Failure Analysis of Pipeline Corrosion Perforation in a Gas Mine

Pipe with an outer diameter of 159 mm and a design wall thickness of 5 mm in a gas mine was corroded and perforated, resulting in gas collection interruption and significant economic loss. The maximum corrosion pit length is 40.7 mm. To explore the specific causes of pipeline failure, the pipelines were analyzed by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and x-ray diffraction (XRD). The results show that the tube section meets the mechanical property standard. The proportion of carbon(C), oxygen (O2) and sulfur in pipeline corrosion products is more than 35 wt.%, resulting in the formation of 1200-1300a.u in other areas of the inner wall of the pipeline. Ferrous carbonate (FeCO3) and ferrous sulfide (FeS) are attached to the tube wall near the 6 o'clock direction. To prevent pipeline failure, CO2, H2S and other impurities should be removed in time.