help on soldering

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Clean it. It may not be necessary, but it takes only about ten seconds. No point whatever in not doing it.

Flux both the pipe and the valve.

That's not helping you. You can solder valves with propane, but it's a *lot* easier with MAPP. It takes a *long* time to get a valve hot enough with propane.

You didn't apply nearly enough heat to the valve. With a propane torch, it can take several minutes to get a valve body hot enough to solder, *long* past the point at which the flux begins to boil.

It's real simple: when the fitting is hot enough to melt solder, then it's hot enough to make the joint.

Yes, but you need to be more patient. It takes a *lot* longer to heat up a valve body with propane than it does to heat up a coupling or elbow.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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I used to do that sort of thing. And did it well. Then, a few years ago, when I was doing a remod where the flame was an issue, I discovered Copper-Bond. A two-part epoxy product that caused me to decide that technology had caused the torch to no longer be necessary. Do what you decide you need to do. But you have my suggestion. Only change I make is to use Q-tip sticks without the cotton, instead of the
provided squarish sticks provided.
snipped-for-privacy@yahoo.com wrote:

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In addition to what every one else said about cleaning and fluxing there is one very important item. You must remove as much water as possible from the pipe system. Any water in the pipe , for 2 or 3 feet, will draw away the heat and you will not be able to get the pipe hot enough to melt/flow the solder.
I was soldering a connection one time and couldn't completely turn the water supply off. I had to open every faucet in the house to divert water away. Luckily there were other faucets that were lower.
A small pump such as a drill powered pump may work to evacuate the pipe.
Kevin
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Hi,
I did practice as everybody suggested and failed again. I used a copper pipe about a feet and had it cleaned, so did brass valve with wire brush and both of them were shiny. I applied flux to both pipe and valve. Then I heated it. I noticed that a smoke came off from the othe end of pipe and the edge of joint turned black and I kept heating until the solder melt, but still it did not flow into the joint. I have removed the shut-off part of valve due to that there is rubber on it. I am wondering whether the flux is no good since after failure, I remove the joint, both surfaces of valve and pipe are black with some kind of oxidized stuff. I believe that those black stuff may prevents solder from working. But I just don't know why. The big problem for me is that I don't know when to apply solder. When solder starts melting at the edge of the joint, is it the right time or not? Since the smoke and black thingy formed during the heating, I don't know what is going on there. thx
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snipped-for-privacy@yahoo.com wrote:

You don;t want the solder there when you start heating the joint. You want the joint to get good and hot first, then apply the solder while continuing the heat. The solder should melt readily when it contacts the joint. If it doesn't, take the solder away and continuing heating, it's not hot enough. The best place to apply the solder is on the side or behing the joint, away from the flame. The heat of the joint should melt the solder, not the torch. You should be holding the flame mostly against the brass valve where it joins the copper pipe.
I've never seen flux go bad. Are you sure this is flux for solder joints? It's normal for maybe a wisp of smoke to show up during heating, but you shouldn't be seeing lots of it and the area inside the joint coated with flux should not be turning black.
What size pipe is this and what kind of torch are you using? Does the torch have a proper pencil point shape blue flame?
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I told you yesterday when to apply the solder. You just touch it and if it flows, it flows. If not. wait. Sounds like you are overheating now.
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Not sure if this is you problem, but you should be using acid type flux for plumbing. Do not use the rosin type flux which is for electronic circuits.
This may not be proper technique but this is what I do: I apply solder to the joint when the metal joint is hot enough to melt the solder - not just the torch flame. That said, while heating, I am constantly testing every 2 or 3 seconds by moving the flame away (flame on pipe but away from joint) for half a second and touching the solder to the joint until I get to the point where the pipe is melting the solder. At the point where the solder starts flowing I just torch everything and feed solder until it looks like solder has flowed all around and the joint is not taking any more - solder is dripping off the pipe. I probably use more solder than is needed.
Kevin
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Thanks everybody for the help, finally I have succeeded and have solered the brass valve for my garden hose. There were 3 things I did differently: 1. I also polished the "diameter" edges of valve and copper pipe along with joint surface 2. apply more flux than I did before 3. stop heating when solder starts melting
I think that step 3 is more important. Since I heard so many things about "propane torch" is not hot enough, I guess that I overheated most of times, and each time I noticed the black thingy. I guess that overheating will prevent capillary action to suceed(my personal opionion). Anyway, thanks so much for so many kind advices and now I consider myself a "half" plumber now.
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Heat the side of the fitting closest to you. Apply the solder from the very first moment you start heating. When the fitting is just warm enough, the solder will flow.
Sounds like you've overheated the fitting, and applied the solder too late.
--

Christopher A. Young
You can\'t shout down a troll.
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Are both pieces perfectly dry as this will affect the solder joint heat the fitting till the solder starts to sizzle then dab the solder to the fitting and keep warm enough to melt the solder then let cool either in air or with wet rag. snipped-for-privacy@yahoo.com wrote:

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