How To Braze Copper Pipe

How To Braze A Copper Pipe (In 5 Steps)

Learning how to braze a copper pipe correctly requires some love and dedication to the welding craft. Anyone can weld, but only few can weld objects like copper pipes properly. That’s where this useful piece of information comes in: In this article, you’re going to learn the copper brazing process step-by-step. Let’s get started right away!

Most copper soldering is done with temperatures from 450 degrees Fahrenheit (232 degrees Celcius) to 600 degrees Fahrenheit (315 degrees Celcius), while most brazing is done in temperatures ranging from 1100 to 1500 degrees Fahrenheit (equal to 593 up to 815 degrees Celcius).

Step-By-Step: Brazing A Copper Pipe

The process of brazing a copper pipe is not actually that complicated compared to regular soldering, but it does require the use of proper equipment. Please note that brazing deals with much higher temperatures, making safety measures all the more important. In short, the following five steps are involved:

  1. Getting equipment ready;
  2. Preparing the copper pipe;
  3. Applying flux to the interior of the fitting;
  4. Igniting the torch for brazing;
  5. Carefully applying solder.

Below you’ll find the step-by-step description on what these steps actually mean in practice, but if you prefer it, you can also get a good visual guide by watching the YouTube video below:

Step 1: Getting Started (Equipment)

First, we are going to need the right equipment for the job. It’s not a lot of stuff, but there are some essentials in there that you cannot miss. In case you are missing something from the list, I’ve added some links to Home Depot website, so you can directly order the tools you need online:

  • Acetylene torch: This type of welding torch will be able to reach higher temperatures due to the specific gases used, which is perfect for brazing.
  • Brazing flux: A combination of carbonate and silicate material used to shield the weld from atmospheric gases. The flux will melt during the welding process and oxidation occurs.
  • Solder: Low-melting alloy, usually sold in the form of a wire.
  • Fittings: Pipe brazing requires custom fittings, which differ according to the type of copper pipe that is brazed. I cannot provide more specific information, because every pipe fitting is different.
  • Cleaning chemical: Used beforehand to clean and prepare the metal for the brazing process.
  • Sandpaper: We’ll need this to smoothen the surface, also used beforehand.

Got everything you need? Great, now it’s time to get going with the real job. Let’s get going to the second step, which is preparing the copper pipe for the brazing process.

Step 2: Preparing The Copper Pipe

Let’s get working on that copper pipe first, because you can’t just go in and start splurging it with your torch of fire and doom. We do require a bit of preparation work first. Here’s an easy overview for you:

  • Take the sandpaper and smooth the area you intend to braze;
  • Make sure to scrape any excess copper particles sticking out of the pipe;
  • Also, sandpaper the cut edges of the copper pipe;
  • Grab yourself a wire brush and start brushing the inside of the fitting;
  • After brushing, make sure to clean any particles off of the inside of the fitting.

This step shouldn’t be taken lightly as it will make the subsequent steps significantly easier to do ánd it will improve the quality of the end result considerably. Let’s grab that flux now, because we are going to rub it all over that pipe.

Step 3: Apply Flux

The interior of the fitting and both ends of the copper pipe should be covered in flux. You might ask, why do we do this? It’s mainly to remove any type of oxidation processes to occur during the heating process hereafter.

The chemicals that make up the flux can be applied using a simple paintbrush, nothing fancy is needed here. Just make sure the whole inside area of the fitting is covered in flux. And while you’re at it, flux up those pipe ends really well too. No need to cover the whole pipe, just the part that will attach itself into the fitting, if you know what I mean.

