In response to a recent change in class location along a section of a natural gas pipeline in Ontario, the authors conducted an analysis, according to CSA(1) Z662, to determine the revised maximum allowed operating pressure (MAOP).The change to a Class 2 location reduced the calculated MAOP from 802 psi (5530 kPa) to 767 psi (5288 kPa) for three road crossings. The reduction in the pipeline pressure due to these three small sections at road crossings prompted the search for a solution to reinforce the sections to prevent a pressure reduction along the entire length of line. In order to maintain the original MAOP the three 12in NPS (300mm DN) road crossings will require additional hoop reinforcement. Possible solutions re-casing the line, reducing the pressure, or use of metallic or nonmetallic sleeves. A reinforcement design was requested which would allow maintaining an MAOP of 802 (5530 kPa) psi. A pre-impregnated carbon fiber composite system with a hybrid carbon and glass fiber architecture was selected. The advantages of a composite repair over other methods of reinforcement are ease of application, avoidance of hot work, conformability, and the application of the composite under live conditions. In addition, this method avoids the cathodic protection issues presented by the installation of casings.

Subject
Piping, Internal stress, Installation, Stress, Composites, Repair, Wall thickness, Steel, Carbon fiber, Maximum Allowable Operating Pressure, Carbon, Risk reduction, Reinforcement
Keywords:
carbon fiber, strain, composite repair, stiffness, location factor, rerating, Moisture Curable
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2016
Association for Materials Protection and Performance (AMPP)
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