Piping - Flushing and Hydrotest 2

[caet]

I want to know, which one,normally, proceed the other. Any explanation will be highly appreciated.

 

[pennpiper]

Flush first then Hydrotest-- You will want to get the forgotten lunch boxes, dead rabbits, hard hats, gloves and other trash out before you Hydrotest otherwise you could have a false positive (the trash plugged the leak that should have been found by the Hydrotest).

 

[racookpe1978]

Also, if any failures (leaks, open flanges or new cuts needs to to correct problems) occurred during the flush, the fixes get tested during the hydro, rather than requiring a second test.

 

[rconner]

Pennpiper said a mouthful (so to speak) that should be intrinsically persuasive [and may well be also helpful particularly if this is a potable water line, when you eventually attempt to pass coliform testing etc., I guess he could have also mentioned such varmints as skunks, mink(s?), muskrats, raccoons, and snakes that also may tend to favor any open holes and culverts etc!]

I should however also mention that standard ANSI/AWWA C600… e.g. for water piping also contains the guidance in Section 4.3.9 Flushing, “Foreign material left in the pipelines during installation often results in valve- or hydrant-seat leakage during pressure tests. The pipelines shall be kept clean during installation. Thorough flushing is recommended prior to a pressure test. Flushing should be accomplished by partially opening and closing valves and hydrants several times under expected line pressure, with flow velocities adequate to flush foreign material out of the valves and hydrants.”
If you get enough velocity, you might even scavenge out some inadvertently trapped air that arguably could cause problems in hydrostatic testing (see e.g.

http://eng-tips.com/viewthread.cfm?qid=271691&page=1

).

 

[caet]

Thank you for your responses.

 

[BigInch]

What nobody but me's found gophers, prarie dogs, porcupines, badgers, armadillos and a baggie full of weed.

If you find one glove, don't stop until you get the other.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[caet]

Hey Biginch,
Did you censored some items?

 

[BigInch]

Do I have to draw you a picture?


"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv