PSSR - Pressure Systems Safety Regulations 2000

What is PSSR?

These regulations require pressure systems to be inspected in accordance with a Written Scheme of Examination.

The Regulations apply to owners and users of systems containing ‘relevant fluids’ (which include steam, gases under pressure and any fluids kept artificially under pressure and which become gases when released into the atmosphere).

Following an assessment, a Written Scheme of Examination must be drawn up by a competent person, and must include a definition of the items included in the system and details of frequency of inspection.

Inspection procedures normally include both a thorough examination (with the system being shut down and vessels opened up) and a working examination of the system under normal operation.

Inspection intervals may vary according to the application of the system(s).

What does the term 'relevant fluid' mean as far as PSSR is concerned?

PSSR is designed to prevent serious injury from the hazard of stored energy. The term ‘fluids’ includes gases and liquids which are capable of exerting a vapour pressure. They do not include hydraulic oils. Hydraulic systems, while using high pressures, do not store energy in the system and so are not covered by PSSR. Under PSSR a relevant fluid is:

steam at any pressure
any fluid or mixture of fluids which is at a pressure >0.5 bar above atmospheric
a gas dissolved under pressure in a solvent (e.g. acetylene)

PSSR refers to an 'Installed' system and 'a mobile' system. What is the difference?

A mobile system is one that can be easily moved from place to place, e.g. an air compressor that is taken from site to site. An installed system is one that is not a mobile system, e.g. a steam boiler.

A steam locomotive is considered to be an installed system despite its obvious mobility. Similarly, a steam boiler fitted with skids (‘package boiler’) may be installed temporarily to maintain steam supply to a site during the replacement of an existing boiler, but this should also be treated as an installed system (see Safety of pressure systems, the ACoP for PSSR paragraph 46).

What is a written scheme of examination (WSE)?

A WSE is a document containing information about items of plant or equipment that form a pressure system, operate under pressure and contain a ‘relevant fluid’.

PSSR regulation 8 places a duty on the user of an installed system and the owner of a mobile system not to allow pressure systems to be used until they have a WSE covering:

all protective devices
every pressure vessel
every pipeline and pipework in which a defect might give rise to danger

An identification of the item of plant or equipment. Unique identification numbers or descriptions may be used.

The nature of the examination required, including the inspection and testing to be carried out on any protective devices.

The preparatory work needed to allow the item(s) to be examined safely, e.g.:

cooling down periods
isolation procedures
The maximum interval allowed between examinations

The critical parts of the system which, if modified or repaired, should be examined before the system (or part) is used again.

The name of the competent person certifying the WSE.

The date of the certificate.

PSSR regulation 9 requires an 'examination in accordance with the written scheme'. What does this mean?

This means a careful and critical scrutiny of a pressure system, in or out of service as appropriate, using suitable techniques, including testing where appropriate, to assess both its actual condition, and whether it will not cause danger up until the next examination (subject to routine maintenance).

A competent person, who will be appointed by the user/owner, will carry out the examination.

Must every pressure system comply with PSSR?

Not all pressure systems need to comply with PSSR. Schedule 1 of the ACoP provides a list of systems that are either excepted from all regulations or from certain regulations. Additionally, Appendix 1 to the ACoP has an easy-to-follow flow chart that specifies which systems must comply.

If the system does not contain a ‘relevant fluid’ then PSSR does not apply.

Note however that if the pressure vessel contains steam at any pressure then PSSR does apply,
irrespective of the pressure x volume product value.

Frequently Asked Questions

Is PSSR a legal requirement?

Yes, the Pressure Systems Safety Regulations (2000) is an approved code of practice and guidance for the safe design and use of pressure systems and vessels. Under PSSR, a Written Scheme of Examination (WSE) is required to identify the components, examinable items, and frequency of inspections.

What is the importance of PSSR inspections?

In addition to legal compliance, pressure vessel and pressure system inspections are crucial for ensuring the health and safety of both your employees and the vessel. By identifying and addressing potential problems before they escalate, you can greatly reduce the risk of accidents, injuries, and severe damage.

How often do pressure vessels need to be inspected in the UK?

Frequencies for pressure vessel inspections vary between the type of system but typically range between 12-120 months. Steam boilers normally require inspections every 14 months, while steam pressure vessels normally require inspections every 13-24 months.

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