
Allseas Contracted by DEME for French Jacket and Substation Installation
Allseas Contracted by DEME for French Jacket and Substation Installation
The project involved transport and installation of 2.4km of 28-inch and 2.2km of 30-inch pipe, both pulled into the onshore valve station through a 1km subsea S-shaped tunnel, drilled and blasted through solid rock. A challenging operation due to the narrow laying tolerances.
Operations kicked off with Oceanic installing multiple counteracts and replacing the messenger wires with bigger pull-in cables. Working in shallow water, the world’s largest pipelay vessel picked up the first pull-in cable, lay around the counteracts and laid down, repeating for the second line.
Good teamwork between the onshore winch operator and on-board tensioner operator was crucial, as any tension difference could lead the pipeline catenary to pulse and touch the tunnel entrance potentially damaging the pipeline.
Source
Allseas Contracted by DEME for French Jacket and Substation Installation