What Equipment Does PSSR Cover? A Guide to What's in Scope
- Nexus Examination
- Jun 26
- 3 min read
Working out whether your equipment falls under PSSR trips up a lot of businesses, because the line is not really about the machine. It is about the fluid inside it and the energy that fluid stores. Here is what PSSR covers, the equipment it catches, and the things it leaves out.
What Equipment Does PSSR Cover?
PSSR covers pressure systems used at work that contain a relevant fluid above 0.5 bar: steam at any pressure, compressed or liquefied gas including air, and pressurised hot water above 110°C. That brings in steam boilers, compressed air systems, autoclaves and refrigeration plant, along with their pipework and protective devices.
In other words, the regulations follow the hazard, not the badge on the equipment. We carry out PSSR examinations across Berkshire and the surrounding counties, and the first job is always working out exactly which parts of a system are in scope.
What Counts as a Pressure System
A pressure system is made up of one or more pressure vessels of rigid construction, the associated pipework, and the protective devices that keep it within safe limits. What pulls it into PSSR is the relevant fluid it holds.
The relevant fluids are steam at any pressure, compressed or liquefied gas including air above 0.5 bar, pressurised hot water above 110°C, and gas dissolved under pressure in a solvent, such as acetylene. The HSE's introduction to pressure equipment sets out the full picture.
Equipment and Systems PSSR Covers
In practice, the regulations reach a wide range of everyday workplace kit. Common examples include:
Steam boilers and steam heating systems
Compressed air systems, both fixed and portable
The air receiver that stores the compressed air, which on an oil-lubricated compressor may be a combined air and oil receiver
Pressure cookers, autoclaves, retorts and steam sterilisers
Heat exchangers and pressurised process plant
Pipework and hoses carrying a relevant fluid
It catches some equipment people never think of, too. A commercial steam coffee machine is a pressure system, which is why HSE lists it alongside industrial plant.
Protective Devices Are Covered Too
A pressure system is more than its vessel. The written scheme of examination must also cover the protective devices that stop the system exceeding safe limits, because a failure there can be just as dangerous as a failure of the vessel itself.
That includes safety valves, pressure gauges and indicators, and drain valves. These are often the items a competent person looks at most closely, since they are what keep the rest of the system safe.
What PSSR Does Not Cover
Not everything under pressure is in scope. Hydraulic systems are the big exception: hydraulic oil is not a relevant fluid, and these systems do not store energy in the same way, so they sit outside PSSR.
Vacuum systems are not covered, nor is pressure created simply by a head of liquid, and anything operating at or below 0.5 bar falls below the threshold. Those systems still need to be safe and maintained, but they do not require a written scheme of examination under PSSR.
How to Tell If Your Equipment Is in Scope
Start with the fluid. If the system holds steam, compressed or liquefied gas, or hot water above 110°C, above 0.5 bar, it is very likely covered. The next question is whether you need a formal written scheme, which for compressed air comes down to whether the vessel reaches 250 bar-litres of stored energy.
If you are unsure, the safest step is to have the system assessed by a competent person, who can apply the decision tree in the HSE's Approved Code of Practice and tell you exactly which parts are in scope.
The Bottom Line
PSSR is about the fluid, not the machine. If your equipment holds steam, compressed or liquefied gas, or pressurised hot water above 110°C, the vessel, its pipework and its protective devices are almost certainly covered.
Work from the fluid first, treat the protective devices as part of the system rather than an afterthought, and bring in a competent person if there is any doubt. Our thorough examination services cover the full range of pressure equipment caught by the regulations.
Comments