Using Gas Safely
Accidents involving gas cylinders can cause serious injury or even death. This guide provides simple practical advice on eliminating or reducing the risks associated with using gas cylinders. It is based on guidance issued by the Health and Safety Executive in June 2004, and is aimed at anyone who manufactures, owns, fills, repairs or uses gas cylinders at work, and especially at those who own or manage small businesses.
Gas cylinders used in adverse or extreme conditions, such as for breathing apparatus, may require special precautions, such as different frequencies for periodic inspections. These are not covered in this guide.
Gas cylinders are a convenient way to transport and store gases under pressure. These gases are used for many different purposes including:
- chemical processes;
- soldering, welding and flame cutting;
- breathing (e.g. diving, emergency rescue);
- medical and laboratory uses;
- dispensing beverages;
- fuel for vehicles (e.g. fork-lift trucks);
- extinguishing fires;
- heating and cooking;
- water treatment.
- impact from the blast of a gas cylinder explosion or rapid release of compressed gas;
- impact from parts of gas cylinders or valves that fail, or any flying debris;
- contact with the released gas or fluid (such as chlorine);
- fire resulting from the escape of flammable gases or fluids (such as LPG);
- impact from falling cylinders;
- manual handling injuries.
- inadequate training and supervision;
- poor installation;
- poor examination and maintenance;
- faulty equipment (e.g. badly fitted valves and regulators);
- poor handling;
- poor storage;
- inadequately ventilated working conditions;
- incorrect filling procedures;
- hidden damage.
All gas cylinders must be designed and manufactured to an approved standard to withstand everyday use and to prevent danger (see section on Legislation). They must be initially inspected before they are put into service to ensure they conform to the approved standard, and be periodically examined to ensure that they remain safe while in service.
Anyone who examines, refurbishes, fills or uses a gas cylinder should be suitably trained and have the necessary skills to carry out their job safely. They should understand the risks associated with the gas cylinder and its contents.
new employees should receive training and be supervised closely;
users should be able to carry out an external visual inspection of the gas cylinder and any attachments (e.g. valves, flashback arresters, and regulators) to determine whether they are damaged. Visible indicators may include dents, bulges, evidence of fire damage (scorch marks) and severe grinding marks etc.;
valves should only be removed by trained personnel using procedures which ensure that either the cylinder does not contain any pressure or that the valve is captured during the removal process.
The law requires that gas cylinders are:
- manufactured to an appropriate standard approved under the relevant legislation; and
- examined by a relevant inspection body to verify that the cylinders are manufactured correctly and conform to the appropriate design standard.
Owners and fillers should satisfy themselves that the manufacturing requirements have been carried out, by examining either:
- the written certificate which accompanies the gas cylinder; or
- the stamp or mark of the relevant inspection body on the gas cylinder itself.
The law requires that all gas cylinders and valves are:
- examined and tested by the appropriate inspection body, in accordance with relevant regulations and at specified); and
- permanently marked by an appropriate inspection body to show the date of the last periodic examination.
Standards for periodic inspection and testing of cylinders and valves can be found on the HSE website at www.hse.gov.uk/cdg/pressure.htm.
For old gas cylinders there are legal requirements which prohibit modifications (with the exception of neck thread cutting) or major repairs to the body of seamless gas cylinders or cylinders which have contained acetylene. However, legal requirements allow for the modification and major repair (i.e. hot work) of other types of cylinders, subject to certain conditions.
For new cylinders repairs are prohibited to welds, cracks in the wall and leaks or other defects in the material of the wall, head or bottom of the cylinder. This allows the re-cutting of neck threads, but restricts hot work to de-denting operations only, and these must be carried out under the approval of a Notified or Approved Body.
Anyone carrying out the filling of gas cylinders should wear appropriate personal protective equipment. This may include safety shoes, protective overalls, gloves and ear and eye protection.
Standards for Inspection of Time of Fill should be followed. A current list of these standards, including standards for Pressure Drums, can be found on the HSE website at: www.hse.gov.uk/cdg/pressure.htm.
Use gas cylinders in a vertical position, unless specifically designed to be used otherwise;
Securely restrain cylinders to prevent them falling over;
Double check that the gas and the cylinder are the right ones for the intended use;
Before connecting a gas cylinder to equipment or pipe-work make sure that the regulator and pipe-work are suitable for the type of gas and pressure being used.
When required, wear suitable safety shoes and other personal protective equipment;
Do not use gas cylinders for any purpose other than the transport and storage of gas;
Do not drop, roll or drag gas cylinders.
Close the cylinder valve and replace dust caps, where provided, when a gas cylinder is not in use.
Where appropriate, fit cylinders with residual pressure valves (non-return valves) to reduce the risk of back flow of water or other materials into the cylinder during use that might corrode it (e.g. beer forced into an empty gas cylinder during cylinder change-over).
Ensure that the valve is protected by a valve cap, or collar, or that the valve has been designed to withstand impact if the cylinder is dropped.
Use suitable cradles, slings, clamps or other effective means when lifting cylinders with a hoist or crane;
Do not use valves, shrouds and caps for lifting cylinders unless they have been designed and manufactured for this purpose;
Gas cylinders should not be raised or lowered on the forks of fork lift trucks unless adequate precautions are taken to prevent them from falling.
Fit suitable protective valve caps and covers to cylinders, when necessary, before transporting. Caps and covers help prevent moisture and dirt from gathering in the valve of the cylinder, in addition to providing protection during transport;
Securely stow gas cylinders to prevent them from moving or falling. This is normally in the vertical position, unless instructions for transport state otherwise.
Disconnect regulators and hoses from cylinders whenever practicable.
Do not let gas cylinders project beyond the sides or end of a vehicle (e.g. fork lift trucks).
Ensure gas cylinders are clearly marked to show their contents (including their UN Number) and the danger signs associated with their contents.
It may be necessary to take special measures with certain types and quantities of compressed gases and fluids in order to ensure their safe carriage.
The transport of gas cylinders is subject to carriage requirements. For example, that:
- the vehicle is suitable for the purpose;
- the vehicle is suitably marked to show that it is carrying dangerous goods;
- the driver is suitably trained; and
- the driver carries the appropriate documentation about the nature of the gases being carried.
- Gas cylinders should not be stored for excessive periods of time. Only purchase sufficient quantities of gas to cover short-term needs.
- Rotate stocks of gas cylinders to ensure the oldest is used first.
- Store gas cylinders in a dry, safe place on a flat surface in the open air. If this is not reasonably practicable, store in an adequately ventilated building or part of a building specifically reserved for this purpose.
- Gas cylinders containing flammable gas should not be stored in part of a building used for other purposes.
- Protect gas cylinders from external heat sources that may adversely affect their mechanical integrity.
- Gas cylinders should be stored away from sources of ignition and other flammable materials.
- Avoid storing gas cylinders so that they stand or lie in water.
- Ensure the valve is kept shut on empty cylinders to prevent contaminants getting in.
- Store gas cylinders securely when they are not in use. They should be properly restrained, unless designed to be free-standing.
- Gas cylinders must be clearly marked to show what they contain and the hazards associated with their contents.
- Store cylinders where they are not vulnerable to hazards caused by impact, eg from vehicles such as fork lift trucks.
The two main sets of regulations covering gas cylinders are The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2004 (CDG) and The Pressure Equipment Regulations 1999 (SI 1999/2001) (PER). These are available from HSE at 020 7717 6303 or from their website at www.hse.gov.uk/cdg/pressure.htm; or from The Stationery Office (formerly HMSO), The Publications Centre, PO Box 276, London, SW8 5DT, Tel: 0870 600 5522, Fax: 0870 600 5533:
The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2004 (SI 568/2004 The Stationery Office 2004 ISBN 0 11 0490630).
The Pressure Equipment Regulations 1999 (SI 1999/2001 The Stationery Ofice 1999 ISBN 0 11 082790 2
List of HSE notified and approved bodies and standards approved by HSE are available on the HSE web-site at: www.hse.gov.uk/cdg/pressure.htm
The United Kingdom Accreditation Service (UKAS) can advise on the appointment of inspection bodies required under both CDG and PER. UKAS can be contacted at 21-47 High Street, Feltham, Middlesex TW13 4UN. Tel: 020 8917 8435, Fax: 020 8917 8499, or from their website at www.ukas.com.
For information about health and safety ring HSE's InfoLine
Tel: 08701 545000, Fax: 02920 859260,
e-mail: Hseinformationservices@natbrit.com or write to HSE Information Services, Caerphilly Business Park, Caerphilly CF83 3GG.
You can also visit HSE's web-site: www.hse.gov.uk