CODE OF PRACTICE 7 THE SAFE USE OF OXY-FUEL …

1 code OF PRACTICE 7 THE SAFE USE OF OXY-FUEL GAS equipment (INDIVIDUAL portable OR mobile cylinder SUPPLY) REVISION 7: 2014 Incorporating Corrigendum 1 January 2017 BCGA CP 7 Revision 7 and Corrigendum 1 code OF PRACTICE 7 THE SAFE USE OF OXY-FUEL GAS equipment (INDIVIDUAL portable OR mobile cylinder SUPPLY) REVISION 7: 2014 Incorporating Corrigendum 1 January 2017 Copyright 2017 by British Compressed Gases Association. First printed 1986. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, without permission from the publisher: BRITISH COMPRESSED GASES ASSOCIATION Registered office: 4a Mallard Way, Pride Park, Derby, UK. DE24 8GX Company Number: 71798, England Website: ISSN 2398 - 9440 BCGA CP 7 Revision 7 and Corrigendum 1 PREFACE The British Compressed Gases Association (BCGA) was established in l971, formed out of the British Acetylene Association, which existed since l901.

2 BCGA members include gas producers, suppliers of gas handling equipment and users operating in the compressed gas field. The main objectives of the Association are to further technology, to enhance safe PRACTICE , and to prioritise environmental protection in the supply and use of industrial gases, and we produce a host of publications to this end. BCGA also provides advice and makes representations on behalf of its Members to regulatory bodies, including the UK Government. Policy is determined by a Council elected from Member Companies, with detailed technical studies being undertaken by a Technical Committee and its specialist Sub-Committees appointed for this purpose. BCGA makes strenuous efforts to ensure the accuracy and current relevance of its publications, which are intended for use by technically competent persons. However this does not remove the need for technical and managerial judgement in practical situations.

3 Nor do they confer any immunity or exemption from relevant legal requirements, including by-laws. For the assistance of users, references are given, either in the text or Appendices, to publications such as British, European and International Standards and Codes of PRACTICE , and current legislation that may be applicable but no representation or warranty can be given that these references are complete or current. BCGA publications are reviewed, and revised if necessary, at five-yearly intervals, or sooner where the need is recognised. Readers are advised to check the Association s website to ensure that the copy in their possession is the current version. This document has been prepared by BCGA Technical Sub-Committee 3. This document replaces BCGA CP 7, Revision 7, 2014. It was approved for publication at BCGA Technical Committee 155.

4 This document was first published on 01/02/2017. For comments on this document contact the Association via the website Corrigendum 1 January 2017 incorporates a correction to the text in Section , a new Section and inclusion of Appendix 2. BCGA CP 7 Revision 7 and Corrigendum 1 CONTENTS Section Page TERMINOLOGY AND DEFINITIONS 1 1. INTRODUCTION 3 2. SCOPE 4 3. KEY PROPERTIES OF THE GASES USED 4 Oxygen 5 Liquefied Petroleum Gas (LPG) Propane, Butane etc. 6 Acetylene 6 Hydrogen 6 Gas mixtures 7 4. PROCESS HAZARDS 7 Backfire 7 Sustained backfire 7 Intermittent backfire 7 Flashback 7 Backflow 7 Decomposition 7 Oxygen ignition 8 Oxygen enrichment 8 Fumes 8 Maintenance 8 5. PRESSURE SYSTEMS SAFETY REGULATIONS 8 Provision of information and marking 9 Written Scheme of Examination 9 Maintenance 9 6. SAFETY PRECAUTIONS - equipment 13 Pressure regulators 14 Hoses 15 Blowpipes 17 Non-return valves 17 Personal protective equipment 17 7.

5 PROVISION OF SAFETY DEVICES 18 Safety devices 18 Installation requirements 18 8. SAFETY PRECAUTIONS WORKING AREA 20 General 20 Confined spaces 21 Oxygen enrichment 22 Work on vessels and tanks 22 BCGA CP 7 Revision 7 and Corrigendum 1 9. cylinder HANDLING AND STORAGE 23 cylinder handling 24 cylinder storage 24 cylinder transportation 25 10. PREPARATION FOR USE 25 Location of cylinders 25 Cylinders 25 Regulators 26 Safety devices 27 Hose and hose assemblies 27 Blowpipes 27 Nozzles 27 Pressurising the system 28 System purging 29 Lighting up 29 11. CLOSING DOWN PROCEDURE 29 12. TRAINING 30 13. EMERGENCY PROCEDURES 30 Key actions for dealing with gas cylinders in the event of fire 31 Sustained backfire 31 Flashback / self-extinguishing backfire 32 Fire damaged gas cylinders 32 14. REFERENCES * 33 Appendices: Appendix 1 Minimum requirement for all hose sizes and lengths 38 Recommended installation providing increased safety 39 Appendix 2 Three-seat cutting nozzles - Dimensions 40 * Throughout this publication the numbers in brackets refer to references in Section 14.

