PSSR 2000: Common Myths & Misconceptions

The Pressure Systems Safety Regulations 2000 (PSSR) establish requirements for the safe operation, maintenance and examination of qualifying pressure systems. However, misunderstandings surrounding written schemes, pressure vessel thresholds and examination requirements remain common.

Here are six common misconceptions and what the regulations and relevant guidance actually say.

PSSR 2000: Common Myths & Misconceptions.

1. Pressure vessels below 250 bar-litres are exempt from written schemes.

Myth: Any pressure vessel below 250 bar-litres is automatically exempt from PSSR examination requirements.

Fact: The 250 bar-litre threshold determines whether certain compressed gas systems require a written scheme, not whether every individual vessel is exempt below this figure.

SAFed PSG09 clarifies that where any vessel exceeds 250 bar-litres, all vessels within that system should be considered for inclusion in the written scheme, regardless of individual size. Steam systems are not subject to the same threshold.

2. Every vessel in a statutory system must be included.

Myth: Once a pressure system contains a vessel exceeding 250 bar-litres, every smaller vessel must automatically be included in its written scheme.

Fact: PSSR Regulation 8 requires the written scheme to identify relevant pressure vessels, protective devices and pipework.

The inclusion of smaller vessels depends on whether their failure may give rise to danger, rather than their size alone. All protective devices must be included, while the exclusion of individual vessels must be appropriately justified.

3. New pressure systems do not require examination or written schemes.

Myth: Newly manufactured or installed pressure systems are exempt until their first periodic examination becomes due.

Fact: PSSR Regulation 8 requires a suitable written scheme before a qualifying system is operated. An initial examination may also be necessary where specified in the written scheme.

New equipment is not automatically exempt, although appropriate manufacturing and

conformity documentation may inform the examination requirements.

4. Pipework is always exempt from examination.

Myth: PSSR only requires pressure vessels and protective devices to be examined, excluding associated pipework.

Fact: PSSR Regulation 8 includes pipework where failure may give rise to danger.

Relevant pipework must be identified within the written scheme, particularly where deterioration through corrosion, erosion or fatigue could result in a dangerous release of

stored energy.

5. Safe operating limits always equal the vessel's design pressure.

Myth: The safe operating limit (SOL) is simply the design pressure marked on the pressure vessel.

Fact: PSSR Regulation 7 requires safe operating limits to be established for the system, incorporating a suitable margin of safety.

HSE L122 paragraph 92 explains that terminology varies, including maximum permissible working pressure for boilers and safe working pressure for air receivers. These limits may be marked on the vessel's data plate alongside its design pressure and may also include temperature limits, depending on the system.

6. Written schemes require Chartered Engineer certification.

Myth: Written schemes of examination must be certified by a Chartered Engineer (CEng).

Fact: PSSR Regulation 8 requires a competent person but does not mandate professional registration. HSE L122 ACOP paragraph 99 identifies Incorporated Engineer level for minor systems and Chartered Engineer or equivalent level for intermediate and major systems, depending on complexity.

UKAS RG2 provides guidance on competence requirements for accredited pressure system inspection bodies. Appendix 1 recognises equivalent qualification and experience levels, including an appropriate HNC or Level 4 vocational engineering qualification with relevant experience as equivalent to Incorporated Engineer level.

As highlighted by BCAS Fact Sheet 315, qualifications alone also do not establish competence, which depends on relevant knowledge, experience and capability and may ultimately be assessed by the courts.

Further Information

For more information, read our What is PSSR 2000? A Guide to Pressure Systems Safety Regulations article.

Additional guidance is available in HSE L122, Safety of Pressure Systems and from the Safety Assessment Federation (SAFed).

Steadfast Compliance Ltd provides independent pressure system examinations and written scheme services across Greater Manchester and the North West.

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