Composite pipes — Beading study

All piping system designers use construction codes and standards to dimension pipes and fittings. It is particularly important to know exactly how structures will fail in the environment the piping system will encounter. Metallic materials, for example, are subject to corrosion, and their ruin manifests itself in the form of leaks. For a new metal tube tested under pressure, the ultimate stage is bursting. In the case of composite tubes, bursting is rarely observed; in fact, the most frequent mode of failure is beading. This specific phenomenon has significant economic consequences, and is the subject of this article. The reader will first be given a brief overview of pipe system design. Next, the parameters influencing beading will be analyzed. The structure of tubes manufactured by filament winding will be considered, in particular the winding angle and the presence of a liner or gel coat. The various mechanical loads imposed on the tubes and the composite material constituents (resin, fiber sizing) will then be examined.