LNG tanker tail shaft fatigue failure, Philippine Sea (1985)

Illustration of an internal forging defect originating in the as-cast structure of a great-big forging blank: solidification weakness at the centerline gets carried through forging, then propagates as a fatigue crack. Ship stopped dead with a full cargo of LNG in the Philippine Sea.

I've seen them. We know how to prevent them. In 1985, I saw one. In one of the other lectures on my welding course, I describe it. I think I describe it on the lectures you'll see this last summer. It's about a tail shaft of a liquid natural gas cargo tanker that stopped dead full of liquid natural gas in the Philippine Sea, because the tail shaft failed in fatigue. It had a defect right in the center of the casting. It wasn't a casting — it started out as a casting, and it got forged into the shaft, but they had a defect right in the center. It's a little more complex than that, but this is the type of thing that can happen.