What is PSSR 2000? A Guide to Pressure Systems Regulations
Updated: 3 days ago
Pressure systems are widely used across UK workplaces, including compressed air installations, refrigeration equipment, steam boilers and industrial machinery. Failure of these systems can result in serious injury from the uncontrolled release of stored pressure energy.
The Pressure Systems Safety Regulations 2000 (PSSR) establish legal requirements for the safe design, installation, operation, maintenance and examination of pressure systems used at work.
This guide explains who PSSR applies to, which systems are covered or exempt, the main legal duties and when examinations are required.
1. What is PSSR 2000 and Who Does It Apply To?
PSSR establishes duties to prevent danger arising from the release of stored energy following pressure system failure. The regulations place responsibilities on:
Users of installed systems: Employers or self-employed persons controlling the operation of installed pressure systems.
Owners of mobile systems: Employers or self-employed persons who own mobile pressure systems.
Designers, manufacturers, suppliers and installers: Those responsible for equipment design, construction, information and safe installation.
For hired or leased installed systems, the user normally retains responsibility, although Schedule 2 permits certain duties to be transferred to the supplier through a written agreement.
PSSR applies across industries including manufacturing, engineering, healthcare, refrigeration and food production. Its requirements extend beyond periodic examinations to
include safe operating limits, protective devices, maintenance and safe operation.
2. What Does PSSR Apply To?
PSSR applies to defined pressure systems containing, or liable to contain, a relevant fluid.
Under Regulation 2, a pressure system may comprise pressure vessels, associated pipework and protective devices, or other specified arrangements involving pipework, pipelines and transportable pressure receptacles.
Relevant fluids include:
Steam at any pressure.
Gases and certain liquids at pressures exceeding 0.5 bar above atmospheric pressure. For liquids, the vapour pressure must also exceed this threshold at their actual temperature or 17.5°C.
Gases dissolved under pressure in a solvent contained in a porous substance, which can be released without applying heat (e.g. acetylene cylinders).
Common examples of pressure equipment and associated components include:
Compressed Air Systems: Air receivers, air/oil separators, bead seaters, sandblast vessels, desiccant dryers and paint pressure pots.
Steam Systems: Steam boilers, blowdown vessels, steam generators, jacketed pans, autoclaves and coffee boilers.
Refrigeration Systems: Packaged refrigeration systems, air-conditioning installations, liquid receivers, condensers, evaporators and surge drums.
Other Fluids: Expansion vessels, accumulators, storage vessels, calorifiers, gas storage tanks and gas mixing vessels containing relevant fluids.
Associated Parts: Safety valves, pressure gauges, pressure regulators, pressure pipework, associated mountings and protective devices forming part of qualifying systems.
What equipment is exempt?
Schedule 1 of PSSR establishes complete and partial exemptions.
Complete exemptions under Part I include:
Aircraft, ships and vehicles: Specified pressure systems, including vehicle braking, suspension, tyres and fuel systems.
Road tankers and transport: Qualifying dangerous goods tankers and systems covered by international transport agreements.
Refrigeration systems: Total installed compressor motor power not exceeding 25 kW, including standby motors.
Portable fire extinguishers: Working pressure below 25 bar at 60°C and total mass not exceeding 23 kg.
Pipelines: Qualifying pipelines operating at 2 bar gauge or less, subject to specified conditions.
Specialised equipment: Certain weapons, research equipment, handheld tools and agricultural slurry tankers.
Other exemptions: Specified diving equipment, compressed-air chambers, cooling systems, turbines and electrical pressure systems.
These exemptions apply only where the conditions in Schedule 1 are satisfied.
Partial exemptions under Part II remove certain requirements rather than PSSR as a whole.
Pressure systems where each vessel containing a relevant fluid other than steam has a pressure-volume product below 250 bar-litres are exempt from Regulations 5(4), 8–10 and 14. For example, a 24-litre air receiver operating at 8 bar produces 192 bar-litres.
Other PSSR duties and applicable legislation, including PUWER, may still apply.
3. What Does PSSR Require?
PSSR establishes duties to ensure pressure systems are safely designed, operated, maintained and examined. The principal requirements include:
Regulations 4–6 — Design, Information and Installation
Pressure systems must be suitably designed, constructed and installed to prevent danger, with appropriate information and marking provided.
