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The Acetylene Safety Regulations 2014 & Safety with Oxyacetylene Equipment

BACKGROUND

The Acetylene Safety (England, Wales and Scotland) Regulations 2014 (ASR 2014) came into force on 1 October 2014.

Acetylene gas poses an additional hazard to other flammable gases as it is also reactive. Under certain conditions, even in the absence of any air or oxygen, it can decompose explosively into its constituent elements, carbon and hydrogen. This hazard is not fully addressed by DSEAR, as a result of which, additional legal requirements for the safe use of acetylene gas at equal to or greater than 0.62 bar (g) (“compressed acetylene gas”) and the equipment used with this are provided by the ASR 2014. The ASR includes for a system of connected acetylene equipment, a requirement for a flame (flashback) arrestor to stop the progression of a flame resulting from the decomposition or uncontrolled combustion of acetylene gas, which could lead to an explosion.

The HSE has also worked with stakeholders to consolidate a range of legislative instruments including regulations and orders into a single set of regulations.  These regulations simplify and where appropriate, modernise legislative arrangements for compressed acetylene gas whilst maintaining pre-existing safety standards.

The main changes include:

  • There will no longer be a requirement to seek HSE approval for certain acetylene equipment (including flashback arrestors and the composition of acetylene cylinders) so long as they comply with current recognised (national/international) standards.

  • Anyone wishing to manufacture, compress or fill a cylinder with acetylene gas greater than 0.62 bar (g) is required to hold a licence, replacing the current complex process for gaining approval.


FIRE/EXPLOSION SAFETY

Under ASR 2014 it is a legal requirement where using compressed acetylene gas or where storing acetylene gas in a manifold that:

  • The safety requirements in Schedule 1 of the Regulations are complied with; and

  • The risk is reduced so far as is reasonably practicable.

Typical oxyacetylene equipment 

The requirements of Schedule 1 of the Regulations are primarily concerned with ensuring the use of correctly designed acetylene equipment and the provision of safety hardware. When considering oxyacetylene equipment these, together with other recognised safeguards, are summarised as follows:

1. Equipment Standards and Compatibility

The provision of gas pressure regulators, safety devices and hoses designed for acetylene and oxygen respectively, manufactured and marked to the appropriate BS EN standards is essential. (The British Compressed Gases Association has issued a Safety Alert (1- 2014), highlighting that the use of an incorrect regulator for acetylene can cause an explosion due incorrect pressure or incompatible materials, and that occasions have arisen where propane regulators have been incorrectly fitted to acetylene cylinders).

√ An acetylene cylinder fitted with a clearly identified acetylene regulator

×An acetylene cylinder fitted incorrectly with a propane regulator


2. Non-return Valves

Non-return valves (also referred to as hose check valves) manufactured to BS EN 730-2 should be fitted to the blowtorch prevent back-feeding. Nowadays, most oxyacetylene hose assemblies from reputable manufacturers are supplied with non-return valves pre-fitted.

A typical non-return valve


3. Flashback Arrestors

In addition to non-return valves, flashback (flame) arrestors manufactured to BS EN 730-1 should be fitted onto the pressure regulators on both the acetylene and oxygen cylinders. For additional safety, flashback arrestors may also on occasions be fitted to the blowpipes, especially if access to the cylinders is confined or they are remote from the operator by virtue of an excessive length of hose, making the cylinders difficult to isolate. 

Typical flashback arrestors


4. Hoses

Hoses should be of the right colour (blue for oxygen and red for acetylene) and the right quality manufactured to BS EN standards. The good condition of hoses is of vital importance to safety. Correct hose connections, property fitted and tested to BS EN standards and retained by suitable clips or ferrules is the preferred option.


Twisted wire or jubilee type clips must never be used for securing hoses. In cases where such practices are encountered, new hose assemblies should be provided.


Where non pre-assembled hoses are used, they must be secured with specially designed “O” clips and an accompanying crimping tool.


