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

A PSSR examination is the statutory examination used to confirm that safety-critical parts of a qualifying pressure system remain safe for continued operation.

It is carried out by a competent person in accordance with the system’s Written Scheme of Examination (WSE).

That distinction is important because there is no single inspection checklist that applies identically to every air receiver, pressure vessel, steam system or autoclave.

The Written Scheme identifies the parts of the pressure system that need examining, the nature of the examination, any testing required, how the system needs to be prepared and the maximum interval between examinations.

Under the Pressure Systems Safety Regulations 2000 (PSSR), qualifying pressure systems need a suitable Written Scheme in place and must then be examined in accordance with that scheme.

Quick Answer: What does a PSSR examination include?

A PSSR examination checks the safety-critical parts of a pressure system identified in its Written Scheme of Examination. Depending on the system, this can include the pressure vessel, protective devices such as safety valves, relevant pipework, fittings and other components whose failure could release stored pressure and cause danger. The competent person examines these parts using the methods and intervals specified by the WSE, records their condition and identifies any repairs, modifications or changes required for continued safe operation.

Learn more about our PSSR 2000 Examinations & Written Schemes service.

Key Takeaways – PSSR Examinations

  • The Written Scheme of Examination determines the scope – there is no universal PSSR inspection checklist for every pressure system.
  • The WSE should cover protective devices, pressure vessels and relevant pipework or pipelines where failure could give rise to danger.
  • The examination may include visual examination, testing of protective devices and specialist techniques such as NDT where the WSE requires them.
  • NDT and internal inspection are not automatically required during every examination – the appropriate examination method depends on the particular pressure system and its WSE.
  • A PSSR examination is not the same as routine servicing or maintenance.
  • The competent person must produce a written report and identify repairs, modifications or other action needed.
  • If the competent person identifies imminent danger, additional immediate reporting and shutdown requirements apply.

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.

You will often see it described online as a PSSR inspection or pressure vessel inspection. However, the Regulations themselves use the term examination.

The purpose is to identify deterioration or defects in safety-critical parts of the pressure system before they can result in danger from the release of stored energy.

HSE defines a pressure system for PSSR purposes as potentially comprising:

  • One or more pressure vessels of rigid construction
  • Associated pipework
  • Protective devices
  • Certain pipelines and their protective devices
  • Certain pipework connected to transportable pressure receptacles

The relevant fluid can include steam, compressed or liquefied gases including air above the applicable pressure threshold, pressurised hot water above 110°C and certain gases dissolved under pressure.

There are also exceptions within PSSR, so not every piece of equipment operating under pressure automatically requires the same PSSR arrangements.

If you’re trying to establish whether your equipment requires a Written Scheme in the first place, see our PSSR Written Scheme of Examination Requirements guide.

The Written Scheme Determines What Gets Examined

This is the most important point to understand about a PSSR examination.

The competent person should not arrive on site and simply work through a generic pressure vessel checklist.

The examination must be carried out in accordance with the system’s Written Scheme of Examination (WSE).

According to HSE guidance, the WSE should identify information including:

  • The plant or equipment forming the pressure system
  • The parts of the system that need to be examined
  • The nature of the examination required
  • The inspection and testing required for protective devices
  • Preparation needed so the examination can be carried out safely
  • Any examination required before first use, where appropriate
  • The maximum interval between examinations
  • Critical parts that should be examined following certain repairs or modifications

That means two pressure vessels that look broadly similar may legitimately require different examination methods or intervals.

Age, design, operating conditions, likely deterioration mechanisms, previous findings and manufacturer information can all influence the examination scheme.

A WSE must also remain suitable throughout the life of the equipment. HSE notes that as plant ages, examinations may need to become more frequent or change in their content or type.

For more on what belongs in the document itself, see What Does a PSSR Written Scheme of Examination Need to Include?

What Happens Before a PSSR Examination Starts?

Before examining the equipment, the competent person needs to understand exactly what pressure system they are dealing with and what the WSE requires.

That can involve reviewing:

  • The current Written Scheme of Examination
  • The equipment included within the scheme
  • Previous examination reports
  • Manufacturer information where available
  • Safe operating limits
  • Previous defects or repairs
  • Changes or modifications to the system
  • The required examination method
  • Any special preparation needed to examine the equipment safely

The competent person should also review the WSE and confirm that it remains suitable.

