Findings: pipe failure is the result ofjoint compound swelling
This simulation of the signature break pattern reflects the origin of the pipe break in the bell-end of the joint. As the chemical reaction occurs in the joint, the joint sealant compound expands and creates a hoop stress on the ring of the joint. Cast iron is a very brittle material and has a low tolerance for flex under pressure. As a result, once the pipe flex limits are breached in the joint the pipe bursts rapidly under the high water pressure in the pipe and causes the top to blow off.
