Two entirely separate aspects of TWI work went into the construction of one of the deepest structures in the North Sea - the Magnus platform.
First, it was asked by British Petroleum to develop welding procedures for the steel jacket construction using the CTOD approach. A large part of the welding was performed using self-shielded flux-cored wire and trials were carried out at TWI to optimise the toughness of the weld metals finally adopted. This involved studies of a range of welding procedures and of the heat treatment schedules to be used for the large nodes.
In an entirely separate initiative a major study was conducted of the mechanised MIG welding procedures used for girth welds in the oil pipeline connecting the platform to the main line between Ninian and Sullum Voe. This was laid using Saipem's Castoro Sei pipelay barge. TWI made and tested over 75 girth welds using a full-scale mock-up of the pipe welding ramp of this barge at Abington.
TWI also helped in development of weld procedures for both girth and longitudinal welds used for the Magnus and Brent section of the Northern Leg Gas gathering pipeline. Fracture mechanics was used to establish girth weld acceptance criteria based on fitness for purpose.