What needs to be removed from both the inside and outside of tubes before soldering?

Before soldering, it is crucial to ensure that both the inside and outside of tubes are free from any burrs. Burrs are sharp, unwanted edges or pieces of material that can form during cutting or machining processes. If not removed, these burrs can create uneven surfaces that hinder proper fit and can prevent effective heat transfer during the soldering process. The presence of burrs can lead to weak joints, incomplete solder flow, and potential leaks in the finished assembly.

By adequately cleaning and deburring the surfaces, a smooth area is provided for the solder to flow and adhere, ensuring a strong and reliable joint. This step is fundamental to achieving a clean and effective soldering result.