There are two very popular types of plumbing materials in use today: Copper and PEX. There are some significant differences between them, including price, longevity, and common applications. Another major contrast is how they are joined. Sweating copper pipe is required to join sections of copper plumbing together; PEX is joined with a variety of clamps and push-to-connect fittings.
What Does Sweating Copper Pipe Mean?
Most homeowners have heard the expression, “sweating a pipe.” But what does it mean, and how is it done?
The Difference Between Soldering and Sweating Copper Pipe
Sweating a copper pipe is actually a form of soldering called soft soldering. When talking about copper plumbing, the terms sweating and soldering are interchangeable. The term sweating is used with copper because as the pipe heats up during the process of soldering, it appears to sweat.
Is Sweating Soft or Hard Soldering?
Sweating is called soft soldering, which indicates that the temperature of the solder remains between 90 and 450 °C. In contrast, hard soldering involves heating solders to over 450 °C and generally results in a stronger joint.
How Sweating Copper Pipe Works
Copper plumbing can be joined with solder, which forms a watertight seal around the connection. This type of solder requires a fitting to keep the joined pipes aligned and in place. The solder merely seals them.
How Do You Sweat a Copper Pipe?
To connect two sections of copper pipe, the ends to be joined are first deburred, which simply means that they need to be made very smooth and even. You can accomplish this by sanding with an emery board or sandpaper and wiping clean. A roughly cut end or any grit or burrs on the pipe will cause the joint to leak.
Flux is a soldering paste that will draw the liquid solder into the joint. Flux paste is applied to the ends of the pipe sections to be joined. A fitting is placed over both ends as the pipes are positioned together.
Using a propane torch, the pipe is heated and the solder is applied by allowing it to contact the hot copper. The solder liquefies on the heated pipe at the edge of the fitting. The liquid solder is then drawn under the fitting by the flux, where it cools and hardens, forming a watertight seal.
What Are the Best Methods for Sweating Copper Pipe?
Sweating copper pipe takes some practice. If you are a beginner, try joining a few sections of pipe outdoors or in a shop where you have plenty of space and good lighting.
Plumbing, unfortunately, is most often located in hard-to-access areas of your home. Take your time and get comfortable with the torch, the flux, and the solder before you try to join copper pipes in a tight or awkward space.
How To Ensure the Joint Won’t Leak
It can’t be over-emphasized that burrs or other imperfections will cause your joint to leak. Sand the pipe ends until you are absolutely sure they are perfectly smooth. Nothing is more frustrating than completing an installation or repair and turning on the water only to discover little beads of moisture seeping through your newly soldered joint.
How Long To Heat Copper Pipe for Solder
To be sure that the solder makes a good join, you only need to heat the pipe until the flux paste begins to sizzle, which only takes about 5 to 10 seconds.
Are There Alternatives to Sweating Copper Pipe?
PEX is one option if you want to avoid sweating copper pipes. There are other means to join two sections of copper plumbing as well, such as push-to-connect fittings. The pipe sections still need to be deburred and inserted correctly, but it’s much easier for beginners to get a tight seal the first time.
Why Opt for Sweating Copper Pipe?
With some less-demanding options available, why would you choose to sweat copper pipe? There are several reasons that a homeowner or plumber would opt to use solder.
Many licensed plumbers feel that the easy-to-use push fittings simply won’t last as long as a properly soldered joint. Push-to-connect enthusiasts argue that this is a fallacy, but it’s a widely held opinion among professionals.
Cost is a factor as well. If you are adept with a blowtorch, it is far less expensive to join copper pipes with copper fittings and solder than to use push-to-connect fittings throughout your building. For new installations, sweating pipes is a common choice.
Finally, there is always the odd joint or awkward location where creativity is required to make a watertight connection, and where a ready-made push fitting just won’t work. Often, when performing a repair, conditions are less than ideal. You might not be able to separate the ends of the pipe enough to insert them into a push-to-connect fitting properly, for example.
Where Sweated Joints Are Required
Unlike PEX, copper pipe is rigid. You can’t bend it around obstacles, so you need to use elbow joints to turn the pipe and run it where it belongs. Each turn requires a fitting, and each fitting needs to be soldered.
You’ll also need to include shut-off valves along the route from the water main to the fixtures in your home and tee joints to run water in another direction off the line. Basically, anywhere the copper plumbing isn’t one straight, continuous section of pipe, you will need sweated joints.
Why Use Copper Pipe?
You might wonder whether it’s worth using copper pipe when PEX is so much easier to install. It’s true that many people opt for PEX, even in new buildings. It’s less expensive upfront than copper, it’s flexible and requires less expertise to install, and it can withstand colder temperatures than copper.
PEX is not a bad option in many instances. However, copper is still the preferred material in most buildings, due to its longevity. Copper lasts an average of 20 years longer than PEX. Copper retains its value over time.
Sweating copper pipe is a skill, and it takes a little practice to master, but copper plumbing will last up to 70 years, and it’s well worth knowing how to install and repair copper pipes.
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