Copper pipe leaks need all the water out of the pipe. Even two propane torches will not get solder to flow and bond if there is some water in a pipe. Repair frozen pipe with soldering
Before we ponder on how to re-solder the joint, ask yourself this; why did it leak in the first place? Solve the problem.
Chances are the leak is due to an improperly cleaned fitting or pipe. If the solder did not ‘take’ to the joint the first time, why would it now? You can usually fix a leak in a copper fitting in the first hour or so. After that, water leaves a trail of calcium or lime making a repair almost impossible without disassembly and cleaning.
Before attacking this problem, some additional safety measures (over and above those on the torch) should include goggles, face protection, long sleeve shirt, and gloves. Nothing hurts like having molten solder land on the skin.
Just cut the copper close to the fitting and remove it the easy way. Using a $.50 coupling to save 10-minutes of frustration to disassemble the leaky joint can be a waste of time because the solder at that joint just will not allow the fittings to come apart.
Once the new pieces are cut and fitted, use plumber’s cloth to sand the pipe clean until it shines. Sand the inside of the fitting just as shiny as you did the pipe. Clean, clean, clean, is the secret to strong solder joints. Don’t touch the cleaned surfaces with your hands or oil from your skin may prevent the solder from bonding.
Put paste soldering flux on the pipe and the inside of the fitting and assemble with a twist. Then heat the fitting, not the pipe, with a propane torch. As the flux ‘sizzles’ out of the fitting apply solder to the joint, away from the torch flame. As soon as the solder starts to melt, back off a little with the torch. The solder should flow until it shows all around the fitting even though you applied it from one location.
Do not get the fitting too hot or the solder will act as mercury to flow to the bottom of the fitting, and most will drip out. When in doubt reheat the fitting and add more solder. If solder refuses to take, brush flux on the hot joint and then try to add solder.
If the soldering suddenly hardens and you hear ‘sizzling’ in the pipe it means water just flowed into you area. Unless you have mapp gas, you may have to start over if the joint leaks.
What You’ll Need
Thankfully, there are only a few supplies you’ll need for this job. Each of the tools you’re going to need is inexpensive, and they come in handy, so you should consider buying them if you don’t already have them available. Here’s what you’ll need:
- Propane torch
- Lead-free solder
- Flux brush
- Measuring tape
- Sharpie marker
- Pipe cutter
- Pipe fitting brush
- Emery cloth
- Pipe deburrer
- Work gloves
2. Safety Precautions
Before you attempt a soldering job, be sure that you wear protective equipment. You will need heavy rubber gloves to prevent burns from the blowtorch, hot pipes or molten solder. Always wear safety goggles when working with metal or fire.
Keep your clothing away from the flame and watch for any sparks. If possible, work in a wide-open space, away from anything flammable. Keep children and pets away from the equipment and your work area. Keep a fire extinguisher close if needed.
5. Melt the Solder
As you heat the solder wire, it will go toward the heat and melt into the joint. Your goal is to work the melted solder all around the joint for a complete seal around the pipe. Keeping the flame ahead of the melting solder is key to sealing larger joints.
Remember to keep the flame moving constantly. Otherwise, you can overheat the copper and blacken it. If that happens, you must take the joint apart, re-clean it, and solder it again. If you do not proceed this way, the joint will not seal properly, and you will have a water leak.