Thermoplastic-Composite-Pipe Flowline Helps Reduce Project and Life-Cycle Costs

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Thermoplastic composite pipe (TCP) is a spoolable, fully bonded, thermoplastic pipe with glass or carbon-fiber reinforcements. The bonded composite pipe has a solid wall like steel pipe and is able to cope with corrosive environments without being affected. For its low weight and collapse resistance, TCP is most often associated with deep water. However, the combination of a solid wall, spoolability, and corrosion resistance makes TCP attractive for production-flowline applications in shallow water also.

TCP

TCP uses a one-material design concept in which the internal liner, the composite layers, and the outer coating are all of the same polymer material (Fig. 1). The pipe is made with an in-situ-consolidation manufacturing process that melt-fuses all layers together to form a strong and stiff solid wall. This produces a pipe that is collapse resistant, spoolable, lightweight, and corrosion resistant.

Fig. 1: Thermoplastic-composite-pipe concept (left) and laminate microscopy.

The orientation of the reinforcement fibers (the lay-up) can be varied for each layer, enabling an optimized design for each set of design requirements, such as internal and external pressure rating, tension capability, allowable bending radius, and fatigue performance. The flexibility and spoolability of the solid pipe are the result of the relatively high strain in the glass-fiber materials and, to a lesser extent, in carbon fibers, compared with steel. Flexibility comes at the expense of tension capacity and vice versa. Therefore, TCP that is designed for high tension (e.g., in dynamic riser applications) will have a larger minimum bend radius than TCP that is optimized for bending. In practice, bending strains of 1 to 3.5% are achieved. For example, a 7-in.-inner-diameter flowline is spooled on a 6-m-barrel-diameter storage drum and has a minimum bend radius in service of 5 m.

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Thermoplastic-Composite-Pipe Flowline Helps Reduce Project and Life-Cycle Costs

10 October 2016

Volume: 68 | Issue: 11

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