Optimisation of a Wet Insulation Coating for Shallow-Water Pipelines

Abstract Conventional technologies used for insulation of flowlines in shallow-water fields, based on thermoplastic foams, are over-specified for the conditions. This has driven development of a low-cost alternative based on a low-density polyurethane thermoset foam. This paper will trace the methodology of an active collaboration between Logstor and TechnipFMC to develop and optimize this alternative coating. It will show the evolution of the developments and progress made over the last two years. The coating resembles a pipe-in-pipe system, however the outer steel pipe is replaced with a polyolefin casing. The coating is designed with a tapered end chamfer so that the casing meets the anti-corrosion coating at the pipe ends. Seals here compartmentalize the coating, making the coating on each pipe individually watertight and make the coating compatible with conventional field joint coatings. The development process has been based on critical examination of the pre-existing insulation coating, using FMEA and study of previous project experience, combined with trial manufacture and full-scale testing to simulate all stages of the life-cycle of the coating. Using this approach, it was possible to closely characterize both the manufacturing process and the coating system itself, which in turn enabled the investigators to identify and reduce inefficiencies in the coating design and also identify other areas where improvements would increase reliability. The insulation coating system described in this paper is an alternative to conventional multilayer polypropylene wet insulation technologies for pipelines situated in shallow water with several key advantages that may be of use to the specifying engineer or designer when designing a flowline that requires insulation.