Interim Report on the Examination of Corrosion Damage in Homes Constructed with Imported Wallboard: Examination of Samples Received September 28, 2009
David J. Pitchure, Richard E. Ricker, Maureen E. Williams, Sandra W. Claggett
Since many household systems are fabricated with metallic materials, changes to the household environment that accelerate corrosion will increase the failure rates of these systems. Recently, increased failure rates have been reported in homes constructed with imported wallboard. At the request of the Consumer Product Safety Commission (CPSC), the National Institute of Standards and Technology (NIST) performed metallurgical analyses on samples removed from these homes to assess the nature and origin of these failures. The samples received by NIST consisted of copper natural gas tubing and two air conditioner heat exchanger coils. The examinations consisted of photography, metallurgical cross-sectioning, optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Leak tests were also performed on the air conditioner heat exchanger coils. A thin black corrosion product was found on the copper samples and XRD analysis identified this layer as a copper sulfide phase: digenite (Cu9S5). Corrosion products were also observed on other types of metals in the air conditioner coils where condensation frequently wets the metals. The thickness of the corrosion product layer on a copper natural gas supply pipe with a wall thickness of 1.2 mm ±0.2 mm was between 5 µm and 10 µm. These results indicate that a chemical compound containing reduced sulfur, such as hydrogen sulfide (H2S), is present. None of the samples examined were failed components, and no evidence of imminent failure was found. All of the corrosion damage observed was consistent with a general attack form of corrosion that will progress in a uniform and predictable manner. Additional work will be required to fully assess the probability of other forms of corrosion causing failure.
, Ricker, R.
, Williams, M.
and Claggett, S.
Interim Report on the Examination of Corrosion Damage in Homes Constructed with Imported Wallboard: Examination of Samples Received September 28, 2009, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/jres.115.012
(Accessed December 10, 2023)