A propane pump explosion had killed one worker and injured three others at a central Ohio factory. The pump was being used to charge aerosol cans with propane propellant at high pressure. The accident occurred when gas leaked past the pistons in the pump. Originally, the pump was built with metal pistons that wore rapidly against the seals. They were replaced with ceramic seals. Designed to pump mud, the ceramic components eventually cracked and loose pieces fell away, causing a massive leak. After examining the crack pattern and characterizing the ceramic material, O’Donnell engineers theorized that the cracking was due to the sudden chilling of the outer ceramic surface. Finite element stress analysis and testing confirmed the theory.