Going nuts sweating 3/4 valve!

cwilliams2000

Sorry for such a basic post, I have sweated at least two dozen fittings over the years general trouble free. I was trying to replace a leaky 3/4" valve and didn't expect so much trouble.



I have failed now 2 times and before I attempt the third, it must be water in the line since basically I can never get it hot enough, and I am using mapp and when I take it apart some water comes out. I let it drain forever, opened and closed fixtures with no success



I havent ever tried the bread trick and saw that oatey sells some poly something that you put in the line.



Can someone tell me if it is common to use the stufing to keep the water back for a few minutes while you sweat it out, I think all my previous work was always on totally dry or new pipes



I just wonder if I am missing a trick to get the water out of the line or if the stuffing is the way to do.



Thanks very much!

Chris

bob_46

Bread

Bread works, done it many many times.

hot_rod

white bread

not wheat!



Shove the bread up the line as far as possible and move fast with the torch and solder, start at the bottom of the joint with the solder.



Remember the bread residue ends up at the first faucet you open, flush it well or it plugs up wash machine, dishwasher and any other device with strainers.



Use to be Hodes and a few other plumbing parts suppliers sold mineral oil capsules. Looked like a jelly bean. Shove it in, solder then heat directly on the "bean" to melt it away. You may still find a product like that at the box stores.



hr

Timco

vac

I put a shop vac over the pipe to be sweated and let it suck (use tape to make a seal) for a while. Open fixtures when you do this...usually gets all the water out quick. If not that, I use 'jet sweat' tools that have an expanding stopper that allows you to seal the pipe several inches back, then sweat on a union or ball valve. The bread does work, and smells really good while the heat is being applied. Typically mapp will overcome a small dribble, but not a steady small flow.



Tim

Jim Bennett

You can't sweat.....

a line with water in it. It helps if you can prop the area up with something so any water can drain away from the area while you are soldering.



The line also needs to be open somewhere so it can vent. When you are heating the fitting, air inside will expand and any water droplets nearby will become steam. If there is nowhere for this pressure to escape, it will vent through the molten solder of your joint and as it cools and solidifies, it will leave a void in the joint that will leak. Open a nearby faucet or, if it is a valve with a waste, open that.



Clean and flux both the pipe and the fitting. After it is clean, do not touch the clean area with your fingers.

Timco

beans

I used the bean type stops once, and it melted while sweating and poured flame out of the pipe. The oil in it was very flammable and I could not believe how much fire poured out of the pipe as the oil from the bean ran out. Would have burned me or certainly caught a box or such on fire. Be careful with those...just my experience...



Tim

Jack

I don't try to make it work...more than once anyway

By the time I screw around with a wet repair I can cut in a union upstream on the wet side. I clean the copper where the union will go prior to cutting. You then have a clean base to work from and that is what this is all about. As well it makes it so much easier to deal with the failed joint, either by disassembly and/or re-sweating.

hot_rod

compressed air or

will blow out systems also, the reverse of what Tim mentioned. Dahl and others make compression valves for "wet" repairs or a press fitting.