Magnetic bearings are being fitted on the motor shafts of a pair of compression systems due to be installed 200–300m below the surface of the Norwegian Sea. The oil-free, frictionless and almost maintenance-free bearings have been chosen to provide the efficiency, reliability and performance needed for continuous operation in the deep-sea Åsgard gas field.

The project involves placing two hermetically sealed compressors on the seabed to maintain gas flow pressure levels. They will maintain discharge pressures in the pipeline and compensate for the falling pressure as the gas field is depleted, thus boosting gas flows.
 
The French magnetic bearing specialist S2M, owned by SKF, has won the two-year contract to supply the custom-built bearings and their associated electronics from Man Diesel & Turbo, Aker Solutions Norway and Statoil.

In a magnetic bearing (above), the rotating shaft is supported and held in place by electromagnetic forces generated in radial and axial directions. These forces are controlled by sophisticated electronics and electromagnets to provide contact- and wear-free operation. The high-efficiency bearings can operate at high speeds, need no lubrication and, because there is no component wear, provide almost maintenance-free long operating lives.