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FAQ (Frequenty Asked Questions)

1. To which installations, equipment does the pressure equipment directive PED 97/23/EC apply?
It is easier to answer this question in the case of pipelines, to which systems it does not apply: systems of free water evaporation, elements to nuclear applications, blast furnaces, heat recovery units, radiators and pipes in CH systems, elements used in military equipment, aviation, transmission pipelines for the transport of fluid or substances to or from an installation (land and water) and similar exceptions. So in practice, the remaining tanks, assemblies, installations and other devices intended for gases, liquefied gases, dissolved gases, vapours, liquids in which the maximum allowable pressure PS exceeds 0.5 bar (or 0.05 MPa or 0.49 atm) will be subject to the Directive. However, it should be noted here that even though PS is higher than 0.5 bar, an element may not be subject to the Directive 97/23 - this is further subject to the product of PS x V and the type of medium. Of course, installations for dangerous liquids or liquids safe to a certain extent will have to meet the requirements of Directive 67/548/EC beyond the requirements of the Pressure Equipment Directive.

2. What materials can be used for pipelines covered by PED 97/23/EC?
Essential Safety Requirements (ESR) described in Appendix No. 1 to the directive identify the materials that are approved for use in systems subject to the PED. These materials are:
a) compliant with the harmonized standards, or
b) covered by the European Approval for Materials (EAM), for the manufacture of pressure equipment, or
c) by applying Particular Material Appraisal (PMA).

3. What do materials compliant with harmonized standards mean?
These are materials manufactured in accordance with the EN standards, but only those that are harmonized with the PED 97/23/EC. In our case it will be mainly the following standards: EN 10216-2; EN 10216-3; EN 10216-4; EN10028-2; EN 10222-2; EN 10222-3; EN 10222-4.

4. What materials are covered by the European Approval for Materials (EAM)?
The current list of these standards can be found at:


5. Can dimensionally appropriate fittings manufactured according to EN 10253-2 be regarded as equivalent to elements according to DIN 2605-2, DIN 2615-2. ?

No. It is true that standard EN 10253-2 is a harmonized standard, but it describes two types of fittings. Type B according to EN 10253-2 corresponds to the elements according to DIN2605-2, DIN 2615-2.

6. Is it acceptable to use A420 WPL6 grade as a replacement for P355NL1?
The designer of the installation may decide whether it is possible to replace the fittings made from P355NL1 grade with the one made from another grade. While making the decision he will take into account: the nature of the installation, if it is subject to PED 97/23/EC, the type and nature of the load (can he agree to a significantly lower yield point, as, for example, in the WPL6 grade), properties of the medium and other important factors.

7. Can the material for forging P355NH be replaced, for example, with the material A350 LF2 according to ASTM?
Here we have a situation similar to that in section 6, that is, the designer should determine whether he permits the use of steel with significantly lower yield point (for P355NH it is 355MPa, while for A350 LF2 it is 253MPa).