How to Desolder Copper Pipe: A Few Tips to Know

A rusty copper pipe can be a pain in the head, but nothing is more frustrating than a leaking pipe that needs immediate replacement. Are you thinking about how to desolder your copper pipe? Then here are a few tips you need to know.

When desoldering a copper pipe, remember these tips:

  • Drain all water from the pipe beforehand
  • Apply steady, even heat without overheating the surrounding pipe
  • Overheating or underheating can cause the joint to leak later
  • There is no set time to heat, just watch the pipe for correct signs

While there are many different acceptable approaches on how to unsweat or desolder a pipe, it’s important to follow tips that are specific to your situation. If you want to learn more about these tips, you should read along further.

Can You Desolder Copper Pipes?

Absolutely. The process of unsoldering can be pretty straightforward if you just follow the right techniques carefully. This is one of the many wonders of plumbing where a fix to a leaking pipe or joint can be an easy task to do. The best part about learning how to desolder copper pipes is that you will no longer have to shell out some cash to pay for a plumber.

Reasons for Desoldering a Copper Pipe

There are many reasons why a person would decide to desolder or unsweat a pipe. The most common reasons are:

  • Replace a joint with a T-joint from a straight joint, or vice versa
  • A leaking joint caused by poor soldering techniques
  • Replace a rusty pipe

Whatever reason you may have, desoldering is a technique that must be learned if you want to be involved in the world of plumbing. Otherwise, you can always have a professional plumber do the work for you. 

How to Desolder a Copper Pipe

You may have heard from people that desoldering is much more difficult to do than soldering. It may be true, but if you just follow the right steps, then it might not be as bad as you would think it would be. Before you start the process of desoldering, it’s important to have your tools or equipment ready. 

How to Desolder a Leaking Copper Pipe and Solder it Back Again

The first method is probably the easiest way to desolder a pipe. However, this method will only work if you have a good amount of working space. 

Materials or Tools Needed

Here are the tools that you may need for this method:

  • Hot air gun or torch
  • Locking pliers
  • Mallet or hammer
  • Heat
  • Wet rag

Drain Water Out of the Pipe

You want to drain water out of the pipe before beginning the process of desoldering. First, you have to shut off the main water valve. Then you can either undo the nut from the meter valve or letting the water run and drain from the sink located at the lowest level of your house.

Step 2: Wrap One Side of the Joint with a Wet Rag

Once you have completely drained the water in the pipes, you are now ready to start heating the joint. But before you do that, you must identify which end of the joint you want to desolder. Of course, you would want to desolder the side where water was coming out or leaking.

To prevent you from heating the entire joint, you must wrap one end with a wet rag. This is to keep the other end from melting.

Step 3: Heat the Other End of the Joint

Using a hot air gun, start pointing it at an angle towards the joint. Refrain from moving the hot air gun. A steady source of heat should do the trick. 

Step 4: Clamp the Copper Pipe with a Locking Pliers

Once you see some signs that the joint has started to soften, you can start to lock your pipe with a locking pliers. Then, grab a hold of the mallet and start hammering the locking pliers until the pipe comes loose. 

Remember, this method only works if there is enough space for your pipe to move. Consider other methods which I will elaborate further down below if this won’t work for you.

Step 5: Wipe the End of the Copper Pipe

Once you have removed the copper pipe, wipe the end with a wet rag to remove the solder. It’s important not to skip this step! Doing so will harden the solder making it impossible to put back the copper pipe together without re-heating it.

However, if you plan to replace the copper pipe with a new one, then you can skip to Step 6 right away.

Step 6: Wipe the Inside of the Joint or Fitting

Just like in Step 5, you must remove the solder inside the fitting with a wet rag. 

Step 7: Dry Fit the Copper Pipe

The good thing about resoldering a desoldered pipe is that you no longer have to reapply a tinning flux to the end of the pipe. A tinning flux is used to clean and tin soldered metals allowing the pipe to fit better and smoothly.

The next step after wiping the solder is to dry fit the pipe. If the pipe doesn’t seem to slide in the joint, then you will need to proceed to the next step. Otherwise, you can skip to Step 9 immediately.

Step 8 (Optional): Sand the Tip of the Pipe

Using a 150 or 160 grit sandpaper, sand the ends and the inner walls of the joint. Once completed, you are now ready to proceed to Step 9, which is the assembly of the pipe.

