Powder Extinguishers

6.13 These extinguishers are suitable for oil fires as well as electrical fires.The extinguisher medium (13.62 kg or 30 lbs contents) is finelyprocessed bicarbonate of soda (dry powder), pressurized by CO

2at a

pressure of 21 kg/cm2 (300 psi). The dry powder is a non-conductorof electricity, is non-corrosive, non-abrasive, and non-poisonous.The CO

2pressure charge may be checked by means of a flush-fitting

pressure gauge fitted to the extinguisher body. There is also othertype of dry powder extinguisher using compressed gas as expellantin a gas cartridge form.

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6.14 To operate the extinguisher, pull out the safety clip and strike theknob on top of the extinguisher. This causes a stainless steel piercerto perforate a metal seal and release the contents. A horizontal fanshaped cloud of powder to be discharged, 7.62 m (25 ft) long, 1.82 m(6 ft) wide and 1.21 m (4 ft) deep. The duration of discharge is about28 seconds and the discharge may be prolonged by interrupting theflow with the lever provided at the hose end.

Carbon Dioxide Extinguishers

6.15 The charge of CO2

is controlled by a valve and lever so that part ofthe charge may be conserved if not fully used. Usually, theextinguisher contains 2.26 kg (5 lb) of CO

2and the pressure inside

the extinguisher body under normal temperature conditions is about59.77 kg/cm2 (850 psi). The period of discharge is about 8 seconds.Being sealed with a domed nickel diaphragm which requires piercingwith the striker to discharge the contents, the extinguisher is virtuallyleak-proof. As carbon dioxide is a non-conductor of electricity theseextinguishers may be used on fires involving electrical appliances.

Colour Coding - Extinguishers

6.16 For the sake of easy distinguishing the type of fire extinguisher acolour coding system is adopted by the Fire Services Department inaccordance with BS5423. The fire extinguishers used in Hong Kongshould have the colour on their bodies as follows:-

Ty p e C o l o u rWater R e dFoam C r e a mCarbon Dioxide (CO

2) B l a c k

Dry Powder B l u e

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Uptake Fire

6.17 Soot and unburnt carbon can deposit on the walls of the boiler uptake(chimney). They form, in effect, another fuel and can catch fire inthe uptake. Although uptake fires do not often occur, they can bevery difficult to extinguish and the hazard builds up quietly andusually undetected. The fire is caused by smouldering of the depositsaccumulated in the uptake. It usually occurs during boiler shutdownor under light load condition. There is evidence that under normalloads the flue gas "cools" the soot and the carbon deposits so that asmouldering fire does not occur. In the absence of flue gas or if theflue gas flow is insufficient to cool the deposits, they can catch fire.

6.18 When an uptake fire occurs, it results in very high exhausttemperatures and excessive thick black smoke, mixed with sparks,coming out of the uptake. The boiler must be shutdown immediatelyand the blower switched off or the damper closed to stop any airsupply to the uptake. The fire service must be called. If the uptake iscommon for several boilers, all the boilers must be shut down. Thekey point is to stop the boiler air supply. No attempt should be madeto extinguish the fire by water unless the water supply is plentiful. Asteam fire may result if the water supply is not plentiful. The fireshould be allowed to die out. The fire must be contained byrestricting and removing any combustibles in the near vicinity.

6.19 To prevent an uptake fire, the operator must clean the uptakeperiodically to eliminate accumulation of soot and unburnt carbon.He should also exercise care in the daily operation of the boiler andmaintain the correct air/fuel ratio to ensure complete combustion offuel and minimize production of soot or unburnt carbon.

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Provision of Fire Extinguishers

6.20 The owner must provide one set each of the following types of fireextinguishers near the entrance to the boiler room:-

(a) at least one 9 litres (2 gallons) foam extinguisher for oil fire;a n d

(b) at least one dry powder extinguisher or carbon dioxideextinguisher for electrical fire.

Fire Drill

6.21 The boiler operators and the workers working nearest to the boilerroom and a supervisor should conduct fire drills at least once every 3months. The drills should include:-

(a) the identification of the type of fire;

(b) the identification of the type of extinguishers to be used; and

(c) any other procedures to be followed.

