Force on a restriction plate in a pipe
Force on a restriction plate in a pipe
(OP)
Hi All,
We need to test a newly installed water distribution main. It is cement lined ductile iron (500mm). There are some issues with the mortar lining coming away from the pipe. The pipe hasn't been commissioned yet but we expect flows of 400-500l/s.
We are worred about further deterioration and damage to the large PRV downstream.
We need to test a seciton of the pipe to see the effect on the mortar of design flows. We can get flows of 100 l/s for testing so would need to create a blockage of approx 80% to have a flow velocity broadly equivalent to 500 l/s.
Unsure yet how to create the blockage but to do that I would like to estimate the force experienced by the blockage under the flows indicated.
Any ideas? Thank you in advance.
We need to test a newly installed water distribution main. It is cement lined ductile iron (500mm). There are some issues with the mortar lining coming away from the pipe. The pipe hasn't been commissioned yet but we expect flows of 400-500l/s.
We are worred about further deterioration and damage to the large PRV downstream.
We need to test a seciton of the pipe to see the effect on the mortar of design flows. We can get flows of 100 l/s for testing so would need to create a blockage of approx 80% to have a flow velocity broadly equivalent to 500 l/s.
Unsure yet how to create the blockage but to do that I would like to estimate the force experienced by the blockage under the flows indicated.
Any ideas? Thank you in advance.





RE: Force on a restriction plate in a pipe
In addition if you're already observing mortar coming away from the wall that will create eddy currents at those locations that will accelerate further damage.
If you put a restriction in the pipe work to create a locallised high velocity you will also create eddies that will give a higher erosion rate.
Worst case- test a section of pipe with water running down an incline until you get the velocity you need. But to be honest- if you see a response from this (or any other short term test) test - then you're pipeline is going to fail very quickly.
As a chem eng/metallurgist the first part of any answer I give starts with "It Depends"
RE: Force on a restriction plate in a pipe
However I would have thought that a sectional pull off test would be easier to establish adhesion.
What does the manufacturer say??
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Force on a restriction plate in a pipe
It is not possible to increase the velocity using just a lower flowrate. Q=VA. The only method to accomplish this is to install a smaller diameter pipe internal to the larger pipe.
It would be easier to set up a test rig consisting of a tank (5 min storage capacity), pump, and a pipe section to test.
The force would be simply pressure (in psi) times the area.
RE: Force on a restriction plate in a pipe
The loose liningwas apparently caused by damage in transit.
We will be doing sectional pull off tests but were looking to see how significant the damage is or if it is very localized.
We are planning to proceed with a swab in the pipe and pump water against it (essentially like the above suggestions). The swab could be moved along the pipe to provide an assessment (of some sort anyway) along the section.
Still concerned about the possible forces of 100l/s in a 500mm pipe against the swab and the securing lines.
Don't think I've ever heard of this done before so is potentially quite exciting.