RA Power Solutions was informed regarding the failure of three nos Crank pin Bearings of MAN B&W 5L60MC main engine onboard a vessel near South Africa.
RA Power experienced team of technicians boarded the vessel in a short time of 18 hours of receipt of intimation regarding the problem faced by the vessel. Following jobs were executed for overhaul and replacement of crankpin bearings in order to operate the engine satisfactorily after Engine repair and Engine overhaul.
I) Inspection and overhaul of the cylinder covers including the fuel and starting valves located in the covers.
II) The cylinder covers cooling spaces were also inspected, cleaned and fitted back with new O-rings.
III) Dismounting, Inspect and overhaul of the exhaust valves, renewed the seats and grinding the valve spindles.
IV) The cylinder liners were cleaned, calibrated and honed in order to restore the liners running surfaces and remove ovality. This ensured that the piston rings perform better and this will lead to a better overall cylinder condition, compared to if honing had not been done. The cylinder liners cooling spaces were also inspected, cleaned and fitted back with new o-rings.
V) The Crank pin bearing caps were dismounted, both top and bottom bearing shells renewed
VI) The Crankshaft Crankpin diameter was checked for the following parameters:
a) Visual inspection to check the presence of any Bearing Line marks or rough surface.
b) All the Crankpins were calibrated for taper & ovality.
c) Hardness was checked and observed within limits.
d) MPI was done to check the presence of any crack.
e) Crankshaft all pins were polished by onsite Crankshaft Grinding Machine removing the bearing line marks and for improving the Crank pin surface finish.
VII) Adjustment of the variable injection timing (VIT)
VIII) The bearing clearances were taken using lead wire
IX) Crankshaft alignment measurement was taken with a dial gauge.
Conclusion: After replacement of Bearings & Jobs described above undertaken at the time of Engine overhaul & Bearing replacement the engine was tested on the load & performance was observed satisfactory.