Sea wall bolt failures

Three or four consulting cases where steel bolt heads broke off after six months in salt water due to corrosion-generated hydrogen. Used to make the point that hydrogen embrittlement does not require welding — corrosion alone can charge the steel.

The nice thing about hydrogen cracking is it's reversible. You can get the hydrogen in the steel, but if you get it out before a crack forms, no harm done. What do you have to do? For example, the ASTM spec for electroplating — because there's different ways to get hydrogen into steel. You can get it from welding. You can get it from corrosion. Corrosion breaks down — if you have 1.1 volts, you can break down the water into hydrogen and oxygen, and that stuff can go right in the bolts. I've had plenty of steel bolts and high strength steel bolts in sea walls, and people want to know why the heads are breaking off the bolts. Well, you're in salt water, and if you have it galvanically coupled to something else — one of you had the titanium pipe with the galvanic coupling. You're going to be generating hydrogen, and that hydrogen will get into the steel and can then embrittle it. Now you were looking at corrosion, but if you had stresses in there you could have cracked it.