Sealing straight threads

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CleRob

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I have a Grohe shower system that I will be installing in a couple of weeks. The adapter between the water supply (hot and cold) and the unit itself are straight pipe threads. I'm assuming that Teflon tape will do for sealing these threads but I've seen plumbers use cord and compound on these threads (you rough up the threads and apply the cord and compound. I'm hoping Teflon tape is good enough for this. I know the straight thread to pipe thread can't be sealed with Teflon. Anyway, input is welcome.
 
If Grohe USA is still using straight pipe threads these days, then they include the stupid "thread". Hard to imagine why they still do it.
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You have to scr@w up the fitting, then use string to seal the joint.
It's a wonder they don't tell you to use oakum and molten lead.
On the remote possibility that I might want to use this method to seal straight threads on a wall mount pot filler, what would be an appropriate thread to use. I am old enough to remember using oakum. The Amazon ( China special) supplier does not think it is necessary to provide such thread. I am considering using waxed flossing thread. Stop laughing, this is serious business here. My wife is already clicking her fingernails on the countertop. Opinions please. The good news in this is, if that fails to work, I can use it to go ahead and hang myself.
 
On the remote possibility that I might want to use this method to seal straight threads on a wall mount pot filler, what would be an appropriate thread to use. I am old enough to remember using oakum. The Amazon ( China special) supplier does not think it is necessary to provide such thread. I am considering using waxed flossing thread. Stop laughing, this is serious business here. My wife is already clicking her fingernails on the countertop. Opinions please. The good news in this is, if that fails to work, I can use it to go ahead and hang myself.
Take a pic of what you’re working with
 
As per your request. Here are the pics. What you are seeing is brass nipple with std tapered thread on the wall side. The exposed threads are straight cut. The faucet fitting has a very short straight thread. Hope this helps.
 

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Tape and dope it then try it out. If it leaks send it all back to where you bought it. Or use some string stuff from Grohe.

Or use some waterproof thread locker and let it cure. I’ve never resorted to that though.

Good luck 👍
 
THX for your reply. Sorry, I couldn’t get a satisfactory pic of the interior of the valve. There is a machined flat seal face. Positioning of the valve body is critical and I have cut two or three flat washers to try when final Assy occurs. At this point in the discussion I believe that the best solution is water proof thread sealant/locker. I have a pending query to Permatex regarding its product’s viability for this usage. Further, the faucet comes with a flanged set screw collar which allows me to mount to the wall and use the set screw to prevent the brass nipple from turning during usage in the extended position. Right now my main concern is sealing the straight thread. I am rapidly reaching the point where I say, Wifey, fill the pot from the faucet on the prep sink just behind you.
 

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THX to all for your well considered replys/suggestions. Problem solved!!! Permatex seal and lock 57537. I tried machining a brass adapter to present a flat seal surface but space constraints became an issue so I buckled and went with the easy way out. This stuff is not cheap - 1.5 oz for $45 and it is also rated permanent. THX again
Doug
 
What does the manufacturer recommend?
Thanks for your interest. Perhaps some history/social commentary will put things in perspective. Retired to Mexico - 2006, built and occupied my home in 2008, used all top of line plumbing equipment (Koehler & Moen) - 2008-2018, “happy, happy life”, 2019 , failures begin, first kitchen faucets drip, no big deal, during trip to US I purchase necessary replacement parts. 2020, pot filler starts dripping around knuckle O-rings, can’t find replacement O rings - out of service until 2022. Mistake #1, I go to Amazon! Mistake #2, I order a new unit, no brand name but decent price. If you haven’t noticed, you can never find a direct connection to any information of value regarding what you have just purchased. In short, I don’t have a clue who the manufacturer is. Further, I have managed to make a connection that does not currently leak. Thank God I don’t have that much life left in me. My fervent hope is that I pass on to my final reward before it does. Have a nice day. I will!!! The sun shines, the water is beautiful, my wife still loves me and I don’t have to worry about what will happen next.
Regards to all,
Doug
 
I realize this is an old thread, I've got a similar problem. Bought a fancy Grohe shower system and it uses straight pipe thread and I can't get it to seal. I used the piddly little sealing cord that came with it, no dice. Bought some Loctite 55 sealing cord and it sealed - for a couple of months maybe. It's now leaking again.

So Dougr, I hope you are still getting notifications from this thread. Did the Permatex 57535 stay sealed?
 
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