CompositesWorld
Issue link: https://cw.epubxp.com/i/546021
AUGUST 2015 52 CompositesWorld INSIDE MANUFACTURING aggressive service conditions, such as water re-injection or gas transmission. Notably, a critical factor in each individual liner design is deter- mining which end of the pipe to pull from. "Te critical factors when pulling a liner tend to relate to the number and locations of the bends involved," Walters explains. In a recent analysis under- taken by APS for a 3.5-km long pipeline that has six 5D bends, for example, diferent pulling force requirements were calculated for diferent directions of pull. Tat is, the pulling force requirement in one direction was calculated as 12 tons, but in the opposite direction it was calculated as requiring nearly 72 tons. Tis difer- ence was primarily due to the location of the 5D bends on the pipeline. Walters interprets the fndings: "Tis analysis shows that it is not just a static tensile value of a liner that is important, but makes it clear that all the host pipe specifcations and param- eters combine to add into and impact onto the fnal calculation process. In the case of this particular pipeline, if the liner were to be pulled in the 12-ton loading direction, the liner then still retained a safety factor of well over 100% in relation to its overall tensile strength." Design and manufacture have followed testing and qualifca- tion procedures in accordance with the American Petroleum Institute (API, Washington, DC, US) Recommended Practice API RP 15S (First Edition, March 2006) Qualifcation of Spoolable Reinforced Plastic Line Pipe, as well as API series 17 Subsea Production System, and applicable ASTM (W. Conshohocken, PA, US) and NACE (Houston, TX, US) standards. All liner-testing qualifcations have been subjected not only to full verifcation 3 After the liner cools and the thermoplastic layers solidify against the core, the liner is reeled onto a transportation drum in a fat confguration. 1 A single-ply, 2-mm-thick cylindrical structure is woven from Kevlar. The aramid fber is drawn from hundreds of spools and woven in a manner similar to sock knitting, in (as shown) vertical format. Source (all step photo) | APS 2 Via a proprietary method, a layer of Solef PVDF (gray) is then extruded over the inner surface of the Kevlar cylinder, and a layer of thermoplastic polyurethane (green) is extruded over its outer surface as the aramid core moves continuously downward, held under tension to assure a smooth and consistent operation.