I’m not a submarine engineer, but I would have expected that some of the more complex systems would have failed before the pressure vessel. Then again, it seems like they chose a seemingly cost effective design that was apparently susceptible to fatigue. Combine that with a profit motive to dive as many times as possible before retiring the hull and I suppose an implosion was practically inevitable. Oh well.
Are those the same regulations that are said to be written in blood because people died before such rules were formed? We also have a saying at work - don’t create the need for a new rule with your name on it.