Pressure Systems Safety Regulations 2000, UK wide
Pressure Systems and PSSR Written Schemes
The hazard in a pressure system is stored energy. A vessel that fails does not need to hold anything toxic or flammable to kill the person standing beside it. AL23 Safety scopes pressure systems, drafts and certifies written schemes of examination and manages the examination programme for clients UK wide.
What is a written scheme of examination?
The document that decides what gets examined, how and how often
A written scheme of examination is the legal instrument at the centre of the Pressure Systems Safety Regulations 2000. It names the parts of your system that will be examined, states the nature of each examination, sets the maximum interval between examinations and describes the preparatory work needed to make the system safe for the examiner.
It is not an inspection report and it is not a maintenance schedule. It is the plan a competent person writes before any examination happens and it is the thing an inspector asks for first. Regulation 8 makes the point bluntly. You must not operate the system unless you have one. Nor may you allow anyone else to operate it.
Two routes are lawful. A competent person can draw the scheme up for you or someone else can draft it and a competent person can certify it as suitable. Both satisfy regulation 8. Neither can be skipped.
Who needs one
Steam at any pressure and most compressed air
- Anyone operating a steam boiler or associated steam plant, whatever the pressure.
- Laboratories, dental practices, hospitals and food producers running steam sterilising autoclaves.
- Workshops, garages, factories and warehouses with compressed air receivers above the size threshold.
- Sites with refrigeration systems exceeding 25 kW of installed refrigerant power.
- Operators of accumulators, calorifiers, pressure cookers and compressed air distribution pipework where a defect could cause danger.
- Owners of mobile pressure systems, where the duty falls on the owner rather than on the user.
The regulations that apply
Your legal framework, in plain terms
The Pressure Systems Safety Regulations 2000 sit under the Health and Safety at Work etc. Act 1974 and are supported by an Approved Code of Practice, L122. The Regulations bite only where the system contains a relevant fluid. Steam counts at any pressure with no threshold at all. A gas counts where it is above 0.5 bar above atmospheric pressure or would be at that pressure at 17.5 degrees Celsius. A liquid counts where its vapour pressure exceeds 0.5 bar above atmospheric at the actual temperature or at 17.5 degrees Celsius. Acetylene dissolved under pressure in a solvent held in a porous substance is caught separately.
Regulation 8. Written scheme of examination
The scheme must cover all protective devices, every pressure vessel and pipeline where a defect may give rise to danger and those parts of the pipework where a defect may give rise to danger. It must be drawn up or certified as suitable by a competent person, reviewed at appropriate intervals and modified where a report recommends it.
Regulation 9. Examination and report
Parts included in the scheme must be examined within the intervals the scheme specifies. The competent person must issue a written report within 28 days of completing the examination or before the date after which the system may not be operated, whichever comes sooner.
Regulation 9 postponement
An examination date may be postponed by written agreement with the competent person, only where the postponement gives rise to no danger, only once for any given examination and only where you notify the enforcing authority in writing before the original date.
Regulation 10. Imminent danger
Where the competent person judges that the system will give rise to imminent danger unless repairs or restrictions are put in place, they must report to you immediately in writing and report to the enforcing authority. The system must not be operated until the specified action is taken.
Schedule 1 exclusion
Systems containing a relevant fluid other than steam are excepted from regulations 8 to 10 where the pressure volume product is below 250 bar litres. Steam has no equivalent threshold.
Where the 250 bar litre line actually falls
Multiply the maximum working pressure in bar by the vessel volume in litres. A 10 bar receiver of 50 litres is 500 bar litres and needs a scheme. A 10 bar receiver of 20 litres is 200 bar litres and does not. That is a small number in practice, which is why most workshop air receivers are in scope and most people assume they are not.
Water at ambient temperature is generally not a relevant fluid. Hydraulic systems running on mineral oil are generally outside PSSR as well. If the risk on your site is the contents rather than the pressure, the duty sits under COSHH or under the DSEAR risk assessment regime instead.
What the service covers
Scope, scheme, examination programme and report handling
- A system by system scope decision, recording what is in the scheme, what is out and the reasoning for each call.
- Identification of every protective device, including safety valves, bursting discs, pressure switches and level controls.
- The nature of each examination, separating external, internal, in-service and out of service work.
- Maximum intervals for each item, justified by duty cycle, fluid, corrosion history and manufacturer guidance.
- Preparatory measures, covering isolation, draining, purging, cleaning, scaffold access and any confined space entry needed to get inside a vessel.
- Certification of an existing scheme where you already hold one and need it confirmed as suitable.
- Review and modification of the scheme after a report recommends change, after a modification and after a change of duty.
- Appointment and management of the competent person carrying out the examinations.
