Low Pressure testing of mains

[OMaille]

Does anyone know of any good documentation on testing active mains under low pressures (long durations)?
I have an existing development to test and will have to test against valves; so i want to try to find a balance between being able to measure the pressure/volume difference and blowing the valves.

 

[dicksewerrat]

A good test has to test at working pressure plus surge. Low pressure won't help you. What are the valves rated at?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[OMaille]

Working pressure + surge may be possible, however most documentation regards rated pressure X 1.5. The valves would be rated above; Working pressure + surge, however they have been in operation for some time and if one was to fail the damage caused to the residence could be high.

 

[dicksewerrat]

Who owns the different parts of the system? Mains, service connections, hydrants?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[gerhardl]

If you test with test pressure above rated test pressure of pipelines and especially valves and other components you will break the pruducers production guarantee, and will risk permanent damage.

NOTE! Valves will have a different test pressure for body (allowable test when valves are open), roughly, depending on types, sizes and pressure class mainly about 1,5 times allowable working pressure, and test pressure against closed valves (test pressure for seats), often at rated class pressure or about 1,1 to 1,2 this value. Figures will vary depending on norm.

You will have to check allowed test pressure for all valves/components and be sure to test below this value. If you need higher test pressure than allowed/given for the valves seat pressure you either have to test with open valves and agains extra mounted blinds, or check with supplier if you for this particular valve can be given guarantee if you test at higher prressure than normally allowd against closed seat.

You might also check your required test pressure by considering the real max working pressure and possible pressure peaks in your line and select your test pressure a reasonable amount (1,2 to 1,5 times?) above this, as suggested by others.