Pump is a type of machinery which is used in large number on board ships, both on deck and engine side. Every seafarer working on ships must be aware of the basic problems associated with pumps and practical ways to troubleshoot whenever the need arise.
While handling pumps on board ships, you do not need to be an expert. All you need to know is how to identify some basic signs and preventive actions which are to be taken whenever required.
Mentioned below are some of the main problems that are associated with pumps on board ships.
Main problems found in pumps are:
1. Delivery Failure – The pump is not able to deliver at the required pressure.
Check the following in order to tackle this issue:
- Ensure that the pump is primed properly
- Check if the pump is moving with sufficient speed
- Check for air leakage
- Ensure that the impeller/gear/screw or other liquid driving mechanism is not broken or damaged
- The pump shaft should move in the right direction
- Check that the suction lift is not more than required
- Ensure the temperature of liquid is not below the “pump-able” limit of the pump.
2. Priming Failure – Priming is required in order to start most of the pumps. If the pump is not able to prime properly, check the following:
- Leakage in pump joint
- Leakage in gland joint
- Air leakage
- Faulty priming drive
3. Inability to Build Pressure – If the pump is not able to build enough pressure in order to ensure smooth flow of liquid, then check
- If the priming is done properly
- The air cocks are not open
- internal moving parts (impeller/ screw etc.) are not damaged
- Wear Rings are not worn out or damaged
- The pump is running at the right speed
- There are no other mechanical defects in the pump
- Check for cavitation in the casing of the pump
4. Excessive Vibration: Sometimes the pump vibrates a lot making a loud noise. If there is a lot of vibration in the pump, check the following:
- Ensure there is no loose foundation
- The alignment of the pump is proper
- There is no impeller imbalance or erosion
- There are no mechanical faults
- The distance piece between the pump shaft and motor shaft is of correct length and is not worn out
- The rubber bush piece connecting the motor and pump shaft is not worn out
- There are no worn bearings or bent shafts
5. Reduced Capacity : Several times due to continuous running, the capacity of the pump reduces drastically. If the capacity of the pump has been reduced or there is insufficient capacity, check
- The pump is running at proper speed
- There is no air leakage
- There is no obstruction in the suction pipe
- Ensure that the suction lift and temperature are not too high
- The total dynamic head is not larger than the rated
- The setting of the pump relief valve is not below required value
6. Motor Overload
This is a very common pump problem found on board ships. If the pump motor overloads, then immediately check:
- The Speed of the pump is not high
- The quantity of liquid pumped is not too much
- The viscosity of the liquid is up to the mark
- Valves in the line are in closed position
- Problem or obstruction in the rotary parts of the pump
7. Loss of liquid
If the pump loses liquid, after starting or during running, check
- Check if the suction lift is as required
- Check for any kind of leakage in the suction line
- Check the temperature of the liquid
- Ensure the relief valve of the pump is set at right value to avoid loss of liquid to overflow line
This is not an exhaustive list of problems, but it does explains all the main problems that would result in faulty pumps. Do you know any other common problems associated with pumps? Let us know in the comments below.
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An ardent sailor and a techie, Anish Wankhede has voyaged on a number of ships as a marine engineer officer. He loves multitasking, networking, and troubleshooting. He is the one behind the unique creativity and aesthetics at Marine Insight.