Due to the existence of the associated gas, the spiral weld of a pipeline in Tahe Oilfield was cracked.In order to clarify the failure reason of spiral weld of the pipeline and provide effective guidance for future pipeline corrosion control, the macro morphology of the cracked part of the spiral weld of the associated gas pipeline, the part far away from the weld and the material surface at both ends of the defect were observed, respectively.The composition of material was analyzed by fluorescence spectrometer.The micro morphology and element components of the cracked part were observed and analyzed by scanning electron microscope and X-ray energy dispersive spectrum, and the cracking reason of the spiral weld of the associated gas pipeline were analyzed.Results showed that the fracture of the associated gas pipeline was the result of hydrogen induced cracking(HIC)and sulfide stress corrosion cracking(SSCC)caused by high content of H2S in the associated gas in the pipeline.The middle of the fissure(i.e.the widest part)was the starting point of the crack.