If the system has changed significantly, deteriorated or been modified since the scheme was produced, the existing WSE may itself need reviewing.

What Is Checked on the Pressure Vessel?

Where a pressure vessel forms part of the Written Scheme, the examination focuses on identifying deterioration or defects capable of affecting its continued safe operation.

The precise checks depend on the vessel, the expected damage mechanisms and the requirements of the WSE.

Depending on the system, the examination may consider:

  • External vessel condition
  • Corrosion
  • Erosion
  • Cracking
  • Distortion or bulging
  • Evidence of leakage
  • Damage around welds or connections
  • Condition around nozzles and openings
  • Accessible internal surfaces where internal examination is specified
  • Evidence of material thinning or other deterioration

It is important not to assume that every PSSR examination automatically includes an identical internal inspection.

The nature and extent of the examination should come from the Written Scheme.

Where internal examination is necessary, the vessel will need to be safely prepared and made accessible before that part of the examination can take place.

Air receivers are one of the most common examples of pressure vessels encountered in UK workplaces. If you operate one, see our Air Receiver PSSR Compliance Guide.

Are Safety Valves and Protective Devices Checked?

Yes – protective devices are a fundamental part of the PSSR examination regime.

HSE states that a Written Scheme must cover protective devices forming part of the pressure system.

These can include equipment designed to prevent the system exceeding its safe operating limits, such as:

  • Safety valves
  • Pressure relief valves
  • Bursting discs
  • Pressure-limiting devices
  • Other protective controls where relevant to the system

The WSE should specify the nature of any inspection and testing required for these devices.

That is an important distinction.

A PSSR examination does not mean every safety valve on every system automatically receives exactly the same test procedure during every visit.

The competent person follows the examination and testing requirements established for that particular pressure system.

Protective devices are critical because the pressure vessel itself may be structurally sound while an incorrectly functioning safety device allows the system to exceed its safe operating limits.

Does a PSSR Examination Include Pipework, Gauges and Fittings?

It can – but again, the Written Scheme determines the scope.

PSSR does not mean that every metre of ordinary pipework connected to a pressure system automatically receives the same examination as the pressure vessel.

The WSE should identify those parts of the system where a defect could result in a dangerous release of stored energy.

Depending on the system, relevant items can include:

  • Associated pressure pipework
  • Connections and fittings
  • Valves
  • Flanges
  • Protective devices
  • Pressure indication or control equipment where relevant to safe operation

HSE guidance makes clear that the scheme should generally cover items within the self-contained pressure system that may give rise to danger.

The question should therefore be:

“Could failure of this component create danger through the release of pressure or stored energy?”

rather than simply:

“Is this component connected to the compressor?”

Does a PSSR Examination Include Non-Destructive Testing?

Sometimes – but NDT is not an automatic part of every PSSR examination.

Non-destructive testing (NDT) can be used where specialist examination is required to identify deterioration that cannot be adequately assessed through normal visual examination.

Methods can include techniques such as:

  • Ultrasonic thickness measurement
  • Ultrasonic flaw detection
  • Magnetic particle testing
  • Dye penetrant testing
  • Other suitable NDT techniques depending on the equipment and suspected deterioration mechanism

The appropriate method should be determined according to the equipment and the Written Scheme.

HSE’s technical guidance on NDT states that the WSE should specify the expected damage mechanism, examination interval and method of examination, including any NDT that is required.

This matters because simply performing an NDT technique does not automatically make an examination suitable.

The technique has to be capable of detecting the type of deterioration that the competent person is actually looking for.

Does a Pressure System Need to Be Shut Down for a PSSR Examination?

It depends on what the Written Scheme requires.

Some examination activities can be completed while equipment remains in an appropriate operating condition.

Others require the pressure system to be taken out of service and safely prepared.

Preparation may involve actions such as:

  • Shutting the system down
  • Depressurising it
  • Allowing hot equipment to cool
  • Isolating relevant energy sources
  • Draining the vessel
  • Providing safe access
  • Opening the vessel where internal examination is required

The WSE should specify any special measures needed to prepare the system for safe examination.

