LNG tanker steel specification practice

Brief cross-reference Tom uses to contextualize the prolongation-testing principle. 20.5 foot-pound Charpy minimum; best plate cut up for test specimens. Used to explain why a big forging needs a separate cut-off prolongation.

Later on, we found out the steel wasn't quite up to snuff, okay. When you write a specification — and this is in the flight of the LNG vessels — all the bottom had an average of like 20.5 foot-pounds. You take the very best plate, cut it up, and make all the test pieces out of that. But when you make a big forging like this, you can't go cutting pieces out of the big piece. So you use what they call a prolongation: the forging has a little end on it that you're supposed to cut off and make all your test specimens, so you know the properties of the steel are okay.