The failure analysis of a leak-off oil pipe ASTM A106 on compact separator at an offshore facility

The failure of pipe ASTM A106 in compact separator unit has been reported. The failure occurs after 2 years in service. The present investigation aims to analyze the main cause of the failure by conducting a standard failure analysis test including chemical composition test, visual examination, microstructure examination by optical microscope and scanning electron microscope–energy-dispersive spectroscopy (SEM–EDS), x-ray diffraction and hardness Brinnel. A pipe leak occurred on connection instrument from compact separator to chamber level instrument. The corrosion and leakage were found at the bottom of the longitudinal pipe ASTM A106. However, previous water analyzes showed no indication of SRB in the fluid so this is a new phenomenon to be investigated. The results of this investigation on the failed component showed that the spool pipe was leak near the flange joint. The leak observed as a rounded hole originated from the inner surface. The analysis on the pipe material is compare with the material specification of ASTM A106 according to their chemical composition and base material microstructure. Examination to the inner surface revealed a thick layer of black and brown deposit. Removing the thick deposit layer showed the leakage hole and some localized thinning of the pipe. The failure of the pipe analysis by EDS spectrum with the existence of sulfur and XRD analysis suspected as a result under deposit corrosion enhanced by Microbially Influenced Corrosion (MIC) where FeS and FeCO3 presence as the result of the reaction.