Pipeline geometry pigging: application of strapdown INS

An autonomous pipeline pigging system has been developed for determining position, orientation, curvature, ovality, and deformations such as dents and wrinkles of operating pipelines. At the heart of this integrated system is a strapdown inertial measurement unit (SIMU), which is integrated with velocity and distance sensors, caliper sensors, weld detection system, and digital recording device. The Geometry pig (Geopig) is designed to operate continuously and autonomously for a week or longer in operating fluid or gas pipelines with diameters of 25-30 cm and larger. The design concepts, system integration, data Acquisition, processing, analysis, and database management are discussed. Results from a recently completed 335-km Arctic crude oil pipeline are presented