Subsea Grouting in Sub-Zero Temperatures24/10/2016
The Artic offshore filling tower was paramount to refueling the Icebreaker ships operating in the North Sea to keep the pathways clear for commercial vessels. The project was undertaken during February 2016 using Ducorit® S5 for the grouting due to its high strength, durability, low shrinkage and ease of installation properties.
The client had approached ITW Engineered Polymers to perform subsea grouting of the pile/sleeve connection of the Artic offshore filling tower in extreme winter conditions, at short notice. ITW was able accommodate by providing a complete solutions package from project management, grout materials, equipment to on-site supervisors.
Working in extreme winter conditions with air temperatures ranging between -20°C to -50°C (- 68°F to -122°F), Ducorit® S5 was transported across the ice in specially heated containers to maintain the integrity of the product. Working at the base of the filling tower with ambient seawater temperatures close to 0°C (-32°F), the subsea work was coordinated with a local diving team to position the pre-heated grout line at the base of the foundation.
With the grout spread prepared on the ice, supervisor’s successfully initiated filling the grout directly into subsea structure -12m below ice level. The grouting process took 36 hours to complete. The initial cure after 7 days in ambient cold water temperatures saw actual strength of > 80 MPa achieved with the Ducorit® S5, surpassing the project design criteria of 75 MPa in 28 days.