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GRE Pipe's Pressure Test

GRE Pipe's Pressure Test

GRE Pipe's Pressure Test

(OP)
How many times a GRE pipe can be under the load of pressure test?
we have a GRE underground pipe that has been under hydrostatic test pressure for 12 times and every time it has failed (we can not find the leak point).
please specify that again and again we can continue to this operation and whether there is any limitation for number of tests or not?
regards

RE: GRE Pipe's Pressure Test

When you are talking about cyclic loading you generally talk in terms of millions of cycles (I had a plastic pipe fail in cyclic loading in a gas well in a quarter million cycles, but that was changing from 30 bar dP outside in to 20 bar inside out in 2 seconds so it was pretty severe). I've pressure cycled GRE several hundred times without noticeable harm.

On the other hand, bruised pipe suffers significant delamination at the bruise site with each pressure cycle. I've had your problem with testing buried pipe--I get a fitting leak, depressurize and get a delamination leak on re-test, depressurize and get a new delamination leak in a different place, etc. Generally if you leave GRE in an open ditch for more than a few hours before backfilling you will have bruise problems that may not be leaks for decades. That is the reason that I stopped using GRE for buried lines.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist

RE: GRE Pipe's Pressure Test

The ISO code 14692 list hydrostatic test as an "occasional load". Twelve times is starting to exceed what could be described as "occasional"

When you say it "failed", what sort of failure did this equate to?

What sort of joints do you have?

I suspect you've come across what happens when you don't do multiple tests of short sections of GRE before you bury it. Having been involved in a few, I would now be very wary of burying GRE pipelines. The risks are just too high that the pipe will fail if not on installation, then within a short time.

Frankly if you can't find the leaks after 12 goes, then it's time to re assess your unpalatable options.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

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