Development and Installation of Light Weight, Low Cost Unbonded Flexible Pipe for Arctic Applications

Unbonded flexible pipe has been successfully operating in oil/gas production applications on the North Slope of Alaska since 1995 as documented in OMAE 1995 paper “Arctic Applications of Flexible Pipe for Production Pipelines and Infield Fluid Transport Systems”, Reference [1]. The pipe and end terminations were subjected to extensive material and full scale testing to confirm suitability for arctic applications and the results are documented in the paper. The products deployed on the tundra were designed to ensure successful, safe operation and mitigate risk for the initial application. The robust design included pipe layers and end fitting materials that exceeded fit for purpose needs and resulted in a heavier, more costly design than was actually needed. To ensure cost effective solutions are available for future projects in the regions, Wellstream in conjunction with the Prudhoe Bay Operating Unit developed an optimized flexible pipe that met the onerous requirements of arctic applications. Pipe specifications included 5.5-inch ID, 3600psi design pressure, thermal loss and cooldown limitations, maximum operating temperature of 140°F and minimum operating temperature of −50°F. This paper will present the results of the design, engineering and analytical process, full scale testing and installation activities. A detailed comparison between the initial products and the current optimized design is presented to illustrate the substantial weight and cost savings achieved.Copyright © 2002 by ASME