The failure mechanisms in and the durability of solvent welded pipeline systems

The failure mechanisms of solvent welded unplasticized polyvinyl chloride (uPVC) pipeline systems are identified to be pipe failure, pull-out failure of the solvent welded joint, and tunnel cracking through the solvent weld. The conditions when each of the above failure mechanisms becomes operative have been established. Pull-out failure may only occur in joints which are in a biaxial stress conditions. At low stress levels and long failure times, the durability of the pipeline system may be controlled by either pipe failure or failure of the solvent welded joint via the tunnel cracking mechanism. The tunnel cracking failure mechanism is largely controlled by the rate of tunnel crack initiation. On the basis of the studies, ways to alter the parameters of the pipe joint to improve the joint strength as well as the durability of the joint are proposed