Trouble description: Unit #5 and #6 top piston rings were found broken during last UPS inspection. We did

Trouble description: Unit #5 and #6 top piston rings were found broken during last UPS inspection.

We did unit #5 decarb at sea, but just after 3 days again top piston ring found broken at butt joint.

We increased cyl oil feed rate from 1.3 first then 1.5 after subsequent UPS inspection.

But at every time we do inspection carbon deposit on ring land is increasing.

Sludge deposit on Unit #5 is very high. But on unit #6 it is ok but top piston ring broken at butt joint.

ME is equipped with HJ SIP Lubricator. SIP closing pr. is 59 to 63 bar. As per maker high limit is 65 bar. SIP Leakage is 2 Itrs per day.

Measures taken: We have already replaced fuel valves and exh valve during decarb. No problem with fuel valve and exh valve.