Nuclear submarine welding hydrogen embrittlement cracks

General reference to Groton submarine welding: if hydrogen isn't controlled, night-shift welders hear cracks running through the steel like rifle shots. Sets up the Sea Wolf case at §5.p7.

They're welding nuclear submarines down in Groton, Connecticut, and if they don't control the hydrogen while they're welding these big egg-crate type of constructions to make a high-strength pressure vessel, guys will be welding during the day and the guys at night who are welding will hear a bang like a rifle shot in the shop. That's a brittle crack that just ran through the steel and broke it right in two. Hydrogen embrittlement, also called delayed cracking. It doesn't usually occur within the first one to four hours. If you look at ASTM specs, if you do something like electroplate steel, that could introduce hydrogen, the ASTM specs say you must put it in an oven at 375 degrees Fahrenheit. This is like cooking a cake, it's not terribly hot, and that will diffuse the hydrogen out of the steel before it has a chance to accumulate at the imperfections and cause cracks.