The Pressure Equipment Directive 97/23/EC (PED)  of the EU sets out the standards for the design and fabrication of pressure equipment ("pressure equipment" means steam boilers, pressure vessels, piping, safety valves and other components and assemblies subject to pressure loading) generally over one litre in volume and having a maximum pressure more than 0.5 bar gauge. It also sets the administrative procedures requirements for the "conformity assessment" of pressure equipment, for the free placing on the European market without local legislative barriers. It has been mandatory throughout the EU since 30 May 2002. This is enacted in the UK as the Pressure Equipment Regulations (PER). The set out standards and regulations regarding pressure vessels and boilerssafety is also very close to the US standards defined by the American Society of Mechanical Engineers (ASME). This enables most international inspection agencies to provide both verification and certification services to assess compliance to the different pressure equipment directives.
Directive 97/23/EC will be fully superseded by directive 2014/68/EU from July 20, 2016 onwards. Article 13 of the new directive (classification of pressure equipment) has already been in effect since June 1, 2015, replacing article 9 of directive 97/23/EC.