Qualification of Composite Pipe

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 27179, “Qualification of Composite Pipe,” by Jonathan Wilkins, Magma Global, prepared for the 2016 Offshore Technology Conference, Houston, 2–5 May. The paper has not been peer reviewed. Copyright 2016 Offshore Technology Conference. Reproduced by permission. This paper describes the qualification process for a thermoplastic composite pipe manufactured for use in high-performance riser, jumper-spool, and intervention-line applications. The pipe is manufactured from polymer, carbon-fiber, and glass-fiber materials with an automated laser-based welding process. Product Architecture The body of the pipe contains no metallic components, only polymer and fibers. These pipes consist of a smooth-bore inner-pipe precursor, extruded from Victrex PEEK polymer, with a thin wall thickness onto which layers of composite tape are welded by laser to form the pipe wall laminate (Fig. 1). This laminate can be any thickness and orientation of fibers, with the function of providing the strength and stiffness of the pipe. Once manufactured, the function of the inner-pipe precursor is to provide high-integrity sealing, resistance to hydrocarbon and other fluid and gas permeations and high temperatures, and a smooth bore for high fluid-flow rate. The internal bore is typically in the range of 2 to 6 in., and the lengths can range from a few meters to kilometers for spoolable applications. At either end are steel end fittings that provide the interface to the external subsea system. The composite end fitting uses a steel collar that interfaces with a taper in the laminate to transmit bending and axial loads from the pipe body to the external system. Manufacturing Processes A thermoplastic composite pipe is typically manufactured from individual composite tapes on the order of 10 mm in width, 0.2 mm in thickness, and several hundred meters in length. The composite tapes consist of many thousands of glass or carbon fibers impregnated with the thermoplastic matrix. Adjacent tapes are placed with the same orientation by robot, to form plies. The plies may be oriented in different directions through the wall thickness of the pipe to tailor the mechanical properties of the structure.