backflow repair

Discussion in 'Irrigation' started by londonrain, Oct 20, 2007.

  1. Call on leaking 1 1/2" back-flow on inlet MA...After further review we suggested the entire assembly be reworked. Cracked MA and compression fittings on both ends= reworked.

    1 1/2" compression fitting...
    replaced the compression fitting on the galvanized 1-1/2" with a 1-1/2" union...
    from the top view you can see how misaligned the inlet side was and caused the MA to crack at the treads...
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,031

    Just curious, couldn't the original compression fitting still work on a stub of sch 40 pipe? (if the elimination of a dissimilar-metals connection was worth pursuing, and said compression fitting a good one)
  3. Since the BF was misaligned and the only way I could see to straighten the inlet side was with four 90's. Then the compression fitting, IMO, would be subject to less lateral support thus the pipe would more than likely come out of the compression fitting under the 100+psi's. Not a big fan of compression fittings on a main line unless there is no way the pipe can move at all..Last thing I wanted was get it all back connected and watch the pipe come out of the compression fitting or a few day later have a 90 with a crack because of movement....been there done that....:hammerhead:
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,031

    I became a fan of 'waterworks' compression fittings when the utility pressure-tested my POC (Ford pack joint) connection, and I suddenly realized I'd forgotten to tighten the outer pipe-clamp screw. Still held fine at about 100 psi.

    (I'd have still opted for a sch 80 union, or even brass - what the hey, it's only {customer} money :))
  5. I went against a sch80 union because if it leaked at the 20 year old galvanized 1 1/2" pipe, I figured I could crank down on a galvanized union greater than a plastic union and have a failure because of a crack. Had a hard time even finding a galvanized union let alone a brass(which was my original plan)....
  6. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,794

    A 1 1/2 brass union would run you about 15-20 bucks. they are not cheap.

    looks good, i would had just used a coupler instead of a union and used the glue 90's as my last glue point.
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,031

    {......if it leaked at the 20 year old galvanized 1 1/2" pipe}

    Maybe if I adjusted the gamma on some of these pictures, I'd see things like the galvanized main. (and aren't they a bunch of fun to play with) - galvanized is certainly the way to go, and as for previous comments....

    "Never Mind"
  8. The only place I was worried about a drip was at the 1 1/2" old galvanized pipe which only had about 2 1/2 good threads left. I was worried about a drip at this point, if I used a coupling and had a drip then complete rework for 1 drip. With a union if I had a drip then I would loosen union, crank on end and re tighten union.
  9. A tip : If you have a threaded PVC fitting break off inside a metal fitting (IE: backflow preventer) , the easiest way of getting it out is with a torch. Heat the broken fitting and pry it out with a screw driver......WARNING - Watch out for the fumes...
  10. BrandonV

    BrandonV LawnSite Platinum Member
    Posts: 4,260

    fire good, me like

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