6 Documents referenced are the edition current at the time of publication, unless otherwise stated. 1 BCGA CP 7 Revision 7 and Corrigendum 1 TERMINOLOGY AND DEFINITIONS The following describes the function of the main items of equipment and explains the meaning of significant terms used in this code . The references quoted in Section 14 should be consulted for more detailed and precise information. Blowpipe A piece of equipment in which separate supplies of oxygen and fuel gas are mixed in the appropriate proportions to obtain the required flame. A number of gas mixing systems can be employed either in the shank, between the shank and the blowpipe nozzle or in the nozzle and these may call for different working procedures. Some blowpipes may, by an interchange of components, be adapted to carry out a wide range of duties. Refer to Section Composite safety device (Flashback arrestor) A unit which embodies 2 or more of these devices: Flame arrestor Non-return valve Temperature sensitive cut-off valve Pressure sensitive cut-off valve Flame arrestor A device which arrests a flame front (caused by flashback or decomposition) and which is suitable for the most severe type of flame which may occur, detonation.

7 Flame arrestors shall conform to BS EN 730-1 (42). Hose assemblies The means by which the gases are conveyed from the regulator to the blowpipe. Refer to Section May Indicates an option available to the user of this code of PRACTICE . Mixing systems That part of the blowpipe to which gases are separately conducted and in which the mixing of gases takes place. The mixer may require the provision of gases at approximately equal pressures (an equal pressure mixer), or may require relatively higher oxygen pressure in relation to that of the fuel gas (an injector mixer). A mixer may be matched to a range of nozzle orifice sizes or to only one. Mixers shall conform to BS EN ISO 5172 (46) and may be detachable units or integral with the blowpipe. They may also derive from assembly by the operator of matching parts. They may be located in the shank, neck, head or nozzle (nozzle mix) of the blowpipe. 2 BCGA CP 7 Revision 7 and Corrigendum 1 Non-return valve A device which prevents the passage of gas in the direction opposite to normal flow.

8 Specifically a non-return valve shall be effective against the return of gas towards the cylinder . Refer to Section Nozzle That part of the blowpipe, which provides the final control of velocity and gas profile as a gas or gases emerge to the atmosphere. Pressure Within this code of PRACTICE the bar is used as the unit of pressure. 1 bar = 100 kPa = 105 N/m2 = lbf/in Pressures used are gauge pressures except where otherwise stated. Pressure regulator Device for regulating a generally variable inlet pressure to as constant as possible an outlet pressure. Refer to Section Pressure relief valve A valve, which automatically vents gas to the atmosphere in order to prevent a build-up of pressure in a system when the pressure exceeds a predetermined value. The pressure relief valve automatically reseats when the conditions causing the over-pressure are corrected. Pressure sensitive cut-off device A device which interrupts the gas flow in the event of a back pressure wave from the downstream side.

9 Safety device A device which, when correctly used and placed, prevents any damage or injury from misuse or malfunction of the blowpipe or associated equipment . The various devices shall conform to BS EN 730 (42), Parts 1 & 2 or ISO 5175 (47) as appropriate. Shall Indicates a mandatory requirement for compliance with this code of PRACTICE and may also indicate a mandatory requirement within UK law. Should Indicates a preferred requirement but is not mandatory for compliance with this code of PRACTICE . Temperature sensitive cut-off device A device which stops the gas flow when a predetermined temperature is reached. Valve with integrated pressure regulator (VIPR) A device intended to be permanently fitted to a gas cylinder connection and comprising a shut-off valve system and a pressure reduction system. Refer to Section 3 BCGA CP 7 Revision 7 and Corrigendum 1 code OF PRACTICE 7 THE SAFE USE OF OXY-FUEL GAS equipment (INDIVIDUAL portable OR mobile cylinder SUPPLY) 1.

10 INTRODUCTION Fuel gases are mostly hydrocarbon based and each has its own unique properties. The choice of a fuel gas is based on its ability to burn in air or oxygen and will be dependant on the specific requirements of the job, as well as the location at which it is being used. There are several useful fuel gases of which acetylene and propane are the most common. Acetylene is an extremely flammable gas and can burn in the presence of air or oxygen. This generates very high flame temperatures, which is the reason why acetylene is so effective for cutting and welding. The acetylene (C2H2) molecule, however, if initiated by heat exposure of a cylinder in a fire, or through excessive fill pressure, can also decompose breaking up into one hydrogen molecule and two carbon atoms. This reaction delivers much less energy than combustion but can, in some circumstances, be strong enough to rupture a cylinder .