While it is easy to agree there was a special on training submarine crews and part of the training they showed were guys installing patches on broken / leaking pipes which gave the impression that pipes could have problems. Or am I just confusing one thing with something else?
We are trained to fix pipe burst yes. Could be any seawater or hydraulic system that it happens to though. A few scenarios are exceeding test depth and pipe pressure ratings and bursting them or a close aboard explosion causing them to rupture. In these cases we might need to patch a pipe or secure the system all together... Does that help?
Yes a little I think. Hydraulic systems are understandable and that would be I would imagine oil. What systems use seawater? The ballast system, showers, toilets, engine cooling or are there other uses?