In this case, involving a liquid nitrogen storage tank that exploded near Los Angles, a failure mechanism well known forty years ago had to be figured out all over again.

The tank, a 40-year old double-walled sphere with an insulated annulus, exploded just after it had been filled, seriously injuring the tank truck driver. The top half of the outer tank was found a quarter of a mile away, but part of the bottom half of the tank was found in shards, most of which appeared to have come from the front of the tank where the inlet and drain lines were. Since steel is brittle at liquid nitrogen temperatures, we knew that liquid nitrogen had leaked into the annulus between the inner and outer tanks and vaporized, causing a pressure sufficient to make the outer tank blow.

More than a dozen experts were involved in this case on behalf of the plaintiff, the owner, the nitrogen supplier, the tank manufacturer (who was now making garage doors) and the maker of a tank pressure relief vent whose spring was found broken after the accident. They all had theories regarding how the accident had happened, of course. The tank had been overfilled; it had been filled empty, and vaporizing nitrogen liquid provided a sudden high pressure; the broken valve reduced pressure relief capability; a metal defect allowed nitrogen to escape from the inner tank, etc. But none of these theories made sense in light of the evidence or engineering experience. Our tests showed that the relief valve actually performed better with the spring broken; thousands of dollars of scanning electron microscopy failed to find a flaw along the seam of the inner tank.

In the end geometry and persistence won the day. The shard positions focused our attention on the front bottom quarter of the tank where the liquid supply line and other lines were located. When the supply nipples were removed, we found a crack in the oxygen supply line at a welded metal transition. Our literature search showed that the infant cryogenics industry had experienced a number of similar failures during World War II, as they strove to get oxygen to pilots so they could fly higher.

Our client, the tank owner, settled for a relatively minor amount soon after Dr. Pesuit's deposition. Dr. Pesuit was later hired by the plaintiff for the workman's compensation case.