max velocity in pipe 30''

[Vladimir99]

We have a crude tank with a 30'' valve at the exit. This line will be the suction of the pump.

My process engineer limit the velocity in the 30'' pump suction line at 4 ft/s.

What do you think ? It is to conservative. I read usually it is between 6 and 10 ft/s.

Thanks,

vladimir99

 

[stanier]

Model the system and determine if the pump NPSHr is compromised.

If you need information on this try

http://www.mcnallyinstitute.com

for technical papers on NPSH.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[BigInch]

That's a good ball park limitation for a 30". There's a lot of moving mass there, so forces from flow starts and stops can be quite high. Also depends on where its going. You generally want to hold velocities toward the low end, inside treating and storage facilities and when filling tanks or the nozzle reactions tend to do bend the walls if too high. Over 5 ft/sec you can easily get into surge problems if pump start/stops and valve closing times are not timed exactly right. 4 fps or less will give you a much lesser chance of higher surge pressures & resulting forces.

http://virtualpipeline.spaces.msn.com

 

[RossABQ]

6 to 10 fps is appropriate on the discharge and distribution side; inlet (suction) piping is generally right where the engineer says.