Abstract: Employee #1 had obtained an old cast-iron tank from a unknown source and planned to use it to collect condensed steam, which would not have required that it be under pressure. He and four prison inmates, including Employee #2, decided to check the tank for leaks by closing and sealing all its openings, applying compressed air to the tank, and administering a soap test. When the compressed air was applied, a gauge on the tank read between 25 and 30 lb. According to witnesses, the compressed air was then shut off to see if the tank would hold the static pressure. Employee #1 then proceeded with the soap test. The tank exploded, injuring Employee #1 and Employee #2, who was standing behind Employee #1. Nine minutes before the explosion, the pressure gauge registered 110 lb, where it froze after the explosion. Evidently, the pressure gauge had malfunctioned, misleading Employees #1 and #2. Pieces of the cast-iron tank were rusted on the broken edge, confirming that the tank had hairline fractures and that compressed air should not have been applied to the tank.