Aging of Polyethylene of Raised Temperature Resistance Pipe Liner After a Four-Year Service in a Crude Oil Gathering System

The use of a polymeric liner onto the inner surface of a steel pipe is an effective way to prevent metal corrosion. The stability of the polymeric liner is crucial for the safety and life of the lined steel pipes. In this work, the aging of the polyethylene of raised temperature resistance (PE-RT) pipe liner after a four-year service in a crude oil gathering system was investigated. The pipe liner was characterized by SEM, durometer, densitometer, tensile testing, FTIR, TGA, DSC, and XRD. The results indicate that the PE-RT pipe liner was swelled by the conveying medium, resulting in the rough surface, higher density, decreased hardness, lower thermal stability, and lower thermal dimensional stability. More importantly, the swelling caused a decrease of crystallinity and orientation. Accordingly, the mechanical properties, including yield strength and modulus, decreased. Based on the above results, aging caused by swelling can be confirmed to occur during its service in the crude oil gathering system, resulting in performance degradation. Graphic Abstract