Rookie install question: Connecting to galvanized mainline?

Discussion in 'Irrigation' started by OKSooner, Jan 20, 2013.

  1. OKSooner

    OKSooner LawnSite Member
    Messages: 235

    Hello everyone,

    After doing service and repair work for the last few years, I'm now getting ready to do my first install - at my own house.

    So, yesterday, in preparation to have a plumber come out and install a PVB, (complying with local codes here) I had a labor crew come to the house and dig up my mainline where it goes under the foundation.

    When we found the mainline, it turned out to be a 1" galvanized steel line. I suppose I shouldn't be surprised at this; the house was built in 1933.

    So, here's the deal. This is probably a dumb question but I ask it because I don't know the answer. How do you tee into galvanized pipe for a new install? (Or more to the point, how is the licensed plumber I hire to install the backflow going to do it?)

    I figure there's gotta be a way because of the number of irrigation systems I see on older homes around here, but still... HOW? Not only is it steel, it's all rusty and grody on the outside from having been in the ground for gee... 80 years. He cuts it for some kind of tee fitting and then what is there? Two rusty old pipes?


    Any pitfalls/hazards/tradeoffs/caveats/warnings to take into consideration?
  2. NC_Irrigator

    NC_Irrigator LawnSite Bronze Member
    from NC
    Messages: 1,455

    I would replace the entire line to your house from the meter with SCH40 PVC or Copper Type K. Check local codes and depth requirements. You can do the work yourself since it is your property. You still probably will need to pull permits.

    Also you need to check local codes to make sure you dont need a separate meter for your irrigation that you want to install. Most areas wont allow you to tie in to your "house meter"

    If it is allowed and you want to go ahead and do it;
    You can rent pipe die threaders that is a hand held ratcheting type threader.
    You will have to cut a section of the metal pipe out and thread both ends and then install the T and rejoin the ends together. Be sure to install a QUALITY shut off valve underground before the backflow preventer for service of the irrigation system.

    I guess the PITFALL or WARNING would be that if the steel pipe has substantially aged it could be brittle and unable to thread once you cut your section out to make the T. So thats why im recommending you replace the entire line that feeds your house. Also galvanized piping collects corrosion on the inside of the pipe and gets worse over time, eventually stopping the water flow.

    ALSO, if you decide to go ahead and replace the ENTIRE line, I would have someone with a camera run down your sewer line from your house to the street and check that pipe integrity as well. It would be convienent to replace both lines at once, since they were probably installed in the same ditch up to your house.
    Last edited: Jan 20, 2013
  3. SoCalLandscapeMgmt

    SoCalLandscapeMgmt LawnSite Silver Member
    Messages: 2,155

    Cut the galvanized line and thread it. Or do it half assed and use a compression tee.
  4. OKSooner

    OKSooner LawnSite Member
    Messages: 235

    Thanks. Our code allows the irrigation system to run off the residential meter. Businesses are required to run a separate meter. Not sure why, but that's the way our local inspector says. Thanks for the tip about the sewer line, but in our case it runs to the opposite side of the house.
  5. OKSooner

    OKSooner LawnSite Member
    Messages: 235

    Thanks for the reply. Again, I'm having this part of the project done by a plumber, as is required by my local code. If I choose to proceed in this way I'll make sure he threads it.
  6. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,335

    Agreed. Galvy that old is nothing short of a nightmare.
  7. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,335

    Using an appropriate compression tee is not half-assed.

    Trying to thread galy pipe that old is ridiculous. I've seen galvy pipe in the ground younger than that where I could almost poke my finger through it.
  8. SoCalLandscapeMgmt

    SoCalLandscapeMgmt LawnSite Silver Member
    Messages: 2,155

    Guess it depends on the line. I've threaded 2" galv lines that were 35+ years old. And just to ease your mind when I said that compression tees were half assed I was referring to those plastic compression tees that they sell at Ewing.
  9. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,358

    Regardless, a union or compression fitting is gonna be required.
    Posted via Mobile Device
  10. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,171

    The man from California speaks the truth. The only time I've used compression couplers was on a Friday afternoon with a long weekend. I could then get back to repair it properly the next week, which usually entailed replacing the galvi.

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