Step 4: Ignite Torch

Let’s start with the good stuff now, heat up that torch for me to a nice scorching hot temperature. The process for igniting the acetylene torch is as follows:

  • Turn on the acetylene and light the fuel gas only (never light both gases at the same time!);
  • Adjust the flame to the proper condition for a neutral flame. Too little fuel gas means a smokey flame, while too much fuel gas will create a scary hellfire of doom (see video below). We want neither, turn off and adjust until we find the perfect middle ground;
  • When the fuel gas condition is just right, introduce the oxygen (or whatever gas you’re using);
  • Make sure to adjust the oxygen until you find a neutral flame, which has a sharply defined inner cone with no outer feather. Please refer to the video below (at 2 minutes and 10 seconds) for a visual.

Below you’ll find a YouTube video tutorial to explain this process in a bit more visual manner. The video example used is for an oxygen-acetylene torch, but there are also other gases used. The principle is roughly similar across the board. I would recommend you to skip to 1 minute and 10 seconds into the video, which is where the tutorial starts:

When brazing, make sure to heat the surface of the pipe evenly and fast in order to create a good bond. In places where the flux is applied, make sure that your movements are slow and smooth.

Please note that you should always keep some sort of movement with the flame while you point it towards the copper material. Otherwise, you can easily burn the surface or torch a nice gaping hole in your piping.

Step 5: Apply Solder

You’re doing great, time for the last step now. Let’s apply solder to the pipe and finish up the job. Here’s what you want to do in this final stage:

  • Make sure your pipe is heated evenly and is ready for the solder to melt into it;
  • Carefully bring the solder towards the pipe, you will notice it will immediately start melting and flowing once it touches the copper surface. Don’t use too much solder, otherwise, you’ll have a molten metal leak on your hands (and you’re going to have a bad time with that);
  • Make sure your solder moves around the pipe evenly and completely. It should also go into the interior, this is what will strengthen the weld.
  • Carefully remove the brazing torch and TURN OFF THE OXYGEN FIRST. I cannot stress that enough. Oxygen first, then you should turn off the fuel gas. Carefully. It’s really hot. Refer to the YouTube video above for visual instructions on how to turn off your torch correctly.
  • Let the newly welded metals cool off on their own, do not attempt to cool it off with something else. Gradual cooling will strengthen the weld, and it is the safest and easiest way to finish up the job as well.

When Should You Choose To Braze A Copper Pipe?

Braze joints are used where greater joint strength is required. The added heat will make sure the joints are welded together with a strength that regular soldering cannot achieve. Applications for brazing are commonly found for use in:

  • Plumbing and water supply;
  • Fuel gas distribution or medical gas;
  • Air conditioning or refrigeration;
  • Fire protection.

Mistakes To Avoid While Brazing

We are handling dangerous tools and extremely warm metals. A lot of things could go wrong and safety always comes first. Here are some of the most common errors I see in the process of brazing copper piping:

  • Not using the proper protective gear: This one is obvious because you’ll need at least some non-flammable clothing and welding gloves for this job.  Preferably, use some safety goggles too, I’ve seen what can happen to people that wave around their torch and put it near their eyeballs. It’s not pretty. Don’t skimp out on your safety gear.
  • Not knowing how to handle acetylene torches: If you’re learning how to use your tools, make sure you have an experienced welder by your side to give you proper instructions. Also, please review the instructions multiple times beforehand.
  • Not turning off the oxygen first: Rookie mistake and it’s one of the most common errors I see with people handling their torches improperly. Never turn off the fuel gas first, always the oxygen.

Learn More About Welding

While brazing is a very specialized method of welding, the broader topic will actually cover a lot more ground that will also be interesting to a lot of people reading this! I wholeheartedly invite you to check out some of my other articles, and let me know in the comments if you want anything else covered.

In case you’re looking for the right equipment and tools, I do have a recommended welding tools section on this page, which covers most of the essential categories that would be relevant in the world of welders. I highly recommend you to check it out, as I share my favorite equipment there that has always worked for me over the years.

You won’t be a good welder without good tools, so make sure to invest in them properly before getting started with a specialized job, such as the copper pipe brazing job described in this article. Have fun welding and see you around!

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