Pump seal frequency is very high

[MIANCH]

Hi All,
I hope this thread will be very interested for some fellow members.
Pump is designed for following conditions.
Inlet temperature 695F
SP,GR at 60 F : 0.95 and at inlet temp: 0.715
Viscosity 0.31 CKS @ 695F
Capacity at inlet temp Normal Design 115 GPM
Capacity at inlet temp: max Design 126
Design inlet pressure is 31 psig
Discharge pressure is 128 psig.
Pump is being operated with following conditions
SP.GR at 60F: 0.59 and at inlet temp:0.477
Viscosity at 100 F 0.17 CKS
capacity at inlet Temp , normal Design 45 GPM
Capacity at inlet Temp, max Design 50 GPM
inlet pressure is killed by installing a level control.
Discharge pressure is recorded more than 150 psig.
22 years are in service and pump seal damaged more than 30 time, pump impeller and pump casing scored heavy rubbing. one time complete impeller and casing also changed. Can someone explain what is wrong with this pump or fluid handling ( I mean service of fluid)

 

[Artisi]

What has the mechanical seal supplier had to say?
Besides the data given, what is the pump style, what is the application, what is the seal failure - any photo's?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[MIANCH]

Artisi,
Centrifugal pump and vertical motor mounted on pump. Pump is for HFO services but used for naphtha service.

 

[FMJalink]

Hi MIANCH,
An inlet temperature of 695F is not really a low temperature. The mechanical seal needs to get rid of the heat generated and the pump construction needs to allow for the thermal expansion and prevent heating up the bearings and driver.
Can you give more details on the pump construction? Your description would also fit a close coupled vertical inline pump, which would not be the most suitable for this operation temperature.

 

[MIANCH]

FMJalink,
These pumps were purchased in 1962, For ADU bottom (HFO services) but in 1998 transfer excess naphtha and off spec kerosene need more pressure to fill naphtha storage tank. 1998 management decided to use this pump for naphtha and kerosene transportation and since the installation and putting in operation, maintenance face seal failure and pump seizing. I know naphtha is getting vaporized and seal is getting heated up / dry as well.

 

[pierreick]

Hi,
May be time to buy a new pump or at least to ask knowledgeable people to have a look (pump manufacturer and/or mechanical seal vendor)?
Over the time, wears appear.
Good luck,
Pierre

 

[horacio Torres]

22 years running with a seal failure once a year in average is not a ban number... I think that clearance into internals are grater that allowed...Time to change the pump

Lifetime for pumps refinery services is around 15 years, your economical analyst will give you the figure is changed is an option against the maintenance cost. 

horacio

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