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I tried soldering some 1/2" copper (to make something like this) and some of my joints are horrible.

I tested it with water and some of the joints leak.

  1. What is the best way to fix the joints?

  2. What is a quick and easy way that will work?

These pipes do not need to much pressure. (they are fed fluid from a holding tank into a float valve - the tank is about 100 gallons and sits about 3 feet above the float valve)

I cleaned them and fluxed them before attaching but since the joints are so close together I am not sure if I burned off the flux in the unsoldered joints before I got to them.

I might also have a torch that is too hot?

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You mentioned your torch might be too hot. Usually it is the opposite - it is not hot enough. Assuming you are using a propane torch, if you plan on doing anything other than a couple solders in your lifetime it might be worth getting a Propylene Gas (MAPP) torch instead. Also, make sure your pipes are dry before starting. Any amount of water in the joint will cause it to fail. –  Steven Jan 6 '12 at 14:16
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Agree with using MAPP. Also, the joints need to be cleaned well.. and your flux (and brush) should be clean too (eg. it's pointless to clean everything and then use a dirty brush and/or dirty flux). The fitting should be hot enough that when you touch the solder to the joint, it "sucks" it in and basically goes all the way around (sometimes you have to touch it to the opposite side to ensure it's all sealed). If you have water in the joint, this won't happen, and you won't get a good joint. –  gregmac Jan 6 '12 at 16:05
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5 Answers 5

Just heat the joint up with your torch, once the solder starts to melt use Channel locks to pull the fittings apart. Once the joint is apart, wipe as much old solder off as you can with a rag. Now you can start over. Clean, Flux, solder.

You should not be applying flux to joints you are not working on, take each joint one at a time. If the joints are all close to each other, try doing the joints out of order. Solder one joint, then move to a joint further away, then back to a joint near the first, etc. This should allow some of the heat to dissipate, and reduce the chances of overheating the joints.

Don't forget to wipe excess solder off the joint before it cools using a damp rag, nothings worse than an ugly joint (except maybe a leaky joint). And don't forget, soldering pipes is an art. And like most things, it takes lots of practice to get good at it.

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Thanks. I've always been able to make good joints when doing house plumbing - the problem arose because these were many joints all in a 2 foot square area and no way around doing both sides of a The problem is that there was no way around wet fitting some joints all at once. I have to rebuild this from scratch –  Tim Jan 6 '12 at 14:17
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Just appltying flux to the joint after its heated up and seein the solder become molten(flux acts as a cleaner).. aplying more solder(solder stick to clean copper) will solve the problem. you do not really need to pull it apart. I had this situation with many contract plumbers after a site build is complete and a leak develops in the ceiling.. just re-apply.. solved. Be sure to flush the pipes properly before using. If going to be used for liquids like making cider or some other compots.. flush frequently to prevent micro bacteria build up. –  ppumkin Jan 6 '12 at 16:52
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Because all of these joints are really close together, you will probably have to redo them all. At a minimum you need to heat up the leaking joints and pull them apart, and then re-solder them.

I doubt you are making them too hot, it is too hot if you get the copper glowing orange/red or if the pipe or fittings are deforming.

I use a MAPP torch and my process is something like this.

  1. Clean the pipe and fitting.
  2. Go crazy with the flux, flux is your friend that "sucks" the solder into the joint. Do not skimp on the flux.
  3. Heat up the fitting, when the flame turns green it is hot enough.
  4. Quickly add the solder all the way around the fitting. It should melt immediately and get sucked into the joint.

I am not great at soldering so I find it really helpful to have someone else help. One person can use the torch and other uses the solder. That way you can start soldering right when the torch is off of the pipe.

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One other note to add to your process: start applying the solder to the side opposite the heat. The flux should pull the solder all the way around toward the heat if you're doing it right. I learned this while replacing fixtures in a bathroom remodel recently, and it worked well for me. –  Mike Partridge Jan 10 '12 at 20:59
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The best way to remove solder is by using a heatgun thats designed for that specific purpose. It is essentially a blowdryer that gets hot enough to melt/soften the solder.

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a heat gun is powerless against a soldered joint –  amphibient Apr 3 at 19:33
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With either propane or MAPP gas it is actually very easy to get the joint too hot. You can actually boil the solder out of the fitting or into the pipe depending on your torch placement. Not so much with larger piping, but with 1/2" it is easy to do it. You should only use about 1/2" to 3/4" of solder to make a joint on that size; don't add more or you could just fill the pipe. Keep a dry rag to knock off excess solder and a wet rag to cool and clean the joint. Flux causes oxidation (turns green). Don't worry about burning off flux: it will take unless it's too hot. There should only be slight discoloration; if there is more then there is too much heat. So as soon as the solder melts, pull your torch away a few inches but make sure to start solder at the bottom and work up, and move the torch around evenly.

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I am no pro at this stuff, but I have found that for my amateur stuff, I have much better luck with the liquid flux than the paste. With the liquid, you don't have to worry about getting dirt back into the mix..

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