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CP2

The Government of the Hong Kong
Special Administrative Region

Code of Practice
on the
Use of LPG
for the
Special Effects Materials

Entertainment Special Effects Licensing Authority
Version 4.3
10 January 2014
Create Hong Kong
39/F., Revenue Tower,
5 Gloucester Road, Wan Chai, Hong Kong.

Preface

LPG is a fuel gas commonly used as a convenient means of heat source for cooking purpose. However, it also has a much less known use of producing special effects.

In fact, LPG has many advantages over pyrotechnic materials in producing flame effects: LPG is cheaper and readily available as it can be found in nearly every kitchen, the size of the flame and fireballs are controllable and repeatable with accuracy the same set up can be used many times when properly maintained, and the by-products are environmentally green.

The aim of this Code is to outline the safety procedures that should be followed in handling LPG equipment. It is hoped that by observing these codes of practice, the potential harm to all who are directly or indirectly involved can be reduced.

In drafting and updating this Code, the author has made reference to many international standards, regulations and guidelines, including the United States Code of Federal Regulations Title 49 Sections 173.34 and 178.51, the US NFPA Code 160, and relevant Guidance Notes published by the Gas Authority of the Hong Kong Government.

Thanks are due to my colleagues in the Special Effects Licensing Unit for suggesting many useful comments and corrections on this and previous editions over the years. Special thanks are due to Mr Tassilo Baur, a First Class Special Effects Operator in California, for his contribution in preparing the standards for LPG mortars given in Sections 3.3 to 3.8. The permission given by the US Department of Transportation to translate into Chinese the US CFR Title 49 Sections 178.51 and 173.34(i), and to produce them in this Code is also gratefully acknowledged. To make the Code up-to-date and to meet the operational need of the local industry, comments from the special effects industry are most welcome. Please send your comments and suggestions to : esela@createhk.gov.hk.

Senior Engineer (Special Effects)
Special Effects Licensing Unit
Create Hong Kong.

Contents

 
Page No.
1.   Scope
4
 
2. Regulatory Requirements
5
 
3. Technical Requirements of LPG Equipment
6
3.1         Introduction
6
3.2         Fire Bars
6
3.3         LPG Mortars
6
3.4         Construction of Accumulators
8
3.5         Means of Filling LPG and Measuring the Pressure in the Accumulator
10
3.6         Means of Rapidly Releasing the Accumulated LPG
10
3.7         Maximum Service Pressure Rating of LPG Mortars
11
3.8         Use of Existing LPG Mortars
12
3.9         Can Poppers
13
 
4. Safe Practices
14
4.1         Characteristics and Potential Hazards of LPG
14
4.2         Use of LPG Indoor or With a Proximate Audience
15
4.3         Safety at Work
16
4.4         Maintenance of the LPG Equipment
18
 
5. Glossary
20
 
Annex I    – US CFR Title 49, Section 178.51
23
Annex II   – US CFR Title 49, Section 173.34(i)
31

 

1. Scope

1.1 The purpose of this document is to help special effects operators and other relevant persons better understand the requirements for the safe use of liquefied petroleum gas (LPG) and associated equipment for the production of entertainment special effects. It also provides guidance for good practice so as to ensure that any person or any property is, as far as is reasonably practicable, protected from any personal injury or unintentional damage arising from the use of LPG.

1.2 The production companies, the special effects operators and all parties concerned shall observe relevant clauses in the Code of Practice on the Use Storage and Conveyance of Special Effects Materials (CP1), another code of practice issued by Entertainment Special Effects Licensing Authority (the Authority).

2. Regulatory Requirements

2.1 The use of LPG for and incidental to the production of entertainment special effects is regulated under Entertainment Special Effects Ordinance Cap. 560 (the Ordinance) and its subsidiary legislation.

2.2 Under the Ordinance and the Entertainment Special Effects (General) Regulation, a discharge permit is required for the use of LPG for the production of entertainment special effects. The discharge shall only be conducted by a licensed Special Effects Operator named as the operator-in-charge in the discharge permit. Other special effects operators and special effects assistants with licensed scope of operation valid for such operation may only be allowed to use LPG under the supervision of the operator-in-charge.

2.3 Conveyance of LPG is regulated under the Gas Safety Ordinance (Cap. 51). Any person may carry in a vehicle an LPG cylinder or cylinders with aggregate water capacity of less than 130 litres. Otherwise, the vehicle must have been issued with a LPG cylinder wagon permit by the Gas Authority.

2.4 Under the Gas Safety Ordinance, the storage or placing of LPG containers in any premises or part of any premises with aggregate water capacity of less than 130 litres is exempted from the approval requirements. Otherwise, it constitutes the construction of a notifiable gas installation and the approval of the Gas Authority is required.

2.5 No person shall use any container for the storage of LPG unless the container has been approved by the Gas Authority for that purpose. Temporary holding of LPG in an accumulator of an LPG mortar for producing entertainment special effects is not regarded as “storage”.

2.6 Any process which involves the transfer of LPG in liquid form from one container (other than a disposable cylinder) to another container is prohibited under the Gas Safety Ordinance unless the approval of the Gas Authority has been obtained.

2.7 All tubings, connections, valves, pressure gauges and regulators etc. shall conform to acceptable standards. Manufacturers’ specifications for the products shall be submitted to the Authority for inspection.

3. Technical Requirements of LPG Equipment

3.1 Introduction

3.1.1 In the production of entertainment special effects, it is often desirable to produce flame and fireball effects through the controlled release of fuel gas. This method offers important safety advantages over the use of other special effects materials because of its relatively high degree of repeatability and predictability.

3.1.2 The type of fuel gas commonly used is liquefied petroleum gas (LPG) which is readily available commercially in steel cylinders. As defined under the Ordinance and the Gas Safety Ordinance (Cap. 51), LPG includes propane.

3.1.3 Flame effects are often produced by means of “fire bars” through which LPG is released in a controlled manner. Fireball effects are often produced through the rapid release of LPG using equipment such as “LPG mortars” and “can poppers”.

