Investigation into Mechanism of Hydrogen Induced Cracking Failure in Carbon Steel: A Case Study of Oil and Gas Industry

摘要: Abstract Although the hydrogen induced cracking (HIC) is recognized as one of destructive modes for pipeline and component steels serving in sour environments, behavior HIC still not fully understood. On other hand, although many efforts have been made to identify effects on laboratory steel specimens, study actual industrial samples has received less attention. In this paper, we studied mechanism a damaged pipe real case oil gas industry (finger type slug catcher) using detection, characterization, microstructural investigation methods. The detection specimens by advanced ultrasonic techniques, failure analysis tensile tests, chemical composition analysis, optical microscopy (OM), field emission scanning electron (FE-SEM), energy-dispersive spectroscopy (EDS) techniques their correlation with microstructure, type, morphology inclusions were conducted. results indicated that value elements, especially carbon (0.13 wt %) manganese (1.44 %), satisfies requirement API 5L specification. Furthermore, inclusions, such elongated sulfide spherical aluminum oxide, pearlite grains or interfaces ferrite–pearlite phases played an essential role phenomenon nucleation propagation places cracks. It was also observed cracks mostly initiated propagated through center near cross-section specimens. This region segregated zone where segregation elements occurred. Finally, linear between susceptibility hardness steel, moving away from (1800 µm) crack edges, increased significantly (179–203 HV), confirming diffusion into traps.