That is why businesses should establish examination requirements in advance rather than expecting an engineer to arrive and inspect an operating pressure vessel with no preparation.

What Happens After a PSSR Examination?

The examination does not finish when the competent person packs away their equipment.

A written report of examination must be produced.

The report provides the dutyholder with a record of what has actually been examined and what the competent person has found.

It should identify matters including:

  • The pressure system examined
  • The parts covered by the examination
  • The condition of those parts
  • Any repairs or modifications required to prevent danger
  • Any work required to maintain the effective operation of protective devices
  • Any necessary changes to safe operating limits
  • The timescale within which required action must be completed
  • The date beyond which the system should not continue to be operated without the next examination required by the scheme

The competent person’s findings therefore directly influence what happens next.

An examination report should not simply be filed away because somebody wants a “PSSR certificate”.

If corrective work is specified, the user or owner needs to act on it within the required timeframe.

What Happens If the Competent Person Finds Imminent Danger?

PSSR contains specific requirements where an examination identifies a defect serious enough to create imminent danger.

This is different from an ordinary recommendation for maintenance at some point in the future.

If the competent person believes the pressure system, or part of it, will give rise to imminent danger unless specified repairs, modifications or changes to operating conditions are made, they must issue the required written notification immediately.

The affected system or part must then not be operated until the required action has been completed.

The competent person must also send a report containing the relevant particulars to the enforcing authority within the period required by Regulation 10.

Important:

An imminent-danger report is separate from the ordinary report of examination. It exists because the defect requires immediate action rather than being something that can safely wait until a future maintenance visit.

Is a PSSR Examination the Same as a Service?

No.

This is one of the most important distinctions for pressure-system owners to understand.

A PSSR examination is a statutory safety examination carried out in accordance with the Written Scheme.

Routine servicing and maintenance exist to keep the equipment operating safely, efficiently and reliably between examinations.

PSSR Examination Routine Servicing / Maintenance
Carried out in accordance with the Written Scheme of Examination Carried out according to maintenance requirements and manufacturer instructions
Focuses on statutory safety-critical examination Focuses on keeping equipment in efficient and reliable condition
Must be carried out by a competent person for the PSSR examination May be carried out by appropriately competent maintenance personnel
Produces a formal report of examination Normally produces maintenance or service records
Cannot be replaced by an ordinary service Cannot be replaced by the statutory PSSR examination

HSE specifically states that an examination carried out under a Written Scheme is not a substitute for regular and routine maintenance.

You need both where each is applicable.

Who Can Carry Out a PSSR Examination?

A PSSR examination must be undertaken by a competent person.

This does not simply mean somebody who has worked with compressors before.

The person or organisation needs the appropriate level of:

  • Technical knowledge
  • Practical experience
  • Understanding of the pressure system
  • Ability to identify and assess defects
  • Knowledge of appropriate examination techniques
  • Independence to reach objective conclusions

HSE emphasises the importance of independence when selecting the competent person.

An in-house competent person can be used where genuinely appropriate, but they should be sufficiently independent from the operating functions of the organisation and have the authority to stop the equipment being used if necessary.

Velocity Safety’s PSSR examinations are carried out by engineer surveyors trained and certificated in PSSR examination requirements, with calibrated instrumentation used where required.

Does Every Pressure Vessel Need the Same Examination Interval?

No.

The examination interval should be specified in the Written Scheme of Examination.

There is no universal PSSR rule saying that every pressure vessel must receive exactly the same examination every 12 months.

The competent person considers what is appropriate for the particular system when determining or reviewing the examination requirements.

Factors can include:

  • Equipment type
  • Design
  • Age
  • Operating conditions
  • Relevant fluid
  • Expected deterioration mechanisms
  • Manufacturer recommendations
  • Previous examination findings
  • Repairs and modifications
  • Operating history

HSE specifically notes that examination frequency or content may need changing as plant ages.

This is why the date of your next PSSR examination should come from the WSE and examination report, rather than a generic internet checklist.

How Should You Prepare for a PSSR Examination?

Preparation starts before the competent person arrives.

Having the right information and equipment access available can make the examination considerably smoother.

