An Overview of Near-Neutral pH Stress Corrosion Cracking in Pipelines and Mitigation Strategies for Its Initiation and Growth

Abstract

Stress corrosion cracking (SCC) of pipeline steels in near-neutral pH environments has remained a significant integrity risk for oil and gas pipelines. Although it has traditionally been termed “stress corrosion cracking,” crack growth has never been observed under a static loading condition. It was determined later that the cracking is driven by corrosion-fatigue mechanisms with some uniqueness. First, the loading frequencies typically vary over a wide range from 10−1 Hz to 10−6 Hz, which is usually beyond the scope of most fatigue investigations. Second, the rate of corrosion is typically well below 0.1 mm/y at which a premature failure solely by corrosion would occur much longer than that actually found in the field. Third, hydrogen, a by-product of corrosion, can be generated to a level at which hydrogen embrittlement may occur only under special conditions. Fourth, pipelines are operated under variable pressure fluctuations that may lead to enhanced crack growth resulting from load-interactions effec...