|
5122 |
|
Wednesday, June 07, 2017, Hall Y 2:00 PM Maritim Industry & Off-Shore Technologies |
|
A case study of repair work on ship engine valve stems |
|
Peter Tommy Nielsen* / FORCE Technology, Denmark Kirsten Grønning Sørensen / FORCE Technology, Denmark Peter Pallesen/ MarineShaft A/S, Denmark |
|
The result of degradation mechanisms of machine parts is a well-known fact, which are 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 vessels down-time will be reduced and the investment will be lower. This paper describes repair work performed on valve stems from a 52 years old ship engine. Due to this long time of operation, the stems were damaged by wear and no longer functional. The requirements on the stems were scarcely documented stating only a few specific requirements, why a short study of the possibilities concerning rebuild material and application method was initiated. This paper will illuminate 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 following high precision machining. In addition, the metallurgical properties of the rebuild coating are examined in regard to adhesion, microstructure and hardness to interpret and support the functionality. |