Composite Repair of a Stainless Steel-GRP Sonar Dome

Abstract

This paper describes the application of composite materials for the repair of corrosion damage on stainless-steel components of hull-mounted sonar domes on typical warships. The domes have an aerofoil shape in plan, approximately 4.08 m nose to tail, 1.27 m maximum width, and 1.83 m high. The sides (acoustic window) of the domes are made of stainless steel and the canoe-shaped bottom is made of glass-reinforced plastic (GRP) composite. A bottom-mounted stainless-steel insert and drain plug unit is used for flooding and draining the dome. Due to the severe marine environment, the stainless steel drain plug suffers extensive corrosion damage and has to be replaced frequently. A study performed to replace the stainless-steel insert and drain plug components with composite material is presented. The approach adopted is to treat the problem as a flush composite repair, whereby an area around the drain hole in the GRP canoe is cut out and replaced with a two-piece composite insert that is bonded onto the GRP canoe. Both the insert and plug are made of glass-reinforced composite material. Details of the material selection, design, fabrication, and process specification for the repair, as well as the challenges involved in undertaking this repair are discussed.