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At Mandate Systems we encounter a lot of clients from a variety of backgrounds, industries and experience and we find that they all have their own terminology for various aspects of Pressure Systems Safety Regulations (PSSR) 2000.  In this blog post, Head of Engineering, Matthew Inness attempts to clarify some of the common terms and definitions we encounter, drawing the definitions from the HSE Approved Code of Practice of Safety of Pressure Systems.

Competent Person – not the individual employee who carries out duties under the Regulations but to the body which employs the person charged with those duties.  For Minor Systems, at least one member of staff qualified to Incorporated Engineer level with adequate relevant experience and knowledge of the law, codes of practice, examination and inspection techniques and understanding of the effects of operation for the system concerned.

Mandate Systems is a Competent Person within the scope of PSSR(2000) and meets the attributes required by PSSR upto and including Major Systems.

Written Scheme of Examination – specifies which parts of the pressure system need to be subject to examination and what types of examination are necessary and the intervals between them.  It can be written and certified as suitable either by a Competent Person.

Safe Operating Limitmeans the operating limits (incorporating a suitable margin of safety) beyond which system failure is liable to occur.  This can sometimes be referred to as the Safe Operating Pressure, Operating Pressure or Maximum Permissible Working Pressure or just Working Pressure.

Examination – means a careful and critical scrutiny of a pressure system or part of a pressure system.  This is sometimes mistakenly known as a insurance inspection or a Pressure Test.

Pressure Test – involves applying stored energy to an assembly of parts, in order to verify its strength, its integrity and/or its functionality. Pressure testing is a high-risk activity and is rarely called for within a MAndate Systems Written Scheme of Examination.

Exam Report – a written report, signed by the Competent Person, which states which parts of the pressure system have been examined, their condition and the results of the examination.  It will also specify any repairs or modifications to, or changes in the established safe operating limits, the next examination date and whether the Written Scheme of Examination remains suitable.  At Mandate Systems we issue one report per component, so there may be many examination reports for a pressure system.

Pressure Vessel – a rigid vessel used, or intended to be used, to contain a relevant fluid.  There must be a pressure vessel in the system for the Regulations to apply.  This can sometimes be referred to as a Tank, Air Receiver, Boiler, Steam Generator, Pressure Receptacle.  A number of components within a pressure system may also fall under the definition of a Pressure Vessel, for example, rigid filter bodies.

Compressor – a mechanical device that increases the pressure of a gas by reducing its volume, this may be the motive force behind the pressure system (especially in the case of compressed air).  A compressor is only included in the scheme if:

(i) its mechanical integrity is liable to be significantly reduced by corrosion, erosion, fatigue or any other factors; and

(ii) failure resulting in the sudden release of stored energy would give rise to danger.

Compressor Set – This is usually a self contained pressure system comprising a Compressor, Air Receiver, Pressure Gauge, Pressure Switch and Safety Valve.

There are many terms across Pressure Systems Safety that may also give rise to confusion, if you are unsure, feel free to contact us at Mandate Systems.