ASTM B366 UNS N06022 / DIN 2.4602 / Hastelloy C22 Pipe Fittings 180° SR Return Bends

ASTM B366 Hastelloy C22 / UNS N06022 / DIN 2.4602 Nickel Alloy Return Bends 180° SR
 
 
ASTM B366 Hastelloy C22 Return Bend (UNS N06022 / DIN 2.4602) refers to a pre-fabricated, 180-degree pipe fitting designed to completely reverse the direction of fluid flow. It is made from a nickel-chromium-molybdenum-tungsten alloy known as Hastelloy C22 and complies with the ASTM B366 manufacturing standard. Unlike a standard long-radius 180° elbow, a "return bend" usually features a compact, tight radius—typically one or one-and-a-half times the nominal pipe diameter (1D or 1.5D). This compact design makes it ideal for use in heat exchanger tube bundles, steam tracing lines, or confined piping systems. The fitting provides outstanding resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking, especially in harsh chemical environments such as wet chlorine, hydrochloric acid, or hot sulfuric acid. 

Applications

• Shell and tube heat exchangers: U-tube bundles for corrosive fluids (e.g., H₂SO₄ coolers).

• Fired heaters (furnaces): Pigtail or serpentine coils in hydrochloric acid or chlorine service.

• Pickling lines (steel industry): Hot mixed acid (HNO₃ + HF) return loops.

• Offshore chemical injection skids: Compact 180° bends for corrosion inhibitor lines.

• Nuclear reprocessing plants: Where oxidizing nitric acid containing fluorides is present.