3.2 Fire Bars

3.2.1 A fire bar is basically a steel or copper pipe and comes in all shapes and lengths. A section of the pipe is perforated with small holes or slots. One end of the pipe is sealed and the other end is connected to a LPG hose which is in turn attached to a LPG cylinder through a cutoff valve with quick-release fitting. To avoid damage to the LPG hose, a sufficient length of the fire bar should remain intact so as to allow dissipation of heat generated from the burning gas.

3.2.2 A fire bar may be bent into various shapes to produce different effects. It can be made into a ring shape to form “burner ring” or connected to other assembly of different shapes such as a “fishtail burner”. Fire bars can be used for many different effects: in windows, doors, in front of camera as foreground flame, or whenever a flame is needed on a set.

3.3 LPG Mortars

3.3.1 An LPG mortar (or sometimes known as an LPG cannon) is used to produce fireball effects through the ignition of LPG rapidly released from its accumulator. It may operate without the use of any pyrotechnic materials. While there is a wide variety of designs, an LPG mortar normally consists of the following elements:

(i) an accumulator which temporarily holds LPG prior to its release;
(ii) a means of filling LPG into the accumulator and of measuring its pressure;
(iii) a means of rapidly releasing the accumulated LPG; and
(iv) the ignition system.

3.3.2 The accumulator can be of many different types and sizes but for reasons of economy and practicality, it is often a steel cylinder. It must be noted that the accumulator shall only be used to hold LPG in vapour form for immediate use and shall never be used as a device for the long term storage or conveyance of LPG.

3.3.3 The means of filling LPG into the accumulator is in some cases the valve originally installed in the LPG cylinder but in most cases, it is replaced by a pipe assembly which consists of:

(i) a quick-release fitting to allow rapid connection and disconnection of the supply of LPG in the field;
(ii) a manually-operated valve to allow the user to control the flow of LPG into the accumulator;
(iii) a pressure gauge to allow the user to measure the pressure of LPG inside the accumulator and to determine the amount of LPG and the rate at which it will be released; and
(iv) in applicable cases, a relief valve may be included to prevent an excessively high pressure from developing inside the accumulator.

3.3.4 The means of rapidly releasing the accumulated LPG may also take different forms but in general it consists of a large diameter, quick-acting valve. This valve is generally of one of the following three types:

(i) an electrically actuated, usually in the form of a normally closed, full-port and internal pilot operated solenoid valve;
(ii) a pneumatically actuated, in the form of a ball valve assembly with an integrated pneumatic actuator or an external actuator assembly consisting simply of a pneumatic cylinder attached to the handle of the ball valve; or
(iii) a mechanically actuated, in the form of a lever or similar mechanical valve (this type of valve is relatively uncommon).

3.4 Construction of Accumulators

3.4.1 An accumulator of an LPG mortar shall conform to the United States Department of Transportation (DOT) 4BA cylinder standard specified in the Code of Federal Regulations, United States, Title 49, Section 178.51 or other standards accepted by the Authority.

3.4.2 The DOT 4BA cylinders commonly available in Hong Kong have a single opening which consists of a fitting, boss, or pad and is securely attached to the container by welding. In general, this fitting holds a valve which serves both as the inlet for filling the cylinder and as an outlet for withdrawing the gas for use. Though this fitting is suitable for filling the cylinder, its diameter is too small to allow the required rapid release of the LPG necessary to provide a visually acceptable fireball effect.

3.4.3 To allow the necessary rapid release of the accumulated LPG, additional outlet or outlets of larger diameter are required. These outlets may be added to the cylinder (the accumulator) in accordance with the following standards:

(i) the regulations set forth in the Code of Regulations, United States, Title 49, Section 178.51 (can be found at www.epa.gov/fedrgstr on the internet, a copy of which is reproduced with permission in Annex I);
(ii) the regulations set forth in the Code of Regulations, United States, Title 49, Section 173.34(i) governing the repair by welding or brazing of DOT-4 series cylinders (can be found at hazmat.dot.gov/regs on the internet, a copy of which is reproduced with permission in Annex II); or
(iii) other welding or brazing standards accepted by the Authority.

3.4.4 In cases where the modifications are not made by the manufacturer of the cylinder, the additional outlets shall be installed in a process similar to that used in manufacturing the cylinder and in compliance with clause 3.4.5 or 3.4.6.

3.4.5 For adding outlets to cylinders of plain carbon steel with carbon over 0.25% or manganese over 1.00% or of alloy steel, the modifications must be in compliance with the following requirements:

(i) such modifications must be made by a competent person;
(ii) the welder shall have available to him information as to the procedure, equipment and rod used during manufacture of the cylinders and shall use a suitable method for the modifications;
(iii) modifications must be made by metal arc welding only;
(iv) welds shall not be made on or near a brazed joint to prevent the possibility of copper penetration;
(v) the cylinders to be modified are free of defects in welded joints in or on any pressure parts;
(vi) the cylinders during welding must be free of any materials that may impair the serviceability of the metal in or adjacent to the weld;
(vii) after modifications, the welds are to be inspected visually for weld quality; and
(viii) after modifications, the cylinder must be reheat treated and leak tested at a test pressure of at least two times the service pressure of the cylinder and show no defects.

3.4.6 For adding outlets to cylinders of plain carbon steel with carbon 0.25% or less and manganese 1.00% or less, the modifications must be in compliance with the following requirements:

(i) such modifications must be made by a competent person;
(ii) the welder shall have available to him information as to the procedure, equipment, and rod used during manufacture and shall use a suitable method for the modifications;
(iii) welds shall not be made on or near a brazed joint to prevent the possibility of copper penetration;
(iv) the cylinders to be modified are free of defects in welded joints in or on any pressure parts;
(v) the cylinders during welding must be free of any materials that may impair the serviceability of the metal in or adjacent to the weld;
(vi) after modifications, the welds are to be inspected visually for weld quality;
(vii) after modifications, the cylinder must be reheat treated and leak tested at a test pressure of at least two times the service pressure and show no defects; and
(viii) in case the test shows leakage through the weld, repair to the weld may be made provided that:
(a) the leakage is not caused by cracking in the weld;
(b) weld defects must be removed by grinding or chipping before repair by the metal arc process. The tungsten inert gas shielded arc process may be used only when the repair can be made by puddling;
(c) if metal arc process is used, only electrodes of type E7015, 7016 or 7018 not larger than 3.2 mm (0.125 in) diameter or equivalent shall be used; and
(d) subsequent reheat treatment of the cylinder after repair is not required.

3.4.7 It is often necessary to install non-pressure attachments to the accumulator to facilitate mounting of the accumulator itself or other components. Addition of these attachments to the top or bottom of the accumulator may be made without reheat treatment provided that the following requirements are met:

(i) the attachments are made of steel of low carbon content;
(ii) the parts of the cylinder for installing the attachments are of similar weldable material and have been previously welded or brazed to the top or bottom of the accumulator and properly heat treated; and
(iii) the welding or brazing does not produce a temperature in excess of 205º C (400º F) in any part of the top or bottom material.

3.4.8 LPG cylinders belonging to the Registered Gas Supply Companies approved by the Gas Authority for containing LPG shall not be used or modified as an accumulator.

3.5 Means of Filling LPG and Measuring the Pressure in the Accumulator

3.5.1 Threaded or other suitable fittings as described in clause 3.4.2 may be used to form a suitable pipe assembly. Such an assembly shall be compatible with the LPG being used and have a pressure rating of not less than the maximum service pressure rating of the LPG mortar.

3.6 Means of Rapidly Releasing the Accumulated LPG

3.6.1 Valves connected to the outlets of an accumulator as described in clauses 3.4.2 to 3.4.6 may be used as a means of rapidly releasing the accumulated LPG provided that:

(i) the valve components must be compatible with the LPG being used; and
(ii) the valve must have a pressure rating of not less than the maximum service pressure rating of the LPG mortar.

3.7 Maximum Service Presure Rating of LPG Mortars

3.7.1 The maximum service pressure rating of an LPG mortar is the maximum pressure in the LPG mortar which must not be exceeded during use. It shall be taken as:

(i) not more than one half of the maximum pressure rating of the accumulator; or
(ii) not more than the maximum pressure rating of any components attached to the accumulator, whichever is the less.

3.7.2 Special effects operators shall clearly mark the LPG mortar with the maximum service pressure rating.

3.7.3 All LPG mortars before being put into service for the first time shall have been subject to the following leakage tests to the satisfaction of the Authority:

(i) in cases where the accumulator can be detached from the LPG mortar, the accumulator has been leak tested at a test pressure of twice the maximum service pressure rating and the whole LPG mortar has been leak tested at a test pressure of 1.2 times of the maximum service pressure rating; or
(ii) in cases where the accumulator cannot be readily detached from the LPG mortar, the whole LPG mortar has been leak tested at the following test pressure:

Maximum service pressure rating (MSPR)

Test pressure

            < 1035 kPa (150 psi)

1.25 x MSPR

                1380 kPa (200 psi)

1.5 x MSPR

                1724 kPa (250 psi)

1.75 x MSPR

            > 2070 kPa (300 psi)

2 x MSPR


Note: The required test pressure for the maximum service pressure rating lying between the above figures may be calculated by interpolation.

3.8 Use of Existing LPG Mortars

3.8.1 LPG mortars which have a track record of safe and successful use in places outside Hong Kong may be used by licensed special effects operators provided that the following requirements have been complied with:

(i) the LPG mortar was designed and constructed by a competent person;
(ii) the LPG mortar has a history of safe and effective use and is free from defects in design, construction and workmanship;
(iii) the LPG mortar has been maintained by the owner in such a condition that it can be operated safely and effectively;
(iv) the interior of the accumulator has been inspected visually and there was no evidence of excessive corrosion or other deterioration;
(v) the welds have been inspected visually for weld quality and no defects were observed;
(vi) all components of the LPG mortar are compatible with the LPG being used;
(vii) all components of the LPG mortar have a pressure rating at least equal to the maximum service pressure rating of the LPG mortar;
(viii) the owner has clearly marked the LPG mortar with the maximum service pressure rating which must not be exceeded during use; and
(ix) the LPG mortar has been subject to the following leakage tests to the satisfaction of the Authority:
(a) in cases where the accumulator can be detached from the LPG mortar, the accumulator has been leak tested at a test pressure of twice the maximum service pressure rating and the whole LPG mortar has been leak tested at a test pressure of 1.2 times of the maximum service pressure rating; or
(b) in cases where the accumulator cannot be readily detached from the LPG mortar, the whole LPG mortar has been leak tested at the following test pressure:

Maximum service pressure rating (MSPR)

Test pressure

            < 1035 kPa (150 psi)

1.25 x MSPR

                1380 kPa (200 psi)

1.5 x MSPR

                1724 kPa (250 psi)

1.75 x MSPR

            > 2070 kPa (300 psi)

2 x MSPR


Note: The required test pressure for the maximum service pressure rating lying between the above figures may be calculated by interpolation.

3.9 Can Poppers

3.9.1 A can popper is a device used to produce fireball effects through the ignition of a sudden release of LPG (including propylene and propane) or other fuel gas stored in a disposable metal container. Immediately before use, a Special Effects Operator will attach to the device a small lifter (a pyrotechnic device normally containing less than 14g (½ oz) of black powder) or other pyrotechnic materials as an ignition source. When fired, the explosion actuates a sharp steel tube to puncture into the LPG container. A flash bag is often placed near the container to ensure ignition of the sudden release of fuel gas.

3.9.2 All can poppers shall be of a safe design and properly maintained. The ends of the can poppers shall be sufficiently threaded and capped. The whole set-up shall be so constructed as to provide the required stability and strength during use. The firing of the lifter or the produced fireball shall not cause failure or distortion of any parts of the can popper.

