Oil pipelines, no. Gas pipelines, yes. The effort to requalify existing gas pipelines for hydrogen use is well underway in Europe. There might be a need to run at lower pressure, depending on the type of steel, but leaks are not an issue.
Hydrogen embrittlement is a massive issue, I’d be interested to hear how this can be engineered around. My understanding is it requires more exotic materials than those used in any existing NG or oil pipelines. Everything I’ve seen claiming it’s viable to use existing infrastructure seems reasonable at first glance, but invariably contains a massive hand-wave or 2.
I think the obfuscation is that they are generally talking about stuffing small quantities of hydrogen into natural gas pipelines. Similar to alcohol in gasoline.
The existing infrastructure was originally built for town gas which is ~50% hydrogen, and run successfully for many decades as such. So this is mainly about checking out the more recently designed parts. My understanding is embrittlement is mainly a problem for storage tanks, which need to use high strength materials due to the enormous pressure -and ironically those materials are more susceptable.
Existing infrastructure is designed for & can be used for hydrocarbons with varying levels of hydrogen in their molecular structure; I don't believe there's an issue there. Most of the H2 in town gas is in the form of hydrocarbons, which are less reactive than pure H2, even if there's a relatively high percentage of H2 in the mix (as the H2 is strongly bound to the carbon). Embrittlement is definitely an issue for more than just storage tanks.
Leaks are an issue… hydrogen is a smaller molecule and leaks from natural gas pipes and there’s a lot of gas infrastructure in the ground in some countries e.g. in UK most houses have a connection
