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The instructions for my Kohler Wall-Mount Supply Elbow say to leave the NPT nipple sticking out of the wall 9/16". I did that but now I can't tighten the elbow all the way to the wall as I'm supposed to. The more I tighten, the more I feel like I'm going to break something -- and I still have over 1/8" inch to go.

What do I do? I feel like I have two options

  1. Keep tightening
  2. Replace the NPT nipple with a shorter one if there is one available (current is 3 1/2")
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  • Are you using pipe dope (tape or paste)? – Tester101 Jun 14 '15 at 16:03
  • @Tester101 I was using nothing at first just to test fit but then I put some teflon tape on just to see if that would somehow help. It didn't. I also have paste around here somewhere – Joe Phillips Jun 14 '15 at 17:25
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Replacing the current pipe nipple with one that is slightly shorter is the best way to go here. The thing to do is to simply cut off the length of the current nipple by the requisite amount and then get that end threaded slightly more. The re-threading step is necessary because the pipe nipple threads are a tapered thread.

If you do not have the tools to re-thread the pipe yourself it is a service often offered by the bigger old school type hardware stores. A machine shop or plumbing shop are places where you could likely also get this service.

Edit:

It occurs to me that if you have only 9/16" of the pipe nipple projecting from the wall that it may be somewhat difficult for you to remove the thing using conventional plumbing tools. A typical pipe wrench would gnash the threads as you tried to remove the nipple.

There is a special tool just for this purpose called an internal pipe wrench that can be used from inside the nipple to remove the long one and re-install the shortened one. These are available from most tool suppliers including via Amazon.

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  • Thanks for the great answer. Do you happen to know why I'm running into this issue? Is it common? Did I make some bad assumptions somewhere? – Joe Phillips Jun 14 '15 at 15:00
  • @JoePhilllips - I cannot say for sure why you may be having this problem but I can make a couple of guesses. 1) Pipe threads are tapered and it could be that the nipple that you selected was not threaded quite as much as a should be. This would cause the joint to tighten up in less length than normally. 2) Maybe you put too much TFE tape in the joint and it got tight sooner than expected. 3) Maybe there is something about the Kohler fitting you are trying to attach that is a little off such as not having been threaded to quite as much depth as a normal fitting. – Michael Karas Jun 14 '15 at 16:59

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