How To Solder Copper Pipe With Water In It

To solder copper pipes that contain water, you need more than torches, gloves, fuels, and some flux. Tube cutters, sandpapers, wire brushes, and safety glasses are important soldering tools too. If you understand the techniques, it's not difficult to solder any diameter of copper pipes with water in them. However, your choice tools will determine the quality of a solder. Let's share some tips with this guide.

Can You Solder Copper Pipes With Water Inside?

When soldering, it's better to keep copper pipes dry. One of the ways of stopping water (inside the pipe) from ruining your soldering task is to use a pipe plug. It doesn't matter whether the water is trickling; stop it with a pipe plug. If water goes through the pipe, keep a bucket under the flow and turn off the supply from its valve. This action will prevent water pressure build-up in the pipe.

It's hard to solder pipe joints with water, and the soldering torch's heat could make steam from the water. Also, the copper pipe gets less heat to melt the solder when you fix pipes that contain water.

How To Solder Copper Pipe With Water In It

Water Plug Applications

The purpose of using water plugs for soldering is to prevent the water from reaching the spot. For DIYers, you could improvise by using a thick paste instead of pipe plugs. Artificial water plugs can be made from materials that form pastes. They include wax capsules, chewing gums, and chewed bread. However, the chances of clogging a pipe's valves, and aerators are high with these materials. Before soldering, you'll need to push the artificial plug into the pipe with a pencil.

One of the advantages of using artificial water plugs is the ease of flushing them after your soldering task. Since they are lightweight materials, the pressure from water through the copper pipe will ensure free flow.

Regular water plugs come with applicator tubes. After your task, dissolve the water plug with the heat from the soldering torch. Place the torch under the area where you have the water plug. It's quite a simple task, and you can find water plugs for ½ and ¾-inch diameters of copper pipes in local plumbing accessory stores.

Techniques For Soldering Copper Pipes

If you considering a pencil torch for soldering, it's better to buy one with built-in igniters. However, you'll need bigger torches for copper pipes with ½ and ¾-inch diameters. Depending on your soldering techniques, copper pipes can have good or bad joints.

However, you wouldn't like to burn the parts of your material by soldering at 1000 degrees. This level of heat could overheat the flux, and damage the copper pipe. Also, you might lose control and trigger a fire when heat distributions to soldering tips are too fast. When the solder joints are too brittle, the copper metal will atomize discharge as fumes.

Prep Before Soldering

To ensure leak-free joints, clean the portions of copper pipes that need to be soldered. Also, you'll need to deburr the internal areas of the copper pipe with your tool. Ensure that deburring doesn't reduce the pipe’s inner diameter significantly. Also, avoid the turbulence that causes a pinhole with rusty copper pipes.

While the sandpaper (emery cloth) cleans the outer diameter of your pipe, ream the internal surfaces with wire brushes. Both processes ensure suitable outer surfaces for the solder to adhere to the pipe.

Protect Joints With Damp Rags

A wet rag for soldering has dual functions - a flame protector and heat absorber. Wet the rag and wrap it around the copper pipe's fitting to protect the portions. Since wet rags absorb soldering heat, it will cool the temperature and ensures the solder doesn't melt.

Flux The Copper Pipe With A Brush

After prepping these portions, apply a thin layer flux (soldering paste) with a brush. An inch of coat on the copper pipe's surface will keep it glued to its fitting, and spread the flux. This soldering process ensures the filler material optimizes capillary action when you apply some heat. Don't forget that the flux helps to prevent oxidation of the base metal and filler materials.

Soldering Temperature

It's important to set your soldering iron at the right temperature. Know the wattage to ensure a good solder. Since wattage relates to soldering temperature, bigger copper pipes need much heat.

Consider the size of your copper pipes before setting the soldering temperature. Normally, ½-inch pipes need less time to gain heat than ¾-inch pipes. Use normal propane fuels that produce 3500 degrees Fahrenheit of heat.

The specification of maximum heat output determines how fast it gets to the iron's tip. In ideal conditions, a 15W device can generate 550 degrees Fahrenheit and the 40W produces at least 800 degrees of heat.

We recommend soldering temperatures of between 750 to 800 degrees for soldering copper pipes. If you decide to set the soldering temperature below 450 degrees, it will take a bit of patience to achieve your task.

Make The Copper Material Sweat

Use lead-free solders if the copper pipe is used for supplying potable water. For example, a '50/50' code on any solder wire product means it's not lead-free. After igniting your propane torch, align its tip to set the flame against the soldering area.

Apply the heat for about 5 seconds for the soldering paste to sizzle evenly. Repeat the same process on the opposite area of the copper fitting for even distribution of heat. If it's your first time of soldering copper pipes, place the solder wire on the pipe to see if it melts. A melting sign shows that your copper pipe is in the mood to solder.

Assemble the pipe's fitting before inserting it in the pipe. When the pipe is hot, infuse a ½ or ¾-inch solder into the joint quickly. Don't forget to clean any excess soldering paste (flux) with the wet rag.

Inspection And Leak Tests

Inspect the joint to ensure that it has been well-soldered. However, you might need to fill any void in the joint with some flux. Then, apply some heat on the joint and solder again.

After the metal's temperature cools, don't forget to test the soldered joint with water. It's a surefire way of checking for leaks.

Final Note

It's often a delight to share experiences from our expert welders and craftsmen. While this article helps artisans to improve their soldering skills, it guides beginners and DIYers. In our next topic, we shall analyze more challenges with the soldering of metals. However, you are set to apply every tip from this guide.

Last Updated on 2 years by Richard Boyer

  • June 8, 2022
Richard Boyer

Richard Boyer has been a professional welder for over 27 years of his life, and now he is a trainer and blogger providing critical information to anyone interested in welding. He is helping out both hobbyists, novice and professional welders to learn newer and better techniques. Read more about me

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