5. Equipment Maintenance/Replacement

The following recommendations contained in Code of Practice 7: Safe use of oxy/fuel gas equipment published by the British Compressed Gases Association (BCGA) should be observed:


  • Each time the equipment is connected together: Checks to be a carried out as per the manufacturer’s instructions – to include a visual examination of gas cylinders, pressure regulators, flashback arrestors, hose assemblies (including non-return valves) and blowpipes to determine suitability for service and freedom from oil or grease contamination. Leak test all joints at working pressure using leak detection fluid.

  • Daily/before using the equipment: Carry out checks as above.

  • Annually or more frequently dependant on conditions of use: Detailed inspection and test of all equipment should be carried out by a competent person. BOC appointed retail outlets, for example, employ specialist engineers for this purpose.

  • Routine replacement/refurbishment: Regulators and flashback arrestors should be replaced every five years from the date of manufacture or more frequently in accordance with the manufacturer’s instructions. More frequent replacement may be required dependant on conditions of use. Both regulators and flashback arrestors will normally have date codes that show the date of manufacture. The replacement of hose assemblies (including non-return valves) and blowpipes will be determined by operating conditions.


6. System Purging and Closing Down

Before attempting to light the blowpipe, it is essential that each hose is separately purged. This operation should take place in a well ventilated space away from any source of ignition.  This procedure should take place following each period of non-use.


It is also essential that the necessary attention is given to completing the correct closing down procedures for short periods such as lunch breaks, and for longer periods, particularly if equipment is left unattended, and at the end of the working day or shift.


7. Cylinder Handling and Storage

Fire precautions concerning the handling and storage of acetylene cylinders include:


  • Cylinders must always be stored and used in a secure vertical position, restrained to avoid toppling. Cylinders must never be rolled.

A proprietary cylinder trolley

  • Cylinders are to be located in a position with good ventilation and where they will be protected from sources of ignition, excessive heat and mechanical damage.

  • Where possible and depending on quantity, cylinders should be stored in a secure detached building of non-combustible construction. As an alternative, cylinders should be housed in an external lockable cage or secure compound, protected from direct sunlight and located at least 6m from buildings, where possible, and at least 2m from the site boundary. Areas around cylinder stores should be kept clear of timber pallets, general rubbish and other combustible materials and free of vegetation and foliage.

    Where dealing with a large quantity of cylinders (in excess of 40 cylinders as per HSE guidance) from which there is a serious exposure hazard to a building housing a vulnerable population (e.g. a hotel), increased spatial distances and/or fire walls may be required.   

  • In circumstances where the scope for external storage is restricted, there may be little alternative but for spare cylinders to be kept internally. HSE guidance permits the storage of a spare cylinder of acetylene and oxygen within a workroom. Where dealing with larger quantities, an internal cylinder store of fire resisting construction will be required incorporating, amongst other safeguards, explosion venting to the open.

  • Oxygen and chlorine cylinders should not be kept in the same store as acetylene cylinders.


Further guidance on the storage of compressed gas cylinders, including acetylene, is contained in HSG139, referenced at the end of this Technical Bulletin.


8. Welding and Cutting Operations

In addition to ensuring the usual safeguards concerning the prevention of the ignition of combustible materials and structures from welding and cutting operations, attention should be given to the following:


  • On no account should welding or cutting operations be undertaken in an area containing flammable vapours, flammable liquids or explosive dust. Tanks or other containers, which have held such materials, must never be cut or welded without seeking specialist advice and adherence to guidance contained in HSE publications such as INDG314: Hot work on small tanks and drums.

    If hot work is necessary, the risks should be avoided by using a specialist company or reduced by using methods such as gas-freeing, cleaning or inerting before hot working. No one should repair or cut up tanks or drums unless they have received adequate training in the risks involved and the precautions to be taken.

