The seawater flows through the tubes and lube oil flows inside the shell of the cooler.
The lube oil pump takes suction from the main engine lube oil sump and delivers it through the
filter to the lube oil cooler.
Number one cooler is in operation while the number two cooler is kept on standby.
The shell and tube sides have separate purge valves.
The lube oil flows through the inlet valve into the shell and flows through outlet valve back to the main engine lube oil sump.
The seawater from the main seawater line is supplied through the cooler inlet valve.
The water flows through the seawater outlet valve to overboard.
While changing over the cooler, proper procedures should be followed to avoid increase in lube oil temperature or drop in lube oil pressure.
Open seawater side purge valve.
When the water comes out of the purge valve, open the seawater outlet valve gradually to full open position.
This will ensure no air is trapped in the seawater side.
Close the purge valve.
Check the inlet and outlet pressure gauges.
The pressure difference indicates the flow of seawater.
Circulate the seawater for fifteen to twenty minutes, before allowing the lube oil into the cooler.
This is to prevent thermal straining of the cooler components.
Open lube oil side purge valve.
Open the lube oil inlet valve by one turn.
When the lube oil comes out of the purge valve.
Open the lube oil outlet valve gradually to full open position.
This will ensure no air is trapped in the shell side and lube oil flows into the system.
Close the purge valve. Open the inlet valve fully.
Check all joints and end covers for leakages.
Check the inlet and outlet temperature of the lube oil.
Check the inlet and outlet temperature of the seawater.
The difference between the inlet and outlet temperatures indicates the performance of the cooler. The temperature difference should be observed and recorded.
If controller is provided set the temperature of the lube oil to be maintained.
The temperature can be maintained manually by adjusting a three-way valve of the cooler.
Shut the seawater inlet valve of the No. 1 cooler that has to be isolated. Shut the seawater outlet valve.
Divert the lube oil flow by adjusting the three-way valve.
Shut the lube oil inlet valve. Shut the lube oil outlet valve.
Adjust the three-way valve back to the normal position.
Now No.2 cooler is in operation and No.1 cooler is isolated.
No comments