What Is A Written Scheme Of Examination?

A written scheme of examination is a legal requirement for the users or owners of compressed air systems, that complies with Pressure Systems Safety Regulations (PSSR). These regulations cover any system which contains ‘relevant fluid’ including gases at over 0.5 bar above atmospheric pressure, pressurised water above 110°C and steam.


A written scheme of examination (WSE) is a legal requirement placed on users and owners of pressure systems by the UK’s Pressure System Safety Regulations 2000 (PSSR). The WSE must be drawn up by a competent person. It is illegal to operate a pressure system without one.

It is a document containing information about selected items of plant or equipment which form part of a pressure system and that operate under pressure and contain what PSSR refers to as a ‘relevant fluid’. It identifies those parts of the system that need to be examined and details the nature of the examinations required.


The scope of an examination is defined by the competent person whose responsibility it is to draw up the written scheme. It must cover the pressure vessels, the pipe work and the protective devices of a system. It must also include a risk-based review of the frequency of inspections.

AES Industrial Supplies offers a comprehensive service to write up a WSE for gas systems and charge a flat fee plus administration. Our experts are available to talk through your needs and advise on the best approach for you.

Exams are used for a number of purposes including placement, selection, skill competency profiling and assessment of learning. However, the scale of university education and its impact on conventions of testing has disrupted the reliability and validity of exams.


In terms of the frequency of an examination, it depends on the size and complexity of a system. However, it’s generally recommended to examine gas pressure systems on a three-yearly basis or more frequently in industrial applications. Alternatively, this can be reduced to a two-yearly cycle in certain circumstances depending on the system’s operating environment and consequences of failure. It is the duty of the WSE competent person to decide on a safe frequency based on its operating parameters.


Having a WSE in place is mandatory under the UK’s Pressure Systems Safety Regulations 2000 (PSSR). In fact, users or owners of any compressed air system can face fines or prosecution without one. The document defines the types of protective devices, pressure vessels and pipework that need examining, what level of thoroughness is required and how often this needs to be carried out.

The WSE also details the name and qualifications of the person who collates and reviews the scheme. This is a requirement of PSSR and must be someone with Incorporated Engineer status and appropriate indemnity insurance.