Pressure and Bending Tests on Fibreglass Augmented Steel Technology Pipes

The demand for the transportation of natural gas over long distances requires larger diameter pipes operating at higher pressure levels. A new technology, Fibre Augmented Steel Technology Pipe (FAST-Pipe™), emerges as one of the more cost-effective options to achieve this goal. As part of the qualification program of this new technology, a total of 15 tests were conducted on FAST-Pipe™ specimens fabricated from 12.75-inch outer diameter, 0.25-inch wall thickness, ERW, X60 steel liners hoop-wound with 0.2- and 0.35-inch thick dry fibreglass. This paper presents the results of several tests, including burst pressure testing of eight specimens to assess the effects of external environment (frozen and frozen/thawed), load duration (0 to 1,200 hours) and the wrap thickness (0.20 to 0.35 inch) on the burst capacity of the FAST-Pipe™. Variations of these parameters resulted in burst capacities ranging from 5,550 to 7,360 psi as compared to the unwrapped pipes whose burst capacities were in the range of 3,400 to 3,650 psi. It was observed during the cold burst tests that failure did not occur at the frozen or frozen/thawed section; instead, failure occurred in the transition zone between the frozen or frozen/thawed section and the dry (unfrozen) region. This paper also presents the results of two specimens that were subjected to constant internal pressure and imposed curvatures until buckle formation (pressure-bend tests) to assess the effects of wrap thickness (0.35- to 0.20-inch) on the bend capacity of the FAST-Pipe™ and to develop data from which to validate the analytical predictions. As expected, the overall curvature and moment capacities were higher for the 0.35-inch thick wrap than that for the 0.20-inch wrap.