Glass reinforced plastic (GRP) pipes are increasingly being used in the offshore industry and their behaviour in fire is studied using mathematical and numerical modelling. The thermochemical response of a single-skinned GRP pipe exposed to hydrocarbon fires is modelled using the finite element technique. Axi-symmetric mathematical and numerical models are developed to quantify the fire performance of thin-walled and large diameter GRP pipes for seawater transport. The mathematical model is based on onedimensional models developed for single-skinned GRP pipes and panels and include:
transient heat conduction;
radial gas mass movement;
mass loss and Arrhenius rate decomposition of resin material and
endothermicity of the decomposition process. The numerical results are presented for a polyester-based GRP pipe with flowing seawater and thickness 1.09cm and compared with those for GRP panels and pipes with the same thicknesses but different boundary conditions, it is shown that for a given set of dimensions and boundary conditions, GRP pipes reach insulation failure (time to 160°C) earlier than GRP panels. The results can be used, in conjunction with the author's previous work (Looyeh & Bettess, 1996), to assess the feasibility of using GRP for offshore pipes and pipelines where severe fire conditions may occur.
Experience with glass reinforced plastic (GRP) pipes is currently being gained on several offshore structures, mainly in the Gulf of Mexico and off the coast of Africa. Although, the use of this material in offshore piping systems is confined mainly to small diameter pipes (D<10cm) at relatively low pressure (=<1 MPa), more stringent applications are imminent. With increasing experience and as a result of technology transfer from the chemical industry, where GRP piping systems have already widely been used, further applications can be expected which will involve process fluids and oil and gas at higher pressures (~10 MPa).
