OVERBOARD VALVES ON THE MAIN SEA WATER LINE DAMAGED :
The vessel after cargo discharge at Chennai was leaving Chennai on ballast. Pilot got down, and the RFA was about to be given.
Suddenly a sharp rise in piston and lube oil temp were noticed. Ballast turbine was still running in finishing up stages of ballast operation .Ballast pump was stopped after informing bridge so also the possible necessity for M/E stoppage was also informed to bridge. SW coolers were checked and found the water flow is stopped.
Doubted the pump and its discharge side valves, checked by opening the vent on the cooler, found SW flowing and the temperature dropping. If the vent is shut, the temperature started rising. Hence doubted the overboard line valves from the coolers. The main engine was stopped and the defective valve located.
After ascertaining the position of valves to be above the water line, removed the defective valve body’s bonnet and found that the spindle’s locking nut threads got worn out from valve lid and the value lid found stuck on its seat .
The spindle along with the nut was replaced from a old broken valve. System reset and the voyage was continued.