PED
The purpose of the Pressure Equipment Directive (PED) is to harmonize the national
laws of Member States in the EEA regarding the design, manufacture, testing and
compliance requirements of pressure equipment and assemblies of pressure equipment.
Harmonization of national laws ensures that pressure equipment can be manufactured and
sold through the European Union without having to go through national approvals in
every member state. The PED requires that all pressure equipment and assemblies within
its scope must be safe when placed on the market and put into service.
The following are definitions of key terms used throughout the PED:
pressure equipment: includes vessels, piping, safety accessories and pressure
accessories. Where applicable, pressure equipment includes elements attached to
pressurized parts, such as flanges, nozzles, couplings, supports, lifting lugs, etc.
vessels: are defined as a housing designed and built to contain fluids under pressure.
piping: means piping components intended for the transport of fluids, when connected
together for integration into a pressure system.
safety accessories: means devices designed to protect pressure equipment against the
allowable limits being exceeded.
pressure accessories: means devices with an operational function and having pressure
bearing housings.
assemblies: mean several pieces of pressure equipment assembled by a manufacturer to
constitute an integrated and functional whole.
Once the manufacturer has confirmed that its equipment is within the scope of the PED,
the next step is to determine the classification of the equipment. There are four
Categories: I to IV. Category I relates to the lowest and Category IV relates to the highest
hazard Category.
In order to determine which Category an item of equipment falls into, the manufacturer
needs to identify:
• the type of equipment - vessel / steam generators / piping
• the state of the intended fluid contents - gaseous or liquid
• the fluid group of the intended contents - Group 1 or Group 2
