Posted by David Stegall on November 12, 2000
I can't believe this old 'Steel Town" term is not on your list.
When making steel, the molten material is poured into molds that forms small drop shaped (sort of) figures, about the size of a fist, that looks like new born piglets (baby pigs). They called it pig iron. When they took the pig iron out of the molds they would put the pig iron in water to cool it off. There was no question what it was and there was nothing that could happen to it. So when something is described as "pig iron underwater" the speaker means that it is safe, secure and there is no question as to what it is. Sort of like "it's in the bank".