4. Safe Practices

4.1 Characteristics and Potential Hazards of LPG

4.1.1 At normal atmospheric pressure and temperature, LPG exists as a gas. Normally, LPG is stored as a liquid inside pressurised containers. Liquid LPG is colourless and odourless. An ordorant having pungent smell is normally added for easy detection of any leakage into environment.

4.1.2 LPG inside a steel cylinder at normal ambient temperature may have a pressure of approximately 480 kPa (about 70 psi). If the cylinder is stored near a heat source or under direct sunlight, its pressure could increase considerably. In a fire situation the cylinder would burst and an explosion would result.

4.1.3 When liquid LPG escapes from a container it will expand rapidly to form LPG vapour approximately 250 times the equivalent volume of liquid released. If brought into contact with the skin, liquid LPG will cause severe frost burns due to the rapid vaporisation.

4.1.4. LPG is not toxic, but may present inhalation hazards. If released in a confined space, LPG can displace oxygen in the air to cause suffocation.

4.1.5 When LPG is mixed with air in a proportion between approximately 2% and 10%, a flammable LPG-air mixture is formed. Small quantities of LPG, particularly in liquid form, escaping from a container can therefore give rise to large volumes of LPG-air mixture and thus produce considerable hazard, especially if it happens indoors or in confined areas.

4.1.6 If an LPG-air mixture within the flammable range is ignited, a flash fire will occur. If the mixture is ignited within a confined space with insufficient ventilation, an explosion will result.

4.1.7. When LPG and air are burned in the correct ratio (about 1:24), complete combustion takes place to give non-toxic products of flue gases such as water rapour and carbon dioxide. When combustion is incomplete due to shortage of oxygen, toxic products such as carbon monoxide will be generated.

4.1.8 LPG is heavier than air and it will tend to fall to low level and flow along the ground into drains, cellars and basements and other low lying places. In still air with little or no ventilation at low level the vapour will persist for a very long time. Leaked LPG may be accidentally ignited some distance from the point of leakage and the resulting flame may travel back to the point of leakage. Explosion could also occur if the LPG is not diluted below its flammability limit.

4.1.9 The LPG stored in steel cylinders is normally odorised to enable early detection of escaping gas by smell. However, for some disposable containers, the LPG is not odorised and therefore leakage may go by undetected.

4.1.10 In some circumstances, leakage of LPG (especially as liquid) may be noticed by sight. It should be noted that at the point of leakage, the cooling effect on the surrounding air causes condensation and even freezing of the water vapour.

4.1.11 A lighted match or other naked flames should not be used to trace a point of leakage. Not only is this extremely dangerous but it is also an offence under the Gas Safety Ordinance. Leakage may be detected with an LPG detector.

4.1.12 Unlike LPG which is heavier than air, town gas weighs only half as light as air and diffuses quickly into the atmosphere when it escapes. Like LPG, town gas has no colour and no odour, and a pungent smell is introduced for easy detection. Because of the different characteristics such as specific gravity, caloric value, gas pressure and different chemical compositions, use of town gas in an LPG equipment must not be allowed.

4.2 Use of LPG Indoor or With a Proximate Audience

4.2.1 The LPG equipment mentioned in the preceding clauses are normally for the use of producing special effects in films in open or ventilated areas, and are not suitable in confined areas or there is a proximate audience.

4.2.2 LPG equipment used in confined areas or where there is a proximate audience will be subject to more stringent safety requirements. In addition to the approval of the effects by means of a discharge permit issued by the authority, the equipment shall be inspected and certified by a LPG Contractor recognised by the Gas Authority.

4.2.3 The LPG equipment shall also be equipped with an emergency stop button (E-stop) which completely shuts down the equipment. The burner heads should have equipped with a pilot confirmation device or a leakage detector.

4.3 Safety at Work

4.3.1 Special effects operators should always take practicable steps to mitigate the risks of using LPG, including:

(i) conduct safety orientation meetings and rehearsal with all appropriate personnel in the manner specified in section 2.5 or 3.5 of the Code of Practice on the Use, Storage and Conveyance of Special Effects Materials (CP1);
(ii) ensure all talents will participate in the rehearsal to allow them to be familiar with the effects and to maintain a comfortable distance from the LPG equipment while performing.
(iii) set up the equipment as close to the time of producing the special effect as practicable so as to minimize the duration of exposure to the hazards;
(iv) activities of highest hazard levels, such as filling up of LPG and installing the ignition system, should only be carried out immediately prior to discharge;
(v) minimize the likelihood of ignition failure at the release of LPG by using a reliable source of ignition:
(a) always use hard pilots whenever practical. In cases where soft pilot is used, the devices must be tested thoroughly prior to use (gas effects ignited by fire or flames, whether pyrotechnic or otherwise, are termed as “hard piloted” and those ignited by other means, such as spark gaps, are termed as “soft piloted”);
(b) use good firing and circuit design techniques and test the circuits before firing to reduce the chances of a misfire or failure of the ignition source(s); and
(c) use redundant ignition sources if necessary;
(vi) prepare an emergency plan to deal with any unforeseen situations or spread of fire quickly and effectively;
(vii) during periods of elevated risk levels (such as when the ignition system and LPG are in place), special effects assistants and trained personnel shall stand by near the firing locations with effective fire extinguishers; and
(viii) take appropriate precautionary measures to prevent the ejected materials from spreading fires when other materials are used with LPG.

4.3.2 Special effects operators shall never attempt to use LPG to produce any special effects unless it is safe to do so, after taking into consideration the circumstances at the time of discharge.

4.3.3 Special effects operators should always remember that changes in atmospheric conditions such as pressure, ambient temperature, wind speed and direction can have a pronounced influence upon the flame and fireball effects to be produced. If the circumstances are getting worse, cancel the effects.

