180° Return Bend (also known as a Hairpin Bend or U-Bend) is a pipe fitting that reverses the flow direction by 180 degrees. Unlike a standard 180 degree long radius elbow, a return bend has a specific "return" geometry where the two ends are parallel to each other but facing opposite directions. Function: As a space-saving, high-integrity connector in heat exchanger tube bundles, pipe racks, steam systems, and expansion loops, where reversing the pipe route without using multiple separate elbows is mechanically and economically superior.

Chemical Composition % of ASTM A815 WPS32205 Duplex Stainless Steel Return Bend Duplex 2205 Pipe Fitting

C	N	P	Si	Mn	Mo	Fe	Cr	S	Ni
1.0	0.03	0.02	2	3.0-3.5	22.0-23.0	0.03	4.5-6.5	0.14-0.2	Balance

Mechanical Properties of ASTM A815 WPS32205 Duplex Stainless Steel Return Bend Duplex 2205 Pipe Fitting

Density	Melting Point	Yield Strength (0.2%Offset)	Tensile Strength	Elongation
7.8 g/cm3	1350 °C (2460 °F)	Psi – 80000 , MPa – 550	Psi – 116000 , MPa – 800	15%

Inspection & Testing Requirements (per ASTM A815)

To ensure quality, the following tests are typically performed:

Chemical Analysis and Tensile Testing (per heat).
Hardness Test (HRC or HBW) – typically limited to ≤ 28 HRC for sour service.
Ferrite Content Measurement – must be between 35% and 65% as per the standard practice.
Hydrostatic Test or Nondestructive Examination (NDE) – such as dye penetrant (PT) or radiographic testing (RT) to check for surface or volumetric defects.
Intergranular Corrosion Test – per ASTM A262 (Practice E) to ensure proper sensitization resistance.

Application

This fitting is heavily used in industries where space is constrained, and piping needs to be routed back in a compact loop:

Heat Exchangers (as U-tubes or return bends in shell-and-tube exchangers).
Oil & Gas (offshore platforms, subsea manifolds, and flowlines) where sour gas (NACE MR0175/ISO 15156) is handled.
Chemical/Petrochemical Processing (handling acetic acid, formic acid, and hot chloride solutions).
Marine Engineering (seawater cooling systems).
Pulp & Paper (digester systems).

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Fired Heater Parts

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Studded Tube

Solid Fin Tube

Serrated Finned tube

Embedded G Fin Tube

Extruded Fin Tube

Wound Fin Tube

Low Fin Tube

Square Fin Tube

Longitudinal Finned Tube

Enhanced Heat Transfer Tube

Fin Tube Support

Return Bend

Heat Exchanger Tube

Stainless Steel Heat Exchanger Tube

Duplex Stainless Steel Heat Exchanger Tube

Super Duplex Stainless Steel Heat Exchanger Tube

Nickel Alloy Steel Heat Exchanger Tube