Performance of flexible composite pipes after service in oil fields

To evaluate the application effect of flexible composite pipes in surface gathering and transportation systems of oil and gas fields, methods such as macroscopic observation, microscopic analysis, hydraulic blasting test, gas sealing performance test, structural composition analysis, thermal analysis, infrared spectroscopy analysis, mechanical performance test were used to analyze two flexible composite pipes to determine their applicability under different working conditions. The results show that after a period of service, the structural layers of the two flexible composite pipes remained intact, no obvious defects were found, and the color of the inner lining layer deepened. The failure mode of both pipelines was tube explosion, and the explosion pressure of sample 1 did not meet the standard requirements due to long－term high－temperature operation. The inner lining layers of the two pipelines were cross－linked polyethylene and ordinary polyethylene, while the reinforcing layers were aramid fiber and polyester fiber, with thermal decomposition temperatures of 580 ℃ and 440 ℃,respectively. However, the tensile strength of aramid fiber was significantly lower than that of polyester fiber.