4.3.4 Special effects operators shall ensure that all performers and support personnel have taken adequate precautionary measures, taking into account the radiant heat and any hazardous debris emitted which can cause burns and damage over considerable distances. The protective measures and safety gears provided to the stunt performers should be commensurate with the size of the fireballs or flame effects to be produced. All other people shall be kept away from the potentially hazardous area.

4.3.5 LPG mortars or accumulators shall only be used to hold LPG in vapour form for immediate use. They shall never be used as a means of conveyance or storage of LPG or other fuel gases.

4.3.6 LPG mortars shall only be filled with LPG immediately prior to use. Prior to charging and when purging-out the accumulator after use, special effects operators shall ensure that flammable LPG-air mixture is not present inside the accumulator.

4.3.7 Any LPG residue in the LPG equipment shall be disposed of after firing in a safe manner.

4.3.8 Never change LPG cylinders during the show, unless specifically approved otherwise by the Authority.

4.3.9 Never connect LPG equipment to a town gas source.

4.3.10 LPG Cylinders (other than disposable containers) shall be at least 3m away from flame source or the flame head is separated by a metal layer with flame on top and the LPG cylinder under the flame within the metal structure.

4.3.11 LPG Cylinders (regardless whether it is empty or containing LPG) shall not be placed near building exits, stairways or in areas used for safe egress of people.

4.3.12 Can poppers shall only be loaded with appropriate gas cylinders and lifters immediately prior to discharge.

4.3.13 Adequate number of effective fire extinguishers shall be available at all times during any activities involving LPG.

4.3.14 Special effects operators and all parties concerned shall observe the relevant clauses in the Code of Practice on the Use, Storage and Conveyance of Special Effects Materials (CP1).

4.4 Maintenance of LPG Equipment

4.4.1 All LPG mortars, can poppers and other LPG equipment shall be maintained in accordance with the manufacturers’ instructions and in such a condition that they can be operated safely and effectively. All parts shall be replaced at regular intervals as suggested by the manufacturers and those that show signs of wear and tear shall be replaced immediately. All components must be compatible with the fuel gas being used.

4.4.2 Special effects operators shall conduct at 6-month intervals visual inspection of the LPG mortar and the accumulator, and ensure that the interior of the accumulator does not show signs of excessive corrosion or other deterioration.

4.4.3 Special effects operators shall conduct at least once in each 24-month period the following leakage tests to the satisfaction of the Authority:

(i) in cases where the accumulator can be detached from the LPG mortar, the accumulator has been leak tested at a test pressure of twice the maximum service pressure rating and the whole LPG mortar has been leak tested at a test pressure of 1.2 times of the maximum service pressure rating; or
(ii) in cases where the accumulator cannot be readily detached from the LPG mortar, the whole LPG mortar has been leak tested at the following test pressure:

Maximum service pressure rating (MSPR)
Test pressure

            < 1035 kPa (150 psi)

1.25 x MSPR

                1380 kPa (200 psi)

1.5 x MSPR

                1724 kPa (250 psi)

1.75 x MSPR

            > 2070 kPa (300 psi)

2 x MSPR

Note: The required test pressure for the maximum service pressure rating lying between the above figures may be calculated by interpolation.

4.4.4 All LPG mortars shall be clearly marked with the maximum service pressure rating, date of last leakage test, name of manufacturer/owner, etc.

5. Glossary

The definitions given below provide a glossary of the terms and jargons used in this Code of Practice. A more comprehensive list of common terms and jargons used by the trade with respect to the use of special effects materials in general is given in the Code of Practice on the Use, Storage and Conveyance of Special Effects Materials (CP1).

Authority (監督) means the Entertainment Special Effects Licensing Authority established by section 3 of the Ordinance.

Black powder (黑火藥) means a pyrotechnic material consisting of an intimate mixture of potassium nitrate, sulphur and charcoal. Black powder is also known as gun powder.

Can popper (樽裝氣爆斗) means an LPG equipment used to produce fireball effects through the ignition of a sudden release of LPG stored in a disposable metal container. This device utilizes a small lifter or other pyrotechnic materials as a power source to puncture the metal container.

Electric match (電火柴) means a pyrotechnic device consisting of a bridgewire coated with a small quantity of heat-sensitive pyrotechnic materials. It ignites when an electric current flows through the bridgewire. An electric match is used to ignite other pyrotechnic materials. Electric matches are often incorrectly called squibs.

Entertainment programme (娛樂節目), as defined under section 2 of the Ordinance, includes –

(a) any film, commercial and television broadcast programme; and
(b) any literary, dramatic, musical and artistic works performed before a live audience or otherwise, and similar production, but does not include fireworks displays.

Entertainment special effects (娛樂特別效果), as defined under section 2 of the Ordinance, means any visual or audible effect or a combination of both created by means of any special effects materials for the production of an entertainment programme.

Fire bar (火條) means an LPG equipment used to produce flame effects through the controlled release of LPG. It is made of steel or copper pipe perforated with small holes or slots and comes in all shapes and lengths to produce many different effects. It may operate without the use of any pyrotechnic material.

Flash bag (引火包或閃光包) means a soft plastic bag containing a small quantity of black powder charge or other pyrotechnic materials and loaded with an electric match. It is usually used with flammable liquids or LPG to guarantee their ignition.

Hard pilot (硬火苗), in relation to the use of LPG equipment, means the ignition of LPG by fire or flames produced by a pyrotechnic material or by other means.

Hazardous debris (危險碎片) means any debris, produced or expelled by the functioning or malfunctioning of any special effects material, that is capable of causing personal injury or unintended property damage. This includes, but is not limited to, hot sparks, heavy casing fragments, duds, misfired pyrotechnic materials and unignited components. Materials such as confetti, lightweight foam pieces, feathers, or novelties, are not to be construed as hazardous debris.

Lifter (升舉彈) means a wrapped black powder charge with an igniter. Lifters are usually fired in a mortar to simulate an explosion or as a lifting charge. The casing of a lifter is made of soft materials such as cardboard and is usually wrapped with several layers of friction tape. Extra wrapping will add to the confinement and subsequent explosion effect. Lifters are also known as black powder bombs.