  • Avoid welding or flame cutting on wheels which have tyres fitted, even if the tyre is deflated. Heat from the hot work can generate flammable vapour from any oil or flammable residue on the inner rim of the wheel. Also, the rubber can degrade when heated, resulting in the release of flammable vapour, which confined by the tyre can cause an explosion. If the tyre cannot be removed, a method of cold cutting must be employed.


9. Instruction and Training

Fundamental to fire safety in the use of oxyacetylene equipment is the need to ensure that all equipment and materials are installed, maintained and operated in accordance with the manufacturer’s instructions, and that staff are adequately trained and supervised to ensure correct operating procedures are followed. Material safety data sheets should be kept to hand and all operatives made aware of the information they contain.


Operatives must be correctly instructed in emergency procedures and the prescribed measures to be taken should a flashback occur.


10. Risk Assessment

The use and storage of oxyacetylene equipment should be fully considered when conducting Fire and DSEAR risk assessments. Guidance on this important aspect is contained in Technical Information Sheet 15: Model Risk Assessment for the Use and Storage of Oxyacetylene Cylinders, published by the BCGA, which can be found in the Information Centre.

                                                                                       

GENERAL HEALTH AND SAFETY

In addition to the fire/explosion hazards associated with oxyacetylene equipment, key considerations relating to general health and safety include the following:

  1. Welding Fumes

    Fumes arising from welding and flame cutting are harmful. Dirt, grease and other contamination can introduce highly toxic substances and particular care requires to be taken when working on certain metals such as zinc, chrome, nickel or manganese, or those with painted or coated surfaces.

    In compliance with COSHH, a risk assessment should be conducted, and the appropriate safeguards implemented, such as the provision of fume extraction and/or filtering respirators. 

  2. Eye Protection

    The provision of suitable eye and face protection to safeguard against heat, glare and flying sparks in compliance with BS EN standards is essential. 

    Depending on the outcome of a risk assessment, other forms of PPE are likely to be required such as flame retardant gloves and clothing, and safety footwear. Safety glasses should be used when handling cylinders.

    All clothing and protective equipment must be kept free from oil and grease. Oxygen must never be used to blow dust off clothing.

  3. Manual Handling

    The manual handling of oxyacetylene cylinders should be avoided. Where this is not reasonably practicable, a risk assessment of the manual handling operation should be carried out and appropriate safety precautions adopted. Elimination of manual handling in its entirety may seldom be accomplished.

  4. Work in Confined Spaces

    Particular care should be exercised in respect of oxyacetylene welding and cutting in confined spaces, in accordance with the Confined Spaces Regulations 1997. A suitable and sufficient risk assessment should be undertaken, and the appropriate safety measures put in place, which in respect of oxyacetylene activities are likely to include:

    • Adoption of a permit to work system;

    • Provision of fresh air ventilation and fume extraction;

    • Atmospheric monitoring capable of detecting any leaks of flammable gas and oxygen enrichment.


SURVEY EXPECTATIONS

The introduction of the Acetylene Regulations serves as a reminder of the hazards associated with acetylene and the need to pay close attention to oxyacetylene welding, cutting and other processes.

Experience shows that familiarity amongst welding operatives can often lead to contempt, with the result that safeguards may be ignored. 

Details of such processes should be included in the report and risk improvements raised where appropriate.


FURTHER REFERENCE

Sources of additional information include:

  • RISCAuthority RC49 Recommendations for reducing business interruption - Part 1: Acetylene cylinders involved in fires

  • HSE INDG327: Working safely with acetylene

  • HSE HSG139: The safe use of compressed gases in welding, flame cutting and allied processes

  • HSE INDG314: Hot work on small tanks and drums. 

The BCGA is a further excellent reference source with numerous publications freely available at www.bcga.co.uk/pages/index.cfm?page_id=6&title=publications.   

Important Note: Whilst this Technical Bulletin is mainly focused on portable oxyacetylene equipment in alignment with the Acetylene Regulations, many of the safeguards described will also apply to automated flame cutting equipment, manifold systems and to other oxy/fuel gases such as propane.

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