ASTM A179 U Bend Boiler Tube Manufacturing Process and Technical Features

The production of A179 U-bend tubes involves several precision processes:

• Cold Drawing Process: Tubes are manufactured as seamless tubes and processed through cold drawing.
• Heat Treatment: After the final cold drawing, tubes undergo heat treatment at 650°C (1200°F) or higher.
• Precision Bending Technology: Advanced manufacturers employ high-precision cold bending technology.
• Wall Thickness Control: The bending process maintains strict wall thickness control with thinning rate ≤7% on the outer arc (measured value: 2.83mm) and thickening ≤8% on the inner arc (measured value: 3.28mm).
• Springback Compensation: Based on dynamic adjustment of material yield strength with ±0.5° precision.
• Stress Relief: Post-bending stress relief at 300°C reduces residual stress to ≤15MPa (meeting ASME Sec III requirements)

ASTM A179 U Bend Boiler Tube Quality Control and Testing

• Pressure Testing: Hydrostatic testing at 35 MPa for straight sections (exceeding standard value of 22.6 MPa). 28 MPa at U-bend areas (exceeding 2.5 times working pressure) 1
• Leak Testing: Helium mass spectrometry leak detection at ≤1×10⁻⁹ Pa·m³/s (nuclear grade requirement) 1
• Non-Destructive Testing: Eddy current testing (ASTM E309) capable of detecting Φ0.2mm through holes. Ultrasonic C-scan (ASME Sec V Art.4) with crack detection limit of 0.1mm. Surface Roughness: Achieved Ra ≤ 0.8μm through pickling and passivation (exceeding standard basic requirements) , with optional electrolytic polishing achieving Ra ≤ 0.2μm (reducing fouling accumulation rate by 60%).

ASTM A179 U Bend Boiler Tube Applications and Industry Use Cases

A179 U-bend tubes are designed for demanding thermal applications:

1. Nuclear Power Equipment: Steam generator U-tube bundles (meeting NUREG-0800 anti-intergranular corrosion requirements).
2. Supercritical Heat Exchangers: Operating at 32MPa@620°C (material endurance strength ≥80MPa).
3. Power Station Condensers: Particularly those with single-pass length >12m.
4. Marine Power Systems: Seawater corrosion resistance (with phosphating film + cathodic protection synergistic design).
5. Ship Seawater Cooling Systems.
6. Multi-effect Evaporator Ultra-long Tube Bundles.
7. Chemical Processing Equipment: Heat exchangers and condensers.