Nord Stream Project

When fast, accurate inspections were needed for the world’s longest subsea pipeline, Shawcor kept the pace.

Traversing the Baltic Sea, Nord Stream’s twin parallel pipelines represent the world’s longest subsea pipeline at 1,224 km, connecting up to 55 billion cubic meters of natural gas per year from western Russia with the European gas grid. During the pipeline’s construction phase, a lay schedule of 2.4 km per day or 200 welds per day was set. To keep pace, Allseas, the contractor responsible for a portion of the pipe lay campaign, needed a timely, accurate inspection from an experienced provider. Shawcor’s Pipeline Inspection Services group made it happen.

Shawcor was tasked with inspecting the girth weld joints for 700 km of 48-inch diameter pipe with varying wall thicknesses from 34 to 41 mm. To quicken overall inspection times while still providing highly accurate results, a cooling system was utilized on the lay vessel to lower the temperature of the pipe. Additionally, we used a heat-resistant material to allow the Automated Ultrasonic Testing (AUT) inspection to be completed above 95⁰C—while still maintaining defect sizing accuracy.

This inspection featured two double-joint weld AUT inspection stations; one mainline weld AUT inspection station; one mainline weld AUT inspection station; phased array for zonal inspection; time of flight (TOFD); and traditional root and cap shots.

With Shawcor, the pipeline’s girth weld joints were inspected accurately and safely in less than four minutes—exceeding our client’s expectations and helping them keep pace with their overall lay-rate schedule.