Written Schemes for Pipework and Ancillaries
A pressure system is more than its vessels. We extend the written scheme to the associated pipework, valves, relief and safety devices, and the steam and ancillary systems that support it.
About written schemes for pipework and ancillaries
The Pressure Systems Safety Regulations 2000 do not stop at the pressure vessel. A written scheme must cover all protective devices and those parts of the pipework which, if they failed, could give rise to danger. In practice the ancillaries are often where risk concentrates, so they need the same disciplined treatment as the vessels.
We extend the scheme to the associated pipework, the isolation and control valves, and the relief and safety devices that protect the system, along with steam mains, separators and other ancillary items where they fall within scope. Each item is identified, the nature of its examination is specified, and the maximum interval between examinations is set.
Treating the vessels, pipework and protective devices as one system means the scheme is consistent across the whole installation. Nothing that matters is left out, and the intervals for related items line up sensibly rather than being set in isolation.
What the scheme extends to
Alongside the pressure vessels, a complete scheme brings the pipework and ancillaries into a single examination regime. This typically includes:
- Pipework whose failure could give rise to danger
- Isolation, control and non-return valves
- Safety valves, relief valves and bursting discs
- Pressure gauges, level and other measuring devices
- Steam mains, separators and steam traps within scope
- Air receivers, filters and ancillary vessels
- The nature of the examination for each item
- The maximum interval between examinations
Why the ancillaries belong in the scheme
Where risk often sits
Pipework runs, small-bore connections and relief devices are common failure points, so their inclusion in the scheme matters.
Protective devices covered
The regulations require all protective devices to be in the scheme, since they are what keep the system within safe limits.
Steam systems in scope
Any system containing steam falls within PSSR, so steam mains and ancillaries are treated on the same basis as gas systems.
One consistent regime
Setting vessel and pipework intervals together keeps the whole installation on a coherent examination programme.
The scheme document you receive
You receive a scheme that lists the pipework, valves, relief and safety devices and ancillary items alongside the pressure vessels, each with its examination method and maximum interval, and the preparation measures needed to examine it safely.
Where the scheme extends an existing vessel scheme, we keep the two consistent so the whole system reads as one document rather than a set of disconnected parts.
As with our vessel schemes, the ancillary scheme is certified as suitable by a competent person and written so that the examiner and the duty holder can both see precisely what is required.
A note on thermoplastic and composite systems
Written schemes are not confined to metallic plant. Thermoplastic and composite pressure systems also require a scheme of examination where they fall within the scope of the Pressure Systems Safety Regulations 2000. The materials behave differently and call for suitable examination methods, but the underlying duty is the same, and the pipework, joints and protective devices are identified and scheduled in the scheme in the same way.
Related inspection services
Need to bring pipework and ancillaries into a scheme?
Talk to our team about extending a written scheme to pipework, valves, relief devices and steam systems.