“A PSSR examination is not a generic pressure vessel checklist. The Written Scheme of Examination determines what must be examined, how and when.”

What actually happens when a pressure vessel is due for its PSSR examination? Does the engineer inspect the inside, test the safety valve or carry out ultrasonic testing?

The answer depends on the pressure system and its Written Scheme of Examination (WSE). The scheme identifies the parts that need examination, the method and frequency of examination, and any preparation needed to carry it out safely.

A competent person then examines the specified parts in accordance with that scheme and produces a written report. This guide explains what that process can include, what you may need to do before the visit and what happens if the examination identifies a defect.

Quick answer: What does a PSSR examination include?

A PSSR examination covers the parts of a qualifying pressure system identified in its Written Scheme of Examination. These can include pressure vessels, protective devices and relevant pipework or pipelines whose failure could give rise to danger. The competent person follows the examination methods and intervals in the scheme, assesses the results and issues a written report identifying the condition of the parts examined, required action and the date by which the next examination must take place.

Explore Velocity Safety’s PSSR examinations and Written Schemes service.

Key takeaways

  • The Written Scheme sets the scope: there is no identical examination procedure for every pressure vessel.
  • The scheme must address protective devices, pressure vessels and relevant pipework or pipelines whose failure could cause danger.
  • Visual examination, internal examination, protective-device testing or non-destructive testing may be required, depending on the scheme.
  • An examination under PSSR does not replace routine servicing and maintenance.
  • The competent person must produce a written report stating the results, required action, the next examination date and whether the scheme remains suitable.
  • A finding of imminent danger triggers separate, immediate reporting and restrictions on operation.

Jump to:

What Is a PSSR Examination?

A PSSR examination is the formal examination of specified parts of a pressure system under the Pressure Systems Safety Regulations 2000.

People often call it a PSSR inspection or pressure vessel inspection. The Regulations use the term examination.

Its purpose is to identify defects or deterioration in the parts covered by the Written Scheme before failure could cause danger from stored pressure. PSSR can apply to systems containing relevant fluids such as steam, compressed air or other qualifying gases, subject to the Regulations’ definitions and exceptions.

A pressure system can include a rigid pressure vessel, associated pipework and protective devices. That is why examining only the outside of a receiver may not satisfy a scheme that also specifies a safety valve or other components.

If you first need to establish whether your system requires a scheme, read our PSSR Written Scheme of Examination Requirements guide.

How Does the Written Scheme Control the Examination?

The Written Scheme of Examination (WSE) is the starting point. It must be drawn up or certified as suitable by a competent person and be in place before a qualifying system is operated.

A suitable scheme identifies:

  • The pressure system and the parts requiring examination
  • The nature of each examination and any necessary testing
  • How protective devices will be examined or tested
  • Any special measures needed to prepare the system safely
  • The maximum intervals between examinations
  • Any examination required before first use, where appropriate
  • Critical parts needing examination after certain repairs or modifications

The scope should reflect the actual system. Two air receivers may look alike but have different operating conditions, histories or likely deterioration mechanisms. Their examinations need not be identical.

The competent person should also review whether the WSE remains suitable. If a system has been modified or its condition has changed, the scheme may need updating rather than simply repeating last year’s procedure.

What Happens Before the Examination?

Before starting physical checks, the competent person establishes what the scheme requires and whether the system presented matches the documentation.

They may review:

  • The current WSE and previous examination report
  • Equipment identity and manufacturer information
  • Safe operating limits
  • Maintenance, repair and modification history
  • Previous defects or recommendations
  • The examination methods specified by the WSE
  • Access, isolation and other preparation requirements

The user of an installed system, or owner of a mobile system, must take appropriate safety measures to prepare it for examination. If the WSE requires a shutdown or internal access, this should be planned before the competent person arrives.

What Is Checked on a Pressure Vessel?

Where the vessel is included in the scheme, the competent person examines it for defects or deterioration relevant to its safe operation. The exact checks depend on the vessel and the method specified by the WSE.

Depending on access and examination scope, findings may include:

  • External or internal corrosion
  • Material thinning or erosion
  • Cracking, distortion or bulging
  • Leakage
  • Damage near welds, openings or connections
  • Deterioration at nozzles or supports
  • Evidence of damage from operating conditions

An internal examination is not automatically part of every visit. Where it is required, the vessel must be safely prepared and made accessible. The competent person then records what was examined, any limitations and the results.

