Investigating a Mechanism for Transgranular Stress Corrosion Cracking on Buried Pipelines in Near-Neutral pH Environments
- 1 October 2007
- journal article
- Published by Association for Materials Protection and Performance (AMPP) in Corrosion
- Vol. 63 (10) , 932-939
- https://doi.org/10.5006/1.3278311
Abstract
Buried carbon steel fuel transmission pipelines, protected by external coatings and cathodic protection, are known to experience transgranular stress corrosion cracking (TGSCC). Failure analysis of failed pipelines and laboratory tests have indicated that hydrogen plays an important role in the overall failure mechanism. However, the role of various groundwater constituents in TGSCC and the source of hydrogen are not well understood. The objective of this research was to further understand the mechanism of TGSCC by examining the environments in which TGSCC can occur and near-neutral pH can be maintained. Specifically, this research focuses on the production of hydrogen through the interaction of iron with carbonic acid (H2CO3) and bicarbonate (HCO3−) as based on the Colwell-Leis mechanism. The Colwell and Leis mechanism attributes the hydrogen generation, in groundwater solutions, to the decomposition of bicarbonate and reaction with metal ions to form metal carbonate. Results from coupon exposur...Keywords
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