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Solder the Joint — Preparation and Safety

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How to Solder Copper Pipes for a Permanent, Watertight Joint · Step 1 of 9

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In this video

Place a heat shield, such as a piece of cement board, behind the pipe to protect the wall. Slide the adapter onto the flux-coated pipe. Light your propane torch and begin heating the fitting, not the pipe directly. This draws the solder into the joint. Keep the tip of the blue flame about an inch from the fitting. After about 15-20 seconds of heating, touch the soldering wire to the joint on the side opposite the flame. If the fitting is hot enough, the solder will melt and flow into the seam. Continue feeding the solder until a continuous silver ring forms around the joint. Turn off the torch and let the joint cool undisturbed. You can wipe away any excess drips with a damp rag, being extremely careful of the heat.

Goal: Create a watertight solder joint

  • Always use a heat shield to prevent fires. Do not point the torch flame at flammable materials.
  • The pipe and fitting remain dangerously hot for several minutes. Do not touch with bare hands.
  • Heat the fitting, not the pipe. This allows capillary action to draw the solder into the joint for a stronger seal.

Used in this video

  • Propane Torch (Tool Type: Plumbing Tools, Power Source: Manual)Heating the pipe and fitting for soldering.
  • Heat Shield (Tool Type: Safety Equipment)Protecting the wall from the torch flame.
  • Damp Rag · optionalWiping away excess solder and cooling the joint.
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FAQs

What type of torch is best for soldering copper pipes, and how do I know I'm applying enough heat?

The K Tool International Self Igniting Propane Torch Head is sufficient for most residential copper pipe soldering. You'll know you're applying enough heat when the pipe and fitting are hot enough to melt the Oatey Safe Flo Lead-Free Solder *by touching the pipe*, not the flame. The solder should then be drawn into the joint by capillary action.

What are the critical safety precautions I must take when soldering pipes indoors?

Always have a fire extinguisher nearby and remove any flammable materials from the work area, especially when using a torch. Ensure good ventilation to disperse solder fumes, and wear safety glasses to protect your eyes from splashes or heat. It's also crucial to turn off the main water supply before starting to avoid accidents and ensure pipes are dry.

Is it really necessary to deburr, ream, and thoroughly clean the pipes before soldering?

Absolutely. Deburring and reaming with a tool like the Husky 1-5/8 in. Inner/Outer Reamer ensures a smooth pipe interior for optimal water flow and prevents solder from being blocked. Thorough cleaning with sandpaper and applying Oatey H-20 Flux are critical to remove oxidation, allowing the solder to properly bond and create a strong, watertight seal.

What are the most common reasons a soldered joint might leak, and how can I avoid them?

Leaks often occur due to insufficient cleaning, inadequate heat application, or not using enough solder. Ensure pipes are shiny clean before applying Oatey H-20 Flux, heat the joint evenly until it can melt the solder, and feed enough solder to completely fill the joint. If a joint leaks, it must be desoldered, thoroughly cleaned, and resoldered.

Transcript
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So for example my copper is half an inch wide so I'm going to bend over half an inch on my wire. I slide on my adapters, light my propane torch and I'm going to use a piece of old cement board here so I don't burn my house down. I want to keep the blue part of the flame an inch or two from the adapter and then test the opposite side with my soldering wire every five seconds or so to check to see if it's hot enough yet. Ideally if you use the right amount of solder it'll fill all the way around the adapter and won't drip down. For the other one here I'll use about three quarters of the wire instead of the half inch just to show you what happens and you'll see how it drips. If you do happen to drip you can just wipe it off with a rag just remember that this thing is going to be steaming hot for a while so never ever touch it with your bare hands until it's had a chance to cool down.

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