Failure analysis of brass portions of dielectric unions

Persistent failures (leakage) were observed in the brass portion of dielectric unions after a relatively short service period. Metallographic examination revealed evidence of severe stress-corrosion cracking within the brass as well as dealloying on the surface. Evaluations using stress calculations and the dynamics of freezing water indicated that the unions were not overtightened during installation, and the water passing through the unions did not freeze. The subject copper alloy was shown to have been insufficient for the intended application due to high susceptibility to corrosion.