Step 9: Assemble the Pipe by Applying a Thin Layer of Solder

Apply a thin layer of solder to the end of the pipe. It’s important not to apply solder to the inner walls of the joint or fitting. Doing so will cause the solder to leak out (imagine a glue leaking out of a paper you’re trying to join together). Adding too much solder will cause more problems in the future – definitely something you would want to avoid!

Step 10: Lock the Pipe with a Locking Pliers

If necessary, add a little bit of a tinning flux around the end of the pipe. Attach the locking pliers to the copper pipe just like how you positioned the locking pliers when you desoldered the pipe. Then, hammer the pliers in the direction that allows the pipe to fit inside the joint or fitting.

Step 11: Wrap the Other Side of the Joint

Similar to what you did in Step 2, wrap the other side of the joint to protect the other side of the joint from melting.

Step 12: Heat the Joint

Heat the joint using your torch until you start to see the solder leak out and melt. As soon as you see the solder leak out, remove the torch away as you do not want to overheat the solder and the flux. Let the pipe cool down on its own.

Important Tip: Avoid cooling down the copper pipe by using a cold rag to wrap around the area. Cooling the copper pipe in this manner can cause microcracks and will cause unnecessary movement during the soldering phase. Doing so can be one reason why a copper pipe or joint will leak.

How to Tell if a Solder has Cooled Down

It’s easy! You will know that the solder has cooled down when the color turns from a metallic sheen to matte. Once it’s cooled down, you can wipe and remove excess solder with a rag.

Step 13: Turn on Water Valve

Once the pipe is soldered back in, then you are ready to turn on the water valve and let the water run again. 

If you’re still confused on how to properly desolder copper pipes, you may want to check out this YouTube video tutorial created by Got2Learn.

How to Desolder a Copper Pipe in Three Minutes

If the first method doesn’t seem to work well with your situation, then you may try this next method as it’s quicker to do.

Materials or Tools Needed

Here are the tools that you may need for this method:

  • Propane torch
  • Igniter
  • Pliers or pipe cutter
  • Face shield
  • Safety goggles and gloves
  • Fire extinguisher (if possible)

Quick Steps to Desolder a Copper Pipe

  1. Turn off the main valve. You do not want to get wet when desoldering. 
  2. Have the fire extinguisher ready beside you. Wear protective goggles and shield to prevent splattering.
  3. By using a torch, heat the fitting or joint for a few seconds up to a minute. Keep the heat above the fitting if you want to remove the fitting or below the copper pipe if you want to remove the pipe itself.  
  4. Observe as the soldering iron starts to melt, keep the flame on for an additional 30 seconds to ensure adequate heating.
  5. Secure the pipe with a pair of pliers. Be careful not to squeeze the softened pipe too hard as it can irreversibly damage the pipe. 
  6. Depending on what you want to remove, carefully twist the fitting or the copper pipe to detach it from the rest.
  7. Twist the pipe in a back-and-forth motion until it comes apart. 

Does the Type of Heat Matter when Desoldering Copper Pipes?

Yes. In the world of plumbing, there are three types of torches: Propane torch, Brazing torch, and Mapp Gas Torch. It’s important to realize that every type of torch is specific for the use whether it be for welding, soldering, or brazing. Moreover, the type of the pipe or joint material will also play a role to determine which type of torch to use.

Here are the three most common types of torches for desoldering that you need to know about:

Propane torches:

  • Propane torches are the most appropriate for copper pipes or tubing. It is most commonly used to join copper pipes or fitting together. 
  • It is also the easiest type of torch to use.

Brazing torches:

  • Brazing torches are used for brass pipes. While this type of torch can still be used for copper pipes, it can be more difficult to use compared to the propane type. 

Mapp gas torches:

  • Last but not the least, Mapp gas torches have gained popularity over the recent years and may be used for copper pipes. Moreover, it can produce higher temperatures of heat reducing the amount of time needed to get the work done. 

How to Properly Use the Torch When Desoldering a Copper Pipe?

Before anything else, make sure to have a fire extinguisher near you especially when dealing with torches.

The copper pipe or joint must be subjected to the hottest part of the flame in order to properly melt the solder. It’s a common misconception by many that the tip is the hottest part of the flame. However, it really isn’t.

