Failure Analysis of the Leakage and Ignition of an Oil-Gas Mixture Transportation Pipeline

Due to the high moisture content and strong corrosion of oil-gas mixtures, the electrochemical corrosion and perforation leakage of their transportation pipelines occur frequently in the western oil fields of China. Using various methods, this work investigates the failure of an L360NB carbon steel pipeline in detail. The obtained results show that the present leakage and ignition of this pipeline are mainly attributed to the local electrochemical corrosion. In fact, the transported oil-gas mixture in this pipeline is usually composed of H2S and O-2, besides CO2 and Cl-. Under their comprehensive actions, the corrosion rate increases, which firstly leads to the perforation and leakage within a local domain. Then, the mechanical friction between the mixture and the insulation layer readily causes static electricity. Consequently, the spontaneous combustion of the corrosion product, FeS, may promote fire formation. In addition, the methods used for removing the H2S gas and corrosion inhibitors are discussed, which provides effective tools for the suppression of the electrochemical corrosion of pipelines.