How to Solder Copper Pipe Joints

How to Solder Copper Pipes

Copper Clean
Clean copper after it has been cut. Photo

 Start by getting the right tools, and measuring the copper pipe. This expert step by step procedure will guide you through the process on how to cut copper properly and have a leak-free joint. Tools needed:

  • Copper Cutter
  • Wire Brush
  • Abrasive cloth
  • Paste Flux 
  • Lead-free Solder
  • Propane Torch
  • Gloves
  • Safety goggles 

Start by Measuring and Cutting Copper

Copper Cutter
Copper Cutter. Photo Facebook

Start by using a measuring tape to mark where the copper will be cut.  Using a tube cutter, cut copper tubing. Using the cutter is very easy, as you will only need to hold the pipe between the cutting wheel and rotate the cutter. The wheel will start to score the pipe all the way around. Keep doing, while tightening the cutter know so it can score deeper. Repeat as needed. This procedure is valid for all types of copper.

Ream and Clean the Copper

Copper Clean
Clean copper after it has been cut. Photo

After the copper has been cut, it needs to clean and cut to have proper bonding surface. Copper cutters normally are equipped with a reaming blade that can be used to clean all burr created after the pipe has been cut. Do not apply extra pressure as it might deform the copper. Now you will need to clean the copper by using abrasive cloth, steel wool or a wire brush that can fit inside the copper pipe. The copper should have a shiny look and cannot have any oxidation mark. Do not limit yourself to the are that will be used for the joint, as you will need to clean a little bit more than the area on which the joint will be to allow for a proper connection. Do not over clean the copper as it might reduce the strength of the copper pipe.  Avoid touching the copper pipe with bare hands, and even if the pipe is new, it must be cleaned.

What is Flux for?

Apply flux carefully. Photo Oatey

Flux needs to be applied evenly at pipe ends and inside the fittings. This product will prevent the copper pipe from oxidizing as you heat the copper, so it will start to boil when it is hot enough to solder. There is no benefit if you use a lot of flux amount, as it will only lead to corrosion inside the copper pipe. Do not use bare hands to apply flux or avoid being in contact with flux as its chemicals might be harmful to the skin. Remove excess flux with a cotton cloth.

How to Solder Copper: Solder Types

Solder Copper
Photo By Sheila in Moonducks

Solder types used on copper pipes are generally available in three types:

  • 40 percent lead/ 60 percent tin;
  • 95 percent tin-antimony/5 percent lead;
  • Lead-free solder.

Soldering copper pipes used for water supply shall be soldered with lead-free solder. The 50 percent lead solder is recommended on copper drain lines, not to be used on potable water pipes.

How to Solder Copper: Applying Solder

Solder will create a silver band. Photo EugenesDIYDen

Once the fitting or pipe is in place, start by applying solder at the top of the joint and once it is heated it will start to drip all the way to the bottom of the joint.When it begins to melt, push the solder into the joint and maintain the torch away from the pipe. The joint should have silver band all around it, but you still need to verify that it is actually good. Some experts will recommend to start at the bottom to create a dam that will prevent from using more solder than required. Propane torches are ideal for small jobs, while acetylene used for pipes larger than 3/4 inch.

Copper Soldering Tips

Soldering torch
Soldering tips. Photo by kboyd
  • Do not solder copper piping when water is still running or in the pipe. Drain the pipe before starting and wait until it is dry.
  • Plumbing torches can be lit preferably with a flint striker. Matches and lighters can be dangerous
  • Heat the copper pipe before soldering and apply heat to both sides.
  • Be sure that pressure inside the copper pipe is released before soldering.
  • Heat the joints of the copper pipe from several sides.
  • Make sure the solder fills the joint on all sides.
  • Rotate the torch around the pipe for even heat distribution.
  • Brass fittings will require extra heat.
  • Set the flame on medium or high to generate enough heat to melt solder. If your flame is adjusted correctly, it will burn different shades of blue.
  • Remove any plastic fitting or adapter from the copper pipe to avoid ruining them.
  • Always look beyond the pipe. Extremely hot temperatures are beyond the visible portions of the flame.