Failure Analysis Expert Examines a Plumbing Failure

A failure analysis was performed on a plumbing failure. The line is a corrugated water line to a bathroom sink. The pipe failure occured at a bend in the water supply line it was due to stress corrosion of the yellow brass line. Microscopic examination of the largest crack showed that there was also dezincification associated with the stress corrosion cracking. Upper left is an overview of the corrugated water supply line. It is cracked where there is mechanical deformation of the brass tubing. The upper right photo is a 10X photomicrograph of the major crack. There are regions of the crack surface where the yellow brass has "red brass" regions. This indicates that there was selective corrosion of the zinc rich portions of the alloy. That is brass dezincification has occured at the crack tip.