Sandwich Pipes for Ultra-Deep Waters

Pipeline systems for deepwater applications must be designed to withstand operational loads and to give adequate thermal insulation to the hydrocarbon being transported. Sandwich pipelines composed by inner and outer steel pipes and either cement or polypropylene as core material are proposed here as viable alternatives to currently used pipe-in-pipe systems. The main advantage of these sandwich structures is that the core material and geometry can be selected so to provide both thermal insulation and good structural performance in conjunction with inner and outer pipes. In this paper, the structural behavior of such sandwich pipes under external pressure is studied through a series of small scale experiments and nonlinear numerical analyses based on the finite-element method.