Written Scheme of Examination

A Written Scheme of Examination (Written Scheme / WSE) is a statutory document that is required to be in place before the system is operated. It details the safety examinations required for pressure systems, including pressure vessels, steam boilers, and associated pipework.

This is a legal requirement as documented in the Pressure Systems Safety Regulations 2000 (PSSR). The primary aim of these regulations is to prevent serious injury from the uncontrolled release of stored energy from a pressure system.

At Design Air we can produce a suitable and compliant Written Scheme of Examination for you and carry out the engineering inspection and thorough examinations required against this.

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Written Scheme of Examination FAQs

What is a Written Scheme of Examination (WSE)?

The Written Scheme of Examination (WSE) is simply a WSE document that is required for most pressure systems containing relevant fluids. It includes details such as;

  • The parts of the system that require examination, such as any pressure vessel, pipework, and protective devices
  • The nature of examination to be performed
  • The maximum length of time between examinations
  • Critical operating limits of the system

This document helps you know the safe operating limits of your equipment.

If you have duties placed upon you under the PSSR as the user of an installed system or owner of a mobile system, it is a legal requirement that you ensure that a suitable and compliant WSE is in place.

Do I Need a Written Scheme of Examination (WSE) for my Pressure System?

Under PSSR, if you have a pressure system containing a relevant fluid (like compressed air, steam, or refrigerant) at a pressure greater than 0.5 bar, and it has a pressure vessel with a product greater than 250 bar litres, you have a duty to ensure you have a Written Scheme of Examination (WSE) in place prior to using the system. The 250 bar litre value is calculated by multiplying the vessel’s safe operating pressure in bars by the size of the vessel in litres.

This is a legal requirement under PSSR and is enforced by the Health and Safety Executive (HSE). Failure to have a compliant WSE in place could lead to unlimited fines or prosecution from HSE. Beyond legal penalties, non-compliance can void your insurance and, most importantly, puts your staff at risk of serious harm.

What Systems Require Written Schemes?

While many people associate these regulations with standard air compressors, written schemes are actually required for a variety of pressure systems. These include:

  • Compressed air systems (fixed and mobile)
  • Steam heating systems and boilers
  • Refrigeration systems utilising compressors (above 25kW)
  • Pressure vessels and autoclaves
  • Gas loaded hydraulic accumulators

I Have a Brand New System, Do I Need a Written Scheme of Examination (WSE) Before I Use it?

Every piece of equipment that falls under the scope of the PSSR is required to have a Written Scheme of Examination (WSE) produced before it is used for the first time.

This is applicable to brand new equipment as well as aged equipment. So in short, if you have a brand new system that has just been installed, you should have a competent person draw up and certify a Written Scheme of Examination (WSE) before this is put into operation.

How Regularly Does My Pressure Equipment Need Examined Under The Written Scheme of Examination (WSE)?

The competent person who draws up your written scheme for the periodic examination (WSE) will determine the frequency and type of examination that needs to be carried out on an item by item basis.

The frequency of periodic reviews may vary depending on the equipment type, age, and condition, but examinations are typically required at least once per year. This ensures ongoing safety examinations are kept up to date.

Is an Examination The Same Thing That my Service Providers do on my Compressor Annually?

It is a common misconception by many of our customers that because we are servicing / maintaining their compressed air or nitrogen system, that this covers the requirements for a thorough examination as set out by the Written Scheme of Examination.

A statutory examination of safety critical components (often called PSSR inspections) should be carried out at intervals defined in your WSE and is a separate job from carrying out maintenance on your equipment.

We can however save costs by carrying out both your service and your statutory examination against your WSE on the same visit.

Who is a 'Competent Person' Who Can Certify a WSE?

The term ‘competent person’ is defined by the PSSR. It refers to an individual or organisation with the necessary practical and theoretical technical experience, training, and knowledge of the pressure system to make an independent and impartial judgement.

This person (or body) must have the authority and expertise to certify the WSE as suitable based on relevant codes of practice (ACOP). They are responsible for determining the examination details and ensuring the system is safe. This role is often fulfilled by a third-party inspection body or a qualified engineer with specialist knowledge (like our DipCAM-qualified engineers) who is independent of your day-to-day operations.

Can I Use a Written Scheme of Examination Template or PDF?

Many business owners search for a “Written scheme of examination template,” “written scheme of examination sample,” or a “written scheme of examination pdf” to try to create the document themselves. However, a WSE is not a generic form; it must be specific to your unique system and certified by a competent person.

Using a generic template without the specific technical engineering inspection required for your pressure vessels can lead to a non-compliant WSE. This risks the safety of your staff and fails to meet legal obligations. Always use a professional service to generate your WSE document.

What Are My Specific Legal Duties Under PSSR?

The Pressure Systems Safety Regulations 2000 are legislated by UK regulations detailed in pressure system safety. The key duty for a business owner is specified in Regulation 8.1 of PSSR: ‘The user of an installed system and owner of a mobile system shall not operate the system or allow it to be operated unless’ they have a ‘suitable written scheme of examination’ in place before the system is used.

This means you, as the ‘user of an installed system’, have a legal duty to ensure that a suitable written scheme is in place and that the pressure system is actually examined in accordance with the written scheme.

What is a WSE Inspection?

A WSE inspection, or schemes inspection, is the physical examination of the pressure system carried out in accordance with the Written Scheme. This engineering inspection verifies that the pressure vessels, safety devices, and pipework are safe to continue operating.

Can Design Air Produce a Written Scheme of Examination for me And Carry Out Examinations Against This?

If you have identified that you need a Written Scheme of Examination (WSE) put in place for your compressed air or steam systems, at Design Air we can help. Get in touch with us for a quick chat about your pressure system and we’ll be able to give you some advice on what your next steps should be as well as a budget cost for producing a Written Scheme of Examination (WSE).

If you choose to go ahead, we would carry out an initial engineering inspection on your pressure system and create a compliant WSE for this system to utilise going forward. We can also build in your statutory safety examinations to occur at the same time as a service visit to help reduce some hassle and costs for you.