Seymour Hersh has had a long and storied career, and he
has made some very bold claims that later turned out to be correct.
He's also, especially recently, made some very bold claims that so far have not turned out to be correct, whether because the truth just hasn't been revealed yet, or because Hersh was wrong or misled by his sources.
It's also worth noting that Hersh - as with any journalist - is only as good as his sources. If people choose to leak juicy secrets to him (not implausible!) he may end up publishing accurate stories that reveal nefarious conspiracies (which has happened). If people choose to give him lies and misinformation, he may end up publishing conspiracy theories instead. And as he keeps publishing, the odds that this will happen (if it hasn't already) keep increasing.
So I absolutely wouldn't write off any claim Hersh makes, but I wouldn't blindly believe it either. And here he is relying, by his own admission, almost entirely on a single anonymous source, giving details that can't really be independently confirmed.
Was Hersh told by someone that the US took out the pipeline? Probably! Does that mean the US did so? I'm not sure I'd seriously update my priors based on this.