Alaska Pipeline brittle fracture risk assessment

The economic case: $60M/day (1970s) to $200M/day (today) of oil flow means the operator has more skin in the game than any environmentalist. Cited to motivate the 80-ft-lb base-plate proposal that follows.

The safety factors had been creeping up. Right as I was leaving, they had just finished building the Alaska Pipeline. There was still a big fury in the press about what if we have a fracture in the pipeline. I remember as a young assistant professor giving lectures and explaining to the students that the oil company has more interest in not having a big fracture in the pipeline than any of the environmentalists do. If you've got two million barrels a day coming down from Prudhoe Bay to Anchorage, and back then it might have been thirty dollars a barrel, that's $60 million a day. Today that would be twice a hundred, so it's going to be $200 million a day coming through that pipeline. If you have a fracture — the fracture in a pressurized pipeline might be 100 feet long when it pops open. Maybe less, maybe only 30 feet long. But you can't just go down to the hardware store and pick up another piece of pipe. If it's in the middle of nowhere in Alaska, you can't get the piece of pipe in storage in Anchorage to the site overnight. You don't FedEx a 40-foot length of pipe, and then you've got to get the welders from Tulsa up there and the heavy equipment.

Tom worked at Bethlehem Steel on high-toughness steel for the Alaskan pipeline. 70 foot-pound Charpy requirement to stop a running brittle crack, motivated by prior pipeline fractures that ran 30 miles.

Originally, if you look at that Navy report, they found that in most of the ships that failed, the plates where the fractures initiated had less than five foot-pounds Charpy energy. The recommendation of the 1946 report was: you'd better have ten foot-pounds of fracture energy in that Charpy bar in order to avoid the brittle fractures and catastrophic failures. In the 1950s, when they started writing the code, someone decided we'd better put a safety factor on, so they upped it to 15. By the 1960s the Coast Guard said we'd better have a bigger safety factor, so they upped it to 20. By the time I was an engineer at Bethlehem Steel and people were designing the Alaskan pipeline, they were saying we need fracture toughness that will stop a running brittle crack. Because there had been fractures in pipelines where the fracture ran for 30 miles in the pipeline once the brittle fracture started. That gets expensive. So they wanted something that would stop a running brittle fracture. They were looking for 70 foot-pounds of fracture toughness, which is one of the reasons I was working on trying to come up with higher-toughness steels.