Abstract

Most types of pipelines used for gas, water or sewage distribution, are currently made from thermoplastic pipes. The majority of them are connected with electrofusion couplers; the technology is mature, simple, cheap and reliable and the joints are maintenance-free for up to 50 years. Meanwhile, due to the much higher mechanical properties required in the oil and gas sector, it is still mainly steel pipes that are used. They are strong and can contain high pressures, but are prone to corrosion and are problematic in installation and maintenance. The recent development of thermoplastic composite pipes (TCPs) seems to offer a viable alternative; the mechanical properties of TCPs can be as good or even better than those of steel pipes, and they are more resistant to corrosion. Currently, these pipes are still connected with mechanical, steel joints, but efforts are being made to create fully thermoplastic solutions using electrofusion joints that will outperform steel pipelines. This paper describes the development of a finite element model for simulating two types of mechanical test, a hydrostatic pressure test and a whole pipe tensile test, in order to optimise the design of the electrofusion fitting. These initial simulations in Abaqus involve a joint between a standard commercially available electrofusion coupler and TCPs and will be validated with experimental mechanical tests, utilising strain gauges and digital image correlation methods. The extra challenge in creating the model is finding suitable input data on the mechanical performance of the different layers in the TCP; these properties are not readily available in the literature and hence have to be obtained by experiment. The TCP material is produced in the form of a pipe by tape winding, it does not exist as flat plates, which makestesting difficult, as most standard tests require flat sample. Therefore, a non-standard set of tests has been developed in order to obtain the mechanical properties needed for the FEA.