How silver solder (braze) a copper pipe (a/c line repair) | GOT2LEARN

How silver solder (braze) a copper pipe (a/c line repair) | GOT2LEARN

What’s up guys and welcome back to
another back to basics video. If you aren’t already SUBSCRIBED to the channel
go ahead and SUBSCRIBE and use the bell icon right next to it to be notified of
upcoming videos. Today I’ll be explaining to you how to
correctly braze a copper joint. There are three easy steps to getting this
accomplished, the first step is to prepare the joint. Skipping this step may
result in an improperly brazed joint. Step two is the actual brazing process which
I’ll get to in just a minute, and step three finishing off the joint. Alright so
let me start off by explaining what brazing is, then pointing out the
differences between brazing and soldering. Brazing is a metal joining
process in which two or more metal items are joined together by melting and
flowing a material into the joint the filler material having a lower melting
point than the adjoining metal. The difference between brazing and soldering
is the temperature necessary to melt that filler metal, that temperature is
defined to be 842 degrees Fahrenheit or 450 degrees Celsius by the American
Welding Society, but is often rounded to 840 degrees Fahrenheit. If the filler
metal melts below 140 degrees Fahrenheit the process being
performed is soldering. Brazed joints are used for refrigeration, high pressure
airlines and HVAC where maximum joint strength is a must and solder joints are
used in low pressure applications such as potable water lines and some heating
systems. The tools and type of filler materials vary from a solder joint to a
braze joint so let’s go through both of them together. When soldering potable water
lines, you’ll be using this type of solder which is called 95/5. This type of
solder can’t be used when brazing so you’re gonna be needing a filler
material such as this. There are many types of filler materials on the market
and you’ll need to choose the right one depending on the type of job you’re
doing. In case of any doubts, don’t hesitate to
ask your local plumbing supply shop for what type of rod you need to use for
your application. For this demonstration, I’ll be using a stay-silv 15 rod which
contains 80% copper, 15% silver and 5% phosphorus. You’ll want to get a
rod that contains phosphorus as their self fluxing, removing the need to apply any flux on the pipe. Seeing silver solder melts at a much
higher temperature, you’ll be needing more heat than your typical soldered joint.
Brazing smaller pipes is possible with a small propane torch but larger pipes
such as 1-inch and up, require more heat, therefore it’s recommended to use an
oxy-acetylene system with an appropriate torch seeing silver solder melts at a much
higher temperature than normal solder. Oxy-acetylene burns much hotter at 3500
degrees Celsius or 6330 degrees Fahrenheit compared to propane
which burns at around 1995 degrees Celsius or 3620 degrees Fahrenheit, and finally the torch. When soldering, a torch like this is used
seeing only one type of gas is needed. Plus, propane torches don’t give out near
as much heat as the following, the oxy acetylene torch. I’m using this oxy
acetylene Port-a-torch kit from Harris which is a Lincoln Electric Company and
is great for light duty brazing tasks such as this one. It comes in a carrying
tote and there are two tanks, one for oxygen and one for acetylene. There’s
also two regulators for each gas and the actual torch. You’ll also notice the
torch tips that come with the kit, but we’ll talk about these later in the
video . You could use a simple air acetylene setup like this but it’s
considerably longer and doesn’t give you a clean joint like an oxy-acetylene kit
does. However, they are more economical and lighter to carry around in tight
spaces, so use what’s best for you. Something else you might want to
consider is making sure your torch has flashback arrestors on both the oxygen
and acetylene side. Most new torches come with them built in. In the past, these
were separate and needed to be installed on the hose itself, so just make sure
your kit is equipped with them as they’ll stop a flame from going into
your tank, which you don’t really want. Some other things I’ll be mentioning in
the video are some wire brushes, an inspection mirror and a fire
extinguisher. Alright, so with that out of the way, let’s get started! If your
brazing on a refrigeration or cooling system with costly components, it’s
highly recommended to purge your lines with an inert gas such as ARGON or
NITROGEN. During the brazing process, a lot of oxidation will occur inside the
pipe, creating scale that could potentially clog these costly components
and even, void a warranty! In this demonstration, I’ll be skipping
this step. So the first thing that needs to be done is to clean our pipe and
fitting. For the pipe, I either use some sandpaper like this or just an abrasive
pad. This step is very important as proper “wetting” is somewhat influenced by
the pipe and fitting’s cleanliness. WETTING is the ability of a liquid to
maintain contact with a solid surface resulting from intermolecular
interactions when the two are brought together. In other words, your filler
