When selecting copper tubes for refrigerant piping, factors such as tube size, wall thickness, and material grade should be considered. The tube size should be compatible with the system’s refrigerant flow rate and pressure requirements. Wall thickness should be sufficient to withstand the system’s operating pressures. Material grade, such as Type L or Type K, should be chosen based on the system’s specific requirements, including corrosion resistance and thermal conductivity. Additionally, the tube’s inner and outer surfaces should be clean and free of debris to ensure proper brazing and minimize the risk of leaks.