Hi

I am working on a water injection pump system. The system details are as mentioned bellow.

Line size: 8”
Pump Suction: Side Suction - 4” - 2500#
Pump Discharge: Side discharge - 3” - 2500#
Analysis Temperature: 250deg F.
Analysis Pressure: 3327Psig

When I analyze the system without friction factor the nozzle loads are within 2times API 610. When I apply friction factor (even 0.1) the nozzle loads are exceeding much. This pump system includes the metering assembly also. Due to layout constraints I can’t change the pipe routing. Only by changing the restraints I have to pass the system. i am not able to come over the friction problem.

Please share your knowledge to solve this problem.

Friction is tricky. For steel on steel a factor of 0.3 is used. This will result in higher nozzle forces cause the pipe can't slide on the supports without first generating a friction force.
A friction factor of 0.01 can be achieved with using sliding plates. This is a theoretical value though, and practical values will probably be higher, especially when the system is longer in use and dirt and wear influenced the friction factor.
In your case I wouldn't use a 0 friction factor cause in practice friction will be there and your nozzle loads will be too high.

Try looking for the supports that have the highest operational load and consequently generate the largest friction reaction. If you are not confident about low friction supports atthose locations, think about hangers.

Hanger could be a solution which offer zero frictional load. But it will increase tendency of pipe vibration ( support closer to pump nozzle ).
Roller support could be another solution that offer frictional co efficient 0.01.

thank you for your valuable replys.

Hi Mr. Muth,

I would first try to rearrange support before using any sliding material as in my experience.. It will be my last option to offer sliding elements because friction change in time.. spring hanger can be use but its cost and availability for support would be another problem.

Regards!