U Return Bend 180 Degree Elbow Carbon Steel ASTM A179 For Bend Finned Tubes

The return bend in finned tubes is a crucial component in heat exchanger systems, particularly in applications like air-cooled heat exchangers (ACHEs), boilers, and economizers. It allows the tubing to make a 180-degree turn, enabling continuous flow within a multi-row or multi-pass configuration.

A179 refers to a low-carbon steel tube material specification (ASTM A179/A179M) commonly used in heat exchangers and condenser applications. When used in finned tubes with return bends, these components are typically found in air-cooled heat exchangers, boilers, and other thermal systems.

Chemical Composition (%)

Mechanical Properties Low-carbon steel (similar to A192 but with tighter tolerances).

Key Characteristics:

Excellent thermal conductivity
Good weldability and formability
Suitable for low to medium-pressure applications
Often used in bare or finned tubes for condensers and heat exchangers

Return Bend Function:

Connects two finned tubes to form a continuous flow path;

Ensures efficient heat transfer by maintaining fluid circulation.

Return Bend Design Considerations

Bend Radius:

Typically short-radius (1xD) or long-radius (1.5xD) depending on flow requirements.

Fin Attachment:
Fins are usually extruded, embedded, or welded on straight sections.
The return bend itself is often left unfinned (bare) for ease of manufacturing.

Connection Methods:
Welded return bends (common for high-integrity applications).
Mechanical (press-fit or threaded) connections for easier maintenance.

Applications

Condensers & Heat Exchangers (e.g., power plants, refineries)
Boiler Economizers

HVAC & Refrigeration Systems
Industrial Process Heating/Cooling