What is A Solder Joint?
A soldered joint is the most common method of joining copper pipe and tubing. The copper pipe must be cut square. All cut tube ends of copper pipe should be reamed to the full inside diameter of the tube end to remove the burr.
All joint surfaces should be cleaned. A flux should be applied before soldering. Flux is a chemically active material that removes and excludes oxides from the joint area during the heating process, and allows the melted solder to spread out on the joining surfaces.
The joining of water-supply piping should be made with lead-free solder and fluxes. “Lead-free” means a chemical composition equal to or less than 0.2% lead content.
Lead-bearing solder can sometimes be visually identified because the solder tends to darken over time. The solder will flow by capillary action toward the heat. Heat causes the copper atoms to move farther apart from each other, and the solder atoms enter the spaces between the copper atoms, creating a strong bond when solidified.