During a planned drydocking at the Öresund in Sweden, machinery and shaftline repair contractor MarineShaft attended the ropax ‘Stena Saga’.
MarineShaft was called in to repair worn-out sealing surfaces on one of the four Wärtsilä Pielstick main engines with laser cladding equipment
On the engine’s cylinder holes welded frames, the sealing surface tolerance was too narrow – about 6 mm under original dimensions – to use planing.
Therefore, MarineShaft suggested welding up the worn surfaces with laser equipment and machining the surfaces back to original dimensions instead of using space rings. This could be carried out in-situ.
One of the advantages of using laser cladding is to avoid high heat input to the surrounding areas of the frame. The technique is also accurate, MarineShaft claimed.
On board ‘Stena Saga’, laser equipment was installed with safety in mind, including covering the area with curtains, erecting warning signs and the wearing of safety glasses.
The repair team used the filler material Inconel 625 for rebuilding the surfaces. Inconel 625 is perfect for reconstruction, and each layer thickness is 0.8 mm, MarineShaft explained.
After welding up the surfaces, a mobile machining tool was installed for re-machining of the cylinder holes’ 12 surfaces.
‘Stena Saga’ left the dock as planned and Stena Line will evaluate the repair and decide if it will be carried out on the remaining three main engines during the ship’s next drydocking period.
