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When a pressure system fails, the stored energy can be released with explosive force, and steam can cause severe scalds. The Pressure Systems Safety Regulations 2000 (PSSR) set out how pressure systems must be designed, installed, examined, operated and maintained.
What counts as a pressure system?
A system containing a relevant fluid: steam at any pressure, or gases and compressed air at more than 0.5 bar above atmospheric pressure. Common examples are steam boilers and pipework, air compressors and receivers, autoclaves, pressure cookers in commercial kitchens, and refrigeration and air conditioning plant above certain sizes.
Who has the duties?
Designers, manufacturers, suppliers and installers have duties to make systems safe. Once a system is in use, the user (the employer or self-employed person in control of an installed system) or the owner (for a mobile system) is responsible for operating and maintaining it safely.
The key duties for users and owners
| Regulation | Duty |
|---|---|
| 7 | Establish the safe operating limits of the system. |
| 8 | Have a written scheme of examination, drawn up or certified by a competent person, before the system is operated. |
| 9 | Have the system examined by a competent person in line with the written scheme. |
| 10 | Act on any report of imminent danger, and do not use the system until it is put right. |
| 11 | Provide adequate operating instructions and make sure the system is operated within its limits. |
| 12 | Maintain the system in good repair. |
| 13 | Make sure modifications and repairs do not create danger. |
| 14 | Keep records of examinations and reports. |
The written scheme of examination
The scheme identifies the parts of the system to be examined, such as vessels, pipework and protective devices like safety valves, the nature of each examination and how often it must be done. The law does not set fixed intervals: the competent person decides them based on the risk. Many organisations use an insurance company engineer as their competent person.
Failures and RIDDOR
The failure of a closed vessel or associated pipework forming part of a pressure system is a dangerous occurrence that must be reported under RIDDOR, even if no one is hurt.
The ACoP and official guidance
| Publication | Status | What it covers |
|---|---|---|
| L122 Safety of pressure systems (revised edition, 2014) | ACoP and guidance | Scope, safe operating limits, the written scheme, examinations, operation, maintenance and records. |
An Approved Code of Practice (ACoP) has special legal status under section 16 of the Health and Safety at Work Act. If you are prosecuted and did not follow it, you must show that you met the law in some other way that was just as good. Guidance on Regulations has no special legal status, but inspectors refer to it and following it is normally enough to comply. Our guide to UK health and safety legislation lists every law and its ACoP or guidance in one place.
Training that helps
The NEBOSH National General Certificate covers work equipment and pressure systems within the wider legal framework, and IOSH Managing Safely gives managers the basics of risk assessment and inspection. Our guide to PUWER covers the wider duties for work equipment.
Frequently asked questions
Do air compressors come under PSSR?
Yes, compressed air systems above 0.5 bar are pressure systems, including the receiver, pipework and protective devices.
How often must a pressure system be examined?
As set out in the written scheme of examination, which the competent person decides based on the risk.
Who can be the competent person under PSSR?
Someone with the knowledge and experience to draw up schemes and carry out examinations, often an insurance company engineer or a specialist inspection body.
Is there an ACoP for pressure systems?
Yes, L122 Safety of pressure systems.
Read the source
The Pressure Systems Safety Regulations 2000 and HSE L122, Safety of pressure systems, Approved Code of Practice and guidance. Facts checked on 7 October 2026.
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