Concrete Pressure Pipe joints are restrained for thrust by welding or by using mechanical joint restraint devices. This paper presents the findings of a leak investigation conducted on a 48-inch (122 cm) Prestressed Concrete Cylinder Pipe utilizing the Snap Ring~® mechanical retrained joint system. In the summer of 2001 during field hydrostatic pipe testing of the Sandy Point Pump Station in College Station, Texas, several 48-inch (122 cm) pipe joints sprang leaks before achieving the specified test pressure. Preliminary investigation of the pipe showed that the Snap Ring~® joints leaked at a pressure less than the specified test pressure and less than the rated pressure capacity of the Snap Ring~®. A more thorough investigation then followed to determine the cause of the observed leaks. As a part of the investigation, two pipe joints were removed in a preserved condition and transported to the pipe manufacturer Hanson Pipe & Products plant in Grand Prairie, Texas for further evaluation. At the plant, the joints were subjected to hydrostatic pressure tests followed by a complete forensic evaluation. The investigation showed that the failure was due to the inappropriate field assembly and installation of the Snap Ring~® pipe joints.
展开▼
