Connecting Dissimilar 3/4" Irrigation Pipes

Discussion in 'Irrigation / Sprinkler Forum' started by Joe Berni, Jul 9, 2018.

  1. Joe Berni

    Joe Berni New Member

    Joined:
    Jul 9, 2018
    Location:
    Denver, CO
    Hello everyone,
    I recently purchased a new house and replaced an old system with a new sub-surface drip irrigation system. One zone required that I use the piping from the old system because it passed under a large flagstone patio, leaving me no way to bury new piping to this front yard zone.

    Upon trying to connect the old pipe to the new pipe installed under the front yard I found that the old pipe was just a tiny bit too large for the standard 3/4" connectors I had been using. I went to Home Depot, found someone who seemed knowledgeable in plumbing, and we were both at a loss. We could not find anything that fit into a piece of the old pipe (slightly larger than modern standard poly).

    He suggested that I use a brass barbed coupler and shrink down a piece of electrical shrink wrap on the side meant for the old piping. I did this, but after two weeks this connection has burst (the system is at only 40psi, btw).

    By chance does anyone have ideas about how to make this connection? I'm guessing that it's fairly old pipe and standard sizes were slightly different from back then, but I cannot find any evidence of this after much time searching.

    Any help would be greatly appreciated.

    Thank you,
    Joe
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    You should get a digital caliper and measure.

    Check the fittings for 1 inch PEX. That might be a good size for you.
     
  3. Sponsor

    Sponsor Paid Advertisement

     
  4. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    quote; I'm guessing that it's fairly old pipe and standard sizes were slightly different from back then, but I cannot find any evidence of this after much time searching.

    And you probably will not. The plumbing industry does NOT arbitrarily decide to make different sized pipes other than the "normal" ones.
     
  5. WorthFlorida

    WorthFlorida Don’t you hate that, take a seat and no paper!

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    How wide is this patio? What type of material is this old pipe? It is a threaded nipple? Male or Female? You might be able to find a heater hose for cars that can slide over the old pipe and clamp it. But to get the new end to mate might be just as difficult. If the old pipe is PVC cut off the end, get a 3/4 glue union and if it doesn't fit, with a grinding stone or sand paper, sand down the old pipe to fit the new glues joint union.

    Another solution is use this old pipe as a conduit. As long as there are no 90 degree bends you might be able to slide in a 1/4 drip tubing (using a fish tape). The outside diameter is .245. (1/2 drip tubing is .700 OD and that would not fit inside a 3/4" pipe. )

    A slight chance that a 1/2 CPVC pipe might work. It's 0.625 outside diameter but CPVC to NPT fitting is sometimes hard to come by and you would not be able to use any unions since it be wider than the 3/4 pipe. HD may only have 10' lengths but plumbing supply houses may have them in longer lengths.

    Depending on how wide this patio is and soil under it, in Florida with all of the sandy soils, the cable guys use PVC pipe with a garden hose fitting and with the water on they push the pipe under the slab or patio and let the water do all the work. Most driveways are no less than 16' but I've seen them do about double that with. If you YOUTUBE search "boring under a driveway" there are plenty of home made ways shown.

    https://www.homedepot.com/p/Rain-Bi...PIPHorizontal2_rr-_-204751445-_-202078362-_-N
     
    Last edited: Jul 12, 2018
  6. Joe Berni

    Joe Berni New Member

    Joined:
    Jul 9, 2018
    Location:
    Denver, CO
    Thank you Reach4. I purchased a caliper today and the OD is 1.07" and the ID is .88". I tried PEX fittings without success.

    WorthFlorida, thank you for the great idea. I loved the idea about using the existing pipe as a conduit, but unfortunately there are likely 90 degree bends and I already have the drip line installed in the zone that is causing me this headache. The patio is about 50' long and is on top of Colorado clay, so boring under isn't an option either.

    There is no threading on the pipe. It looks and acts just like poly, except for its dimensions.
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    1-inch PEX is 0.875 inch ID, and 1.25 OD. Your ID looks like a nice match for a PEX crimp or clamp connector. I would think you could use a 1-inch PEX fitting (NOT a fitting made for expansion, but one made for crimp or clamp). If the fit is a bit tight, maybe gently heat the tubing a bit. Then put 2 worm gear hose clamps in place, with the worm gears staggered.
     
    Last edited: Jul 12, 2018
  8. Joe Berni

    Joe Berni New Member

    Joined:
    Jul 9, 2018
    Location:
    Denver, CO
    Could it be schedule 10? ID I found for 3/4 schedule 10 is 0.884 (my measurement was 0.8835).
     
  9. WorthFlorida

    WorthFlorida Don’t you hate that, take a seat and no paper!

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    If you can find a machine shop, have then fabricate a fitting with brass stock or other material to fit this poly pipe and use clamps. Th eother end can be cut and threaded to NPT.

    It could be the original black plastic pipe that came tobe in the 1960's and it was a poly pipe like material. I think at the time it was called funny pipe but not the same funny pipe as of today. My dad used clamps on the fittings. It was a very rigid flexible pipe.

    Around 1965 we hand drilled (rammed a pipe 23' into the ground with a 50 lb weight) a well in the basement and use this pipe to bring the water to outside spigots. It looked like this poly pipe from AU. https://smartwatershop.com.au/product/ld-poly-pipe-19mm/ld-poly-pipe-19mm-x-200-meters
     
Similar Threads: Connecting Dissimilar
Forum Title Date
Irrigation / Sprinkler Forum Disconnecting the hose at the sprinkler head barbed fitting..... May 11, 2017
Irrigation / Sprinkler Forum Connecting irrigation to water main with pex homerun system Apr 11, 2012
Irrigation / Sprinkler Forum Connecting one valve to two stations to get more cycle times Jul 2, 2009

Share This Page