Liquefied petroleum gas (石油氣), as defined under section 2 of the Gas Safety Ordinance (Cap. 51), means any gas which is a mixture of

(a) hydrocarbons primarily consisting of butanes, butylenes, propane or propylene; or
(b) all or any of the hydrocarbons referred to in paragraph (a).

LPG (石油氣), an abbreviation for liquefied petroleum gas.

LPG equipment (石油氣設備) means equipment involving the use of liquefied petroleum gas to produce flame, fire, fireball or explosion effects.

LPG mortar (石油氣爆斗) means an LPG equipment used to produce fireball effects through the ignition of LPG rapidly released from its accumulator. It may operate without the use of any pyrotechnic material. Maximum service pressure rating (最高許用壓力) means the maximum pressure of an LPG equipment which must not be exceeded during use.

Mortar (爆斗) means a tube or a pot-like device used to direct and control the effects produced by the discharge of special effects materials contained therein.

MSPR (最高許用壓力), an abbreviation for maximum service pressure rating.

Perfomer (表演者) means any person active in a special effects scene excluding the audience or support personnel. Performers can include, but are not limited to, actors, singers, musicians, dancers, stunt performers and acrobats.

Propane (丙烷) means a type of fuel gas used with an LPG equipment to produce special effects. Under the Gas Safety Ordinance (Cap. 51), liquefied petroleum gas means any gas which is a mixture of hydrocarbons primarily consisting of butanes, butylenes, propane or propylene, or a mixture of all or any of these hydrocarbons.

Propylene (丙烯) means a type of fuel gas used with an LPG equipment to produce special effect. Under the Gas Safety Ordinance (Cap. 51), liquefied petroleum gas means any gas which is a mixture of hydrocarbons primarily consisting of butanes, butylenes, propane or propylene, or a mixture of all or any of these hydrocarbons.

Pyrotechnic material (煙火物料) means a chemical material which is designed to produce heat, light, sound, gas, smoke, or a combination of these effects as a result of a self-sustaining and self-contained exothermic chemical reaction by combustion, deflagration or detonation.

Soft pilot (軟火苗), in relation to the use of LPG equipment, means the ignition of LPG by spark gaps or any other means not involving hard pilot.

Special effects material (特別效果物料) means any of the material specified in the Special Effects Materials List Regulation. It is either listed as a pyrotechnic special effects material or as a non-pyrotechnic special effects material.

Support personnel (支援人員) means any individual who is not a performer or member of the audience or the general public. Among others, support personnel include the production crew, camera crew, special effects operators, stage hands, property masters, security guards, fire watch officers, janitors, or any other employees.

 

Annex I

Code of Federal Regulations, United States
Title 49, Section 178.51
(Revised as of October 1, 1999)

TITLE 49--TRANSPORTATION

CHAPTER I--RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

PART 178--SPECIFICATIONS FOR PACKAGINGS--Table of Contents

Subpart C--Specifications for Cylinders

Sec. 178.51 Specification 4BA welded or brazed steel cylinders.

(a) Type, size, and service pressure. A DOT 4BA cylinder is a cylinder, either spherical or cylindrical in shape, with a water capacity of 1,000 pounds or less and a service pressure of at least 225 and not over 500 pounds per square inch. Closures made by the spinning process are not authorized.

(1) Spherical type cylinders must be made from two seamless hemispheres joined by the welding of one circumferential seam.

(2) Cylindrical type cylinders must be of circumferentially welded or brazed construction.
 
(b) Steel. The steel used in the construction of the cylinder must be as specified in table 1 of appendix A to this part.
 
(c) Identification of material. Material must be identified by any suitable method except that plates and billets for hot drawn cylinders must be marked with the heat number.
 
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings.

(1) Seams must be made as follows:
 
  (i) Minimum thickness of heads and bottoms must be not less than 90 percent of the required thickness of the side wall.

(ii) Circumferential seams must be made by welding or by brazing. Heads must be attached by brazing and must have a driving fit with the shell, unless the shell is crimped, swedged or curled over the skirt or flange of the head, and must be thoroughly brazed until complete penetration by the brazing material of the brazed joint is secured. Depth of brazing from end of the shell must be at least four times the thickness of shell metal.

(iii) Longitudinal seams in shells must be made by copper brazing, copper alloy brazing, or by silver alloy brazing. Copper alloy composition must be: Copper 95 percent minimum, Silicon 1.5 percent to 3.85 percent, Manganese 0.25 percent to 1.10 percent. The melting point of the silver alloy brazing material must be in excess of 1,000 deg.F. The plate edge must be lapped at least eight times the thickness of plate, laps being held in position, substantially metal to metal, by riveting or by electric spot-welding. Brazing must be done by using a suitable flux and by placing brazing material on one side of seam and applying heat until this material shows uniformly along the seam of the other side. Strength of longitudinal seam: Copper brazed longitudinal seam must have strength at least 3/2 times the strength of the steel wall.
 
(2) Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3.
 
(e) Welding and brazing. Only the welding or brazing of neckrings, footrings, handles, bosses, pads, and valve protection rings to the tops and bottoms of cylinders is authorized. Provided that such attachments and the portion of the container to which they are attached are made of weldable steel, the carbon content of which may not exceed 0.25 percent except in the case of 4130 x steel which may be used with proper welding procedure.
 
(f) Wall thickness. The minimum wall thickness of the cylinder must meet the following conditions:
(1) For any cylinder with an outside diameter of greater than 6 inches, the minimum wall thickness is 0.078 inch. In any case the minimum wall thickness must be such that the calculated wall stress at the minimum test pressure may not exceed the lesser value of any of the following:
 
  (i) The value shown in table I of appendix A to this part, for the particular material under consideration;

(ii) One-half of the minimum tensile strength of the material determined as required in paragraph (j) of this section;

(iii) 35,000 pounds per square inch; or

(iv) Further provided that wall stress for cylinders having copper brazed longitudinal seams may not exceed 95 percent of any of the above values. Measured wall thickness may not include galvanizing or other protective coating.
 
