Subcon Supports TurkStream Pipeline Project

Subcon has completed multiple pipeline supports using its engineered solution.

Support for the 32-inch TurkStream pipeline was required where the seabed transitioned from the continental shelf to deep water.

Multiple grouted supports were installed at this location to reduce pipeline stresses during MEG swabbing. Complexity in the design was caused by 30° axial and 22° transverse cliff faces with rocky features, Subcon explained.

A collaboration was formed with Subcon, IntecSea and Allseas to engineer a solution. Engineering was completed in The Netherlands and Australia, fabrication in Australia and Europe, with execution in the Russian Black Sea.

Key features included a pipe clamping mechanism for temporary stability, bespoke fabric formworks, support frames with an integrated, ROV operated, levelling system and Subcon’s subsea grout connector hotstab technology.

Each formwork and frame was tailored to the specific support location’s bathymetry to ensure correct fit to seabed.

“Collaboration to form the solution was a key factor in the team’s success,” explained Cameron Stirling, Subcon’s European general manager. “We drew together IntecSea’s analytical expertise, Allseas’ Innovation Division and Subcon’s engineering to deliver an elegant solution to a highly complex challenge.”

A fullscale System Integration Test was performed at Subcon’s Western Australian facility. This included an exact replica of the cliff face bathymetry at the steepest support. A 50Te downward vertical load was applied to the pipe joint to demonstrate the strength of the shear connection between the base of the support and the seabed.

Allseas project manager, said: “This was one of the most technically complex pipe supports Allseas has encountered. The smooth execution is a credit to all parties involved.”