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DIP tie-in hydrotest or spool piece hydrotest
- Thread starter JARivera1
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AWWA C151 specifies that each pipe be subjected to a hydrostatic test of not less than 500 psi with the pipe under
the full test pressure for at least 10 seconds. The hydrostatic test pressure applied to fittings is a leak tightness test only.
the full test pressure for at least 10 seconds. The hydrostatic test pressure applied to fittings is a leak tightness test only.
While the inquiry may not be real clear, it sounds like bimr may have thought you were talking about required factory testing of pipes/material. If you are instead talking about a field test after installation of e.g. just a tie-in, consisting of say just a sleeve or coupling and/or a few feet of pipe installed only after a successful test of e.g. a new section of piping, it may not really be practical or desirable to test that, at least in the same fashion as the rest of the new piping.
If the sleeve and piping is restrained, however, and the system (thrust restraint etc.)design is not totally dependent on that piping being backfilled for stability, maybe the piping, joints etc. could be assembled with great care, left at least briefly without full backfill, and then at least be examined once the working pressure is turned back "on"? (I think something resembling this is sometimes done also in welded process piping or welded systems i.e. a great deal of care in procedures etc. -- you may search under "Golden Weld")
If the sleeve and piping is restrained, however, and the system (thrust restraint etc.)design is not totally dependent on that piping being backfilled for stability, maybe the piping, joints etc. could be assembled with great care, left at least briefly without full backfill, and then at least be examined once the working pressure is turned back "on"? (I think something resembling this is sometimes done also in welded process piping or welded systems i.e. a great deal of care in procedures etc. -- you may search under "Golden Weld")
- Thread starter
- #4
Thanks bimr & rconner for yor feedback.
Rconner you are right, it is for a new main installation. A straight section 14 m of 1640 m approximately is not going to be tested plus the tie-in sections (each end). There is no way to test unless test the entire system. Is there any precedence to waiver the hydro´s as per AWWA C600.
Rconner you are right, it is for a new main installation. A straight section 14 m of 1640 m approximately is not going to be tested plus the tie-in sections (each end). There is no way to test unless test the entire system. Is there any precedence to waiver the hydro´s as per AWWA C600.
In special situations, Utilities may approve modifying the hydrostatic test pressure to match the pressure in existing adjacent City Watermains. In such situations, the pipe components are swabbed with a chlorine solution before assembly.
To summarize, how to handle all manner of different tie-ins of newly constructed sections of pipeline systems is not discussed in ANSI/AWWA C600.
IMO (probably worth little more than that as I am not on this Committee) this subject would thus fall in the "Special Issues" or "Conditions not discussed" guidance of this standard, where e.g. quoting per the former section, "its applicability under any circumstances must be reviewed by a responsible engineer".
In this regard, if the tie-in happens to be to another newly installed, but yet untested pipeline section of the same contract, I think I have seen in at least some cases in the past the constructor will simply test the second section and at the same time in effect re-test the previously tested section as well in a longer test segment, and of course the tie-in in this case between the two goes along for the ride to exactly the same requirements.
On the other hand, if you are tie-ing into existing (and in some cases much older) piping, that itself might even be scheduled e.g. for replacement at some point in the future, in many cases it would probably/simply not have the strength or other features to be exposed to the same level of test as the modern ductile iron piping. In my first response I suspected this may well have been your case. I think I have also even seen in the past some very narrow "windows" of time for making some tie-ins to working systems, that didn't even allow for normally specified testing duration or test boundaries, to avoid unreasonably shutting down critical Customers on the existing segments involved.
The subsequent guidance of bimr to throughly clean and sort of pre-chlorinate the tie-in piping right before it is installed (not unlike as if it were a common insertion or repair operation etc.) is prudent in such cases, particularly where the piping will not get a subsequent disinfection or flush (it is certainly helpful to have the review of a "responsible engineer" in these cases!)
IMO (probably worth little more than that as I am not on this Committee) this subject would thus fall in the "Special Issues" or "Conditions not discussed" guidance of this standard, where e.g. quoting per the former section, "its applicability under any circumstances must be reviewed by a responsible engineer".
In this regard, if the tie-in happens to be to another newly installed, but yet untested pipeline section of the same contract, I think I have seen in at least some cases in the past the constructor will simply test the second section and at the same time in effect re-test the previously tested section as well in a longer test segment, and of course the tie-in in this case between the two goes along for the ride to exactly the same requirements.
On the other hand, if you are tie-ing into existing (and in some cases much older) piping, that itself might even be scheduled e.g. for replacement at some point in the future, in many cases it would probably/simply not have the strength or other features to be exposed to the same level of test as the modern ductile iron piping. In my first response I suspected this may well have been your case. I think I have also even seen in the past some very narrow "windows" of time for making some tie-ins to working systems, that didn't even allow for normally specified testing duration or test boundaries, to avoid unreasonably shutting down critical Customers on the existing segments involved.
The subsequent guidance of bimr to throughly clean and sort of pre-chlorinate the tie-in piping right before it is installed (not unlike as if it were a common insertion or repair operation etc.) is prudent in such cases, particularly where the piping will not get a subsequent disinfection or flush (it is certainly helpful to have the review of a "responsible engineer" in these cases!)
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