Where applicable, have ready:

  • The current Written Scheme of Examination
  • Previous PSSR examination reports
  • Equipment identification and manufacturer information
  • Details of repairs or modifications completed since the previous examination
  • Maintenance and servicing records where relevant
  • Safe operating limits
  • Access to the equipment covered by the WSE

You should also establish whether the WSE requires the system to be shut down, isolated, depressurised, drained, cooled or opened for examination.

Trying to establish this after the engineer has arrived can result in unnecessary delays or an incomplete visit.

If your system is newly installed, don’t assume new equipment can simply be put into operation without considering PSSR. See Do New Air Compressors Need a Written Scheme of Examination?

What Types of Pressure Systems Can Require PSSR Examination?

PSSR can apply across a wide range of workplace pressure systems.

Examples examined by Velocity Safety include:

  • Air receivers
  • Compressed air systems
  • Pressure vessels
  • Air/oil receivers
  • Vacuum vessels
  • Expansion vessels
  • Autoclaves
  • Accumulators
  • Pressurised vessels and vats
  • Commercial coffee machines where the relevant PSSR requirements apply

The exact regulatory position depends on the equipment, pressure system and relevant fluid, including any applicable exceptions.

If you’re unsure whether your particular equipment falls within PSSR, it is better to establish its status than assume it is outside the Regulations because it looks small or was supplied brand new.

Book a PSSR Examination

Not sure what your next PSSR examination actually needs to include?

Velocity Safety carries out PSSR 2000 examinations for pressure systems across the UK, including air receivers, compressors, autoclaves, pressure vessels and associated equipment.

We work from the Written Scheme of Examination to assess the safety-critical components identified for your particular system and provide clear documentation of the findings, defects and required actions.

If your documentation is missing or you are unsure whether your existing WSE remains suitable, we can also help you understand what needs to be in place before the examination.

📞 Call: 01254 933 486
📩 Email: info@velocitysafety.co.uk
🌐 Or contact Velocity Safety online.

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Frequently Asked Questions

What is checked during a PSSR examination?

The exact scope is set by the Written Scheme of Examination. It can include pressure vessels, protective devices and those parts of pipework or pipelines whose failure could give rise to danger. The WSE also specifies the nature of the examination and any testing that is required.

Is a PSSR inspection the same as a PSSR examination?

“PSSR inspection” is a commonly used phrase, but the Pressure Systems Safety Regulations use the term examination. The statutory examination is carried out by a competent person in accordance with a Written Scheme of Examination.

Does every PSSR examination include an internal vessel inspection?

No. The nature and extent of the examination depend on the particular pressure system and its Written Scheme. Internal examination may be required for some vessels, while different examination methods may be specified for others.

Does every PSSR examination include ultrasonic thickness testing?

No. Ultrasonic thickness measurement and other forms of non-destructive testing may be used where appropriate, but they are not automatically required during every PSSR examination. Any required NDT should be determined according to the system, expected damage mechanisms and WSE.

Are safety valves checked during a PSSR examination?

Protective devices must be addressed by the Written Scheme of Examination. The WSE should specify the nature of the examination and testing required for protective devices such as safety or pressure relief valves where they form part of the pressure system.

Does the pressure vessel need to be shut down for inspection?

It depends on the examination requirements. Some activities may be possible without a complete shutdown, while internal examination or other specified checks may require the system to be isolated, depressurised, cooled, drained or otherwise safely prepared.

Is a PSSR examination the same as servicing a compressor?

No. A PSSR examination is a statutory safety examination carried out according to the WSE. Routine servicing and maintenance keep the equipment in safe and efficient working condition. HSE states that the statutory examination is not a substitute for routine maintenance.

How often does a PSSR examination need to be carried out?

The maximum interval between examinations should be specified in the Written Scheme of Examination. There is no single examination interval applying identically to every pressure system.

What happens if a pressure vessel fails its PSSR examination?

The competent person’s report will identify any repairs, modifications or changes required and the timescale for action. Where a defect creates imminent danger, the additional requirements of Regulation 10 apply and the affected system must not be operated until the specified corrective action has been completed.

Do new pressure vessels require PSSR examination?

Qualifying pressure equipment needs a suitable Written Scheme in place before operation and must be examined in accordance with that scheme, including before first use where the scheme requires it. New equipment should not automatically be assumed compliant simply because it has recently been supplied.

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