Sulphide Stress Cracking (SSC) Research Paper Publication in Engineering Failure Analysis
The paper describes a root cause failure investigation of a corroded AISI 304L stainless steel pipeline used to carry hydrocarbon gas.
The corrosion was originally identified due to a leakage observed following removal of a section of lagging insulation. It was assumed by operating staff that corrosion under insulation (CUI) had occurred on the external surface of the pipe and the plan was to replace the section of pipe and replace the lagging. However, the plant decided to investigate the problem further and perform a forensic examination on the pipe section. Interestingly, the investigation revealed a three stage mechanism of attack had occurred; both intergranular cracking and transgranular cracking was present originating from both the internal and external surfaces.
It was shown that although CUI had resulted in the initiation of stress corrosion cracking (SCC) on the external surface of the pipe which propagated full wall, the primary driving force for CUI actually came from inside the pipe due the mechanism of sulphide stress cracking (SSC).
It was later found that water carryover had occurred upstream which produced localised sour conditions (hydrogen sulphide) which attacked the internal surface of the pipe. The SSC cracking then propagated to the external wall and resulted in leakage of the corrosive species.
The Forensic Engineering team at ESR Technology Ltd. regularly perform forensic investigations on oil and gas plant and machinery. This involves failure investigation, mechanical engineering and tribological testing on both upstream and downstream equipment, on-shore and off-shore plant and subsea exploration components.
If you have any corrosion issues related to the oil and gas industry, or have issues relating to failure investigation feel free to contact Steve Gill on 01925 843428 or This email address is being protected from spambots. You need JavaScript enabled to view it..
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