SOHIC Corrosion Failure Mechanism of High Strength Low Alloy Oil Pipeline

Investigation had been carried out on oil pipeline corrosion in Kenneyak Oilfield.Based on macro and micro corrosion morphology analysis,material mechanical property tests and chemical composition analysis,it is showed that the corrosion on the coupling external wall was induced by environmental hydrogen damage in which H2S corrosion is dominating,including exfoliation corrosion,internal hydrogen induced cracking (HIC) and stress oriented hydrogen induced cracking (SOHIC) resulted in fracture.The pipeline made up of high strength low alloy (HSLA) steels like SM90SS with hardness less than HRC22 tends to SOHIC in sour service environment.The results may help to prevent pipeline from corrosion perforation and/or cracking,and keep the safety of oil well.