How to Solder Copper Pipe the Right Way

How to Solder Copper Pipe the Right Way

In this article, I’ll be thoroughly explaining how to solder copper pipes to get a nice, leak-free joint. If you’re unfamiliar with soldering, you’ll be able to solder any diameter pipe after this article with ease and peace of mind.

There are 3 steps to solder a copper joint.

Step 1 is preparation.  Preparation is the secret to getting a leak-free joint. If you skip or half do it, it will most probably leak and cause damage to your property, so this step needs to be followed very closely.

Step 2 is the actual soldering process which I’ll get into details in just a bit.

And Step 3 is finalizing the joint.

With that said, let’s get started.

Tools and Materials

The first thing I want to go through, are the tools and materials you’ll be needing to complete the task.

ool number one is a torch. You’ll find a good torch at your local hardware store that should cost you between 20 to 50 dollars. There are better models out there for commercial plumbers, but if you’re a do-it-yourself, doing minor work, these will do just fine.

To be able to use your new torch, you’ll be needing some fuel. There are two varieties of fuels for you to choose from. You’ve got your ordinary propane gas, which you can either find in your camping aisle or in the plumbing section at the store, or mapp gas.

The difference between both of these is that mapp gas burns hotter than propane, which in turn heats up your joint quicker, so it’s up to you to choose which one you want to use.

Next up is a lighter for your torch. If your torch doesn’t have one built-in, you can either use a dedicated igniter which can be somewhat costly, or use a $1 BIC lighter like I do.

Your pipe and fitting will need to be cleaned from any surface corrosion or dirt that could compromise the joint while soldering. To do this, you’ll be needing some sandpaper or emery cloth for the pipe and wire brushes for the fitting.

Something else you’ll need is some soldering flux or paste. The primary purpose of flux is to prevent oxidation of the base and filler material, without it, soldering is literally impossible.

And the last thing you’ll be needing is solder. There are many filler materials that can be used for soldering copper, but the most two common ones are lead-solder and lead-free solder. Lead- free solder, which is also known as 95/5, is what’s used for potable water lines.

When doing copper drains, lead-solder, which is also known as 50/50, can be used, seeing it won’t come in contact with anyone.

Step 1: Preparation

So as I mentioned earlier in the article, preparation is key to having a good leak-free joint. The first step to accomplish this, is to clean both parts that will be joined together. To clean the pipe, take your sandpaper and sand the portion that will penetrate the fitting till there are no more surface spottings.

Next is the fitting. You want to use a dedicated sized brush to get your fitting clean. They most often arrive clean from the manufacturer, but it’s important to get the surface roughed up a bit, so the solder can adhere better.

If you’re a commercial plumber and are cleaning a large number of fittings in a day, a cool trick that I learned is to cut off the tip of these brushes and use them in a drill, making the process much quicker and less tiring.

With both of your surfaces now prepped let’s assemble them, but before, you’ll need to apply some flux. Applying flux is pretty self-explanatory, all that’s needed is enough of it to cover both surfaces that touch.

With your flux now applied, it’s time for the actual soldering process which is step 2.

Step 2: Soldering

The goal here is to heat the portion you want your filler material to be pulled into. There’s a scientific term for this and it’s called capillary action. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces, meaning it will flow upwards which is pretty cool.

It’s imperative to start heating your joint at the bottom first for two reasons. The first reason is, if you start heating the top first, your solder will want to flow down due to gravity but won’t have anywhere to go since the bottom of the joint is too cool to melt the solder, so always start from the bottom and work your way up.

And the second reasons is, as you heat the bottom the heat rises and heats up the top of your joint, as opposed to starting on top, which takes longer for the heat to go down. So keep on heating it up while testing your solder every now and then to see if it gets sucked in.

Eventually your joint will be hot enough to accept your solder so go ahead and run a nice bead all around the joint to ensure full coverage. A good tip here is to always inspect your joint after soldering it. If you haven’t correctly heated the joint, you should get something that looks like this. If this happens, all you have to do is reapply a bit of flux, heat up the joint and solder the affected area.

Step 3: Finalizing the Joint

As a final step, when you’re sure that your joint is soldered correctly, wait a couple of minutes for it to cool down. Some plumbers will use flux to clean up the joint while it’s still very hot, but doing this could cause a big drop in temperature in very small amount of time and can fracture the joint causing a leak.

Once your solder solidifies, use a rag to wipe off any excess flux that could potentially eat up your pipe in the long run and you’re done.

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