ABSTRACT

For subsea hydrocarbon transportation, one of the key challenges is to maintain the appropriate product temperature within the pipeline to avoid the formation of wax or hydrates. A Pipe-In-Pipe (PIP) system, consisting of an outer pipe and a concentric inner pipe, has been increasingly used recently owing to their exceptional thermal insulation capacity. The outer pipe is used to withstand the external hydrostatic pressure and the inner pipe is used to convey the hydrocarbons. The annulus between the inner and outer pipes is either empty or filled with dry insulation materials like polyurethane foam, mineral wool, aerogel, granular of microporous materials or ceramics (Bai and Bai 2014). PIP system can achieve excellent heat insulation with such a design.