(2) Cylinders that are cylindrical in shape must have the wall stress calculated by the formula:

S = [P(1.3D2 + 0.4d D2 )] / (D2 - D2 )

Where:
S = wall stress in pounds per square inch;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches;
d = inside diameter in inches.
 
(3) Cylinders that are spherical in shape must have the wall stress calculated by the formula:
S = PD / 4tE
Where:
S = wall stress in pounds per square inch;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches;
t = minimum wall thickness in inches;
E = 0.85 (provides 85 percent weld efficiency factor which must be applied in the girth weld area and heat affected zones which zone must extend a distance of 6 times wall thickness from center line of weld);
E = 1.0 (for all other areas).
 
(4) For a cylinder with a wall thickness less than 0.100 inch, the ratio of tangential length to outside diameter may not exceed 4:1.
 
(g) Heat treatment. Cylinders must be heat treated in accordance with the following requirements:

(1) Each cylinder must be uniformly and properly heat treated prior to test by the applicable method shown in table I of appendix A to this part. Heat treatment must be accomplished after all forming and welding operations, except that when brazed joints are used, heat treatment must follow any forming and welding operations, but may be done before, during or after the brazing operations.

(2) Heat treatment is not required after the welding or brazing of weldable low carbon parts to attachments of similar material which have been previously welded or brazed to the top or bottom of cylinders and properly heat treated, provided such subsequent welding or brazing does not produce a temperature in excess of 400 deg.F in any part of the top or bottom material.
 
(h) Openings in cylinders. Openings in cylinders must comply with the following requirements:

(1) Any opening must be placed on other than a cylindrical surface.
 
(2) Each opening in a spherical type cylinder must be provided with a fitting, boss, or pad of weldable steel securely attached to the container by fusion welding.
 
(3) If threads are used, they must comply with the following:

(i) Threads must be clean-cut, even, without checks and tapped to gauge.

(ii) Taper threads must be of a length not less than that specified for American Standard taper pipe threads.

(iii) Straight threads, having at least 4 engaged threads, must have a tight fit and a calculated shear strength of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
 
(i) Hydrostatic test. Each cylinder must successfully withstand a hydrostatic test, as follows:

(1) The test must be by water jacket, or other suitable method, operated so as to obtain accurate data. A pressure gauge must permit reading to an accuracy of 1 percent. An expansion gauge must permit reading of total expansion to an accuracy of either 1 percent or 0.1 cubic centimeter.
 
(2) Pressure must be maintained for at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat treatment and previous to the official test may not exceed 90 percent of the test pressure.
 
(3) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
 
(4) Cylinders must be tested as follows:

(i) At least one cylinder selected at random out of each lot of 200 or less must be tested as outlined in paragraphs (i)(1), (i)(2), and (i)(3) of this section to at least two times service pressure.

(ii) All cylinders not tested as outlined in paragraph (i)(4)(i) of this section must be examined under pressure of at least two times service pressure and show no defect.
 
(j) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material, as follows:

(1) The test is required on 2 specimens cut from one cylinder or part thereof having passed the hydrostatic test and heat-treated as required, taken at random out of each lot of 200 or less. Physical tests for spheres are required on 2 specimens cut from flat representative sample plates of the same heat taken at random from the steel used to produce the spheres. This flat steel from which 2 specimens are to be cut must receive the same heat treatment as the spheres themselves. Sample plates must be taken from each lot of 200 or less spheres.
 
(2) Specimens must conform to the following: (i) A gauge length of 8 inches with a width not over 1½ inches, or a gauge length of 2 inches with a width not over 1½ inches, or a gauge length at least 24 times the thickness with a width not over 6 times the thickness is authorized when a cylinder wall is not over 3/16 inch thick. (ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section. (iii) When size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens. (iv) Heating of a specimen for any purpose is not authorized.
 
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:

(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM Standard E8.

(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.

(iii) For the purpose of strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 pounds per square inch, and the strain indicator reading must be set at the calculated corresponding strain.

(iv) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
 
(k) Elongation. Physical test specimens must show at least a 40 percent elongation for a 2-inch gauge length or at least 20 percent in other cases. Except that these elongation percentages may be reduced numerically by 2 for 2-inch specimens, and by 1 in other cases, for each 7,500 pounds per square inch increment of tensile strength above 50,000 pounds per square inch to a maximum of four such increments.
 
(l) Tests of welds. Except for brazed seams, welds must be tested as follows:

(1) Tensile test. A specimen must be cut from one cylinder of each lot of 200 or less, or welded test plate. The welded test plate must be of one of the heats in the lot of 200 or less which it represents, in the same condition and approximately the same thickness as the cylinder wall except that in no case must it be of a lesser thickness than that required for a quarter size Charpy impact specimen. The weld must be made by the same procedures and subjected to the same heat treatment as the major weld on the cylinder. The specimen must be taken from across the major seam and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3. Should this specimen fail to meet the requirements, specimens may be taken from two additional cylinders or welded test plates from the same lot and tested. If either of the latter specimens fail to meet the requirements, the entire lot represented must be rejected.
 
(2) Guided bend test. A root bend test specimen must be cut from the cylinder or welded test plate, used for the tensile test specified in paragraph (l)(1) of this section. Specimens must be taken from across the major seam and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3.
 
(3) Alternate guided-bend test. This test may be used and must be as required by CGA Pamphlet C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines a to b, must be at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 pounds per square inch, as provided in paragraph (k) of this section.
 
(m) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair of brazed seams by brazing and welded seams by welding is authorized.
 
(n) Markings. Markings must be stamped plainly and permanently in one of the following locations on the cylinder:

(1) On shoulders and top heads not less than 0.087 inch thick.
 
(2) On side wall adjacent to top head for side walls not less than 0.090 inch thick.
 
