Cylinders in Fires

Gas cylinders are designed and constructed to safely contain a gas under pressure which, dependant on the type of gas and usage from the cylinder, can vary from a low pressure to a very high pressure.

Exceptionally, dissolved acetylene has distinct properties which requires specific post fire actions.The direct heat of a fire may, in extreme circumstances, initiate decomposition of acetylene. This is an exothermic (heat creating) reaction, which can cause a dissolved acetylene cylinder to reheat after the initial fire is extinguished.

Acetylene is the most flexible oxy-fuel gas and is used across multiple welding and metal cutting applications. Put simply, there is no direct replacement for acetylene. When handled, stored and transported correctly, acetylene is perfectly safe and has been invaluable to industry for over one hundred and sixty years.

From 2003 until November 2012, and only in the UK, the Fire & Rescue Services had what has since proven to  be a somewhat excessive precaution for dissolved acetylene cylinders, which  involved water cooling them for at least 24 hours, during which a hazard zone of 200 metres radius was usually maintained throughout. Whilst very safe, this often led to major disruption, which, in turn, prejudiced safety away from the incident.

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Research

Five stakeholder parties, namely BCGA, HSE, CFOA, the Department for Transport (DfT) and Transport for London (TfL) funded a major research project which was conducted over 2008 and 2009 by the German Federal Institute for Materials Research and Testing (BAM). BAM is world renowned in acetylene science and research.

Their task was to find out, with certainty – after how many hours of realistic cooling to a dissolved acetylene cylinder can we be sure that no decomposition can be ongoing and therefore that it is safe to close out an incident completely? The results from the BAM work may be summarised as follows:-

  • Mechanical impact alone CANNOT initiate acetylene decomposition.
  • Decomposition of acetylene cannot be initiated until at least 350 °C, meaning that only a cylinder which has been exposed to direct fire impingement can be at any risk.
  • Polymerization reactions of acetylene can occur at temperatures below 300 °C, but these are pressure-reducing reactions and therefore not of direct concern to the Fire & Rescue Service.
  • BAM confirmed that the previous 24 hour cooling had been very excessive and that one hour cooling was more than enough in the vast majority of acetylene incidents.

The BAM work was discussed extensively with the Fire & Rescue Service and with the Department for Communities and Local Government’s (DCLG) expert panel of consultant Professors. A recommendation was accepted that one hour cooling, followed by a further one hour monitoring as a precaution would be more than prudent. This agreed with the empirical evidence found at real incidents.

The Executive Summary report on BAM’s work may be viewed by clicking here and BAM’s Opinion on the revised one hour plus one hour protocol may be viewed by clicking here. The findings of the BAM research is of global significance, providing a scientific basis to the procedures adopted by our Fire and Rescue Service, and we trust that the new UK protocol may be adopted in other countries too and thereby mitigate needless disruption.

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Fire & Rescue Service Guidance & Acetylene Safety Regulations

The Fire & Rescue Service initially published their revised guidance, the Fire & Rescue Service, Operational guidance, Incidents involving hazardous materials, in November 2012.

The findings from the BAM research were incorporated into the guidance, which advised a 1 hour cooling, plus 1 hour monitoring protocol for acetylene cylinders which have been exposed to direct fire.

This Fire Service guidance format was subsequently updated in early 2018 (but the 1+1 hour protocol for acetylene cylinders remains unchanged) and information on managing hazardous materials is now available to the Fire & Rescue Service within their National Operational Guidance Programme. The National Operational Guidance is extremely detailed and is of limited interest to other than operational firefighters. It can be viewed by clicking here and here.

The Acetylene Safety (England and Wales and Scotland) Regulations (SI 2014 No. 1639) came into force on 1 October 2014. They include a very important new provision which MANDATES the use of flashback arrestors on oxy-acetylene sets.

The HSE provide guidance on the safe use of acetylene, along with a range of additional information, on their website and a copy of the Acetylene Safety Regulations can be downloaded here.

Publications

Publications

CP44 The storage of gas cylinders. 2016

1766 Codes of Practice CP44

This document defines the principles of safe practice for the storage of gas cylinders and bundles. It promotes the use of an external store, in a secure location, with good natural ventilation and away from any sources of ignition.

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GN13 DSEAR risk assessment guidance for compressed gases. Revision 1: 2021

1829 Guidance Notes GN13

Provides guidance on the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) which require all sites, where there are gas containers, to undertake a risk assessment and, where necessary, to implement appropriate controls.

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TIS15 Model risk assessment for the storage and use of gas cylinders for oxy-fuel applications. Revision 1: 2015

1965 Technical Information Sheets TIS15

This document lays out a model risk assessment. Included are a series of tabulated risk assessment sheets which address the main aspects of the storage, transportation and use of oxygen / fuel cylinders. A copy is also provided in a format that allows the user to modify the contents to suit their specific needs.

Where this document is downloaded as an Excel Spreadsheet, the user has the option of amending the contents and, as such, it is beyond the direct control of the BCGA. In this situation, the user takes full responsibility for the contents of the document.

Please see the TIS 15 below to download the amendable Excel Spreadsheet.

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TIS32 Acetylene or propane (for welding, cutting and allied processes). Revision 2: 2019

2004 Technical Information Sheets TIS32

This document provides technical information on the different properties of acetylene and propane to help the user make an informed choice when choosing a fuel gas for welding, cutting and allied processes.

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L6 Cylinders in fires. Revision 5: 2017

1886 Leaflets L6

BCGA Leaflet L6 provides advice on the actions to take in the event of a fire on or near gas cylinders.

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BCGA publish several publications providing advice on managing gas cylinders. All BCGA publications are accessible via the Publications page.