No, I don’t know this happened. From PJF in comments.
I don’t even have enough to know that this could have happened – just don’t know enough about engineering.
But if this is possible, methane hydrates in a shut down gas pipeline, unless you’re really careful with the maintenance. Then yes, having lived over there for a number of years, yep, sure, maintenance could well be bad enough to make this happen.
It does in fact explain all about what happened too.