prEN 18191

This document applies to industrial metallic valves for hydrogen use. It contains recommendations and additional requirements applicable to material selection, design, manufacture, and final assessment.
This document addresses the following four services/damage mechanisms, which might exist in combinations:
-  low temperature applications;
-  hydrogen environmental embrittlement (HEE) or hydrogen-induced cracking (HIC);
-  high temperature hydrogen attack (HTHA);
-  hydrogen service with cyclic loads (fatigue).
The document considers the difference between gaseous hydrogen (GH2) and liquid hydrogen (LH2), where necessary.
The additional provisions set out in this document do not cover corrosion such as electro-chemical corrosion of metals under participation of hydrogen (e.g. sour gas).
This document is based on the requirements contained in the standards specified below:
-  applications with a maximum allowable pressure PS greater than 0,5 bar in accordance with the European legislation for pressure equipment, the applicable provisions of EN 16668 apply;
-  additional requirements for valves in chemical and petrochemical applications are specified in EN 12569;
-  additional requirements for valves in gas distribution systems are specified in EN 13774;
-  additional requirements for valves in gas transportation systems are specified in EN 14141.