Saved 80% of the cost of a repair carried out using traditional methods
Croatian research and development company as2con-alvaeus reports that it successfully masterminded the renewal of more than 500m of ballast pipe onboard a Croatian bulk carrier, using the Compa overlay method.
The repair was performed during drydocking at the Viktor Lenac yard in Croatia in April 2010, which as2con-alvaeus believes is the first time the process has been used on this scale onboard a merchant ship. The company says that Compa involves lamination of a damaged pipe surface using carbon fibre reinforced plastics. The repair plan and materials presented in the technical documentation for the task were approved by the Croatian Register of Shipping and accepted by Bureau Veritas. The shipowner is estimated to have saved around 80% of the cost of a repair carried out using traditional methods. The saving was achieved though there being no need for piping to be removed or handled, and no openings through the tank top were necessary. Pipe of sizes between DN100 and DN350 were repaired, in topside and double bottom ballast tanks of four cargo holds.
Prior to the renewal, the ship was surveyed to determine critical locations of the ballast piping, after which a local subcontractor prepared the piping surface in order to remove rust and old paint. Piping renewal began immediately after surfaces preparation. Carbon fibres were soaked in epoxy resin and applied to the damaged surfaces. The resin hardens over time and permanently bonds to the surface while impregnating fibres, thus reinstating the strength of the damaged part. The procedure is claimed to create a new solid layer of material providing full water-tightness. According to the company, high-end materials such as carbon fibre and epoxy enabled the project to be quickly completed and guaranteed a robust repair.
Despite adverse weather conditions, including rain, low temperatures and high humidity levels, the repair was successfully managed, and, a year after the repairs were completed, the client’s superintendant reports that the ballast piping is operating normally and that the Compa repair was successful.
Further advantages of this method over traditional cutting and welding are said to be the avoidance of high temperature operations and no degasification of tanks is required. The method can be applied to any accessible component and can be performed during a voyage. The epoxy material employed is resistant to osmosis, so a lifetime measured in decades can be expected. The company believes that the method could be equally applicable to repairs of hull plating and structural members, something which is currently being considered by an EU FP7 project known as Co-Patch.
Source: Motorship