Soldering copper pipe works primarily through capillary action, creating a strong, leak-proof joint. Here's a breakdown of the process:
1. Preparation is Key:
- Cutting the Pipe: The copper pipe needs to be cut cleanly and squarely. A tubing cutter is ideal for this.
- Cleaning: Thoroughly clean both the inside of the fitting and the outside of the pipe using a wire brush or emery cloth. This removes oxides and contaminants, allowing the solder to bond correctly. The surfaces should be bright and shiny.
- Applying Flux: Apply a thin, even layer of flux to both the inside of the fitting and the outside of the pipe. Flux is a chemical cleaning agent that prevents oxidation during heating, further promoting solder flow and adhesion.
2. Assembling the Joint:
- Insert the Pipe: Insert the cleaned and fluxed pipe into the fitting, ensuring it's fully seated.
- Wipe off Excess Flux: Wipe away any excess flux that squeezes out.
3. Applying Heat:
- Heat the Joint Evenly: Use a propane or MAPP gas torch to heat the fitting evenly. Direct the flame primarily on the fitting itself, and allow the heat to conduct to the pipe.
- Test the Temperature: Periodically touch the solder to the joint. When the pipe and fitting are hot enough (the flux will start to bubble), the solder will melt on contact.
4. Soldering Process:
- Apply the Solder: Touch the solder to the joint where the pipe and fitting meet. The heat will melt the solder, and capillary action will draw it into the gap between the pipe and fitting. Continue applying solder around the entire circumference of the joint until a bead of solder is visible.
- Don't Overheat: Avoid overheating, which can burn the flux and weaken the joint.
5. Cooling and Cleaning:
- Allow to Cool Naturally: Let the joint cool naturally without disturbing it. Forced cooling can weaken the joint.
- Wipe Excess Solder: Once cooled, wipe off any excess solder or flux residue with a damp cloth.
In summary, soldering copper pipe involves cleaning, applying flux, heating the joint to the correct temperature, and allowing capillary action to draw the molten solder into the fitting, creating a sealed connection.
