thrust blocks

Discussion in 'Irrigation' started by tonypop, Mar 13, 2006.

  1. tonypop

    tonypop LawnSite Member
    Messages: 5

    :confused: Does anyone installing systems on athletic fields use thrust blocks, seems that all installs I have seen lately they have been omitted, have I been missing something? have been using 2mil poly backed up with 12.00 concrete.
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    We only thrust block on 4" or larger PVC.

    We don't do Poly out here, so I don't know about thrust blocking poly.
  3. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    We don't use poly here either. We only thrust block large main lines if the line can creep straight out. But you're right... thrust blocking seems to be on the decline except for those special occasions. Don't know if this is the result of better glue or installation practices like butting a 90 against virgin compacted soil, etc.
  4. tonypop

    tonypop LawnSite Member
    Messages: 5

    Thanks Jon; Engineering specs for county calls for blocking 3 in.down to 1.50for this install, can see blocking the 3 in.,but was skeptical abouut the rest. will have to debate this. no fun wrapping plastic and pouring concrete.
  5. ESprinklers

    ESprinklers LawnSite Member
    Messages: 39

    I can see using a thrust block on the 3" and larger pipe, but for 1½" stuff. If that was the case, we would be using thrust blocks all the time.
  6. Green Sweep

    Green Sweep LawnSite Senior Member
    Male, from Pittsburgh, PA
    Messages: 322


  7. PSUturf

    PSUturf LawnSite Senior Member
    Messages: 663

    For me it would depend on the operating pressure. I would use some sort of thrust block on just about anything if the pressure is 100 psi or higher. Most of my irrigation background is golf so maybe you don't see the higher pressure on athletic fields.
  8. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    I'm wondering if the people who advocate thrust blocking are also the ones who are into using gasketed pipe and fittings as well? I could see water hammer blowing a gasketed fitting apart long before a glue one. But then again, those are a real PITA to get together, so maybe I'm not giving them enough credit.

    A properly done glue joint should be stronger than the pipe itself, If the pipe is butted up against virgin soil I can't really see a need for thrust blocking on smaller pipe.

    We maintain/install additions a condo complex that has 3" and 4" mains (Around 85-100 PSI pressure) all over the place. As far as I know, none of the 3" is thrust blocked, and its been doing fine for 15 years.
  9. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    A properly seated gasketed bell joint actually sucks in farther than a glue joint. If your're using cast els then it's a toss-up as far as depth is concerned and I'd thrust block those. We also do use glued els/tees on gasketed pipe and never had a problem.

    I can remember one main line project about 12 years ago where gasketed pipe was a real PITA. It was Crestline pipe and the beveled ends were too steep. We had to take a file and re-bevel each end and then push them together with a Case trencher's front blade with LOTS of "duck butter." I have used gasketed 6" and 8" pipe before that has gone together swiftly with nothing more than a pry bar applied to the end of the pipe.

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