Feature Machine building, frameworks & safety Keeping control of the pressure
Achieving compliance with the Pressure Equipment Regulations (PER) is not a process that machine builders can afford to get wrong. Paul Laidler, business director for Machinery
Safety at TÜV SÜD Product Service, explains how taking a step-by-step approach makes achieving compliance a straightforward process
Directive (97/23/EC) in the UK. While this may conjure up visions of costly and time-
M
consuming third-party testing and compliance procedures, this is not necessarily the case. Before assuming the worst, it is worthwhile following a step-by-step procedure to determine whether a simpler route to compliance is actu- ally all that is needed.
Taking steps The first step is to decide whether the equipment under consideration really does fall within the scope of the PER. There are a number of exclusions, and information about these can be found on the Department for Business, Innovation & Skills website (DTI publication URN 05/1074, ‘Pressure Equipment – Guidance Notes on the UK Regulations’). This details a number of exclusions in Annex A, including paragraph 10 about equipment comprising casings or machinery. However, as the wording is open to interpretation, it is advisable to proceed on the assumption that the equipment is covered by the PER.
Paragraph 6 of Annex A also includes a specific exclusion
for equipment that is classified as ‘no higher than category 1’. The only way to decide if this is appropriate, however, is to undertake the following steps: The first stage is to decide whether the equipment should
be categorised as a vessel, which is defined as ‘a housing designed and built to contain fluids under pressure; piping, which covers components intended for the transport of fluids when connected together for integration into a pres- sure system; or a steam generator, such as a boiler’. Except in the case of a steam generator, it is also necessary to decide whether the fluid contained in the equipment is a gas or a liquid, and whether the fluid has to be treated as a Group 1 or Group 2 fluid. If there is any doubt whether the fluid is a gas
or liquid, the regulations require the fluid to be treated as a gas if it has vapour pressure greater than 0.5 bar at the maximum allowable tempera- ture for the equipment. Information about vapour pressure at various temperatures should be
Design Solutions JUNE 2013
achine builders often find that part of the equipment which they are designing falls within the scope of the Pressure Equipment Regulations 1999 (PER), which implement the European Pressure Equipment
readily available from the fluid supplier. Deciding between Group 1 and Group 2 fluids is equally
easy, as Group 1 covers fluids that are explosive, flammable, toxic or oxidising, with all other fluids falling into Group 2. Further information regarding these groups is included in the DTI guidance document. The next stage in the process is to refer to the Directive (and
“If part of the
equipment being designed falls
within the scope of
the PER, it does not necessarily mean third-party testing and compliance procedures are needed”
DTI guidance document), which contains nine charts that define the route to compliance. The classification table guides the machine builder to the relevant chart for their product. It is then a case of plotting the volume of the equipment under consideration against the maximum pressure, placing the equipment in one of five categories: SEP, I, II, III and IV. Each category has its own route to compliance and for categories II, III and IV, the machine builder can choose their preferred route, working in conjunction with a notified body. If the equipment falls under the SEP (sound engineering
practice) category, no special measures are needed for compliance and the equipment is not permitted to carry the CE marking. For equipment in Category 1, all that is required, in addi-
tion to the Machinery Directive requirements, is to produce technical documentation. This includes an assessment to show that the equipment conforms, covering its design, man- ufacture and use. In contrast to SEP equipment, category 1 equipment must carry the CE marking. It is also worth noting that for equipment in both SEP and
Category 1, it is not necessary to involve a notified body in the PER compliance process. At first sight this is a useful exclusion that eliminates the need to go through further steps. However, the only way to decide whether the equipment should be ‘classified as no higher than category 1’ is to go through the process for equipment in categories II, III and IV.
Paul Laidler
Achieving compliance While there are many instances when achieving compliance with the PER is far less challenging than is first imagined, it is not a process that machine builders can afford to get wrong. By taking a step-by-step approach, achieving compliance with the PER is a relatively straightforward and inexpensive process. However, final decisions relating to pressure equipment should only be made after referring directly to the Pressure Equipment Directive.
TÜV SÜD
www.tuv-sud.com
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