Joints & Joining
Plastic Pipes Conference Association # 2001 Munich
Stokes, Potter, Metcalfe, Bowman, Graham
The response of three different forms of polyvinyl chloride (PVC) pipe has been explored when the pipes had attached to them ferrule straps. Pipes were subjected to fluctuating internal pressure (fatigue) loading at 20°C, and the lifetimes, location of any failures and the types of failures recorded. Tests were made with the ferrule straps attached using different torque values, and with varying spacing between ferrule straps. The results show that with ferrule straps attached and subjected to fatigue loading, the ferrule acts as the focus for failure for all three types of PVC pipes. The torque applied to bolts to secure the ferrule straps influenced performance, higher torques extending the fatigue life of the pipes. The spacing between multiple ferrules had little influence on the lifetimes of PVC pipes. The best performing PVC pipe was the molecularly oriented (PVC-O) pipe, followed by conventional un-plasticised PVC-U pipes and pipes with a toughening agent added, the alloy (PVC-A) pipes. The results of these tests should assist water engineers in setting guidelines for the installation of ferrule straps on PVC water pipes that may be subjected to fatigue loading.
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