Traction calculation model for RTP insertion for subsea long-distance pipeline repair

Subsea long-distance pipelines are often zigzag with many elbows and high curvature, which together with limitations of operation space and power supply on platform induce higher repair cost and technical risks. In this regards, a tensile-type reinforced thermoplastic pipe (RTP) is developed. It is a kind of highly flexible RTP with additional aramid fiber tensile composite layer. Therefore, this pipe possesses the characteristics of small bending stiffness, big radial stiffness, strong tensile ability, light weight, wear resistance, high pressure resistance, safe and reliable. Taking the tensile-type RTP insertion for subsea long-distance pipeline as an example, the relevant traction calculation model is established through theoretical derivation and experimental verification. The model is successfully used in the repair of a 17 km long-distance pipeline in a PETRONAS offshore oil-gas field by intercrossing method.