scope:

NG/H blends are considered to be equivalent to 100 mol % Hydrogen with respect to limits on design stresses, the potential effect on the material properties, and damage and defect categories and acceptance levels, unless an additional technical evaluation is carried out to qualify the materials.

NG/H blends containing in excess of 10 mol % Hydrogen are considered to be equivalent to 100 mol.% Hydrogen with respect to all other requirements except for hazardous areas (see Section 10).

This Supplement gives additional recommendations for PRIs and installations:

• with an upstream maximum operating pressure (MOP) not greater than 100 bar

• with an outlet pressure greater than or equal to 7 bar

• for use with Hydrogen or NG/H blends with a Hydrogen content greater than 10 %

• operating with a temperature range between -20°C and 120°C.

This Supplement also gives additional requirements relating to the repurposing of NG PRIs to Hydrogen service. These requirements are in addition to those in the main body of the document, which continue to be applied except where explicitly superseded by the requirements of this Supplement.

Repurposing in accordance with the requirements of this Supplement are to be considered only for PRIs and installations which have full maintenance records in accordance with the recommendations of the main document.

Note: The material performance factors defined in ASME B31.12 are based on limiting the hoop stress, not derating the tensile properties. The design factors in Table S1 are based on the material performance factors for pressures not exceeding 137.9 barg (2,000 psig).