6.22 A written procedure in case of fire should be posted outside theentrance to the boiler room.

6.23 A record book of fire drills with the dates, names and signatures ofpersons participating in the fire drill should be kept in the boilerroom for inspection.

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CHAPTER 7

ACCIDENTS AND DEFECTS

General

7.1 It is the responsibility of the owner of a boiler to report to theAuthority when:-

(a) an accident occurs in or to the boiler or its auxiliaryequipment; or

(b) he is aware of any defect in the boiler or in its auxiliaryequipment that is likely to cause danger to life or damage top r o p e r t y.

7.2 The owner must forthwith stop the use and operation of the boilerand shall, as soon as practicable and in any event within 24 hours,notify the Authority of the accident or defect, as the case may be,and, where applicable, shall, at the same time, send to the Authoritythe latest Certificate of Fitness issued in respect of the boiler.

7.3 Every such notice shall include the following particulars:-

(a) the address or place at which the boiler is installed;

(b) a general description of the boiler;

(c) the purpose for which the boiler is or was used;

(d) where applicable, the name and address of the Boiler Inspector who issued the latest Certificate of Fitness in respect of theb o i l e r ;

48

( e ) in the case of an accident in or to a boiler:-

(i) the number of persons killed or injured, if any;

(ii) details of the part thereof that failed and the extent offailure generally, if known; and

(iii) the pressure at which the same was being operated at thetime of the accident; and

(f) in the case of a defect in a boiler, details of the nature of the d e f e c t .

N.B. It must be pointed out here that a safety valve with its seal broken,whatever is the cause, is considered a defect. Although such a defectdoes not create immediate danger, the owner must immediatelyarrange a Boiler Inspector to examine and re-seal the safety valve.

4948

(e) in the case of an accident in or to a boiler:-

(i) the number of persons killed or injured, if any;

(ii) details of the part thereof that failed and the extent offailure generally, if known; and

(iii) the pressure at which the same was being operated at thetime of the accident; and

(f) in the case of a defect in a boiler, details of the nature of the defect.

N.B. It must be pointed out here that a safety valve with its seal broken,whatever is the cause, is considered a defect. Although such a defectdoes not create immediate danger, the owner must immediatelyarrange a Boiler Inspector to examine and re-seal the safety valve.

Fig.

1

FIR

E-T

UB

E B

OIL

ER

Appendix I

5150

Fig.

2

FE

ED

WA

TE

R S

YST

EM

Fig.

3

FU

EL

OIL

SY

STE

M

5150

Fig.

2

FE

ED

WA

TE

R S

YST

EM

Fig.

3

FU

EL

OIL

SY

STE

M

5352

Fig. 4 A BASIC WATER-TUBE BOILER Fig. 5 A MODERN WATER-TUBE BOILER

WITH SUPERHEATER AND REHEATER

5352

Fig. 4 A BASIC WATER-TUBE BOILER Fig. 5 A MODERN WATER-TUBE BOILER

WITH SUPERHEATER AND REHEATER

54

Appendix II

The following are examples of the types of equipment which the holdersof different Certificates of Competency may operate:-

A) All Classes (I to VI)

B) Class I

C) Class I(A)

D) Class I(B)

E) Class II

TYPE OF BOILERS/STEAM RECEIVERFOR WHICH THE CERT I F I C ATE IS

VA L I D

C E RT I F I C ATE OFC O M P E T E N C Y

i) All Boilers (including automaticallycontrolled with superheaters); and

ii) Steam Receivers

i) All Wa t e r-tube Boilers (includingautomatically controlled withsuperheaters); and

i i ) Steam Receivers

i) Wa t e r-tube Boiler (includingautomatically controlled but withoutsuperheaters); and

ii) Steam Receivers

i) Manually Controlled Wa t e r- t u b eBoilers (without superheaters); and

ii) Steam Receivers

i) All Fire-tube Boilers (includingautomatically controlled); and

ii) Steam Receivers

55

Certificates of Competency issued before the year 1981 namely, the B & Scertificates, shall remain valid for the type of equipment as specified in thecertificate. Any person who has any query about such certificates shouldconsult the Boilers and Pressure Vessels Division.

