Wartsila VASA 12V32 LN Crankshaft Repair
RA Power Solutions was approached by a leading Cement manufacturing Plant based in Nepal regarding failure of their Crankshaft of Wartsila Diesel Generator model no. WARTSILA VASA 12V32 LN.
A team of RA Power Solutions technicians were deputed to Nepal and on inspection following observations were made.The Wartsila engine details are also given below:
S. NO | Crankshaft Details |
|
1 | Engine Make | Wartsila |
2 | Engine Model | VASA 12V 32 LN |
3 | Crank pin Diameter Standard | 270 mm |
4 | Crankpin Bearing Width | 93 mm |
5 | Place of execution of crankshaft repair | Cement Plant in Nepal |
Wartsila Diesel Generator Crankshaft Main Observations:
i) On inspection of all the crankpins visually the Bearing of crankpin no. 3 was observed damaged and bearing material was found in the oil sump.
ii) On removal of connecting Rods from crank pin no 3. A & B bank, it was found that the bearing was badly struck to the crankpin diameter and it was a case of bearing failure.
iii) The Bearing was removed from the crankpin and on visual inspection it was observed that bearing material was embedded on the crankpin. The radius fillet of both sides of the crankpin was found damaged and the profile of radius fillet was distorted.
iv) After cleaning and little polishing of crankpin to remove the bearing material the crack detection test by MPI method was undertaken. No crack was observed.
The hardness was also checked and it was observed in the range of 600 HB in a scattered formation which is considered to be on higher side.
v) The crankpin was subject to the dimensional inspection and following dimensions were observed.
a) Minimum diameter observed- 269.52 mm
b) Maximum diameter observed- 270.00 mm
Against the standard diameter of 270 mm the ovality of 0.48 mm was observed which is considered to be very much on a higher side.
vi) The multiple deep bearing line marks were observed on the crankpin circumfrance.
Action taken for successful repair of Wartsila Diesel generator 12V32 LN Crankshaft
i) The onsite grinding of crankpin no. 3 was started by the portable onsite crankshaft grinding machine.
ii) The ovality of 0.48 mm which was observed initially at the time of inspection of the crankshaft was removed by undersizing the crankpin diameter to 269.00 (1.0 mm undersize). Unfortunately deep bearing line marks were still present on the crankpin. In this situation it was decided to further grind the crankpin no. 3 till the line marks are removed.
iii) The crank pin diameter was reduced to 268.50 mm (1.5mm undersize) and the crankpin was inspected. Due to the presence of line marks it was again decided to further grind the crankpin to the undersize of 2.0 mm.
iv) The crank pin was finally ground to the size of 268 mm (2.0 mm undersize) and following dimensions & tolerance were maintained:
a) Minimum diameter observed after grinding/ polishing- 267.98 mm
b) Maximum diameter observed after grinding/ polishing- 268.00 mm
As can be seen from above dimensions the taper & ovality was controlled in 0.02 mm only which is far better than the tolerance stipulated in the Wartsila Engine manufacturer manual.
v) The surface finish after grinding & polishing was checked by mitutoyo surface test equipment and was again observed in the range 0.10 RA Value. Photographs are enclosed.
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