The degradation mechanisms of machine parts are well-known facts, usually resulting in replacement of components. However, in some cases, for instance, parts for large ship engines, repair will often seem more attractive. Time-wise, the vessel’s down-time will be reduced and the investment will be lower. This paper describes repair work performed on valve stems from a 52-year-old ship engine. Due to this long time in operation, the stems were damaged by wear and were no longer functional. The requirements for the stems were scarcely documented stating only a few specific requirements; therefore a short study of the possibilities concerning rebuild material and application method was initiated. This paper illuminates the manufacturing process used; twin wire arc spraying with Monel as the rebuild material. Monel is chosen to meet the requirements for hardness and the subsequent high precision machining. In addition, the mechanical and metallurgical properties of the rebuild coating are examined in regard to adhesion, microstructure and hardness to interpret and support the functionality.

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