F) Class II(A)

G) Class II(B)

H) Class III

I) Class III(A)

J) Class IV

K) Class V

L ) Class VI

i) Automatic Fire-tube Boilers; and

ii) Steam Receivers

i) Manually Controlled Fire-tubeBoilers; and

ii) Steam Receivers

i) All Electrically Heated Boilers(including automaticallycontrolled); and

ii) Steam Receivers

i ) Manually Controlled ElectricallyHeated Boilers

i) Sterilizing and Vulcanizing Boilers

i) Special Purpose Boiler as specified

i) Steam Receivers

56

Appendix III

BLOWING OF WATER LEVEL GAUGE

A Typical Water Level Gauge

It is a very common design to have all the FIVE cock handles pointingdownwards while the water gauge is in use.

Procedure of blowing:-

When the boiler is in operation, the steam cocks A, D and water cocks B, E areopen and drain cock C is shut.

(a) First shut both steam and water cocks A, D, B and E. Open draincock C to prove that all the gauge cocks are in order. Then, with thedrain cock C still open, cocks B and E should be opened. If waterblows out freely from cock C, cocks B and E are clear.

57

(b) Shut off cocks B and E and open cocks A and D with the drain cockC still open. If steam blows out freely from cock C, cocks A and Dare clear.

(c) To cross test, close cocks D and B, leaving E, A and C open. If waterblows out from cock C, then E, A and the water-column are in order.

(d) Close cocks E and A, leaving D, B and C open. If steam blows outfrom cock C, then D, B and the water-column are in order.

When any of the cocks are found to be clogged, shutdown the boiler andoverhaul the water level gauge.

Possible causes of gauge glass indicating incorrect level

(a) If cocks A and D or steam passage is shut or choked, boiler pressurewill press the water level in the glass higher than the real water levelof the boiler. The water level indication in glass will, therefore, bei n c o r r e c t .

(b) If cocks B and E or water passage is shut or choked, steam willcondense on upper column of glass and accumulate. The apparentwater level shown can be higher than the actual water level, causingfalse reading.

Water gauge glass should be tested daily at l e a s t at every change of attendant.The safety of boiler operation relies greatly on proper functioning of the watergauge glass.

58

Appendix IV

BASIC KNOWLEDGE OF COMBUSTION

Liquid fuel (e.g. diesel oil) and gaseous fuel are hydrocarbon fuelscontaining molecules made up of carbon and hydrogen atoms. Hydrocarbonmolecules can be written as C

mH

n, where m and n are integer variables

indicating the number of carbon atoms and hydrogen atoms building up themolecule respectively. Both carbon atoms and hydrogen atoms can react withoxygen chemically under high temperature. This chemical process is morecommonly known as burning or combustion. Some impurities exist in the fueland also undergo chemical changes during combustion. Harmful products maybe produced depending on the type of impurities e.g. sulphur can form acidicoxide. However, impurities usually occupy a very minor part in the fuel.Careful operation can minimize or even eliminate the effect of harmfulimpurity products.

Hydrocarbon molecules combine with oxygen at high temperature toform carbon dioxide and water. At the same time a large amount of heat isgenerated. Part of this heat energy is in turn used to maintain the hightemperature favourable for the combustion (chemical process) of the fuel,while most of this heat is extracted for use. In our subject of discussion onfossil-fuel boilers, bulk of the heat generated is used to raise temperature of theboiler water to form steam. Chemical Equation:-

