Only a perfectly clean and corrosion of pipes should be used. All possible contamination must be saved pipes and components during installation. Copper pipe will be clean and sealed as received, and it must be connected at all times, except in the cases when the adoption of a joint. Use the plastic caps provided tube - they can easily be seen and not remain on the tube. Cork paper and rags, as a rule, is forgotten and left in place. Steel pipe will have oily coating upon receipt, and it is important that it should be destroyed, because the oil is to be done in the sump and pollute the proper lube oil. If the pipes are not so clear, compressor oil must be changed before the plant has passed.
You can avoid garbage, loose pieces of welding fluxes, and short pieces of wire is often used as temporary props for butt welds. The pipe should only be cut with a gas burner, if all of oxidized metal can be washed away once before closing the pipe.
It should be borne in mind that all refrigerants have strong influence of the solvent and chips, rust, scale, water, oils and other pollutants will cause harm to the system, and possible problems and shortens life.