Reinforced thermoplastic pipe (RTP) is an alternative to traditional pipelining materials. It consists of three basic layers including a thermoplastic liner, helically wrapped continuous high-strength fiber reinforcement and an external thermoplastic jacket. The liner acts as a bladder, the fiber reinforcements provide strength, and the jacket protects the load-bearing fibers. Applications include oil and gas gathering and produced water transfer.
A study was conducted to verify the operational performance of RTP. This study consisted of testing and inspection of cut-out samples of previously operated RTP to determine if any significant level or form of degradation had occurred as a result of normal operation.
Thirty samples of Flexpipe Line Pipe (FPLP) RTP were cut out from different pipelines for inspection and testing. The service fluids included gas, oil emulsion and produced water in both sweet and sour service. The operating pressures ranged from 51 psi to 720 psi and the operating temperatures ranged from 37°F to 104°F. The duration of operation prior to the removal of the samples ranged from twelve to forty-one months.
The average burst pressure after service was found to be 99.7% of the average burst pressure measured at the time of manufacture. Dissection and inspection of the liner of the cut-out samples found no signs of blistering, swelling, cracking or collapse. The fiber reinforcements did not display any signs of discoloring, fraying, breaks, cuts, buckling, reorientation or other damage. The jacket was free of cracks, penetrations and ballooning. Tensile testing of fiber reinforcement and liner material from four of the cut-out samples found that the material properties remained close to typical values measured at the time of manufacture.
The test results demonstrate that FPLP RTP did not degrade after being exposed to a wide range of normal gas, oil emulsion, and produced water applications with operation durations ranging from twelve to forty-one months. This finding supports the results of the qualification testing that has been performed on this product in accordance with API RP 15S and CSA Z662-07.