Learn how to solder and braze copper fittings to pipe.

How to Solder and Braze Copper


If you live in an older home, there’s a good chance the pipes in your plumbing system are copper. Inevitably, there’s going to come a time when you’ll have to replace a section of pipe. Whether it freezes in cold winter temperatures or springs a pinhole leak, something is going to happen sooner or later.

When you’re faced with having to join two pieces of copper pipe, you now have many choices of repair fittings; Sharkbite, Speedfit, and Copper Press fittings. But, before these innovative products were invented, you only had two choices, soldering or brazing. Some plumbers still prefer soldering or brazing copper fittings instead of the new solderless fittings available. Even if you aren’t sure what the terms soldering or brazing mean, they’re something you can do on your own, with the right tools, materials and knowledge.

What’s the Difference Between Soldering and Brazing?

Both soldering and brazing are processes for joining two pieces of metal together in a joint through melting a filler metal. The difference between the two has to do with the temperatures at which the filler metals melt. If the filler metal melts between 400°F.and 840°F. the process is called soldering. Conversely, if the filler metal melts above 840°F. then the process is brazing.

Brazed copper joints are used in spots where maximum strength is a must. Examples include HVAC and refrigeration. Soldered copper joints are found in places where lower pressure exists like heating systems and residential water lines.

Tools Needed for Soldering and Brazing

Solder or Brazing Rod: To get started you will need the right kind of filler material based on the type of project you’re working on. There are many different filler materials available so, make sure you do the research necessary ahead of time and choose the right one. For residential copper water pipes you will need a lead free solder. Brazing rods are different combinations of metal that melt at higher temperatures and when cooled produce a much stronger bond than normal soldering. For brazing copper a brazing rod with a mixture of 92.9% copper and 7.1% phosphorus will produce a tensile strength of 91,000 psi.

Flux: A quality fluxing agent is required for soldering and brazing projects. The flux removes oxides from the copper and also prevents oxidation during the heating process to allow a continuous flow of the solder or brazing filler material. Brazing flux is not the same flux used for soldering. Brazing flux is formulated to withstand the higher temperatures used in brazing applications. No flux is needed for brazing rods made of copper and phosphorus when brazing copper to copper.

Acid Brush: A flux brush, more commonly known as an acid brush, will allow you to cleanly apply the flux to the copper pipe and fittings.

Torch: A propane or MAPP gas torch will be needed in order to heat the copper pipe for the solder to melt. Lighting a torch with an open flame can be dangerous. That’s why it’s always a good idea to purchase a self-igniting torch. These types of torches use a simple and reliable piezo trigger igniter. If you purchase a torch without a self igniting feature you will need to light it with a match or flint striker. Self-igniting torches usually have a internal pressure regulator which will keep the flame lit even when you turn the torch to different angles.

Copper Pipe Cutter: Copper pipe cutters are the quickest and easiest tool to use when you need to cut appropriate lengths of copper pipe. Good pipe cutters should leave a straight edge and minimize burrs, but you should always clean the burrs off. Most copper pipe cutters include a reamer attached to the pipe cutter and will help you remove the burrs quickly and safely.

Copper Cleaning Tools: Copper cleaning tools are essential for making sure the pipe and fittings are clean. Sandpaper or emery cloth is often used to clean the outside of the copper pipe. A wire fitting brush works much better than sandcloth to clean the inside of the fittings.

Gloves: It would be wise to wear some type of heat resistant gloves during the soldering process. Many professional plumbers use cotton gloves or jersey gloves so they can wipe the joint of any excess solder when the heat is removed. However, keep in mind these are profesionals who have been soldering for many years.

Safety Equipment: Since you’re going to be dealing with fire, make sure you have the appropriate safety equipment close by. These items include a spray bottle with water, fire extinguisher and a fire cloth. Flame shield blankets are available to help protect walls, studs, and floors from torch flames. Made of woven ceramic they will protect up to 2300°F. for five minutes and are flexible for use in awkward places or close quarters

Steps to Solder and Braze Copper Pipes

Once you have all the necessary tools and materials, it’s time to get the project started.

