April 07, 2015
The Armada Platform is operated by BG Group and exploits three gas condensate fields in the Central North Sea, 250km east of Aberdeen, Scotland. In 2009, the living facilities on the platform were extended to accommodate an additional 59 personnel. Corrugated nickel-containing stainless steel was used for the structural cladding of these accommodation modules. Austenitic stainless steel grade 1.4401 (UNS S31600) with a 2B standard mill finish in accordance with EN 10088-2 technical standards was chosen.
While carbon steels need regular repainting and maintenance in harsh offshore environments, stainless steels typically require little upkeep. It’s not easy to carry out maintenance in the severe conditions of the North Sea and the cantilevered design of the modules means that it is even more challenging. In order to avoid costly maintenance over the 30 year design life, it was stipulated that all steel exposed to external conditions should be stainless.
The stainless steel panels were prefabricated with the insulation and welded onto the carbon steel structural frame. After fabrication, the sheets were acid cleaned to remove any embedded iron particles which might rust when exposed to marine conditions.
The completed modules were transported by road to the coast, then shipped to the Armada Platform. Lifting pad-eyes were attached to the carbon steel frame at the four corners of each module through the cladding. The pad-eyes also doubled as guides for positioning the modules on the second level. The lower modules were attached to the module support frame (MSF) using steel grade A4-80 bolts (S31600 with 800MPa tensile strength).
The modules were connected together in a 2-on-2 formation with a provision for a third storey in the future. The stair modules were attached at either end and sit on their own support frame.