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Written Scheme

of Examination

A Written Scheme of Examination is a document containing information about selected items of plant or equipment which form a pressure system, operate under pressure and contain a ‘relevant fluid’.


The term relevant fluid is defined in the Regulations and covers compressed or liquefied gas, including air, at a pressure greater than 0.5 bar (approximately 7 psi) above atmospheric pressure; pressurised hot water above 110°C; and steam at any pressure.

Typical contents of a Written Scheme of Examination include:


  • Identification of the items of plant or equipment within the system;

  • Those parts of the system which are to be examined;

  • The nature of the examination required, including the inspection and testing to be carried out on any protective devices;

  • The preparatory work needed for the item to be examined safely;

  • Where appropriate, the nature of any examination needed before the system is first used;

  • The maximum interval between examinations;

  • The critical parts of the system which, if modified or repaired, should be examined by a competent person before the system is used again;

  • The name of the competent person certifying the written scheme of examination; and

  • The date of certification.


Written Schemes of Examination (WSE’s) are required as a mandatory exercise and cannot be circumvented without the potential risk of prosecution by the H&SE in the event of a system ‘failure’. 


In order to provide pricing for a Written Scheme of Examination, we require brief details regarding the major components in your pressure system.


We can conduct initial site visits to collate information towards preparing pricing proposals, if necessary.


Typically, our circle of activity surrounds producing Written Schemes of Examination for pressurised gas systems.


The following gases have featured in our Written Schemes of Examination: -


  • Compressed air


Laboratory gases, such as: 

  • Medical compressed air

  • Nitrous Oxide gas

  • Nitrogen gas

  • Carbon Dioxide gas

  • Oxygen gas

  • Argon gas

  • Helium gas

  • Hydrogen gas

  • Sulphur Hexafluoride gas

  • 5% Carbon Dioxide in Air mix gas


To produce a Written Scheme of Examination, our engineer(s) shall attend your facility and survey the pressure system, in order to obtain specific details from items of plant/ equipment required to establish the ‘Safe Operating Limits’ of the pressure system, principally with regards to pressure and temperature.


All details are logged to our electronically prepared ‘Components for Examination’ spreadsheet, or handwritten documentation, if the nature of the site/ facility prohibits the use of electronics.  


A hand drawn System Schematic Diagram (P&ID) will be produced on site for later computer aided design (C.A.D) production in our office, and any relevant information such as copies of manufacturer’s certification for major items will be obtained, where applicable.


All requisite items in the pressure system shall be labeled using our component tags & ties, annotated with alphanumeric references in order to aid identification of components/ equipment throughout the Written Scheme of Examination and drawing(s).


The Written Scheme of Examination, complete with System Schematic Drawing(s) and certification is formulated in our offices and sent to your preferred email address, in a readily available electronic format.

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