The most important part of the soldering process is to make sure the pipe and fittings to be soldered together are clean. Clean the outside of the pipe where the fitting is to be attached with sandcloth or an outside tubing brush until the surface is bright metal clean. Likewise, clean the fitting by inserting a wire fitting brush and then turning the brush back and forth inside the fitting until the inside of the fitting is bright metal clean. Even if you are using brand new copper pipe and fittings you must still clean the inside of the fitting and the outside of the pipe where the fitting will be soldered. Once clean, do not touch the cleaned part of the pipe or fitting.

Using an acid brush, apply a thin layer of flux to the outside cleaned section of pipe. Apply a thin layer of flux to the inside of the fitting. Insert the pipe into the fitting making sure the pipe is shoved all the way inside the fitting. Twist the fitting gently to make sure the flux covers the whole surface evenly.

Now, unwind and cut one foot of solder wire from the spool and bend the bottom two inches at a 90-degree angle. This is where the fun begins. Ignite the torch and hold it so the flame is on the center of the fitting. Solder will flow to the heat. Heat where you want the solder to flow to. If the flame is on one side of the fitting, touch the bent end of the solder wire to the oposite side of the pipe where the fitting is and when the temperature is hot enough the solder will suck right into the joint. As soon as you see the solder melting pull the heat off and away from the fitting. You can hold the solder at the fitting for a second or two until you are sure it has flowed into the joint.

The biggest mistake people make when they are learning to solder is to keep the flame on the fitting too long before they try to put the solder to the fitting. Once the temperature of the fitting is hotter than the melting temperature of the solder, the solder will not flow. At that point when you try to touch the solder to the fitting it will just seem to spit and not flow. You will then need to cool down the fitting and start over. That's why as soon as you apply heat to the fitting you should put the solder near the joint and just tap it near the joint until you see the solder begin to flow and then pull the heat away.

Wipe away excess solder with a rag or with your glove and let the pipe cool.

Brazing copper to copper is somewhat different than soldering. You still need to clean the pipe and fittings but you do not need to add flux if you are using copper-phosphorus brazing rods. The copper-phosphorus brazing rods self-flux on copper. If you are brazing brass or bronze to copper then you will need to flux the brass or bronze. The heating process is slightly different also. The heating process should start on the tubing first and then progress to the fitting to assure an even heat transfer to both the tubing and the fitting. The critical part of the brazing application occurs during the heating of the joint and applying the filler material (brazing rod). Most brazed joints are fabricated at close to 1400°F. These high temperatures can damage the base material if not properly managed. The brazing operator must pay close attention to the metal casts in the base material and the fluidity of the brazing rod. The brazing should be conducted within the pasty range of the brazing rod with just sufficiently more heat applied to activate the fluidity action of the brazing rod. When the joint has good fill capacity remove the heat and let the fitting cool.

The last step is to turn on the water and check for leaks.

Soldering Ball Valves

Ball valves can usually be found throughout your plumbing system. They’re lever controlled quarter-turn or half-turn valves that control the flow of liquid through the positioning of an internal, rotational, hollow ball inside.

Understanding How Ball Valves Work

The ball inside the valve has an open hole in the surface at each end. On each side of the valve, you’ll find copper tubes. When the valve is open, the holes in the ball are aligned with the holes in the pipe. When the valve is closed, the holes aren’t lined up with the pipe and water can't flow through. Ball valves usually fail due to extensive usage. Ball valves can also fail if the ball becomes detached from the arm that holds it in place.

Steps to Soldering a Ball Valve

Use a wire fitting brush to clean the inside of the valve. Clean the outside of the pipe with sandcloth (memory cloth). Next, apply an even coat of flux to both the inside of the ball valve and the outside of the pipe. Now, make sure the valve is in the open position and the ball valve handle is parallel to the pipe.

Push the pipe inside the valve socket. Light your torch and position the solder wire close to the valve and heat the valve where the pipe enters the valve. Keep applying heat until the solder melts and fills in the entire seam. Repeat the process on the opposite side and let the pipe cool.

Practice Makes You Better

Soldering and brazing can be intimidating if you’ve never done it before. Rightfully so. You’re dealing with extremely hot surfaces and a flammable torch. The good news is that if you have the right materials, it’s a job you can perform on your own. Make sure you do some research ahead of time and that your safety is close at hand in case something goes wrong. Just like anything, the more you practice, the better you’ll get. And the best part, you’ll save yourself the hassle and money of hiring a professional to do the job for you.


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