Will heat from soldering affect teflon tape?

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Old 03-23-13, 10:22 PM
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Will heat from soldering affect teflon tape?

I have an old (1950s) Moen brass shower valve body that was originally attached to 1/2" galvanized pipe. Galvanized has been replaced with 1/2" copper. I used male threaded copper adapters at the valve body with pipe dope. One of the adapters has a very slow drip at the thread side. I let it drip for a month hoped it might gather some minerals inside and seal itself. Today I cut the copper, unscrewed the adapter, installed a new fitting using Oatey Great White Pipe Joint Compound with PTFE and reattached the copper tube. It still leaks slowly.

I was considering using Joint Compound and Teflon tape on the threads. Will the heat from soldering affect the Teflon tape? Is there a different Joint Compound or product I should be using?
 
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Old 03-24-13, 12:17 AM
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Yes, the heat from soldering will adversely affect the joint compound you use on the threads no matter what joint compound you use. Best to either solder direct to the valve body (take out the guts first) or use unions or first solder stubs to the threaded adapters first to move the next-to-be-soldered joints further away from the threaded adapters.
 
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Old 03-24-13, 12:26 AM
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Try another male threaded adapter first. Copper is so soft that I have found that many times copper threaded pieces get little burrs or bumps in them which prevent proper seating. If you are shopping at a self serve plumbing section, try hand threading the male adapter into a female adapter until you find one that seats nicely. You will find that many are hard to get a smooth turning motion out of. If you get a smooth one, you will have solved you leak problem.
 
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Old 03-24-13, 12:09 PM
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I'll look for another adapter.

If I have to move the heat away from the adapter at the valve body for the next solder joint how far away is safe to preserve the compound integrity? Currently I have a 1 piece of copper attached to the adapter which means the next solder joint is close. Is 1" too close?

The melting range of Oatey SafeFlo Silver Solder is 420 to 460 degrees (from Oatey tech specs.) The Oatey Great White Compound with PTFE is rated to 500 degrees with liquids and 400 degrees with gases. Seems like they should be compatible.

What about using: Permatex High Temp Red RTV Gasket Maker (handles temp up to 650 degrees)?

Thanks
 
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Old 03-24-13, 12:45 PM
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If you are using Mapp gas to solder your copper, it has a flame temperature of 5300 degrees Fahrenheit. An inch is going to be tight.....

How did you do the first ones as you had the same specs as far as distance.

I stopped using threaded adapters for the very reasons you are experiencing. Instead, I direct solder to the universal rough-in. 1/2 inch copper fits perfectly inside the area where the threads are. It takes a little more heat to get the brass up to temperature to solder but way easier than what you are trying to accomplish.

Try this, as a loose item, thread the adapter onto the valve assembly and crank it down tight. Mark the 12 o'clock position of the tight adapter and unscrew. Solder your components on to the adapter using the mark as a reference point to 12 o'clock. Pipe dope and tape your adapter and thread the pre-assembled units on. Use a slip coupling to make the final connection to the existing supplies.
 
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Old 03-24-13, 01:34 PM
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I got lucky on the other connection (hot side) and, it is 2 away from the threaded adapter. On the cold side (problem side) a 90 elbow has to be installed within 1 of the valve body - a 2 x 4 stud prevents further lateral distance.

How do I solder the adapter into the brass valve body? Do I clean and flux the valve threads, add flux to an adapter, thread it in tight and heat/apply solder? Or, is there a different technique?

When I was testing the valve I used Teflon tape to attach two 2 galvanized nipples with brass adapters to 2 washing machine hoses attached to a water supply of same pressure. The galvanized nipples with tape did not leak. Im think short brass nipples into the brass valve body might work. But, if heat is destroying the compound, are Sharkbite fittings the answer?
 
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Old 03-24-13, 02:37 PM
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No, forget about the threads on the brass assembly all together, you don't use them. 1/2" copper pipe fits inside the opening of the valve assembly. Think of the threaded portion as a oversized coupler, just insert the straight copper tube and solder as you would any other joint. The threads are outside, not used at all, adapter not used at all. Of Course, wire brush, and flux before soldering. The brass takes a little longer to heat up. It may effect the other joints that you taped. Go with the last recommendation. Thread the adapter on, tighten it down, scratch a reference line in the adapter representing 12 o'clock (don't scratch the threads), remove, then assemble and solder pieces away from the assembly, let cool, screw finished pieces (already attached to the adapter) on to the assemble and tighten until your reference scratch mart returns to the 12 o'clock position. Then make final attachment to the supply line with a no-stop coupler that slides completely over the copper tube so you can position the two pipes together, then slide the coupling over the joint and solder.
 
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Old 03-24-13, 03:32 PM
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You can also wrap a wet rag around any previously soldered connections to preclude them from loosening while soldering connections in near proximity.
 
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Old 03-24-13, 04:21 PM
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"The threads are outside, not used at all, adapter not used at all."

The threads are on the inside of the valve body. The adapters were male.

I'm going to try a USA made 90 degree compression on the copper side, threaded on the valve side.
 
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Old 03-24-13, 05:56 PM
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Wow, sorry... I assumed that the adapter was female and not male. That's how all the ones I have dealt with are. Anyway, my alternative of marking a 12 o'clock position should still work.
 
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Old 03-24-13, 08:35 PM
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After my last post the compression/threaded fitting was installed with pipe compound and tape - not leaking. I'll wait a few days before I close the wall. Thanks for your help.
 
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