material won’t fuse properly if they aren’t perfectly clean. Also deburr the
inside of the pipe using either a round file or a dedicated pen reamer like this
one. Now’s a good time to choose what tip you’ll be using for your application.
Each manufacturer comes with a chart that specifies what tip you need for
whatever thickness of material you’re dealing with. For this demonstration I’ll
be using a number two tip from Harris. Once both tanks have been filled, give
them a quick purge to ensure no contaminants are going into the torch
assembly. Install both regulators, then connect both of your hoses and finally
the torch. Now open up both tanks and adjust both regulators to around 5 psi.
Once full pressure is reached on the oxygen side, you could fully open the
valve. On the acetylene side however, it’s recommended to open the valve only a
quarter turn after the gauge reaches full pressure, this will allow for easy
closure if an accident occurs. More pressure than this will result in an
unstable flame so I recommend sticking with these numbers. Also, using the same
pressure on both tanks means they’ll deplete equally which means one trip to
refill instead of two. Go ahead and first open the acetylene knob about halfway
and light the end of the torch with a striker like this. You’ll see a mix of
soot and smoke in the air, this is normal, just wait for both of
them to clear up and slowly open up the oxygen side. There are three types of
flames, one you don’t want is a carburizing flame, here’s what a
carburizing flame looks like. It’s easily distinguished by its three colors and
lead’s to excessive carbonization on the pipe which isn’t necessary and could
compromise the joint. Secondly, is an oxidizing flame which you don’t want
either. This type of flame ,as the name states will oxidize your work piece
which is unwanted. And lastly, a neutral flame. A neutral flame is what you’re
looking for as it doesn’t carburized nor oxidize, it has a perfect mix of
oxygen and acetylene and is typically a clear blue color like this. Before
brazing make sure your pipes are well supported and make sure to have a fire
extinguisher just as a precaution. The first part you wanna heat is the pipe.
The reason being is that between the fitting and the pipe is a small gap of
air. Seeing air doesn’t transfer heat very well, it has to be heated
independently in the beginning to make sure it reaches brazing temperatures.
Once the pipe has been heated, start heating the fitting’s hub, always staying
in motion. Every once in a while use your filler material to test if it’s hot
enough and once it is you’ll see it start to melt. At this point, you want to
make sure you don’t heat the actual filler material you want the heat from
the joint to melt it so to make sure you do it the right way, don’t apply any
concentrated heat on the actual brazing rod itself. You may notice your pipe
becoming red-hot but, don’t use more heat than that as to not overheat it. As I
mentioned earlier, proper wetting is crucial when brazing and overheating the
joint will inhibit proper capillary action. Capillary action is the ability
of a liquid to flow in narrow spaces without the assistance of or even in
opposition to external forces like gravity. A good example of capillary
action is when a paintbrush or paper towel is dipped in a liquid. The liquid
is absorbed without the aid of external forces. When you feel that that joint is
completely filled, apply a small “filet” or cap where both the pipe and fitting
meet. A proper filet or cap should be concave just like this. When you’re
finished brazing slowly close the oxygen knob on the torch
followed by the acetylene knob and then close both tank valves to make sure no
gases are passing through. I always like to purge my hoses before saying I’m
completely done. With your joint properly brazed, wait for it to cool down
naturally. Applying water to a heated pipe as such could cause a fracture in
the joint resulting in a leaky joint. Once the joint is cooled down, get your
wire brush and remove any scaling that occurred on the surface of the pipe. You
want to be able to inspect your work and make sure that there aren’t any voids. If
you’re in a tight spot, a mirror could help you analyze your joint to see if
any adjustments may be needed. Here’s an example of a purged line versus a non
purged line. As you can see, there are enough contaminants that formed inside
the pipe the clog a metering device or whatnot, the difference is obvious and
should be taken into consideration when brazing on expensive equipment. And
that’s how to properly silver solder or braze a copper joint. If you’d like to
see a great example on how to correctly solder a copper pipe I’ll put a link in
the description box below that links to it in this video. You’ll learn all the
necessary steps to correctly solder a copper joined with ease and with very
basic tools. I also have a ton of other informative plumbing videos to check out
on my channel so don’t miss out on them. If you found this video helpful, let me
know in the comments below and as always if you like this type of video I invite
you to subscribe to the channel as I have more cool content on the way and
until the next video, thanks for watching


