c 900 blue brut
c 900 blue brut
(OP)
Is there a maximum that a joint can slip out when hydro testing??
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RE: c 900 blue brut
If you're observing movement during testing, you'll learn that maximum in due course. The pipe should be secured prior to testing. Then in the real world things move under pressure- if it holds it holds
Alex Traw
Rainbow Fire Sprinklers
Albany, Oregon
RE: c 900 blue brut
RE: c 900 blue brut
RE: c 900 blue brut
As the rest of the guys mentioned no matter what the manufacturer claims pipe will always move under pressure unless is threaded.
RE: c 900 blue brut
In a recent presentation I believe I heard an expert in polyethylene pipes claim that an originally 20 feet long stick of DR 21 pvc pipe (I guess pressurized in kind of short-term fashion to its current/liberalized pressure rating of 200 psi) would shrink in axial length due to Poisson effect of pressure alone about ½ inch (this perhaps thrown out there to somewhat sort of blunt in advance concerns of even more pronounced tendency to shrink of polyethylene pipes?) While I guess some thermal movements could be as much or more, it would appear that in even a long, reasonably straight run of just Reiber-gasketed pvc piping, Poisson effect alone would appear (if one looked closely/carefully enough) as at least a small "slip" in the joints. That is why I was skeptical of the claim of "no movement".
RE: c 900 blue brut
That being said, notice also the quote many years ago from the manager of the Johns-Manville research lab mentioned also in the prior thread at http://eng-tips.com/viewthread.cfm?qid=227976 that indicates perhaps non-obvious axial movement may even occur with very short duration higher pressure spikes, "Since PVC pipe moves axially as well as circumferentially in response to pressure surges ("Poisson's ratio effect"), pipe may undergo scratching of the outside when buried and in contact with sharp stones in the backfill. This area requires further study."
All of this nevertheless does not appear supportive of a "no movement" claim.