Numerical analysis of hot polymer-coated steel pipeline joints in bending

A numerical method to analyse the effect of the application of polymer coatings on the bending resistance of steel pipeline joints is presented. Experiments were conducted by Heerema Marine Contractors at Heriot Watt University to investigate the influence of the thickness of polymer field joint coatings and the cooldown time provided after applying the coating on the behaviour of pipeline joints when being bent during reeling operations. Temperature readings were obtained from thermocouples inside the polymer field joint coating during the application process, and pipeline ovality measurements were taken during mechanical testing. Thermal modelling of the coating application procedure was developed using COMSOL Multiphysics; this model was validated against the thermocouple readings, while a mechanical model simulating the pipe being bent to a reel was developed in Abaqus finite element modelling software. The temperature outputs, areas of stress concentration and pipe ovalities obtained from the experiments are shown to be predicted accurately by the numerical models. Upon successful validation of the numerical models, a parametric study was conducted assessing the influence of field joint coating thickness and cooldown times, in order to find an optimal design solution to reduce the cooldown time required prior to bending the pipe without buckling.