CmH

n + (m+n/4)O

2 = mCO

2 + (n/2)H

2O + HEAT

Air contains about 20% by volume of oxygen. It is a cheap andconvenient source of oxygen for combustion. From the chemical equation, itcan be seen that a certain minimum amount of oxygen, or air, is required for aparticular hydrocarbon fuel to burn completely. Insufficient air supply causespoor combustion producing sooty smoke, less heat, carbon monoxide, etc.Taking into consideration air/fuel mixing efficiency and to ensure completecombustion, excess air is required. For most thermal oil heaters, 20-50%excess air is usually arranged. Excessive air will, however, lower the eff i c i e n c yof the boiler, cause flame instability and create undesirably high flue gas

59

temperatures. The correct amount of air depends on the fuel as m and n varywith the type or supply of fuel. The operator should consult the fuel supplierand the burner appliance maker for the optimal air/fuel ratio. The operatorshould adjust the air blower damper mechanism as necessary to establish anoptimal flame. An optimal flame is a stable flame (i.e. the shape of the flame isstable) with a near colourless exhaust.

The burner injects gas or atomizes oil fuel which mixes with the airfrom the blower. Turbulence produced by the air draught thoroughly mixes thefuel particles and air producing plenty of reacting contact surfaces between thehydrocarbon molecules and oxygen molecules. If a flame exists, the heat willcause the chemical process described above to occur and sustain the flame. Ifthere is no flame but an ignition spark is produced, the high temperature spark(2000ºC or above) starts the combustion process and creates a flame. Thecombustion process is self-sustaining and the flame continue as long as there isfuel and sufficient air being supplied and mixed at the correct ratio.

Diesel oil vaporizes even at room temperature. The vapour is similar, inits effect, to gaseous fuel and is combustible. After a flame has beenextinguished or a boiler has been shutdown, residual diesel oil vaporizes andmixes with the air inside the furnace. This mixture is flammable and extremelydangerous. If any hot material is present it may set off a very rapid combustionwith a large amount of heat released in an extremely short time or, moree x a c t l y, an explosion can occur. A spark for ignition purpose would be hotenough to cause such an explosion. This can happen if the operator tries toignite a flame inside the furnace to start the boiler without knowing that thereis an explosive mixture present. The spark can ignite the explosive mixturebefore igniting the fuel/air mixture to make the flame. A similar phenomenonapplies in the case of gaseous fuel. The operator must take every precaution toeliminate accumulation of the explosive mixture. The rule is to purge thefurnace every time before attempting to ignite a flame and to purge the furnaceafter extinguishing a flame. Never try to ignite a flame using the heat of thefurnace. Under such circumstance, a large amount of fuel is injected into thefurnace giving a very good opportunity for an explosive mixture to build upand to explode subsequently.

60

During ignition, the jet of fine fuel particles as atomized by the burner athigh pressure or injected through gas nozzle mixes with air. This is aflammable mixture but got ignited and burnt before accumulating to larg e .H o w e v e r, if it fails to ignite a flame after several sparking, a considerablevolume of flammable mixture, which is explosive, may have created. Theoperator should not insist on attempting to ignite a flame. He should shut offthe fuel supply, purge the furnace thoroughly to remove any explosive mixturewhich might have been created. He should check and eliminate any fault in theburning system. Most automatic combustion control fitted for automatic fossil-fuel boilers will carry out the above practice, except examining the system,a u t o m a t i c a l l y. Nevertheless, the operator should make himself aware of theconsequence and should never be complacent. In case of failure of automaticdevice, the system shall be changed over to manual control where the operatorhas to exercise the above practice.

A LWAYS PURGE THE FURNACE BEFORE MAKING A FLAME!

61

Appendix V

BASIC KNOWLEDGE OF ELECTRICITY

Electric Circuit-a network of paths designed for electric current to carry out aspecified function.

Circuit Breaker - one form of switch providing ON/OFF function andautomatic tripping of the electric circuit in the event of shortcircuit or circuit overload. The point at which the breakertrips depends on the rating of the circuit. The breaker can bereset to operate again after the fault has been cleared.

Fuse - a conductor, usually in the form of a wire or a cartridge, of low meltingpoint material placed in the electrical supply circuit and forms part ofthe circuit. It serves to protect the electric circuit from short circuitingor overloading. It melts to interrupt the electricity supply because theexcess current produces a large amount of heat. Unlike the circuitb r e a k e r, it must be replaced with a new unit after blowing.

