Definition - What does Sour Corrosion mean?
Sour corrosion is the degradation and/or rust formation on a metal surface due to the presence of a highly acidic environment containing hydrogen sulfide. Sour corrosion can cause material failure at stress levels less than their normal yield strength.
Corrosionpedia explains Sour Corrosion
Sour corrosion is common in the petroleum industry because high concentrations of hydrogen sulfide are a common chemical component of crude oil and refinery operations. Sour corrosion can develop in petroleum storage tanks, pipelines and manifold systems due to periodic commodity stagnation that produces a build-up of hydrogen sulfide on metallic surfaces. The metal then becomes embrittled due to contact with hydrogen sulfide, the resulting oxidation reaction and the loss of electrons.