Trying to eliminate bead of water inside wall from new shower arm

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Neil.Steiner

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I set out to replace a shower head and realized I would have to also replace the shower arm, since the ball at the end of the existing arm doesn't unscrew. So I used a 1/2" tap to clean up the threads inside the wall, before putting 5-6 turns of teflon tape on the arm and screwing it in. I went hand tight, and then did I think two full turns with pliers. (It's really awkward because the ceiling is low.) I placed a 1/2" cap on the other end of the shower and turned on the water, and saw no leaks. So I took a shower and looked closely inside the wall afterward. I saw a tiny bead of water inside the wall right at the top of the arm, and evidence of at least one drip from the bottom of the arm, also inside the wall. I got the locking pliers back out, forced the arm to make another full turn, nicely scratching the arm in the process, and hoped for the best, but the next day I again saw a bead of water after taking a shower.

I'm pretty sure I wouldn't be able to make another turn with the shower arm, at least not the way I did it, so I'm wondering what my options are. On one hand, even though I used a tap and thought I had done a good job, perhaps I need to tap the threads some more. I might possibly damage the female pipe head in the wall in the process, and that would be unfortunate. Or I might tap it too far, if such a thing is possible. Or if I'm willing to make this my forever-shower-arm, I could put some loctite on the threads when reinserting the arm. Or I could modify my technique and try to force the shower arm to make another turn by putting a screwdriver or a wrench handle into the arm, but I already deformed the outside of the arm a little out of round near the head just to get enough leverage to turn it as far as I did. I suspect that mineral deposits would eventually seal up whatever path that little bead of water has found, but I don't like leaving knowns leaks inside walls. Any suggestions for me?
 

Jadnashua

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Did you use an IPS tap, or straight threaded one? It is normally nearly impossible to thread in a properly done IPS pipe thread with 5-6 wraps of tape...that just makes it too tight and the tape may just be balling up around the end rather than getting jammed inside of the threads. IPS is a tapered fit and the pipe dope or tape gets jammed in with that taper like a wedge rather than a cap.

screwdriver-shower-arm-leverage.jpg
 
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Neil.Steiner

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[Am I confused? When you asked about IPS (straight) versus straight threaded, didn't you mean NPT (tapered) versus IPS (straight)?]

I used an NPT tap because that's what the shower arm threads are. Doesn't NPT require tape or pipe dope to allow the two parts to screw tightly enough together? Or are you saying that I used too much tape? But the shower arm is stainless steel, which I'm sure is not as soft and deformable as brass.
 

Reach4

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I placed a 1/2" cap on the other end of the shower and turned on the water, and saw no leaks. So I took a shower and looked closely inside the wall afterward. I saw a tiny bead of water inside the wall right at the top of the arm, and evidence of at least one drip from the bottom of the arm, also inside the wall.
I don't have a good picture of the symptoms. I have no expertise on this, but your situation sounds interesting.

You get no leak under pressure. You get moisture after showering with a non-closed showerhead. I am thinking either
  1. condensation from a cold shower pipe?
  2. water traveling on the outside of the pipe, past the escutcheon, through the hole, inside of the wall.
  3. water splashing to the wall, and the wall not being waterproof enough to stop flow inside.
These each seem unlikely. But given the no-leak with the capped pressure test, I don't see the water coming out of either port on the elbow up top being the source of the water.

I would consider tying a paper towel etc around the shower arm just outside of the wall. Take a shower. Does that paper towel stay dry? If not, the water may be somehow coming in from the shower area.
 

Jadnashua

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Five wraps of tape is often too much for the pipe to actually start properly into the fitting and will tend to roll back the tape as you insert it. Yes, a tapered pipe thread requires something to keep it from leaking. If you had use a straight thread tap, it would leak with tape. Often, you can adjust when the fitting gets tightened where you want by adding another wrap, but there are limits. Some people use the belt and suspenders solution by using both tape and pipe dope. Normally, though, if that extra tape was used to adjust where it tightened, you can normally make another full turn if needed after you think it's tight enough to get things to align. Note, if you threaded the fitting too deep, it's possible it bottomed out versus wedging in, and it could leak as a result of that. More tape in that case, might get it tight enough higher up. If that is your situation, I'd use the belt and suspenders approach.
 

Neil.Steiner

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Concerning pipe dope, I see that I had a can of never used RectorSeal 5 from many years ago, but was a little astonished to see the dope completely yellow. I thought it was supposed to be white, and the pictures or videos I've seen online show it white. Is there any case for concern?

On the back of the bottle, it says "For use in devices handling gasoline, petroleum oils and butane not exceeding 2 in. pipe size." But elsewhere on the back it also says "For use with potable water (hot or cold), DW, natural gas and LPG, compressed air and most other industrial gases."

Anyhow, is there any reason why I shouldn't use this simply because it's yellow in color?

Z.jpg
 

Jadnashua

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I'm not positive, but it may be yellow to signify that it is rated for use on natural gas and other connections related to hydrocarbons. If it says it's okay for potable water, use it.
 

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