Earth Line - a conductor or wire which electrically connects the boiler metalcasing with the earth terminal provided by the electricity supplyc o m p a n y. This line plays a very vital role in the prevention ofelectric shock.

Electric Shock - this is a phenomenon whereby the human body has become apath for electric current. The human body may suffer burnsand heart difficulties which can result in death.

62

When an electric wire of high potential becomes loose or exposed and is incontact with the metal casing of the boiler, the casing will also be at a highpotential relative to the earth. If the earth line is also defective, the casing willbe maintained at a high potential. There may not be any indication of the highpotential but when a person is in contact with the casing and he is also incontact with the earth, an electric path for current is established through thehuman body. Potential differences above 50V, A.C. or D.C., are able to driveelectric current through the body. This is what is termed an electric shock.Alternating current has a more serious effect in that it can cause the victim tobecome paralysed while still holding firmly onto the faulty electric part. Thenormal mains supply in Hong Kong is nominally 220V A.C. which is wellabove the threshold voltage of 50V. However, it should be noted that,depending on the physical conditions of a person, potential difference less thanthis threshold voltage has been known to cause serious injuries.

I M P O RTANT NOTE:- Never try to repair any faulty electric circuit. Therepair should be carried out by a registeredelectrical worker only.

63

Appendix VI

QUOTED REFERENCES ON STATUTORY PROVISIONS

Paragraph of the Code- - - - - - - - - - - - - - - - - - - - - - - - - - -1 . 2

1 . 3

1 . 4

1 . 5

1 . 7

1 . 9

1 . 1 0

1 . 11

1 . 1 2

1 . 1 3

1 . 1 4

1 . 1 5

1 . 1 6

1 . 1 7

1 . 1 8

1 . 1 9

1 . 2 0

Section(s) / Regulation(s)- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -4(3) & 66(1)

1 3

1 5

1 6

6 ( 1 )

4 9 ( 7 )

49(7) & 67

22(1) & 27(1)

33(6), 49(1) & 62(a)

4 9 ( 1 )

3 2 ( 1 )

32(2) & (3)

1 7 ( 1 )

25 & 26

1 7 ( 2 )

2 & 26(1)

6 3

Ordinance / Regulation- - - - - - - - - - - - - - - - - - - - - - - - - - - -Boilers and PressureVessels Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

64

Paragraph of the Code- - - - - - - - - - - - - - - - - - - - - - - - - - -1 . 2 1

2 . 1 2

2 . 1 3

2 . 1 5

5 . 1 2

5 . 1 9

6 . 3

6 . 7

7 . 1

7 . 2

7 . 3

Appendix II

Section(s) / Regulation(s)- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -15A / 50(1)

22 / 51(1)49(1) / 49(8)49(6) / 49(10)49(7) / 49(8)5 55 6R e g 4 ( 1 ) ( a ) / R e g 1 7 ( 1 )

Reg 3(1)(a)(i)

Reg 3(1)(a)(iv)

Reg 3(1)(a)(ii)

4 4 ( 3 )

27(1), 37(1) & 38(1)

Reg 9

Reg 10(1)

6 3 ( 1 )

6 3 ( 1 )

6 3 ( 2 )

Form 4

Ordinance / Regulation- - - - - - - - - - - - - - - - - - - - - - - - - - - - -Boilers and PressureVessels Ordinance, Cap 56Ordinance, Cap 56Ordinance, Cap 56Ordinance, Cap 56Ordinance, Cap 56Ordinance, Cap 56Ordinance, Cap 56Boilers and PressureVessels Regulations, Cap 56

Regulations, Cap 56

Regulations , Cap 56

Regulations , Cap 56

Ordinance , Cap 56

Ordinance, Cap 56

Regulations , Cap 56

Regulations , Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Ordinance, Cap 56

Boilers and PressureVessels (Forms) Order, Cap 56

Please refer to the relevant Ordinance or Regulations for full details of thestatutory provisions referred to in this Code.