Soldering and brazing are:

Soldering and brazing are often classified as adhesive processes because they involve the joining of materials using a filler metal without melting the base metals. In these processes, the filler metal adheres to the surfaces being joined and forms a bond upon cooling. This bonding is achieved through capillary action between the closely fitted surfaces, which is characteristic of how soldering and brazing function.

Brazing typically occurs at higher temperatures than soldering but still well below the melting point of the base metals. This characteristic aligns with the idea that they are not fusion welding processes, as fusion welding involves melting the base materials to join them. Therefore, while soldering and brazing could be considered low temperature in comparison to some welding methods, they are not defined primarily by their temperature levels nor solely suited for boiler construction as their applications extend to various industries.

Understanding that soldering and brazing work through adhesion rather than melting the workpieces is critical in recognizing their importance in fabrication and repair scenarios in plumbing, HVAC systems, and electrical applications.