Regulation 7 — Safe Operating Limits
Users and owners must establish safe operating limits, including relevant pressure and temperature limits, before operation.
Regulations 8–9 — Written Schemes and Examinations
Where required, a written scheme must be prepared or certified by a competent person. Pressure systems must then be examined in accordance with that scheme, with the required examination report issued.
Regulation 10 — Imminent Danger
Where an examination identifies imminent danger, the competent person must immediately notify the user or owner and provide the required written notification to the enforcing authority.
Regulations 11–13 — Operation, Maintenance and Repair
Pressure systems must be operated safely, supported by suitable instructions and training, maintained in good repair and repaired or modified without creating danger.
Regulations 14–15 — Records and Prevention of Pressurisation
Prescribed examination reports and records must be retained. Precautions must also be taken to prevent pressurisation of certain vessels where danger could arise.
Together, these requirements address pressure system safety throughout the equipment's working life.
4. When is a PSSR Examination Required?
Pressure systems requiring a written scheme of examination (WSE) must be examined by a competent person in accordance with that scheme.
Before First Use
A suitable written scheme must be in place before operation. An initial examination is required where specified by the scheme, considering the equipment's design, condition and supporting documentation.
Periodic Examinations In Accordance with a Written Scheme
Examinations must take place within the intervals specified in the Written Scheme of Examination. PSSR does not prescribe universal examination intervals; these are determined by the competent person based on equipment condition, operating circumstances and deterioration risks.
Typical examination intervals may include:
12–24 months: Steam boilers, autoclaves, coffee boilers, medical and jacketed pans.
24–48 months: Air receivers, air/paint containers and shot blast vessels.
48–72 months: Air/oil separators, desiccant dryers and expansion vessels.
These are indicative intervals only. The actual examination frequency must be specified in the WSE, with protective devices examined at least as frequently as the equipment they protect.
SAFed PSG 01 provides further guidance.
Repairs and Modifications
Significant repairs or modifications may require additional examinations or revisions to the WSE before returning equipment to service. SAFed PSG 15 provides relevant guidance.
Routine maintenance and servicing do not replace examinations required under a Written Scheme in accordance with PSSR.
5. Common Terms Used in PSSR
Understanding commonly used terms can help businesses identify their responsibilities and interpret pressure system examination requirements.
Pressure System
An arrangement of pressure vessels, associated pipework and protective devices, or another configuration defined under Regulation 2. A pressure system may comprise several interconnected components operating together, rather than a single vessel or item of equipment.
Relevant Fluid
Steam at any pressure; gases above 0.5 bar gauge; and liquids above 0.5 bar gauge with a vapour pressure exceeding 0.5 bar gauge at their actual temperature or 17.5°C. Also includes gases dissolved under pressure in a solvent within a porous substance that can be released without heat, such as acetylene.
Written Scheme of Examination (WSE)
A formal document identifying the pressure-containing components and protective devices requiring examination. It specifies the nature and frequency of examinations, necessary preparations and any additional requirements. The scheme must be drawn up or certified by a competent person.
Safe Operating Limits
The maximum or minimum operating parameters established to prevent danger, including relevant pressure and temperature limits. These limits must reflect the system's design and operating conditions and be established before the pressure system is operated.
Protective Device
A device designed to prevent pressure system failure or provide warning that failure might occur. Examples include safety valves, bursting discs and appropriate pressure or temperature controls, which protect the system against potentially dangerous operating conditions.
Nature of Examination
PSSR examinations may be conducted in-service or out-of-service, depending on the equipment and Written Scheme of Examination. Out-of-service examinations are commonly termed Part 1 or thorough examinations, while in-service examinations may be termed Part 2 or working examinations. These terms are often used interchangeably within industry, although the examination requirements are determined by the written scheme.
Further Information
For further guidance on PSSR, refer to the Health and Safety Executive's L122 Approved Code of Practice, INDG261 (Pressure Systems: A Brief Guide to Safety) and INDG178 (Written Schemes of Examination). Additional technical guidance is available through SAFed.
Steadfast Compliance Ltd provides independent PSSR examinations across Greater Manchester and the North West, including compressed air systems, steam equipment and refrigeration installations. We also provide written schemes of examination within our scope of competence.
For further information or to arrange an examination, visit Steadfast Compliance or email info@steadfastcompliance.co.uk.
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