Connecting Dissimilar 3/4" Irrigation Pipes

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Joe Berni

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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
 

Reach4

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You should get a digital caliper and measure.

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

hj

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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.
 

WorthFlorida

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......with a new sub-surface drip irrigation system. .....Thank you, Joe

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
 
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Joe Berni

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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.
 

Reach4

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I purchased a caliper today and the OD is 1.07" and the ID is .88". I tried PEX fittings without success.
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.
 
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WorthFlorida

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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
 

Joe Berni

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I finally solved the mystery. The pipe is from an old company named Rain Jet (acquired by Toro). The pipe is one-inch CTS polyethylene tubing. without the usual markings. The ID is 7/8" and there is a part specifically for connecting these older pipes to 1" poly, which I found under the name Spears Rainjet Adapter Fitting Poly, 1"x7/8".

Thank you for everyone's help! I hope this info helps someone else down the road...
 
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