Pressure systems and gas cylinders

1. Introduction

This Policy Statement replaces University Guidance Note S5/90 and, from a practical point of view, no real changes are made. The Policy reflects requirements contained in the Pressure Systems Safety Regulations 2000 and the Carriage of Dangerous Goods (Classification, Packaging and Labeling) and Use of Transportable Pressure Receptacles Regulations 1996.

The Policy aims to prevent serious injury from the hazard of stored energy due to the failure of a pressure system or one of its component parts.  The Policy addresses steam at any pressure, gases which exert a pressure above 0.5 bar above atmospheric pressure and fluids which may be mixtures of liquids, gases and vapours where the gas or vapour phase may exert a pressure above 0.5 bar above atmospheric pressure.

A pressure system is a system (fixed or mobile) comprising one or more pressure vessels of rigid construction and any associated pipework and protective devices.  It also includes a pipeline and its protective devices.

See Appendix 1 to identify the requirements that apply to your pressure system.

‘Protective devices’ means devices designed to protect the pressure system against system failure and devices designed to give warning that system failure might occur and includes bursting discs.

Typical pressure systems found in the University, together with responsibilities for compliance are as follows:

Steam systems (boilers) 1
University Surveyor
Air compressors and receivers
Hot water systems and chlorifiers
University Surveyor
Laboratory/research equipment
Pressure cookers

2. Provision of information and marking

Designers and suppliers are required to pass on information to users about pressure systems and how they can be operated, maintained and examined safely.

3. Design, construction and modification

Any person who designs, manufactures or modifies a pressure system must design and construct it so as to prevent risk. The design must be such that all necessary examinations can be carried out safely and without putting those involved at risk.

Protective devices (eg to protect against system failure) must be fitted.

4. Installation

The employer of a person who installs a pressure system has to ensure that it is installed such that the system does not give rise to risk and does not impair the operation of any protective device or inspection facility.

For compressed air systems, there should be space around and beneath drain valves on air receivers so that they can be easily reached and so condensate can flow from the valve.  Compressors should be installed in a well ventilated, cool and clean air environment.  Inlet air to compressors must be drawn from an area which is free from potentially flammable or corrosive vapours or air excessively laden with moisture or dust.

5. Safe operating limits

The user of a pressure system must know its safe limits of operation.[2] Safe limits of operation will be provided by the manufacturer or supplier.  For systems in current use, information should already be available. 

Risks associated with second‑hand equipment will need to be assessed thoroughly.

The operating limits need to be reviewed at examinations and where significant modifications or repairs are carried out and when there are changes in the relevant fluid contained within the system.

6. Written scheme of examination

Owners of systems must have a planned scheme for examinations of relevant parts of the system.  The scheme has to be drawn up by a competent person, or a scheme drawn up by another person must be certified as being suitable by a competent person.

The written scheme may be drawn up by the manufacturer or owner of the system and certified as suitable by a competent person.

The term competent person is used in connection with three distinct functions:

(a)  advising on the scope of written scheme of examination;

(b)  drawing up or certifying schemes of examination;

(c)  carrying out examinations under the scheme.

One individual may or may not have sufficient knowledge and expertise to carry out all three functions.  Persons carrying out more than one function should be separately accountable for their activities as a competent person and it is important that each function is clearly defined.

It is expected that in the majority of cases, the competent person will be an outside contractor.  If 'in‑house' expertise is used, both the duty to perform and the technical qualifications required of the duty holder must be described in writing by the employing department.  Clarification of the term competent person can be found in the Approved Codes of Practice: ‘Safety of Pressure Systems’, ISBN 0 7176 1767 X.

7. Examination in accordance with the written scheme

The user of a system must ensure that the parts of the pressure system that need examination are examined by a competent person at the intervals identified in the scheme.

If a system has not been examined and the date for examination has passed, the system must not be used further until a suitable examination has been carried out.

8. Action in case of imminent danger

Where a serious defect is discovered during the system examination, the competent person must make a report specifying the necessary repairs and/or modifications and a written report must be sent to the Health and Safety Executive.

9. Operation of pressure systems

Owners of systems must provide, for persons operating the systems, detailed instructions to ensure the systems are operated within their safe operating limits and to cover any special procedures that may be necessary for the safe operation of the systems in emergency situations. 

10. Maintenance

Systems must be properly maintained and kept in good repair.  Some parts of systems require routine, regular checks and replacement.

11. Keeping of records

Users of fixed systems and owners of mobile systems must keep records of examinations.  Records to be kept are:

(a)  last report made by competent person;

(b)  any previous reports if they contain information that affects the safety of the system;

(c)  information about the design or marking.

For installed systems, the records must be kept at the premises of use, for mobile systems the records must be kept at the premises from which the deployment of the system is controlled.  These records must be readily available for inspection.

12. Gas cylinders

The general duties regarding lifting and handling, transport and correct storage remain.  In particular:

(a)  All cylinders must be stored in an area designated for storage.  Full and empty cylinders should be segregated.  Cylinders containing flammable and explosive gases, eg acetylene and hydrogen, should be stored separately from oxygen and toxic gases and preferably segregated by inert gases;

(b)  Cylinders must be properly supported at all times.  Freestanding cylinders should not be permitted;

(c)  Trolleys must be used for transporting cylinders;

(d)  Only the minimum number of gas cylinders commensurate with the number in use should be permitted in the building.  Cylinders not in use should be stored outside the building in the designated storage area;

(e)  Specific precautions on the use of acetylene are to be found in University Guidance Note S4/89;

(f)  Unless the department or University actually own cylinders, there will be no additional requirements other than those associated with the pipework and protective devices which must be inspected and maintained regularly.

13. Action to be taken

(a)  Ensure that there is an up to date inventory of all relevant systems.

(b)  Ensure that the competent person(s) has (ve) been appointed in writing.

(c)  Ensure that there are written schemes of examination for each and every relevant system.

(d)  Ensure that the necessary examinations/inspections are being carried out.  (Usually these will be carried out by engineers employed by the University’s insurers.)

(e)  Ensure that appropriate records are being kept in the department.  It is necessary to monitor that examinations/inspections are carried out at the appropriate intervals.

For gas cylinders:

(a)  Departments should review their general arrangements as regards storage, handling and use.

(b)  Departments should review their programme of inspection/testing of appropriate pipework and protective devices associated with gas cylinders including their formal record keeping system.

(c)  Where any department owns gas cylinders, the department must ensure that they are examined and tested by a competent person in accordance with recognised national standards or the relevant design specification; marked with a stamp or label to show that they have been examined and tested; marked with a stamp or label to show when the next examination is due; checked by an appointed verification body before being resupplied if modified or repaired.


[1] Except in the Sir William Dunn School of Pathology, where two steam boilers are under the control of the department.

[2] Operating limits mean maximum and minimum temperature and pressures; nature, volume and flow rates of contents; operating times; heat input; and coolant flow.

November 2000