When observing the flame, you will notice that it exhibits three colored layers. The innermost part will bear a blue-colored hue, then gradually lightens to a yellow color. Finally, the tip will bear a yellow or orange hue. The hottest part of the flame is right in the middle, just outside the blue cone. 

It’s important to let that middle area touch the edge of the pipe so it doesn’t take too long to melt the solder.

Does Desoldering Produce Solder Fumes?

Whenever a solder flux starts to melt due to heat, it produces a chemical reaction that releases fumes. Unfortunately, prolonged exposure to solder fumes can produce chronic health effects. This is why it’s important to wear Personal Protective Equipment (PPE) such as safety goggles and face shields to prevent the inhalation of these noxious fumes.

What are the Health Hazards Associated to Solder Fumes When Desoldering Copper PIpes?

Some of the health hazards that are associated to prolonged inhalation to solder fumes are:

  • Irritability of the mucous membranes: Fumes can irritate our nose and eyes so you might notice some redness of the eyes and a runny or itchy nose. This is often observed when exposed to resin-based solder flux. 
  • Allergic hypersensitivity: This is often triggered by repeated inhalation. Hypersensitivity worsens over time and you may experience wheezing and shortness of breath.
  • Asthma: If you suffer from asthma, always provide adequate ventilation when desoldering copper pipes as this can trigger an asthma attack. It’s important to wear face goggles as this lessens your direct exposure to the fumes.
  • Headaches: Not only will it affect your respiratory system, but it will affect your nervous system as well.  
  • Chronic bronchitis due to chronic inhalation of fumes
  • Dizziness as the fumes displace air in your lungs, leading to low levels of oxygen

Can You Burn the Flux During Desoldering?

Yes. This is why it’s important to pay close attention when you’re in the heating process as you do not want the flux to get burnt or charred. This becomes difficult to clean and eventually can do more harm than good to your copper pipes. 

How to Clean the Flux Off?

Flux can be easily removed with a wet rag or brush. This is an important step not to skip when you plan to solder back the copper pipes again. Flux residue can corrode the copper pipes when not removed. If the flux was overheated during desoldering, you will need a wire brush and will need some grinding materials to aid with the removal.

Incomplete removal of the old solder flux will pose a problem when soldering back the pipes again. This can lead the pipes to leak and wiggle as the new solder will not be able to grip the copper pipes well because of solder residue.

Video Tutorials to Watch

If you’re still having trouble getting a good grasp on how to properly desolder copper pipes, checking out some of the video tutorials that may work for you:

Again, it might not be easy the first time you try it. Desoldering is a process that takes practice to perfect. While each situation may be different, the different techniques of desoldering has one main goal – to successfully remove the copper pipe and solder it back together again.

Conclusion

Desoldering a copper pipe can be an easy task to do if you just follow the appropriate steps to take apart a copper pipe from the joint. A propane torch is the most convenient type of heat to use when desoldering copper pipes. 

Before touching any pipe, it’s important to shut off the main water valve and drain out water in the pipes so that water does not leak out during the process of desoldering. Applying an adequate amount of heat can melt the solder without damaging the pipe. 

Moreover, it’s important not to overheat the solder as this can be harder to remove. Stuck solder flux can corrode the copper pipes overtime if not removed.

Sources

https://www.instructables.com/How-to-UNSOLDER-Copper-Pipe-Click-to-WATCH/
https://www.rooterguard.com/2020/08/19/how-to-unsolder-copper-pipe/#:~:text=Occasionally%2C%20you%20need%20to%20get,leak%20in%20the%20soldered%20joints.
https://www.oatey.com/products/oatey-no-95-tinning-flux-617577034
https://www.plumbingsupplynow.com/types-of-torches
https://www.harrisproductsgroup.com/en/blog/2016/june/five-misconceptions-about-flux.aspx#:~:text=When%20flux%20is%20used%20properly,or%20burn%20on%20the%20part.

Alexander Berk

A bit about myself: I am a certified international welding engineer (IWE) who worked in different welding projects for TIG, MIG, MAG, and Resistance Spot welding. Most recently as a Process Engineer for Laser and TIG welding processes. To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding. I sincerely hope it will help you to improve your welding results as much as it did improve mine.

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