A chemical plant has a leak at a valve's flanged connections. Workers close the valve to isolate one of the connections and replace the gasket. The other connection cannot be isolated; plant procedures require that an outside contractor be called in for on-line repairs. A band is clamped around the joint, and sealant is forced into the space between the flanges. During the repair, the bolts holding the flanges fail, and scalding hot water pours onto one of the workers.

Injection of sealant between flange faces increases the force on the bolts, but this increase is negligible compared to the force the bolts can usually withstand.

It is discovered that during the first repair, many of the bolts broke when workers attempted to remove them. This was unusual; the bolts had not shown the corrosion necking that usually precedes bolt breakage. Furthermore, the bolts were stainless steel, and many showed cracks and corrosion where they broke. There had been a breakdown in communication; when the contractor arrived, he was not informed of the condition of the other bolts.

Stainless steel does not normally corrode, but the water was loaded with chloride ions that attacked the bolts in a process known as stress corrosion cracking. Someone, years ago in the plant, thinking that bolt corrosion could be prevented, had replaced the carbon steel bolts with stainless steel ones. This set up a situation where the connection failed without warning.