Do I Need to Throw In a Few Feet of Head to Account for Pigging?
Do I Need to Throw In a Few Feet of Head to Account for Pigging?
(OP)
Hi guys. A question. When sizing a pump that charges a pipeline that will be pigged, and if this charge pump is also used as the motive force to drive the pig during the pigging, do I need to throw in a few extra feet of TDH oomph to account for the friction of the pig against the pipe wall?
In other words, if my pump calc says I need 500' TDH, do I throw in 2% or some odd more to make sure I've covered my pokey during the pigging?
Thanks guys! Pete
In other words, if my pump calc says I need 500' TDH, do I throw in 2% or some odd more to make sure I've covered my pokey during the pigging?
Thanks guys! Pete





RE: Do I Need to Throw In a Few Feet of Head to Account for Pigging?
Best regrads
Morten
RE: Do I Need to Throw In a Few Feet of Head to Account for Pigging?
Are you planning to pig at full design flowrate or something??? If you think you will do that, then ya, you might need to add some head at your BEP.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Do I Need to Throw In a Few Feet of Head to Account for Pigging?
David
RE: Do I Need to Throw In a Few Feet of Head to Account for Pigging?
You wouldn't need to add head to the pump, if you're prepared to accept what would usually be a lower flowrate. Adding a pig increases resistance at least a little, so the pump will run back on the curve as it increases the discharge head in the attempt to find that little bit of extra head needed to move the pig. That will also mean at least some tiny reduction of flow. If you can live with whatever that lower flowrate is during the pigging operation, then you don't need to get a pump with a higher discharge head output curve. That will almost always be the case, but it is conceivable that a pump already working at low capacity in the flat region of its curve might lose a considerable amount of flow with little to no increase in head if somebody dropped a pig, or a bunch of spheres in the line. In that case you would need to get some more differential head from somewhere, most commonly by lowering the outlet pressure of your pipeline. If you couldn't do that, another alternative might be to increase the pump's suction pressure. If you couldn't do that, then the last alternative at that point would be to get a pump (or boost) to a higher discharge head.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus