Plastic Lined Pipe for Oil and Gas Service - The Corel Project

The COREL – corrosion resisting liners – project has been running since 1997 with the aim of qualifying plastic lining systems for use in upstream oil and gas pipelines. Lined carbon steel pipes can be cheaper to install and operate than alternatives such as corrosion resistant alloys or large corrosion allowances and chemical inhibition. Collapse of liners has been the major technical hurdle preventing the adoption of this technology. Over time, gas permeates through the lining into the annulus between it and the steel host pipe. When pressure within the pipe is reduced either during depressurisation or normal operational fluctuations, the expansion of the gas within the annulus may cause partial or total collapse of the lining. The COREL project identified 2 potential technologies to overcome this problem : perforated liners and externally longitudinally grooved liners. The first enables internal continual venting of permeated gases. The grooved liner (as patented by Safetyliner Systems LLC) provides a means of annular communication to fixed vent points. Both have undergone proof of concept testing of venting efficiency with encouraging results. COREL Phase 3 began in January 2001 and incorporates large scale flow loop testing of the favoured technologies, in both Polyethylene (PE) and Nylon PA-11 (PA), to fully test the technologies under representative flowing conditions with real crudes and condensate. In conjunction, small scale onshore field trials are being sought and remaining enabling technologies are being developed by service companies. Phase 3 will comprise a 9 month programme culminating in a set of design guidelines and test results such that upstream business units will be able to confidently specify the use of lined pipelines for their own applications.