Soldering is the process of joining two pieces of metal together. You will need solder, flux and a heat source for soft solder. For this example, we can use a propane torch. This is what a lot of plumbers use to plumb your house for water.

You will need to clean both pipes on the outside ends and deburr the inside of them to make sure there are no objects that can break free in the pipe and cause clogging or issues with the operation of the refrigerant cycle. Now we clean the inside of the fittings as well, typically using an emery cloth or sand paper. After cleaning all surfaces by sanding, you will want to wipe them with a cloth to remove any residual debris. Then, you will need to put the flux on the areas you cleaned and connect them together with the coupling. Now that they are together we can solder them.

Flux paste cleans and assists in the bonding of the solder to the pipes. When you solder you will need to heat the fitting in the middle as to draw the solder into the fitting. The fitting has to be hotter than the pipe. If they are the same temperature, the solder will not flow inside or wick into the fitting between the pipe and the fitting; it will just drip onto the ground. If that is the case, cool the pipe down with a rag that has been wet with water and then try again until it is right.

Applications for solder are as follows: Refrigerant lines that will not exceed around approximately 200psi when using 50/50, which is 50% tin and 50% lead. This will work for low pressure refrigerant and non-potable water (not drinkable).

95/5 solder is 95% tin and 5 percent antimony and can be used for drinking water applications. 95/5 is stronger as well for HVACR applications which can handle pressures up about 275psi. Now there is a lot more involved than this. This is just an informative view. Other variables include pipe strengths, tensile strengths and types of copper you are using. “Example: type k, l or m which is a rating of copper pipe for wall thickness changes the maximum pressure each can handle. The lowest of the three is M and the highest is K. But it even has an annealed version and a drawn which changes the pressures as well.