man writing on a tablet for a written scheme of examination

When Do I Need a Written Scheme of Examination or WSE?

As part of your efforts to comply with the UK Safety Regulations, it is necessary to create a Written Scheme of Examination (WSE). This document lists all examinable items such as protective devices and pressure vessels in your system that could require examination.

An appropriate individual must prepare and approve a Work Safety Evaluation plan in order to operate equipment, while users of installed systems or owners of mobile systems cannot begin operating equipment until this has occurred.

close up construction engineer using tablet

In-service examinations

A WSE (Work Site Safety Evaluation) is an essential legal document required of any pressure system that falls within the purview of Pressure Systems Safety Regulations (PSSR). It includes all examinable items, including protective devices, pressure vessels, and pipe work that, if they fail, could become hazardous; how frequently they must be examined; as well as any additional tests, such as non-destructive testing, that may be required to ensure safety.

This document must be created by an individual with sufficient training, skills, experience, and knowledge of pressure systems to produce it. Once complete, it must be collated by someone qualified to conduct an intensive examination of such systems before being certified by an incorporated engineer for certification purposes. Furthermore, WSEs must be updated frequently so as to remain compliant with PSSR regulations.

Therefore, the WSE can give you peace of mind that your compressed air equipment is regularly checked and examined, meeting one of the requirements under Pressure System Safety Regulations 2000. Furthermore, its purpose is to demonstrate awareness of safe operating limits related to pressure and temperature in systems.

An in-service examination is a written test designed to measure physician competence within their specialty area. It involves both case-based questions and item-based ones. Test items are developed by an In-Service Exam Writing Committee comprised of physician content experts and psychometricians for review before exams are administered by approved examiners.

Out-of-service examinations

A Written Scheme of Examination (WSE) is a legal requirement for gas professionals that documents all examinable items within your pressure systems, including protective devices and pressure vessels, along with when your system must be examined. A qualified individual with relevant skills, knowledge, and experience, such as an incorporated engineer or chartered engineer, should compile the WSE.

Depending on the nature and usage of your gas pressure systems, whether or not a written scheme of examination is required depends on their nature and use. A mobile system, for example, can easily move from place to place, while installed systems cannot. An air compressor could easily move around between sites, while steam boilers would fall under this category of installed systems.

When a pressure system fails an out-of-service examination, it must be immediately taken out of service and will not return until repaired or modified. A competent person should then prepare a report detailing any defects with recommendations on how they can be remedied and send this copy of their report directly to the enforcement authority.

Under PSSR Regulation 9, the university is obliged to ensure all equipment it operates has a Work Safety Evaluation (WSE) and to conduct periodic examinations in accordance with it. This applies whether it is owned by us or hired temporarily for temporary use. Our approved inspection provider Zurich will keep a record of WSEs and examination reports on Crimson for portable and installed equipment such as our conventional gas welding sets (portable twin cylinder and oxyacetylene). Any uninspected equipment will be labelled by Zurich accordingly to identify it as having no valid WSE.

Periodic reviews

Operating pressure equipment legally requires having a written scheme of examination in place, which includes safety operating parameters and an inspection schedule. Furthermore, this document includes details on who conducts the examination and when certification takes place. Regular updates to this document are vital; otherwise, it could lead to enforcement action from the Health and Safety Executive (HSE) or Local Authority Environmental Health departments.

Our interviews suggest that although periodic reviews are widely required, they are often implemented inconsistently. This could be the result of unclear requirements, limited agency staff resources and no culture to foster regular reviews, or due to difficulty balancing thorough reviews with operational efficiencies, leading to rushed reviews that increase risk exposures related to regulatory violations or financial crime.

An intensive periodic review can be a time-consuming and resource-stretching task, so to limit its impact, institutions should first identify any limitations in current operating practices that prevent a comprehensive analysis. Such limitations might include limited customer access or ineffective systems for managing this data. A periodic review can help firms detect changes to client risk profiles so they can take appropriate measures accordingly.

Periodic reviews are critical in order to maintain the validity of systems and processes impacting pharmaceutical production, such as previously validated systems and processes that directly influence production. They can also serve as scientific justification for requalifying or revalidating high-risk equipment.

The frequency of reviews should depend on factors like the impact, complexity, and newness of a system, carefully documented and approved by management at a regulated company. Responsibility and decision criteria for reviewing and setting review periods must also be clearly articulated.


The Written Scheme of Examination is a legal obligation on users (or owners) of pressure systems and is designed to ensure their safe use. It outlines the nature and frequency of examinations that must be undertaken on any system by a competent person based on factors like its purpose and use as well as wear-and-tear effects incurred over time. This enables a competent person to create an appropriate schedule of exams while taking into account any risk assessments of that system that might affect it.

WSE must cover all pressure vessels, protective devices, and pipework that could pose a danger if failed, such as pressure vessels and protective devices as well as pipework that, if ruptured, could create danger for those using them. It should also specify examination timeframes and any specialised safety measures taken, along with whether a competent person believes the scheme to be adequate or needs modification (with reasons why), should they deem any modifications necessary.

WSEs should be prepared by an independent person with sufficient knowledge, experience, and independence to carry out examinations under them. They must possess Incorporated Engineer status and suitable indemnity insurance; they must also be qualified to assess fitness-for-service issues related to systems, determine the suitability of examination methods used and determine the hazards and risks associated with each type of pressure system.

Employers appreciate professional certifications as an asset to employees’ marketability. Certifications allow you to keep abreast of new developments in your field and offer you an edge against other job candidates; many companies even provide structured learning programmes to assist employees in attaining the necessary certifications.