An Overview of Fin-to-Tube Attachment Methods in Finned Tubes

The efficiency and reliability of finned tubes depend greatly on how the fins are attached to the base tube. The attachment method determines not only the heat transfer performance but also the mechanical strength, corrosion resistance, and suitability for different industrial environments. Several widely used fin-to-tube connection techniques include high-frequency welding, extrusion, embedding, and brazing.
High-frequency welding is one of the most common and robust attachment methods. In this process, steel fins are welded to the base tube using high-frequency resistance heating, creating a strong metallurgical bond. This method provides excellent mechanical stability and high-temperature endurance, making it ideal for boilers, power generation, and petrochemical heat exchangers.
Extrusion is typically used for aluminum finned tubes. During this process, an aluminum sleeve is mechanically extruded over the base tube and simultaneously formed into tightly bonded integral fins. This method yields exceptional thermal conductivity and corrosion resistance, making extruded fin tubes popular in air coolers, HVAC systems, and gas-to-liquid heat exchangers.
Embedding, also known as the “gilled” or “grooved” method, involves inserting a fin strip into a machined spiral groove on the tube surface. The fin is then mechanically expanded or locked into place. Although not as strong as welded fins, embedded fins offer good heat transfer performance and are suitable for medium-temperature operations where cost efficiency is important.
Brazing is another technique used primarily for copper or aluminum finned tubes. In this process, a filler metal is melted and drawn into the joint by capillary action, forming a secure bond between the fin and the tube. Brazed finned tubes deliver excellent thermal performance and are widely used in refrigeration and compact heat exchanger designs.