Small leakes in the begging of a test...then it just stops. Why? 4

[pguevara]

I would like to know if its normal to have a Leak in a Test during filling conditions, but in pressure is complete LEak proof.

Imean, i am testing a 24 inch PVC pipe with gasket joint 1000 Ft lenght. During filling we detect small leaks in 4 joints, but once the pipes gets just a little pressure (about 35 PSI) the leak stops and pass the 2 hours test ay 150 PSI with no problem. The main problem now is that the inspection is killing me with questiong regarding to if this is normal. A couple of PVC pipe manufacturer told me that its perfectly normal, but when i ask to a document (standard, essay, textbook or something) they told me that there isn't any. It's this true? where i can find info about it if this is possible

Thank you ! i have only 2 days to answer to the inspection before they consider the test as Fail!.

Regards,

 

[btrueblood]

It's fairly typical. During installation, gaskets can slip to the inside edge of their retaining groove, and small gaps may open due to the corners rolling, or dirt pickup. During filling, the pressure will eventually press the gasket to the outside of its groove, and provide a squeezing force, filling any small voids that may have opened.

 

[MTPipeliner]

I don't know that it will buy you much ground with the inspector, but irrigation lines do this all the time.

When you lay them out and turn the valve on they leak all over the place, but as the pressure builds up they quit leaking.

 

[inspektor]

I agree with Btrueblood,gaskets often are displaced slightly when the spicket is pushed into the bell. Adding pressure returns them to the intended postion. You might also google "allowable leakage", it is a formula we use when testing pipe. good luck

 

[rconner]

I didn't happen to see the behavior you describe detailed in the treatise for the reported now most common design for such accessible at

http://www.hultec.co.za/downloads/RIEBER_SEALING_n_America.pdf.

However, I did see the claim on page 4 that "different sealing mechanisms" can be at work between pressurized and non-pressurized conditions, and a hint also that maybe some problems have in somewhat cryptic fashion been blamed on incorrect insertion with the verbiage, "Insertion of the spigot beyond the insertion mark may cause the spigot to wedge itself into the neck of the bell, thus preventing hydrostatic pressure from reaching the gasket through the gap between the pipe bell and spigot, and preventing proper functioning of the gasket..."