Posted by Andy Kidd on 25-Oct-2017 12:45:32

What is a Written Scheme of Examination?


Under the Pressure Systems Safety Regulations 2000 (PSSR), all users and owners of pressure systems need to be able to demonstrate that their equipment is safe to use and that they are firmly aware of its safe operating limits.

This is achieved by having a Written Scheme of Examination (WSE) completed by a ‘Competent Person’ with associated thorough examination reports. The WSE needs to be in place before the system or equipment is launched for operation, ensuring that any mandatory examinations within the Scheme are completed safely on time, this is a legal requirement in the UK.

But what is a WSE?

A WSE is essentially a document that has been created by a ‘Competent Person’, such as an Engineer Surveyor from a third-party inspection company. It includes information about the:

  • Identification of the items of plant or equipment within the system;
  • Parts of the system which are to be examined;
  • Nature of the examination required;
  • Inspection and testing to be carried out on any protective devices;
  • Preparatory work needed for the item to be examined safely;
  • Nature of the examination required, before the system is used for the first time;
  • Maximum interval between examinations;
  • Critical parts of the system which, if modified or repaired, should be examined by a ‘Competent Person’ before the system is used again;
  • Name of the ‘Competent Person’ certifying the WSE; and
  • Date of certification.

The Written Scheme is required for items of plant equipment, or equipment which operates under pressure and contains a relevant fluid, these are specified in the regulations. Relevant fluid includes compressed or liquefied gas, or air at greater than 0.5 bar (approximately 7 psi) above atmospheric pressure; pressurised hot water above 110⁰ C; and steam at any pressure (HSE).

The Written Scheme document will clearly detail what your pressure system does and all the safety features and measures that are critical to its safe operation. On larger or more complex plant, the Written Scheme is an essential part of a Risk Based Inspection (RBI) approach towards plant operations. This can include extending the inspection intervals for the item.

For more information on how you could use RBI to extend engineering inspection intervals, read our blog ‘When can RBI be used to extend engineering inspection intervals’ by clicking here.

When do I need a WSE?

As a general rule, a Written Scheme is required if the system contains a relevant fluid and a vessel greater than 250 barlitres or any steam system.

Each system is likely to be unique, but the following questions outlined in the Health & Safety Executive’s ‘Written Schemes of Examination: Pressure Systems Safety Regulations 2000’ can help you effectively arrive at a conclusion:

  • Do the manufacturers of the plant or equipment forming the pressure system give guidance, instruction and precautions to take for safe operation of the system?
  • Could failure of any part of the pressure system cause someone in the vicinity to be injured by the release of pressure, fragments or steam?
  • Does the pressure system contain any protective devices?

If the answer is yes to any of these questions, then you may need to include these items in your Written Scheme.

When don’t I need a WSE?

There are a small number of exceptions when a WSE won’t be required. For example, a small air system that doesn’t have a vessel greater than 250 barlitres would not require a WSE.  You wouldn’t normally need to include the compressor associated with an air receiver in the Scheme of Examination.

Furthermore, the following pressurised systems are exempt from the Regulations and will not require a Written Scheme:

  • a machine tool hydraulic system
  • any pipeline and its protective devices in which the pressure does not exceed 2bar above atmospheric pressure; and
  • A portable fire extinguisher with a working pressure below 25bar at 60⁰ C and having a total mass of no more than 23kg.

The best reference point to find out whether your plant or equipment is exempt is the ‘Safety of Pressure Systems. Pressure Systems Safety Regulations 2000. Approved Code of Practice’.

If you are based outside of the UK, you must take extra care when deciding whether or not you will require a WSE. It’s often the case that in some countries you don’t need a WSE for certain types of equipment. However, in order to import and use equipment in the UK, you will always need to meet the local safety requirements. It’s not uncommon for foreign companies to realise that they need a Written Scheme at the very last moment - resulting in serious project delays. Therefore, our advice is to be well prepared and learn as much as you can, as quickly as you can, about UK legislation.

Click here to download 'Essential questions to ask your engineering inspection  supplier'

Who needs to issue my WSE?

WSEs need to be issued by a ‘Competent Person’. Under the regulations, this is a person who has the necessary knowledge, experience and expertise of the pressure system and pressure equipment in general to do so. It is not only your legal responsibility to have a Written Scheme in place, but choosing a supplier with sufficient competence to issue the Written Scheme for you lies in your hands as well and you will be personally liable for any failures resulting from their lack of knowledge or experience.  As a general rule, in the UK, bodies holding UKAS accreditation to the standard for inspection bodies (BSEN ISO/IEC 17020) have demonstrated appropriate competence.

At British Engineering Services, we are a Type A UKAS Accredited Body and we are proud to have over 150 directly employed Engineer Surveyors that can issue Written Schemes throughout the UK and Europe. Our service can provide a minor or intermediate Scheme at the time of initial inspection for items of equipment, such as air-receivers. Larger or complex systems may require more work to develop an appropriate WSE, these are often completed as a project for the system.

All of our WSEs are posted electronically and each one of our clients has 24/7 access to their own web-based portal, which means that your Written Scheme will be instantly available to you, at all times.

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Topics: Written Scheme of Examination

Andy Kidd

Written by Andy Kidd

Chief Engineer