In the Oil and Gas industry, there is a huge opportunity for replacing traditional metallic pipes with non-metallic alternatives, such as reinforced thermosetting resin (RTR) composite pipes, with the promise of significant cost savings achieved by eliminating corrosion. The NIC Foresight Review1 concluded that one of the medium-term gaps in the industry is the development of new connections and sealing systems for large diameter (>16”) high-pressure (>1500 psi) applications.
The Non-Metallic Innovation Centre (NIC) is developing an innovative method for joining reinforced RTR composite pipes that has the potential to replace an adhesive joint and a sealing gasket, contributing to a more reliable joining solution for the oil and gas industry. The proposed solution is to replace the adhesive with a welded solution. Thermoset composites themselves cannot be welded in the same way their thermoplastic counterparts can, but a thermoplastic interlayer can act as both a joining element and a seal, if the right materials are selected and the welding process is process is carried out correctly. Welding thermoset composites is, however, not straightforward. Depositing the thermoplastic layer on the surface of the thermoset has to be carried out in a way that not only provides sufficient adhesion strength, but is also compatible with 16-inch pipe diameters. The approach adopted by the NIC is first to deposit a layer of thermoplastic onto both surfaces of the GRE components using a friction process. After trimming, the pipes and coupler can be joined in the field, again using a friction process or another welding process, such as induction welding. The process under development has already successfully joined RTR composite pipes of up to 200mm (8-inch) in diameter, and plans to extend the capability to accommodate 16-inch pipes.
Beyond the novelty of the approach that makes the welding of RTR pipes possible, the method under development can easily be automated, is less reliant on manpower expertise, and should therefore translate into more reliable connections over time. This paper aims to present some conceptual aspects of the technology, and share several attractive prospects for an increased productivity during the deployment phase and an improved reliability of the connection over its life cycle.
Location: Building 19, Level 3, Hall 1-2.
Consultant at TWI