Fracture failure of oil-collecting steel wire reinforced thermoplastic composite pipe

Abstract

A steel wire-reinforced thermoplastic composite pipe (SRTP) used as an oil connecting experienced fracture failure after 1.8 years’ service. In this paper, we conducted through on-site working condition investigation, visual physical inspection, analysis of the inner lining structure composition, physical and chemical properties analysis, thermal analysis, and mechanical analysis, and morphology analysis. The lining material of the SRTP exhibited significant swelling, which reduced its performance, and operation at high temperatures (>75°C) accelerated this process. Due to the swelling of oil and the permeation of CO2 and H2S, the oil and acid gases penetrated the interlayer of the composite pipe and accumulated in the annular space, continuously corroding and weakening the steel wire. This process gradually reduced its load-bearing capacity and pressure resistance. It is recommended that non-metallic pipes should be selected according to the service conditions to ensure that the materials are consistent with the design requirements.