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jmol 11-03-2008 05:12 PM

Pressure Testing Black Pipe
Hi, I recently had a new run of black pipe installed from the meter to where the new boiler will be installed. They pressure tested the line to 25psi and 5 days later it dropped to 5psi and failed inspection. The plumber returned, pressurized the line to 100psi and found a leak at a joint. The joint was fixed and the line was pressurized again to 26psi. 6 days later, today actually, the gauge now reads 14 psi. The re-inspection is scheduled for this coming Wed. but it looks like it may fail again.

Is there a certain amount of time or a minimum amount of pressure that the pipe has to hold indefinitely?


glennjanie 11-04-2008 02:20 PM

Welcome John:
If there is a leak, it will loose 100 pounds in hours; if there is not a leak, it will hold 25 pounds forever. I personally like to use 15 pounds and soap spray the joints; if there is a leak the soap will bubble right away.
If the pipe is exposed to weather changes, the pressure can vary 5 to 10 pounds either way so, I don't like long holding periods. It sounds like your installer is very concientious and I think you will be fine.

triple D 11-04-2008 10:26 PM

in our area....
The pressure must be at 15psi. any more or less and you fail. I have never seen fluxuation in pressure that was really noticible (more than 1psi.) and I have watched many guages over the years. Some I have seen on test for weeks at a time with no change at all. So like glenn says, go for 15psi, and then wait a couple days. If it leaks down, you do have a leak. Good luck.....

jmol 11-05-2008 09:37 AM

Thanks for the info guys, the new boiler is being installed as I type this reply. Yesterday, the plumber came back and we found two slight air bubbles at two separate elbows. They fixed the leaks, repressurized to 30psi and it held 30psi for 24hrs. The reinspection was earlier today and it passed.

Thanks again

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