Pressure Systems Safety Regulations 2000

PSSR explained: written schemes, examination and certification of pressure systems

If your site runs compressed air, steam or any system that stores enough pressure, PSSR is the law that decides whether you are compliant or exposed. It turns on one document most other regimes do not have: a Written Scheme of Examination, drawn up and certified before the system is used.

We are an independent competent person. We certify your scheme and examine the system to it, so your compliance is impartial, documented and defensible from day one.

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Before use

A certified Written Scheme must be in place first

250 bar litres

Or steam at any pressure brings a system into PSSR

Reg 8 & 9

Written scheme, then examination to that scheme

HSE

Enforced by the Health and Safety Executive

The regulation

What is PSSR, and why does it exist?

PSSR stands for the Pressure Systems Safety Regulations 2000. They came into force under the Health and Safety at Work etc. Act 1974, and they are enforced by the Health and Safety Executive.

The hazard PSSR controls is stored energy. A pressure system that fails does not simply stop; it can rupture, releasing that energy as an explosion, flying debris or scalding steam. The regulations exist to stop that happening, by making sure systems are designed, installed, operated and examined so they stay within safe limits.

What sets PSSR apart from the other statutory regimes is its structure. It does not work to fixed national intervals. Instead it requires a tailored Written Scheme of Examination, certified by a competent person, that defines what is examined, how, and how often, for your specific system. Get the scheme right and the rest follows. Operate without one and the system is unlawful to run.

At a glance

Full name: Pressure Systems Safety Regulations 2000
Made under the Health and Safety at Work etc. Act 1974
Enforced by the HSE and local authorities
Applies to owners and users of pressure systems at work
Centred on a certified Written Scheme of Examination
Below the threshold, PUWER 1998 governs the equipment instead

Scope

What pressure systems does PSSR cover?

PSSR applies to a system that holds a relevant fluid under pressure: the vessel, the pipework, the valves and the protective devices that keep it safe. A system comes into scope at steam at any pressure, or when pressure multiplied by volume reaches 250 bar litres.

Air receivers

Compressed air receivers and the wider compressed air system, by far the most common pressure plant on UK sites.

Steam boilers

Steam raising plant and the associated steam and feed systems. Steam brings a system into scope at any pressure.

Pressure vessels

Process vessels, autoclaves, sterilisers, expansion vessels and steam receivers of rigid construction.

Pipework & valves

The associated pipework and the protective devices, safety valves, bursting discs and gauges, that keep the system safe.

A relevant fluid (in scope)

Steam at any pressure, with no lower threshold
Compressed or liquefied gas, including air, above 0.5 bar
Pressurised hot water above 110°C
A gas dissolved under pressure in a solvent, such as acetylene

Not a relevant fluid

Hydraulic oils. They use high pressure but do not store energy the same way, so PSSR does not apply
Systems below the 250 bar litre threshold, where PUWER governs instead
Vehicle tyres, and systems forming part of a weapon
The many other items listed in the PSSR Schedule 1 exceptions

Your legal duties

The four things PSSR requires of you

Strip PSSR back and it asks four clear things of every owner and user. The written scheme sits at the centre; the other three protect it. Miss one and it is usually the gap an HSE inspector finds first.

1

Know your system and its safe limits

You must establish the safe operating limits of the system and understand what it contains, what it is made of, and how it behaves under pressure. That knowledge underpins everything else.

Every system must be suitably designed, constructed and installed, and provided with the right protective devices, so that pressure cannot build beyond a safe level.

2

Have a certified Written Scheme of Examination

This is the heart of PSSR. Before a qualifying system is used, a Written Scheme of Examination must be drawn up or certified by a competent person, identifying every part to be examined, the nature of each examination, and the maximum interval between them.

The system must not be operated without one. The scheme is a living document: it is reviewed and updated as the plant ages or the way you run it changes.

3

Examine the system to the scheme

A competent person must examine each part of the system at the intervals set in the scheme, and before first use. A proper examination is far more than a walk-round: it confirms gauge accuracy, proves the safety valves lift correctly, and checks the vessel inside and out.

It is a statutory examination, not maintenance. Servicing your plant does not discharge the legal duty, and the two should never be confused.

4

Operate, maintain and keep records

The system must be operated within its safe limits by people who are properly instructed, and maintained in good repair. Every examination produces a written report you must keep and act on.

Act on imminent danger fast: if an examination finds a danger of serious injury, the competent person reports it to you at once, you must stop using the system, and a copy goes to the enforcing authority within 14 days under Regulation 10.

Examination intervals

How often must a pressure system be examined?

Here is the point most people get wrong. PSSR sets no fixed national interval. Unlike other regimes, the frequency is decided by the competent person and written into your scheme, based on the system, its duty and its condition. The numbers below are recognised industry benchmarks from SAFed PSG01, not a legal default.

Typical interval	System	Notes
14 months	Steam boilers	And many autoclave pressure chambers
26 months	Air receivers	External; internal on a longer justified cycle
2 to 6 years	Refrigeration plant	By fluid, size and condition
By scheme	Everything else	Set by the competent person in the WSE

The old habit of treating everything as annual is a hangover from pre-PSSR rules, not the law. A well-built scheme matches the interval to the real risk: tighter for hard duty, longer where genuinely justified, which is where it saves time and money.

What is a “PSSR certificate”?

