The PED (97/23/EC) provides a legislative framework at the European level for equipment subject to pressure hazards.
It applies to manufacturers of items such as vessels, pressurised storage containers, heat exchangers, steam generators, boilers, industrial piping, safety devices and pressure accessories.
Components to be included in a piping system
By components, we mean pipes, fittings, flanges and so forth – in other words, elements connected together to form a piping system. Each piping component is not itself considered to be pressure equipment. Therefore, CE marking of such items is not considered to be applicable.
The client is considered to be responsible for the design, manufacture and choice of materials for pressure equipment unless otherwise specified. Components are defined as falling in two groups – materials and components.
The following products will be regarded as materials:
- rolled products: plates, coils and bars
- forged products
- seamless tubes
- seamless fittings: as long as they have been made from forgings, castings or seamless tubes without subsequent welding or other processes which could alter their material characteristics
- welded pipes and tubes: as long as the pipe/tube has been continuously machine-welded from coil and heat treated after welding.
Other products are considered to be components – welded pipes made from plates, for example.
The requirements of PED, Annex I, are applicable to both groups, with the exception of section 4.3, which only applies to material manufactures. Requirements depend on the relevant products.
Where pressure equipment in categories II, III and IV is concerned, the welding procedures and welders must be approved by a competent third-party organisation. Qualified NDT personnel must be approved by a competent third-party organisation.
In the event that a material manufacturer has an appropriate quality-assurance system, certified by a competent body established in the European Community and having undergone a specific material assessment for materials, certificates issued by the manufacturer are presumed to certify conformity with the requirements without the necessity of a final third-party assessment.
In practice, this requirement is satisfied when the certified quality management system is of at least ISO 9002 type, and when the field of validity of the certification specifies the production of material of relevant types.
We consider the supply of these products with EN 10204 3.1 certificates, incorporating the above-mentioned requirements, to be sufficient for meeting the requirements of the PED.
Products which are considered pressure equipment
These products may be vessels, valves, pipe spools and so forth. Since they are considered to be inherently pressurised equipment, they may need to be CE marked. Classification of pressure equipment must be conducted in accordance with Annex II of the PED, and is performed on the basis of:
- its maximum allowable pressure PS
- its volume V or its nominal size DN, as appropriate
- the group of fluids for which it is intended.
Fluids are divided into two groups. Group 1 comprises fluids which are considered hazardous. See article 9 of the PED. Group 2 comprises all other fluids.
In cases where we are asked to supply products not defined as piping components, a separate assessment will be made in order to identify the PED requirements.
Ductility and toughness of materials for pressurised parts
Section 4.1 specifies that materials used for pressurised parts should be sufficiently ductile and tough. In order to ensure this, section 7.5 specifies that, unless other values are required, the steel is considered sufficiently ductile if a tensile-test elongation after rupture is not less than 14 per cent and its bending rupture energy, measured on a ISO V test piece, is not less than 27 J, at a temperature not greater than 20°C. The test temperature for the latter test must not be higher than the lowest scheduled operating temperature.
Where Norsok materials specified by MDS C01 and C02 are concerned, the client is responsible for determining the requirement for use of these materials in compliance with the essential safety requirements of the PED when ASME B31.3 is used as the design code.