Owners in a newly constructed condominium experienced brown discolored or rusty looking water when drawing water out of a faucet. J.E.I. Metallurgical was retained to investigate the metallurgical cause of the discolored water. Piping was removed from the facility for examination. An overall view of the galvanized hot water pipe is shown in the photograph below..
An end view of the subject water pipe is shown in the photograph below.
Corrosion tubercles are noted dispersed uniformly around the pipe inside surface.
The pipe was sectioned, and isolated corrosion tubercles were observed to be uniformly dispersed throughout the inside pipe surface as shown in photograph in the photograph below.
Of note, is the fact that the corrosion tubercles are uniformly dispersed around the inside pipe surface and are not aligned with the electric resistance (ER) weld used to fabricate the subject pipe.
A close-up view of the corrosion tubercles is shown in the photograph below.
The Tubercles noted in photograph D were formed in less than six (6) months of service.
Metallurgical sections revealed classic pits-in-pits surface topography. Pits-in-pits corrosion topography is a classic characteristic of sulfate-reducing bacteria (SRB) corrosion. A close-up view of microscopic view of the pits-in-pits topography is shown in the photograph below.
Further examination revealed that the galvanized zinc layer on the inside of the pipe, which was produced outside of the United States, was of inadequate thickness and did not meet the required ASTM pipe specifications.