- Tracking of report dates, expiry dates and the single permitted postponement so nothing runs past its date unnoticed.
- Close-out of examination findings, including repair specification, retest and evidence that the action was completed.
- A written record of the decision where equipment falls below the 250 bar litre threshold so you can show why no scheme exists.
- Interface checks with PUWER, DSEAR and your permit to work arrangements.
Our process
Surveyed, scoped, drafted, then examined against the dates
- 01
Asset survey
We walk the site and build or correct the pressure equipment register, capturing nameplate data, working pressure, volume, protective devices and current examination status. Vessels missing from the register are the most common first finding.
- 02
Scope decision
We apply the relevant fluid test and the Schedule 1 threshold to every item, then record which systems need a scheme and which do not.
- 03
Scheme drafting or certification
We draft the written scheme or review and certify the scheme you already hold. Every entry names the part, the nature of the examination, the interval and the preparation required.
- 04
Examination programme
We appoint the competent person, brief them on access and preparation and manage the examination against the dates in the scheme.
- 05
Report handling and review
We read every report, translate the findings into a costed action plan and review the scheme where the competent person recommends a change.
What you get
A certified scheme and a register that holds
- A written scheme of examination covering each system, drawn up or certified as suitable by a competent person.
- A pressure equipment register showing last examination date, next due date and the operative expiry date from each report.
- A scope note explaining, item by item, why each piece of equipment is in the scheme or outside it.
- Examination reports with a plain English summary of what each finding means for continued operation.
- A prioritised remedial plan separating imminent danger items from planned work at the next shutdown.
- A review schedule for the scheme itself so it does not quietly go out of date.
What we need from you
Nameplates, past reports and a realistic shutdown window
- Nameplate details, manufacturer documentation and any design or fabrication certificates you hold.
- Existing written schemes and the last two examination reports for each system.
- Records of any modification, repair or change of duty since installation.
- Access to plant rooms, compressor houses and boiler houses, plus a realistic shutdown window.
- The name of the person who can authorise a system to be taken out of service.
Why AL23 Safety
We own the scope, appoint the right examiner
Accountable
Where a system has been running past the date in its last report we say so in writing on the day we find it. We do not date a scheme backwards to tidy up a gap.
Expert and chartered
Qualified, chartered professionals who work to the Regulations and to ACOP L122, with the scope decision recorded rather than assumed.
Practical, not just compliant
We scope the work, appoint the right specialist, interpret the results and turn them into an action plan you can actually deliver. Your maintenance team gets dates, not a filing job.
UK wide
We manage pressure system compliance for single sites and multi-site groups across the UK, alongside your wider machinery and lifting equipment regime.
Not sure whether your air receiver is even in scope
Send us the nameplate and we will tell you
Working pressure and volume are usually enough for us to answer the scope question on the phone. If you have a scheme already, we will tell you honestly whether it needs certifying, rewriting or leaving alone.
Common questions
Answers, up front
Cannot see your question? Get in touch and we will answer it directly.
Contact usA competent person, as defined in regulation 2. That is an individual other than an employee of the user or a body of persons. L122 grades the level of competence by system size, expecting incorporated engineer level for minor systems and chartered engineer status with supporting technical staff for intermediate and major systems. An in-house competent person should be independent of the operating functions and must have the authority to stop the equipment being used.
Regulation 8 prohibits operating the system at all without a scheme and running past the date stated in the last report means the system is being operated unlawfully. In practice this ends in a prohibition notice under section 22 of the Health and Safety at Work etc. Act 1974, which takes effect even if you appeal. Fee for Intervention applies to a material breach at an HSE hourly rate of £188 from 1 April 2026, covering inspection time, report writing and any follow-up investigation.
PSSR sets no fixed interval. The maximum interval is whatever the written scheme specifies and it is the competent person's judgement based on the fluid, the duty, the condition and the consequence of failure. Anyone quoting you a universal frequency before seeing the plant is quoting a habit rather than a duty.
Yes. The limits are tight. The postponement must be agreed in writing with the competent person, must give rise to no danger, may be made only once for a given examination and you must notify the enforcing authority in writing before the original date passes. Informal slippage agreed verbally with a contractor does not meet any part of that test.
We own the scope, the scheme, the interpretation and the action plan. The statutory examination itself is carried out by a competent person, commonly an engineer surveyor working through an engineering inspection body or insurer, which we appoint and manage. We are clear about that boundary and we check the quality of what you receive.
Cost is driven by the number of systems, whether a register exists, whether an existing scheme can be certified rather than rewritten, the amount of pipework in scope and the number of sites. Certifying a sound scheme for four air receivers is a very different job from building a scheme for a steam plant from scratch. Send us the asset list and we will price it properly.
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