ASTM B444 Inconel 625 Seamless U Bend Tube
Product Overview
Precision Cold-Bent Nickel Alloy U Tubes for High-Corrosion and High-Temperature Service
ASTM B444 Inconel 625 Seamless U Bend Tubes are manufactured from solid-solution strengthened nickel-chromium-molybdenum alloy UNS N06625. The alloy provides excellent resistance to chloride-induced corrosion, oxidizing and reducing acids, and elevated-temperature oxidation. ASTM B444 covers cold-worked seamless nickel alloy pipe and tube, with UNS N06625 supplied in annealed Grade 1 or solution-annealed Grade 2 depending on service requirements.
Cold bending is performed using controlled tooling to maintain bend radius accuracy, wall thickness uniformity and ovality within project specifications. U tubes are suitable for fixed tubesheet heat exchangers where thermal expansion compensation and long-term reliability are required.
Technical Specifications
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Item
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Specification
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Product Name
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ASTM B444 Inconel 625 Seamless U Bend Tube
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Material Grade
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Inconel 625 / UNS N06625
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Standard
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ASTM B444 / ASME SB444
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Tube Type
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Seamless U Bend Tube
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Manufacturing Process
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Cold Drawn + Cold Bent
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Delivery Condition
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Annealed or Solution Annealed
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Outside Diameter
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12.7–50.8 mm
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Wall Thickness
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0.8–6.35 mm
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Bend Radius
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As Per TEMA or Customer Drawing
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Tube Leg Length
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Customized
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Inspection
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UT, ET, Hydrostatic, PMI
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Certification
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EN 10204 3.1
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Product Features
- Solid-Solution Strengthened Nickel Alloy
Excellent mechanical strength without precipitation hardening.
Controlled bend radius, low residual stress and consistent wall thickness through the bend section.
- Outstanding Corrosion Resistance
Suitable for chloride-containing environments, seawater, acidic media and mixed chemical processing streams.
- High-Temperature Oxidation Resistance
Maintains structural stability in elevated-temperature applications.
- Tight Dimensional Control
Tube straightness, bend geometry and leg parallelism are verified before shipment.
Typical Applications
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Shell & Tube Heat Exchangers
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Steam Surface Condensers
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Waste Heat Recovery Units
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Petrochemical Process Heaters
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Offshore Process Modules
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Flue Gas Desulfurization (FGD) Systems
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Marine Cooling Equipment
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Nuclear Auxiliary Heat Exchangers
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Chemical Reactors
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Geothermal Heat Recovery Systems
Equivalent Material Grades
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Standard
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Grade
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ASTM / ASME
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B444 / SB444
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UNS
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N06625
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Werkstoff
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2.4856
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EN
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NiCr22Mo9Nb
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ISO
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Alloy 625
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Inspection & Testing
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Positive Material Identification (PMI)
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Eddy Current Testing (ET)
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Ultrasonic Testing (UT)
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Hydrostatic Testing
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Bend Radius Inspection
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Wall Thinning Verification
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Ovality Measurement
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Dye Penetrant Test (Optional)
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EN 10204 3.1 Documentation
FAQ
Can the bend radius be customized?
Yes. U bend radius and leg length can be manufactured according to TEMA standards or customer drawings.
Is solution annealed material available?
Yes. Both annealed Grade 1 and solution-annealed Grade 2 can be supplied in accordance with ASTM B444.
What inspections are performed?
PMI, ET, UT, hydrostatic testing, bend inspection and dimensional verification are available.
① Straight Tube vs U Bend Tube
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Feature
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Straight Tube
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U Bend Tube
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Fabrication
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Direct Installation
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Cold-Bent Form
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Thermal Expansion
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External Compensation
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Built-in Flexibility
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Common Equipment
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General Piping
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Shell & Tube Heat Exchangers
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② Inconel 625 vs Hastelloy C276
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Alloy
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Main Advantage
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Typical Service
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Inconel 625
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High strength + oxidation resistance
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Heat exchangers, offshore, aerospace
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Hastelloy C276
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Wider chemical corrosion resistance
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Aggressive chemical processing
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③ Technical Terminology
- Cold Drawn Seamless
- Cold Formed U Bend
- Minimum Bend Radius
- Wall Thinning Control
- Residual Stress Relief
- Leg Parallelism
- Ovality Tolerance
- Springback Compensation
- Solid Solution Strengthening
- Thermal Expansion Compensation
- Crevice Corrosion Resistance
- High-Temperature Oxidation Resistance
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