Pipe pigging: recommended type of pump?

[LaSalle1940]

When water is to be used as the motive fluid for a pipe pigging operation in relatively small lines (let's say 3" or 4"), what type of pump is typically used (assuming there is no utility source of water at a sufficiently high pressure)? I'm thinking in terms of either a gear pump or a multiple-stage centrifugal pump, but please set me straight.

 

[zdas04]

This is facinating. I've never heard of putting in a foreign fluid to push a pig. Most people use pigs to either clean up a line (with the in situ fluids) or to separate products in a transmission line. Could you share your goal in pumping water in to move a pig?

In terms of type of pump that really depends on terrain. The force to move a pig is differential pressure. If a 3-inch pig weighs 2 lbm and the friction coeeficients double the effective weight being moved, then it will take less than 1 psi applied to the 7 in^2 area to move the pig. You could do that with the head on a tank. If there are terrain issues then you need to select a pump that can develop enough head to overcome the uphill sections full of water with the downhill sections empty. In my area, 1,000 ft elevation changes are common so I'd need to be able to develop something over 441 psi and would do it with a multi-stage centrifigal or a triplex plunger pump.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The harder I work, the luckier I seem

 

[stanier]

A progressive cavity type pump would be ideal.