Microbial Influenced Corrosion of Copper Piping
Specimen: 1.0-in. OD copper sprinkler line piping
Material: Copper
Environment: Sprinkler line, containing stagnant water. Water was untreated with no corrosion inhibitors or biocides.
Background: After installation, the lines were filled and left wet, with primarily stagnant conditions. Pin-hole leaks had been discovered at multiple locations on multiple floors.
Service Life: The sprinkler line copper piping had been in service for approximately 14 years.
Findings: Through optical and scanning electron microcopy it was found that the copper sprinkler piping had failed prematurely from Microbial Influenced Corrosion (MIC). Strong evidence was found including regions of “biofilm”, large crystals of Cu2O and the base of corrosion pits, micro, bore-like holes adjacent to corrosion pits, and the very random nature of the pitting all indicate failure due to MIC.
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Longitudinal cross-section through copper pipe showing 2 corrosion sites covered by “mounds” of bright green-colored corrosion products. Note: Black-colored coating on the inside wall of the copper pipe |
