This Supplement gives additional requirements and qualifications for the distribution of Natural Gas/Hydrogen blended mixtures (subsequently referred to as NG/H blends), and for the repurposing of Natural Gas (NG) pipelines for NG/H blends and is only to be used in conjunction with IGEM/TD/3 Edition 5.

The clause numbers in this Supplement (preceded by ‘S’) refer to the clause numbers in the main document and specify the requirements and qualifications which are in addition to those in the main document. Where there is no numbered clause in this Supplement corresponding to a clause in the main document, the requirements of the main document apply in full.

This version of the Supplement has been developed using the latest publicly available information and may include some conservative requirements which further research may deem not necessary. The Supplement will be updated regularly following the publication of new research into the application of NG/H blends.

This Supplement was published in December 2022.

S2.1 This Supplement covers the design, construction, inspection, testing, operation and maintenance of steel and polyethylene (PE) pipelines and the repurposing of NG pipelines for NG/H blends with MOP not exceeding 7 bar for:
• NG/H blends with less than or equal to 20 mol.% Hydrogen.

The Supplement outlines the requirements for repurposing an existing NG distribution pipeline for NG/H blends operating at pressures below 7 bar which has been maintained in accordance with previous versions of IGEM/TD/3, including pipelines constructed of iron and fabricated by different methods historically. It also covers modification and connection to these existing pipeline systems.

S2.2 This Supplement covers PE and steel pipelines operating at a MOP not exceeding 7 bar and at a temperature from 0ºC to 20ºC inclusive for PE and -25ºC to 40ºC inclusive for steel.