Two documents prove your compliance. The Written Scheme of Examination is certified by the competent person and names them, the items covered and the intervals. Each examination then produces a written report, issued as soon as practicable, confirming whether the system is safe to keep using.

Together the certified scheme and a clean report are your proof. We issue both digitally, so they are on file the moment we leave site.

What does the examination involve?

A real examination goes well beyond a look round. We verify gauge accuracy against a calibrated reference, prove the safety valves lift at the right pressure, and check the vessel inside and out for corrosion, cracking and wear.

Where the scheme calls for it, we add ancillary techniques such as non-destructive testing. Hydraulic pressure testing is used only where genuinely necessary, not as a routine.

Who is responsible

Responsibilities and the competent person

PSSR splits the work across clear roles. The legal duty sits with the owner or user, but safe compliance depends on the competent person being genuinely independent, with the authority to stop the plant if it is not safe.

Owners & users

Establish the safe operating limits of the system
Make sure a certified scheme is in place before use
Arrange and fund examinations to the scheme
Operate within limits and maintain the plant
Keep the reports and act on every defect
The duty applies even if the system is hired or leased

The competent person

Draws up or certifies the Written Scheme of Examination
Has the engineering knowledge and experience for the system
Is independent of the operating function, with no reason to pass unsafe plant
Examines each item to the scheme and reports findings
Has the authority to stop the system and report imminent danger

Operators & staff

Run the system only within its limits and as trained
Carry out routine checks, such as draining receivers
Report faults, leaks and unusual behaviour at once
Never override or tamper with protective devices
Keep the plant accessible for examination

Common confusion

PSSR vs PUWER: which one applies?

They are easy to mix up, because the line between them is the pressure threshold. The simplest way to hold them apart is to ask what the equipment stores and how much.

PSSR

Pressure systems, specifically

The focused law for systems holding a relevant fluid above the threshold, governed by a certified Written Scheme of Examination.

Trigger: Steam at any pressure, or 250 bar litres or more
Frequency: Set by the competent person in the written scheme
Output: Certified scheme plus a written examination report

PUWER

All work equipment

The broad law covering every piece of work equipment, including pressure plant that sits below the PSSR threshold.

Trigger: Any work equipment used at work
Frequency: No fixed interval, risk-based and suitable to use
Output: Inspection record, not a statutory certificate

In short: above the threshold, PSSR applies; below it, PUWER does instead. A small low-pressure receiver may fall under PUWER, while the compressor next to it clears 250 bar litres and needs a full written scheme. If you are not sure which side of the line a system sits, the calculation itself should be documented as evidence.

Why it matters

What happens if you do not comply?

PSSR is enforced under criminal law, and the penalties scale with the seriousness of the breach. Sentencing guidelines tie fines to the level of harm and the turnover of the business, so for a larger company a single serious failing can run well into six figures.

Beyond the fine, the costs that hurt most are the ones not in the judgment: a stopped plant, an invalidated insurance policy, and the reputational damage that follows a preventable explosion or scalding.

Fines set against harm and turnover, with no upper limit for the most serious cases
Improvement and prohibition notices that can stop the plant immediately
Prosecution of the company and, in serious cases, of individual managers
Imprisonment for the gravest breaches such as gross negligence
Serious injury or death from rupture, blast or escaping steam

Five habits that keep you compliant

Keep a live register of every pressure system, with its safe limits and due dates
Make sure each system has a current, certified written scheme before it runs
Review the scheme after any modification, repair or change of duty
Set diarised reminders so an examination is never missed
Use an independent competent person and keep every report on file

FAQs

PSSR questions, answered

What does PSSR stand for?

PSSR stands for the Pressure Systems Safety Regulations 2000. It is the UK law that protects people from the stored energy in pressure systems by requiring a written scheme of examination and competent examination.

Do I need a Written Scheme of Examination?

You do if your system holds steam at any pressure, or a relevant fluid where pressure multiplied by volume reaches 250 bar litres or more. The system must not be operated until that scheme is in place and certified by a competent person.

How often must a pressure system be examined?

There is no fixed legal interval. The competent person sets the frequency in your written scheme, based on the system and its condition. As an industry benchmark, steam boilers are often examined around every 14 months and air receivers around every 26 months.

Is a PSSR examination the same as servicing?

No. A PSSR examination is a formal statutory examination of the integrity and safety of the system, carried out to the written scheme by a competent person. Routine maintenance and servicing are important but do not satisfy the legal duty.

Who can act as the competent person?

Someone with the engineering knowledge and experience for that system who is independent of its operation, with authority to stop the plant if it is unsafe. This is why the examiner should not be the same party that operates or maintains the equipment.

Are hydraulic systems covered by PSSR?

No. Hydraulic oils are not a relevant fluid. Although they run at high pressure, they do not store energy in the way a compressed gas or steam does, so hydraulic systems fall outside PSSR, though they remain work equipment under PUWER.

What happens if an examination finds a serious defect?

Under Regulation 10, the competent person reports an imminent danger to you immediately and you must stop using the system. A written report follows, and a copy goes to the enforcing authority within 14 days.

How long must I keep PSSR records?

You must keep the written scheme and the last examination report, plus any report still relevant to the system’s safe operation. Records can be electronic, but must be secure from tampering and available to an inspector on request.

Book your PSSR written scheme and examination

We provide independent, impartial PSSR written schemes, examination and certification across the UK, with the report on file the moment we leave site. We handle both stages, so nothing falls between providers.

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