For more detail on a common workplace pressure vessel, see our Air Receiver PSSR Compliance Guide.

Are Safety Valves and Protective Devices Examined?

Yes, where they form part of the pressure system, protective devices must be addressed by the WSE. They help prevent the system operating outside its safe limits.

Depending on the installation, these may include safety valves, pressure relief valves, bursting discs and other pressure-limiting devices. The scheme should specify the examination or testing needed to establish that they remain effective.

That does not mean every device undergoes the same test on every visit. The method must be suitable for the device and the particular system.

This part of the examination matters because a vessel can appear sound while a defective or incorrectly set protective device leaves it vulnerable to overpressure.

Does the Examination Include Pipework, Gauges and Fittings?

It can, where the WSE includes them. The scheme should cover relevant pipework or pipelines whose failure could give rise to danger. It should also identify other parts that need examination for the system to remain safe.

Depending on the arrangement, the competent person may need to examine specified:

  • Pressure pipework and connections
  • Valves, flanges or fittings
  • Protective devices connected to the pipework
  • Pressure indication or control equipment relevant to safe operation

This does not mean every metre of pipework automatically receives the same examination as a pressure vessel. The WSE identifies the safety-critical parts and the appropriate method for each.

Does Every PSSR Examination Include NDT or Internal Inspection?

No. Non-destructive testing (NDT) and internal examination are used where the WSE and the expected deterioration mechanisms call for them. They are not universal additions to every PSSR visit.

Depending on what needs to be detected, suitable NDT may include ultrasonic thickness measurement, ultrasonic flaw detection, magnetic particle testing or dye penetrant testing.

The method needs to answer a specific question. For example, a thickness measurement may help assess material loss, while another technique may be needed to investigate a suspected crack. Simply carrying out “some NDT” does not prove that the relevant risk has been assessed.

HSE’s technical guidance on inspection and NDT explains that the WSE should identify the expected damage mechanism, examination interval and examination method, including required NDT.

Does the System Need to Be Shut Down?

That depends on the examination specified by the WSE. Some checks may be possible while the system is in an appropriate operating condition. Others require it to be taken out of service.

Preparation could involve shutting down, isolating, depressurising, draining or cooling equipment, or opening a vessel for internal examination. Safe access may also need to be arranged.

The dutyholder should agree these requirements before the visit. An engineer cannot complete an internal examination if the vessel remains pressurised and inaccessible when they arrive.

What Does the PSSR Examination Report Include?

After the examination, the competent person must produce a written report. It is more than a sticker or a simple pass/fail certificate.

Under PSSR Regulation 9, the report must state:

  • Which parts of the pressure system were examined, their condition and the examination results
  • Any repairs, modifications or changes to safe operating limits needed to prevent danger or maintain effective protective devices
  • The date by which those actions must be completed
  • The date after which the system must not be operated without a further examination under the scheme
  • Whether the WSE remains suitable or needs modification, with reasons if a change is needed

The report should be sent as soon as practicable and within the period required by the Regulations. The dutyholder then needs to complete any specified action by its deadline and arrange the next examination in time.

Do not treat the report as paperwork to file away. Its findings determine whether repairs, changes to operating limits or an updated WSE are necessary.

What Happens If Imminent Danger Is Found?

Regulation 10 sets out an additional process when the competent person concludes that the pressure system, or part of it, will give rise to imminent danger unless specified repairs, modifications or changes to operating conditions are made.

The competent person must issue a separate written report immediately to the relevant user or owner, identifying the system and required action. They must also send the required particulars to the enforcing authority within 14 days of completing the examination.

The affected system, or the affected part, must not be operated until the specified action has been completed. This is distinct from a defect for which the ordinary examination report sets a future completion date.

Practical point: An imminent-danger finding needs immediate action. A routine service booking at a later date is not an appropriate response to continued operation being prohibited.

Is a PSSR Examination the Same as Servicing?

No. A PSSR examination checks specified safety-critical parts in accordance with the WSE. Routine servicing keeps the equipment maintained and operational between examinations.

