The vessel Normand Seven was chartered from Solstad Offshore ASA by Subsea 7 and converted into a subsea pipe laying vessel for a long-term contract in Brazilian waters. Subsea 7 looked into ways to dynamically test the flexible pipe tensioner installed on the vessel.
A standard Cranemaster unit with SWL of 400 metric tons and 4,3 meter stroke was chosen as an affordable, convenient and safe solution for the operation. The Cranemaster unit was attached to the vessels’ stern and a wire was run from the Cranemaster unit to a test pipe held by the pipe tensioner. The pipe was then run out and in of the tensioner to test that it could work under maximum work load. To increase the load on the wire which was retained by the cable tensioner, the Nitrogen pressure in the Cranemaster unit was simply increased. If the cable tensioner should break down or the wire snap, the only thing that would happen was that the piston rod would safely return to zero stroke. When the load test was finished the Nitrogen pressure was released and the unit hooked of.