  1. I've always wanted to see how to do some brazing, excellent video and I think it covered quite a bit too.

  2. Good video. Just something to consider: Those random numbers flashing above the text in some segments seem completely arbitrary and don't jive with a skills/training/learning video vibe enough that I had to pause and write this.

  3. Not to bad my man. I’m typically pretty critical about people on YouTube pointing out bad info people give on these type of informative videos because I’m a sprinkler fitter/pipefitter by trade. But this video pretty much covers it start to finish. Only thing you left out is that you can braze with a b-tank. You just need the bigger tip. We call them turbo torches. That’s what we use. But all in all man that was pretty damn good. Hats off.

  4. Nice video, should recommend people take welding class, because of other inherent dangers associated with this type of torch set. Lots of guys out there looking to do skilled trade work, without proper training.

  5. surprised to see so many fitters applauding this video. Good info but the technique was pretty poor. The heat should be used to draw the filler around the joint as well as into it. The heat and dab moves are for welding not brazing… COME AT ME!
    25 yr HVAC/R service tech

  6. Ok, I haven't watched this video yet, but I've yet to see one of your videos that I wouldn't recommend to others on "how to do it well". Thanks for what you do.

  7. We have kids in our class that want to finish off this joint!!!! Especially having to watch this video. But all in all good stuff.

  8. I need to do brazing qualification as per sec 9 for copper half inch and 1 inch pipe. Shall i use nitrogen gas for purging pls advise

  9. I aced my brazing/soldering practical assessment because of this channel.

    I wish there was a video about reading diagrams and about measuring and making allowances for fittings mj clamps etc

  10. My a/c stopped working in my house. I inspected my unit and found that there is a small copper line coming out the side of my condenser that was rubbing against another line. It rubbed a small pin hole in the line and all my Freon leaked out.
    I called a company and they gave me a estimate of almost $1000 to fix it. I can't afford that.. Can I braze that pin hole myself? Only thing is I don't have a acetylene torch. I only have a propane torch.. Would that work to heat a silver rod enough just to cover a tiny hole?
    Once I get hole fixed then ill figure out how to recharge the system lol

  11. does your kit came with the flash back arrester? i am looking to buy the same kit but not sure.
    great video by the way…thanks alot

  12. NO ! dont turn of oxygen first !!! turn of acetylen first, and lissen to him is like lissen to an idiot how read the book (solder for dummies)

  13. Make sure to wear safety glasses 🥽 when brazing the heat from the torch can burn your eyes and cause damage or even blindness

  14. Er, that's a bit presumptuous of you to assume I don't want the flame going back into the tank (Flash-Back-Arrestors), O.o


  15. I have a small crack in the liquid line at the bend just above the compressor. tight spot, wondering if I should use 15% or higher and also a jewelers torch so I can avoid over heating / damaging the compressor? Did this happen because the 3 compressor anchor bolts were tightened down too much causing too much vibration on the liquid line.

  16. Great video man, I’ve been learning more about how to Braze at my job and this helped answer a lot of questions I had!

  17. Reminds me of oxy-acetylene welding week, good times. When the puddle blows up in your face. I was so scared of getting a backfire and a flashback. But the equipment I found is relatively fool proof and safe

  18. That is not the proper way to silver Soldier or braze the copper pipe. It doesn’t draw in by capillary action. You must force it in all you did was cap the joint.

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