I posted about Hydrogen in the DBNGL previously. I am a 42 year...

I posted about Hydrogen in the DBNGL previously. I am a 42 year NDT tech. I worked on the DBNGL pipeline and assesed the welding quality.
When dealing with hydrogen in the gas mix it's not the steel of the line that's the weak link its the weld joining the pipes together.

In sour service, when there is H2S, hydrogen sulfide in the gas the welds must be done to a higher standard then normal.
DBNGL is welded to what is known as a sweet gas standard. The initial or root pass is allowed to have defects of up to 12 mm in length for lack of fusion or inadequite penetration, on a sour service line that is not allowed as it give the small molecule hydrogen a starting point into the weld.

If your building a pipeline for high concentration of hydrogen, and they do exist, I've worked on 90% H2S lines in western Canada the welding specification simply states that the root pass shall have zero visible welding defects

The engineers and licensing authorieties will have to decide how much can be allowed into the gas mix safely