Pressure Systems

If pressure equipment fails in use it can seriously injure or kill people nearby and cause serious damage to property. Examples of pressure systems and equipment are:

  • Boilers and steam heating systems
  • Pressurised process plant and piping
  • Compressed air systems, fixed and portable
  • Heat exchangers and refrigeration plant
  • Valves, steam traps and filters
  • Pipework and hoses
  • Pressure gauges and level indicators

The principal causes of accidents include:

  • Poor equipment and/or system design
  • Poor maintenance of equipment
  • An unsafe system of work
  • Operator error
  • Poor training/supervision
  • Poor installation
  • Inadequate repairs or modifications

To reduce the risks you need to know and act on some basic precautions as contained in the Pressure Systems Safety Regulations.


Pressure Systems Safety Regulations

To reduce the risks you need to know and act on some basic precautions as contained in the Pressure Systems Safety Regulations:

Design and Construction

Designers, manufacturers and any person who supplies equipment or a component intended to be part of a pressure system must ensure that it is fit for the purpose, so as to prevent danger. The pressure system should be designed and manufactured from suitable materials for the liquid or gases it will contain.

Provision of Information and Marking

Sufficient information on the:

  • design
  • construction
  • examination
  • operation
  • maintenance of the equipment

should be provided in writing by the designer or supplier of a pressure system or component part. Basic information should be permanently marked on the vessel.


The employer of the person who installs a pressure system must ensure, for example:

  • That those doing the installation have the required skills and experience
  • Adequate supervision taking into account the complexity of the system being installed
  • Suitable foundations to support the system taking into account the nature of the ground and design loads such as the weight of the system and any likely external services
  • The most suitable method of lifting and handling the vessels, protective devices and pipework so as to prevent accidental damage
  • The system is protected from adverse weather conditions
  • There is sufficient space for access around and beneath valves
  • That the installation work is checked and approved by a competent person

Safe Operating Limits

A written statement specifying the safe operating limits of the system must be provided and be legibly and durably marked on the system.

Written Scheme of Examination

A written scheme of examination should be drawn up by a competent person. It is the duty of the user of an installed system and the owner of a mobile system to ensure that the scheme has been drawn up.

The written scheme of examination must cover all protective devices and must include every pressure vessel and those parts of pipelines and pipework which, if they fail, may give rise to danger. The scheme must specify the nature and frequency of examinations.

Action in Case of Imminent Danger

If the competent person carrying out an examination under the written scheme of examination is of the opinion that the pressure system or part of the pressure system will give rise to imminent danger unless certain repairs or modifications are carried out he shall make an immediate written report to that effect identifying the system and specifying the repairs or modifications.

Within 14 days a written report containing the same particulars must be sent by the competent person to the enforcing authority for the premises at which the pressure system is situated.


The user of an installed system and the owner of a mobile system shall provide for anyone operating the pressure system adequate and suitable instructions for the safe operation of the system and the action to be taken in the event of an emergency. This includes:

  • start-up and shutdown procedures
  • precautions for standby operation
  • function and effect of controls and protective devices
  • likely fluctuations expected in normal operation
  • the requirement to ensure that the system is adequately protected against overpressure at all times
  • procedures in the event of an emergency


All pressure equipment and systems should be properly maintained. There should be a maintenance programme for the system as a whole and should take into account the system and equipment age, its uses and the environment.

Modification and Repair

The employer of a person who modifies or repairs a pressure system at work shall ensure that nothing about the way in which it is modified or repaired gives rise to danger or otherwise impairs the operation of any protective device or inspection facility.

Keeping of Records

The last report made by the competent person relating to the pressure system shall be kept by:

  • the user of an installed system
  • the owner of a mobile system

Where a system is sold or otherwise changes hands the previous user/owner has a duty to pass all documents pertaining to the system to the new user/owner.

As a result, valuable information about the pressure system can be made available to those now responsible for the system. Records must be available, upon request, for inspection by inspectors from the relevant enforcing authority.


  1. The Pressure Systems Safety Regulations (LEGUK)
  2. L 122: Safety of Pressure Systems - Pressure Systems Safety Regulations - Approved Code of Practice (HSC)
  3. L 3: Pressure Systems Legislation - A Summary (BCGA - British Compressed Gases Association)
  4. INDG 178: Written Schemes of Examination: Pressure Systems Safety Regulations (HSE)
  5. INDG 261: Pressure Systems - Safety and You (HSE)