Offshore Sheathing

Sheathing offshore in copper-nickel is applied either for splash zone corrosion protection or biofouling and splash zone protection on legs and/or risers. For straight splash zone corrosion protection, the copper nickel is usually welded into position as for the Morecambe Field. For biofouling protection it is supplied as a composite product of half cylinder sheets, perforated sheet, granules or wire onto an insulating backing, e.g.neoprene.

One product, which has been successfully used for splash zone protection of structural legs, cross bracings and riser pipes, involves discrete granules of copper-nickel, 1mm diameter and 1mm long bonded into the surface layer of 3mm thick neoprene sheet. The processing ensures that the granules are distributed and exposed over the surface such that about 30% of the surface is copper-nickel and each granule is close enough to its neighbour to allow complete surface protection.

Sheets of the composite are press cured and can be then cut to the required sizes, slit to strip, or even rejoined to form continuous tapes up to 50m long. The product can be hot bonded onto elastomeric corrosion coatings or cold bonded directly onto steel. The track record dates back to 1984 with 13,000 square metres supplied for several platforms world-wide.

Antifouling subsea markers using copper-nickel are attached to pipelines and underwater areas for offshore platforms and other marine structures. They are used for identification purposes and to guide divers around structures and along pipelines. Fouling resistance is achieved by a surface layer of fine interwoven copper-nickel wire mesh embedded into a bright yellow, pigmented polyester gel. By altering the pigment of the polyester gel for numbers and letter, identification can be readily seen. The copper-nickel layer is insulated from the metal substrate by fibreglass, polyurethane or rubber backing and the marker can be bonded, strapped, bolted or clipped into position. Currently, the longest known exposure for the markers is 15 year.