Failure Reasons and Prevention Measures for Polyolefin-Lined Oil Pipeline in Tahe Oilfield

The failure types, failure causes and preventive measures of polyolefin-lined oil pipelines in Tahe oilfield were analyzed by macroscopic observation, microwave scanning drtection techniques and ANSYS software. The results showed that the main failure types of polyolefin-lined oil pipeline were metal base pipe perforation, flange puncture, steel wrapping puncture, collapse, high temperature damage of lined layer and tube burst. The corrosive medium penetrated into the interlayer between lined layer and metal base pipe, and with the prolongation of service time, CO₂-H₂S corrosion occurred in metal base pipe. The subsidence of terrain caused the fracture of steel ring of polyolefin-lined joint, resulting in the leakage of crude oil. The corrosive medium penetrated into the lined layer between lined layer and metal base pipe, during the pigging and pressure relief process of the pipeline, the lined layer collapsed preferentially at the places where the liner layer did not fully recover deformation and local scratches. When the operating temperature and operating pressure of polyolefin-lined layer exceeded its design temperature and design pressure, the lined layer suffered from high temperature damage and tube burst.