Schaeffler UK has custom designed a set of maintenance-free spherical plain bearings to support a newly constructed process module extension column, which is fixed to the main offshore platform located in the North Sea.
The function of the bearings is to provide a flexible support between the mono column and main rig, allowing for movement of the column caused by waves and tidal current relative to the main rig. The bearings, which have a bore diameter of 1m, are designed to transfer these loads from the column to the main rig.
Chris Head, Application Engineer at Schaeffler UK comments: "After several meetings with the customer and its main contractor for the extension column, it was clear to us that the customer would require a unique design of bearing that offered both a very high level of reliability and zero maintenance. We therefore proposed Schaeffler's range of ELGES spherical plain bearings, but customised with extra sealing features and low-friction sliding layers. These would ensure maximum reliability and zero maintenance."
Schaeffler's standard ELGES spherical plain bearing is fitted with only one seal on each side of the bearing, so a special sealing arrangement was discussed with the customer. The custom bearings are therefore fitted with additional seals and designed with an extra sliding layer in the bore. This ensures low friction when the extension column moves relative to the main rig due to the ocean waves.
As Chris Head states: "We offered additional sealing features in the form of a grease layer, which would allow us to lubricate the outermost lip seal, added a special seal, which acts as a barrier for the grease, with another seal to prevent the grease from contaminating the bearing sliding layer."
The bearings were manufactured according to strict customer specifications, with all bearing materials, components, manufacturing and quality processes all fully traceable. The bearings were installed on the offshore platform extension column in May 2013, and in order to ensure that the installation of the bearings could proceed without difficulty under the challenging and constricted conditions present on an offshore platform, an installation trial was carried out. This was performed by two experienced fitters from Schaeffler and allowed important details and the special tools required for offshore installation to be included in the work planning.
Thanks to Schaeffler's Global Technology Network, the service personnel were well prepared, having been brought into the project planning and implementation process at an early stage by the sales and application engineering functions. The customer was so impressed by the professional skills displayed during the installation trial that he requested a Schaeffler fitter be present when the preliminary work was carried out on the platform, in order to support the other companies involved and to monitor their work operations.
Alan Stewart, regional sales manager North at Schaeffler UK comments: "This is a first for the oil and gas sector. This project is the first one in which a process module extension column of this type is supported by bearings. The customer deemed the bearings to be a high priority on this project, as their function is absolutely critical in supporting the extension column."
He continues: "We were informed by the customer that we won this business due to our technical knowledge and expertise, and because we understood exactly what the customer required. As the bearing supplier, we successfully met all of our deadlines, helped enormously by excellent cooperation between the three main parties involved - the end customer, the construction contractor and Schaeffler."