(3) On a cylindrical portion of the shell which extends beyond the recessed bottom of the cylinder constituting an integral and non-pressure part of the cylinder.
 
(4) On a plate attached to the top of the cylinder or permanent part thereof; sufficient space must be left on the plate to provide for stamping at least six retest dates; the plate must be at least 1/16 inch thick and must be attached by welding, or by brazing at a temperature of at least 1100 deg.F., throughout all edges of the plate.
 
(5) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder.
 
(6) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 25 pounds.

[Amdt. 178-103, 59 FR 38074, July 26, 1994, as amended by Amdt. 178-108,
60 FR 40038, Aug. 4, 1995; Amdt. 178-110, 60 FR 49111, Sept. 21, 1995]
APPENDICES TO PART 178
Appendix A --Specifications for Steel

Table 1 Open-hearth, basic oxygen, or electric steel of uniform quality. The following chemical composition limits are based on ladle analysis:

Designation
Chemical composition, percent-ladle analysis
Grade 11
Grade 21,2
Grade 32,4,5
Carbon
0.10/0.20
0.24 maximum
0.22 maximum.
Manganese.
1.10/1.60
0.50/1.00.
1.25 maximum.
Phosphorus, maximum.
0.04
0.04
0.0456
Sulfur, maximum
0.05
0.05
0.05
Silicon.
0.15/0.30
0.30 maximum
Copper, maximum
0.40
Columbium.
0.01/0.04
Heat treatment authorized
(3 )
(3 )
(3 )
Maximum stress (p.s.i.)
35,000
35,000
35,000

  • Addition of other elements to obtain alloying effect is not authorized.
  • Ferritic grain size 6 or finer according to ASTM E112-63.
  • Any suitable heat treatment in excess of 1,100 deg.F., except that liquid quenching is not permitted.
  • Other alloying elements may be added and shall be reported.
  • For compositions with a maximum carbon content of 0.15 percent of ladle analysis, the maximum limit for manganese on ladle analysis may be 1.40 percent.
  • Rephosphorized Grade 3 steels containing no more than 0.15 percent phosphorus are permitted if carbon content does not exceed 0.15 percent and manganese does not exceed 1 percent.

[Reproduced with the permission of the US Department of Transportation]

 

Annex II

Code of Federal Regulations, United States
Title 49, Section 173.34(i)
(Revised as of October 1, 1999)

§173.34(i) Repair by welding or brazing of DOT-4 series and DOT-8, welded or brazed cylinders

Repairs on DOT-4 series and DOT-8 series welded or brazed cylinders are authorized to be made by welding or brazing. Such repairs must be made by a manufacturer of these types of DOT cylinders or by a repair facility approved by the Associate Administrator for Hazardous Materials Safety and by a process similar to that used in its manufacture and under the following specific requirements:


(1) Cylinders with injurious defects in welded joints in or on pressure parts must be repaired by completely removing the defect prior to rewelding.
 
(2) Cylinders with injurious defects in brazed joints in or on pressure parts must be repaired by rebrazing.
 
(3) Cylinders during welding must be free of materials in contact with the welded joint that may impair the serviceability of the metal in or adjacent to the weld. (Precautions must be taken to prevent acetylene cylinder steels from picking up carbon during repair.)
 
(4) Neckrings, footrings, or other nonpressure attachments authorized by the specification may be replaced or repaired. Repair or replacement of footrings, neckrings, or other nonpressure attachments authorized by the specification for DOT-4BA and 8AL (Secs. 178.51 and 178.60 of this subchapter) cylinders may be made without conforming to the requirements of paragraph (i)(6) of this section provided the following requirements are met:

(i) Must be done by a manufacturer of these types of DOT cylinders or by a repair facility approved by the Associate Administrator for Hazardous Materials Safety.

(ii) The welder shall have available to him information as to the procedure equipment, and rod used during manufacture and shall use a similar method for repair.

(iii) Repairs must be by metal arc welding only. Welds shall be 3 inches maximum length and spaced at least 3 inches apart.

(iv) Welds shall not be made on or near a brazed joint (to prevent the possibility of copper penetration).

(v) After repair the welds are to be inspected visually for weld quality.

(vi) After repair the weld area is to be leak tested at the service pressure of the cylinder.
 
(5) After removal, and before replacement of attachments, cylinders must be inspected and defective ones rejected, repaired or rebuilt.
 
(6) After repair, cylinders must be reheat-treated, tested, inspected and reported when and as prescribed by the specification covering their original manufacture when welding or brazing seams in a pressure part of a cylinder; or when welding or brazing on pressure parts of cylinders of plain carbon steels with carbon over 0.25 percent or manganese over 1.00 percent or of alloy steels except as provided in Sec. 173.34(i)(7).

Note 1: Heat-treatment is not required after welding or brazing weldable low carbon parts to attachments of similar material which has been previously welded or brazed to the top or bottom of cylinders and properly heat-treated, provided such subsequent welding or brazing does not produce a temperature in excess of 400 deg.F. in any part of the top or bottom material.
 
(7) Repair of cylinders must be followed by a proof pressure leakage test at prescribed test pressure and visual examination for weld quality when welding on pressure parts of cylinders of plain carbon 0.25 percent or less and manganese 1.00 percent or less, or when repairing steel types 1315, NAX and GLX by the following procedure:

(i) Leakage through the welding metal may be repaired without subsequent reheat treatment of the cylinder.

(ii) Repair permitted only by either the metal arc or tungsten inert gas shielded arc process. E7015, 7016, or 7018 electrodes not larger than 1/8 inch diameter shall be used for the metal arc process.

(iii) Weld defects must be removed by grinding or chipping before repair by the metal arc process. The tungsten inert gas shielded arc process may be used for repair only when such repair can be made by puddling. Repair weld shall not exceed 1 inch in length nor be closer than 3 inches to the next repair area.

(iv) Repair of weld defects which have any cracking is not permitted.


[Reproduced with the permission of the US Department of Transportation]
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