Experts from joint integrity and engineering services company Hydratight found an innovative solution to a tricky repair for Statoil, by using a MORGRIP connector to repair a 6in super duplex pipe located within the constrained space of a subsea manifold, 340m under the surface of the North Sea.
Hydratight was called in to repair a damaged pipe on a subsea wellhead “Christmas tree” on the Troll C oil and gas platform, 100km north-west of Bergen, Norway. A mandrel and its 6in supporting pipe were pulled out of position during an operation, overloading the pipe and forcing the shut-down of an associated 10in line, halting production.
“At that depth solutions were limited,” said Hydratight application engineer Mark Fisher.
A 6in super duplex MORGRIP end-connector had to be a specially engineered solution to fit within the significant physical constraints of the damaged manifold.
“The cracked pipe was partially inside the manifold, so we had to ensure that the MORGRIP’S overall dimensions were an absolute minimum to get it to fit,” explained Mark.
The pipe – which carries a mixture of water, oil and gas – was pressure-tested to 267bar after the procedure, and will be tested again from time to time to make sure the pipe hasn’t deteriorated further.
The MORGRIP successfully sealed the line in accordance with Statoil’s requirements. The pipe integrity was retained with no de-rating of the pipeline or deviation from original design.
Source: Hydratight, April 12, 2012; Image1: Statoil