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Unions Vs. Slip-Fix for repair situations

Discussion in 'Irrigation' started by RhettMan, Aug 28, 2013.

  1. RhettMan

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,570

    I like that unions seem to hold the pipe "steady-er"

    I like that Slip-Fixes are easy.

    But I'd like to hear your thoughs on advice on when to use one, and when to use the other, in certain and differing situations.

    Please sirs
  2. bcg

    bcg LawnSite Bronze Member
    from Tx
    Messages: 1,865

    Slip-Fix on laterals, fix the pipe on the main (usually do 4 90's or 4 45's or dig and use a couple of couplers). I don't typically use unions except for larger valves (1.5" and up) or occasionally for a backflow.
  3. RhettMan

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,570

    thx , before i forget i also want to ask:

    if one were to tighten a union to the best of his hand-tightening ability, what PSI might it be expected to hold? (specifically: at the gasket-compression point)?
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,267

    depends on who made them - get KBI sch 80 unions
  5. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    I prefer spears unions myself.
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,267

    KBI, pre-buyout by NDS, was my go-to choice, as I could get them by name, and the union threads are larger in diameter than most, and that makes them stronger. Suppliers are just as likely to have a made-in-China sch 80 union in the shelf cartons these days.
  7. SoCalLandscapeMgmt

    SoCalLandscapeMgmt LawnSite Silver Member
    Messages: 2,117

    The Nibco slip-fix are the best IMO. I've been extremely disappointed with the Spears slip fix type repair couplings. We've had a large number of them fail in the last year, mostly from cracking and splitting. This is surprising given that Spears makes the best PVC fittings in the industry. We pretty much use slip fix for all lateral and main line repairs from 1" all the way up to 3". Depending on the situation we will occasionally repair a main with a union or by building a bridge out of 90's but that's mostly when we are dealing with large trees and we don't want to disturb or cut the roots. The thing about slip fixes (as I'm sure you all know) is that they have to be absolutely straight. They cannot have even the slightest bend or they will leak or crack. If you keep them straight and you measure everything precisely then they will pretty much last forever.
  8. ArTurf

    ArTurf LawnSite Platinum Member
    Male, from Ark
    Messages: 4,263

    Regarding expansion couplings, do you install them mid or full extension?
  9. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,100

    With changing velocity, that slip-fix will move around. Best to measure and get it fully extended. That said, I still like unions or 90 ring-arounds.
  10. greenmonster304

    greenmonster304 LawnSite Gold Member
    Messages: 3,589

    Recently we did a job where we pulled in 1200' of 2" PVC mainline with wire. We glued up 200' sections the day before. We dug pits and used sch 80 KBI unions to join the 200' sections. I just didn't want to install slip fixes on a brand new system.

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