Safety with gas cylinders

(also known as transportable pressure receptacles or transportable pressure vessels)

1.  Introduction

Gases contained in cylinders are used for many different purposes such as in research work, for soldering, welding and flame cutting, as fuel for vehicles (e.g. fork-lift trucks) and for extinguishing fires. They are safe when adequate risk control is in place but users and others sometimes suffer accidents if careful risk assessment has not been carried out. The main causes of accidents with gas cylinders are:

(a)  inadequate training and supervision of users;

(b)  poor installation;

(c)  poor examination and maintenance;

(d)  faulty equipment and/or design (e.g. badly fitted valves and regulators);

(e)  poor handling;

(f)  poor storage;

(g)  inadequately ventilated working conditions.

2.  Risk control

(a)  Where any department or institution owns gas cylinders these must be designed and manufactured to an approved specification to withstand everyday use and to prevent danger; they must be periodically examined by a competent person at the intervals set out in a written scheme of examination to ensure that they remain safe in service; and the filling of the gas cylinders must be described in a detailed working procedure.

(b)  Anyone who 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, in particular:

(i)  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.

It is necessary to keep a record of annual and formal inspections which must be carried out by a competent person who may be a contractor. NB it is general industry practice to renew regulators five yearly and in the case of toxic gases two yearly.

(ii)  Gas cylinders should be used in a vertical position, unless specifically designed to be used otherwise.

(iii)  Cylinders should be securely restrained to prevent them falling over from static locations and when they are being transported to and from storage. Cylinder trolleys should be used wherever practicable.

(iv)  Users should always double check that the cylinder/gas is the right one for the intended use.

(v)  Before installing connecting a gas cylinder to equipment or pipework, users should make sure that the regulator and pipework are suitable for the type of gas and pressure being used. All connection and disconnection operations must be subject to risk assessment. There may be risk of harmful gases being released at these times and appropriate precautions must be taken.

(vi)  When required, users should wear suitable safety shoes and other personal protective equipment for handling gas cylinders.

(vii)  Users should not drop, roll or drag gas cylinders.

(viii)  Users should close the cylinder valve and replace dust caps, where provided, when a gas cylinder is not in use.

(ix)  Where appropriate, users should 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).

3.  Storage

(a)  Gas cylinders should be stored in a secure, dry, safe place, on a flat surface, in the open air. If this is not reasonably practicable, storage should be in an adequately ventilated building or part of a building specifically reserved for this purpose. Storage areas should be identified with an appropriately sized warning sign. Cylinder stores should be identified in contingency planning and marked up on any plans.

(b)  Gas cylinders should be protected from external heat sources that may adversely affect their mechanical integrity.

(c)  Gas cylinders should be stored away from sources of ignition and other flammable materials.

(d)  Avoid storing gas cylinders so that they stand or lie in water.

(e)  Valves should be kept shut on empty cylinders to prevent contaminants getting into the cylinder.

(f)  When not in use, gas cylinders should be stored properly restrained, unless designed to be freestanding.

(g)  Gas cylinders must be clearly marked to show what they contain and the hazards associated with their contents.

(h)  Cylinders should be stored where they are not vulnerable to hazards caused by impact, e.g. from vehicles.

4.  Action required

(a)  Identify the gas cylinders in use in the department and institution and ascertain whether they are leased or owned.

(b)  If cylinders are owned, check that they are stamped with a record of examination carried out in accordance with 2.(a) above and that there is a detailed written procedure for filling the cylinders.

(c)  Check that leased cylinders are stored and used in accordance with the guidance given above and check that there are records of the inspection identified in 2.(b)(i) above.

THIS STATEMENT FORMS PART OF THE UNIVERSITY SAFETY POLICY.  PLEASE AMEND THE INDEX.

June 2003