Wednesday, February 5, 2020

Maintainance and troubleshooting centrifugal pump on ship

Problem found in pump

Delivery failure : The pump is not able to deliver at required pressure .
Fault-
a) Ensure that the pump is primed properly.
b)check if the pump is running with sufficient speed.
c)check for air leakage.
d)ensure that the impeller or other is not broken or damaged.
e)clogged suction screen
f)wrong direction of rotation.
g)ensure the temperature of liquid is not above the limit .

Priming failure-
Fault
1) Leakage in pump joint.
2)leakage in gland joint .
3)air leakage
4)faulty priming drive.

Excessive vibration;-
Fault
1) No loose foundation
2)The alignment of pump is not proper.
3) check there is no impeller imbalance or erosion.
4)check for worn bearing in motor

Motor overload or pump consuming more power
Fault
 1) The speed of the pump is high.
2)suction valve closed
3) gland too tight on shaft.
4)obstruction in rotary parts of the pump
5)worn out or damaged bearing
6)Bent shaft, oversized impeller.

Mechanical seal leakage;
Fault
1)incorrect type of mechanical seal.
2)bent shaft
3)dirt in sealing face
4)mechanical seal improperly installed
5)O-ring damage

Insufficient capacity;
Fault
1)Air leakage in suction line
2)Insufficient speed
3)Discharge valve closed
4)Mechanical defect such as worn wear ring or casing ring or mechanical seal .

Maintainance on centrifugal pump

1)Daily inspection if abnormal seal leakage or motor bearing high temperature.
2)After overhauling a pump inspect the shaft and the impeller.
3)check impeller for wear down,erosion mostly occur at periphery because of cavitation.
4) check the impeller vanes for erosion, cracking or if it is chocked
5)check the clearance between impeller wear ring and casing wear ring. If clearance is extremely high then change the rings (both , single depend upon the clearance)
6)Now check the condition of shaft sometime it bends(in lathe machine)
7)check condition of roller bearing of motor(racing and balls)
8)check the condition of coupling between motor and pump.
9)check the mechanical seal length of stationary and rotary part . Change O-ring and seal if damaged.


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