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Mainline piping Schedule or Class PVC

Discussion in 'Irrigation' started by Planter, Jan 6, 2002.

  1. Planter

    Planter LawnSite Member
    from Utah
    Messages: 214

    What are you guys using for mainline, schedule 40 PVC or Class 200? Here many use schedule 40 in a main that's under 2 1/2 inches and class 200 when it's over 2 1/2 inches. They then use class 200 for the laterals.

    I have often wondered if there was a problem with class 200 for a mainline. We are using it for the laterals and it has to handle the pressure and water hammer for that, so why won't it handle it for the main? I realize the main in under constant pressure, but does that make a difference here?

    I have seen polyethelyne used as a main and it has a lower pressure rating than the class 200.

  2. longslawn

    longslawn LawnSite Member
    Messages: 201

    We use class 200 for the main and laterals. We use schedule 40 if it is rocky soil. I think class 200 can withstand 160psi. We never have that much pressure here. I have use 200 class for 12 years and have not had one failure yet due to pipe.

  3. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Messages: 1,712

    Guessing only becasue I don't have the site conditions, sch 40 for main and class 200 for laterals if you have rock. If it is sharp rock maybe sch 40 for all. Sch 40 has a thicker wall and would stand more abrasion.
  4. SprinklerGuy

    SprinklerGuy LawnSite Bronze Member
    Messages: 1,778

    schedule 40 for all mainlines.....see more and more commercial jobs aroundhere using cl200 for main though. They must have been cutting costs to save money?Or to make some profit.?
  5. Planter

    Planter LawnSite Member
    from Utah
    Messages: 214


    What is the diameter of the class 200 they are using on commercial sites?

    Class 200 has thicker walls than schedule 40 in the larger diameters.

  6. G.Williams

    G.Williams LawnSite Member
    Messages: 36

    Schedule 40 on all main piping to valces and thinwall there after.
  7. gusbuster

    gusbuster LawnSite Bronze Member
    Messages: 1,930

    A lot of the local municpalities(my area) by code require at least sch 40 and must be virgin plastic for valves. They are starting to allow the use of class 200 pipe if it meets a min. pressure rating. Freezing is not an issue but sharp edges from our clay\rock soils can crack due to settlement. The cost between the 2 is not that much. Last time i checked, schd 40 was $.20 more expensive.
  8. Lance Takara

    Lance Takara LawnSite Member
    Messages: 73

    Planter's on the right track. The s40 pipe wall thickness is fairly constant over small to large pipe sizes. Therefore the pipe pressure rating ranges from a high of over 600 psi for 1/2" pipe to less than 200 psi for 6" pipe. Class 200 pipe has a constant pressure rating of 200 psi. Therefore its wall thickness increases as the pipe diameter gets larger. At approximately a 4" diameter pipe, the pressure rating (and thickness) are about the same.

    In other words, s40 pipe is thicker from 1/2" to about 4 or 5" then class 200 is thicker for larger sizes.

    We use S40 for all mains and laterals for 2 main reasons. Relatively speaking, the cost difference for class 200 is insignificant (for residential projects) and class pipe is too easy to break when future planting is done where any digging is involved. That is regardless of how deep the pipe is buried unless it is to a ridiculous depth. Basically, for an insignificant material cost increase, there is more insurance against accidental physical damage to the piping.

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