PSSR examination Routine servicing
Follows the Written Scheme of Examination Follows the maintenance programme and manufacturer instructions
Examines specified parts for pressure-system safety Maintains equipment condition and performance
Carried out by a competent person for PSSR purposes Carried out by appropriately competent maintenance personnel
Produces a statutory report of examination Produces maintenance or service records

HSE explicitly states that an examination under a WSE is not a substitute for regular and routine maintenance. Having a compressor serviced does not, on its own, establish that its PSSR examination is current.

Who Can Carry Out a PSSR Examination?

A PSSR examination must be carried out by a competent person with the knowledge, experience and independence appropriate to the pressure system and examination.

HSE notes that an in-house competent person should be independent of the organisation’s operating functions and have sufficient authority to stop use of the equipment if necessary. An external provider can also fulfil the role where suitably competent.

The competent person must be able to assess the system and WSE, apply appropriate examination methods, interpret findings and identify action needed to prevent danger.

How Often Is a PSSR Examination Required?

The maximum interval comes from the Written Scheme of Examination. There is no single annual examination rule that applies identically to every pressure vessel.

The interval and method depend on factors such as equipment design, age, operating conditions, relevant fluid, expected deterioration and previous findings. The competent person should review whether the WSE remains suitable as those factors change.

The examination report states the date after which the system must not continue operating without a further examination under the scheme. Use that date and the WSE to plan the next visit.

How Should You Prepare for a PSSR Examination?

Start with the WSE. It tells you what equipment must be available and whether any shutdown or specialist preparation is needed.

Useful information to have ready includes:

  • The current WSE
  • The previous examination report
  • Equipment identification and manufacturer details
  • Safe operating limits
  • Records of significant repairs or modifications
  • Relevant maintenance and service history
  • Access to every item listed for examination

Confirm any isolation, depressurisation, cooling, draining or opening requirements in advance. If equipment has changed since the WSE was prepared, tell the competent person before the examination.

For a newly purchased compressor, see our guide to Written Schemes before first use.

Which Pressure Systems Might Need an Examination?

Qualifying systems can include air receivers and compressed air systems, steam boilers, autoclaves, process pressure vessels and associated protective devices or pipework.

Whether a particular item falls within PSSR depends on the system, relevant fluid, pressure and any applicable exception. Equipment should be assessed on its actual specification rather than its name or apparent size.

Book a PSSR Examination

Need to establish what your next examination should cover?

Velocity Safety provides PSSR examinations and Written Schemes of Examination for workplace pressure systems. We can review your documentation, examine the parts identified in the scheme and provide a report setting out findings and required actions.

To help us assess your requirements, send the current WSE and previous report if available, along with details or data-plate photographs of the equipment.

Call: 01254 933 486
Email: info@velocitysafety.co.uk
Online: Request a quote

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PSSR Examination FAQs

What is checked during a PSSR examination?

The WSE sets the scope. Depending on the system, the examination can include pressure vessels, protective devices and specified pipework or pipelines whose failure could give rise to danger.

Is a PSSR inspection the same as a PSSR examination?

“PSSR inspection” is a common informal term. The Regulations use “examination” for the statutory process carried out by a competent person in accordance with the WSE.

Does every examination include an internal vessel inspection?

No. Internal examination is carried out where required by the WSE. The appropriate method depends on the vessel and the deterioration being assessed.

Does every examination include ultrasonic thickness testing?

No. Ultrasonic measurement or other NDT may be specified where appropriate, but it is not an automatic part of every PSSR examination.

Are safety valves examined?

Protective devices forming part of the pressure system must be addressed by the WSE. It specifies the nature of their examination and any testing required.

Must the system be shut down?

It depends on the work specified by the WSE. Internal examination or other checks may require isolation, depressurisation, draining, cooling or opening the vessel.

Is a PSSR examination the same as a compressor service?

No. The statutory examination follows the WSE; servicing follows the equipment’s maintenance programme. Both may be needed.

How often is a PSSR examination required?

The WSE specifies the maximum interval. The competent person’s report states the date after which the system must not operate without another examination under the scheme.

What happens if an examination identifies a defect?

The report identifies required repairs, modifications or changes to safe operating limits and the deadline for completing them. Imminent danger triggers separate immediate reporting and restrictions on operation.

Does new pressure equipment need a WSE?

Qualifying pressure equipment needs a suitable WSE before operation. Examination before first use is required where the scheme provides for it. New equipment is not automatically exempt.

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