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enter image description hereI found that my above ground replacement sprinkler valve is not a perfect match for the existing pvc pipes. The pvc pipes are 1/4” too close together. I dug down along the pvc pipe to expose the pipe that elbows and continues horizontally to the sprinkler heads in the hope that I could nudge the pipes apart 1/8” each to fit the sprinkler valve.

Will this create too much of an angle and ruin the threading? I am adding a threaded Union to make future replacements easier. Can someone tell me if this is an acceptable adjustment in a sprinkler system—or if it must be an exactly perfect match. I’ve seen other people shift the pipe apart or closer by about an 1/8”. Is 1/4” too much to shift safely? Any expert advice and experience would be appreciated. I’m adding a photo (for some reason it ends up upside down no matter what I do)

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  • pictures, please
    – jsotola
    Commented May 21, 2023 at 4:50
  • Valves should be installed before continuation of the pipe and should be slip connections not threaded if underground. Please post a picture and a better explanation of what you are trying to accomplish.
    – RMDman
    Commented May 21, 2023 at 12:08
  • Thanks for helping-it’s above ground. The vertical pvc pipe extends underground another 8” or so
    – Diy didi
    Commented May 22, 2023 at 18:35

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Threaded connections do need to be aligned fairly well in order to screw together nicely, and PVC unions with o-ring face seals are particularly sensitive to alignment in order to get them to seal.

It's fine to push the pipe around to make it align the way you need it to be. You've done exactly the right thing in digging and exposing the pipe to make it easier to push around. The configuration of the piping below ground plays a big role in how easily they can be moved. Pipe does not compress or stretch along its length but it does flex.

Using the axis of the valve as a reference, after the outlet pipe gets into the ground, which way does it run? If it runs left or right then you can uncover maybe 2-3 feet of pipe and easily bend it the 1/4 inch that's needed to fit the valve. If the pipe runs parallel to the valve body then things are harder. You'd need to dig along the pipe until you find its next change of direction, plus 2-3 feet more -- or just cut about 3/8 inch out of the pipe and then re-join it with a coupler. In that latter case a person would first cut the pipe, second assemble the connection to the valve, and lastly re-join with a coupler at the cut. This sequence ensures that the pipe is re-joined with the riser portion going up at just the right angle and position.

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  • If you really couldn't move the pipes, you could extend them and use a pair of right-angle connections to put a "Z" in one of the legs which moves it about the right distance outward. Rotating the middle leg of the Z a bit would fine-tune the distance between the two pipes. Not the prettiest solution, but it works. ("Remember, if you cut a piece of wire too short you can always splice on another piece, but if you cut it too long you're stuck with it...")
    – keshlam
    Commented May 22, 2023 at 22:15

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