TWI Frequently asked questions
by Alan Smith
The pressure equipment directive (PED), implemented in the UK as the Pressure Equipment Regulations 1999, is a directive from the EC enforced across the member states of the EU and adopted by associated states. It became mandatoryon the 30 May 2002. All equipment going into service with a maximum allowable pressure greater than 0.5bar has to comply. For the purposes of the directive, pressure equipment means vessels, piping, safety accessories or pressureaccessories.
Its purpose is to promote a 'level playing field' within Europe and remove technical barriers to trade. It harmonises national laws relating to design, manufacture, testing, marking and labelling, inspection and materials ofpressurised equipment and requires compliance with what are termed 'essential safety requirements'.
The responsibility of conformance is placed on the 'responsible' person. Generally this will be the manufacturer (see Further information, below). The manufacturer may be the importer, he may be the supplier or he may be theauthorised representative.
To demonstrate compliance, a manufacturer needs to conform with a module that specifies various quality assurance requirements. It is up to the manufacturer to decide which module they need to use by carrying out a 'ConformityAssessment Procedure' (see Further information, below). Each of the modules involves a Notified Body. A Notified Body has the power to check that a vessel design conforms to the Pressure Equipment Regulations (see Further information,below; DTI website). Currently, there are 15 Notified Bodies appointed in the UK and five recognised third party organisations. TWI is a recognised third party organisation for weld procedure approval and welder certification.
There are several exclusions listed in Schedule 1 of the PED. These include equipment covered by other directives such as a simple pressure vessel and aerosols and for those transporting dangerous goods. It also excludes equipmentnot higher than category 1 (see Further information, below; FAQ: What is a Conformity Assessment Procedure?) that is covered by other directives and it excludes pressure equipment assembled on site under the responsibility of theusers.
To maintain consistency across the community, the development of guidance on the use of the PED is seen as a crucial tool. Guidance is developed through two working groups: the working group on pressure, and a sub-group - theworking party on guidelines. The guidelines assist in defining scope and application and do not have legal status.
Further information
Information on the pressure equipment directive can be obtained from the DTI website.
FAQ: Who is responsible for conformity to the Pressure Equipment Directive?
FAQ: What is a Conformity Assessment Procedure?
Guidance notes on the UK Regulations, URN 05/1074, April 2005, from The Department for Business Enterprise and Trade Reform.
