scope:

This Supplement covers the design, construction, inspection, testing, operation and maintenance of steel pipelines and certain associated installations in Hydrogen service, and the repurposing of NG pipelines to Hydrogen service, at maximum operating pressure (MOP) exceeding 7 bar and not exceeding 137.9 bar.

Where required reference is to be made to IGEM/TD/13 Edition 2 and the Hydrogen supplement to it.

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 (see clause S5.8). 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.

The design factor of pipelines in Hydrogen service is limited to 0.5 (as compared to 0.72/0.8 in NG service). A material performance reduction factor, as defined in ASME B31.12, is applied to reduce the allowable design factor for grades higher than L360 (X52) (see Table 1). Materials may be qualified to operate in Hydrogen service at higher design factors through testing (see clause S5.8).

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).