SS Libra LNG vessel tail shaft failure

33-inch propeller shaft forged from killed-steel ingot stopped dead full of LNG in the Philippine Sea on Indonesia-to-Japan run. Lear jets airlifted fittings for emergency LNG transfer to sister ship. Tom uses this to make the killed-steel ingot top-cropping point and the related Homeland Security RPG concern about Boston Harbor LNG traffic.

In the welding course I actually talk about how one company ended up forging this casting into a 33-inch diameter shaft. I told you about my 33-inch diameter fracture in the mid '80s. This went as a propeller shaft on a liquid natural gas carrier, and it stopped dead full of LNG in the middle of the Philippine Sea. They were airlifting in Lear jets fittings so they could transfer the LNG to another empty LNG cargo tanker that was coming back from Japan. This is a whole series of LNG ships going from Indonesia up to Japan and back. This one was going up to Japan full, and when it lost power and couldn't go anywhere, full of LNG, you could have had a big explosion which would have upset a lot of people. May not have killed very many. But remember, those same LNG tankers come in once or twice a month into Everett, right through Boston Harbor. One of the biggest concerns that Homeland Security has for Boston is, all you need is a rocket-propelled grenade when that thing's coming in, and you will wipe out half of Boston. So they have a little security to try to make sure there are no terrorists with RPGs. But nonetheless, this thing stopped dead in the Philippine Sea.

In October 1980, the SS LNG Libra — a 125,000-ton liquefied-natural-gas tanker built at Quincy Shipyard — lost power fully loaded in the Philippine Sea when her thirty-three-inch solid steel tail shaft sheared in two. ABS surveyors transferred the LNG cargo to a sister ship at Davao City and dry-docked the vessel in Singapore, where Tom Eagar examined the fracture. The shaft contained a football-sized shrinkage pipe (the ingot had not been topped enough because the Seattle steel mill was at its maximum ingot-casting capacity and was already losing money on prior scrapped attempts) and a brittle "clink" crack — an internal flaw caused by thermal stresses when the cold, brittle interior of a large ingot is heated too rapidly in a forging furnace. A lab technician had detected the void by ultrasonics and documented it in writing; his supervisor refused to act. The shaft was shipped to Quincy without incoming inspection, ran for three to four years until the fatigue crack reached critical size, and broke. Litigation settled with the shipyard paying $6–8 million of a roughly $15 million loss, despite the steel mill being the primary culprit, because of pre-existing bad blood between the shipowner and General Dynamics.

I wanted to do a little case study, since you guys are in the Navy. This one I do on one of the other videos, so you can fast forward, but in the revised way I'm putting this course together, this is a good place to talk about it. Anybody know what surveying is in shipbuilding?