Product Overview
Yuhong Group Co., Ltd. manufactures and supplies a comprehensive range of heat transfer equipment and components, including heat exchangers, pressure vessels, air-cooled units, tube bundles, U-bend tubes, finned tubes, and accessories such as tubesheets, baffles, and heads. This page focuses on our ASME SB163 UNS N04400 Monel 400 seamless U-bend tubes, engineered for condenser and heat exchanger service under demanding corrosive conditions.
ASME SB163 covers seamless nickel and nickel alloy tubes for condenser and heat-exchanger applications. UNS N04400, commonly known as Monel 400, is a nickel-copper alloy selected for combined strength and corrosion resistance. U-bend tubes are supplied with stress relief heat treatment after bending, as required for U-bend configurations under ASME SB163.
Key Specifications
| Parameter | Value |
|---|---|
| Standard | ASME SB163 |
| Material | UNS N04400 (Monel 400) |
| Form | Seamless, U-bend |
| Outer Diameter | 3 in. (76.2 mm) and under per SB163 scope |
| Wall Thickness | Minimum 0.148 in. (3.76 mm) and under; average 0.165 in. (4.19 mm) and under |
| Nickel Content | 63.0% min |
| Copper Content | 28.0–34.0% |
| Tensile Strength | 517 MPa (75 ksi) min |
| Yield Strength (0.2% offset) | 172 MPa (25 ksi) min |
| Elongation | 35% min |
| Condition | Annealed or stress-relieved per ASME SB163 Table 2 |
Material and Corrosion Performance
UNS N04400, commonly known as Monel 400, is a solid-solution nickel-copper alloy (approximately 67% Ni, 23% Cu) that cannot be strengthened by heat treatment but develops higher strength through cold working. Its corrosion resistance profile is particularly relevant for heat exchanger and condenser service:
Seawater and brackish water: Exhibits low corrosion rates in rapidly flowing seawater and resistance to cavitation and erosion.
Chloride stress corrosion cracking: Alloy 400 is virtually immune to chloride-ion SCC in typical environments.
Reducing acids: Resistant to de-aerated hydrochloric and hydrofluoric acids. Performance in sulfuric acid is limited to modest temperatures and concentrations.
Alkalis and salts: Excellent resistance to neutral and alkaline salt solutions.
Temperature range: Maintains mechanical properties from subzero temperatures up to 1020°F (548°C).
Manufacturing and Quality Control
Seamless tubes are produced through cold drawing, followed by annealing to restore ductility and corrosion resistance. The base tube is supplied in the annealed condition prior to U-bending to ensure formability, with the bend radius and adjacent six-inch leg subsequently stress-relieved by resistance heating under inert gas (Argon) to prevent inner-diameter oxidation.
ASME SB163 UNS N04400 tubes are delivered with chemical composition verification, tensile testing, and one or more of the following non-destructive examinations: hydrostatic test, eddy current test, and ultrasonic test. Dimensional tolerances conform to ASME SB163 requirements for outer diameter, wall thickness, and length.
Typical Applications
ASME SB163 UNS N04400 U-bend tubes are specified in shell-and-tube heat exchangers and condensers across the following service environments:
Seawater-cooled condensers on offshore platforms and marine vessels
Chemical processing plant heat exchangers handling reducing acids and halide-bearing media
Petrochemical and refinery condenser and cooler service
Power generation steam condenser tubing
Desalination evaporator and brine heater tube bundles
Offshore platform heat recovery units
FAQ
Q: Why specify U-bend tubes instead of straight tubes? U-bend configurations reduce tube-to-tubesheet joint count and accommodate thermal expansion within the tube bundle, simplifying shell-and-tube exchanger assembly.
Q: Does ASME SB163 permit stress-relieved rather than fully annealed U-bend tubes? Yes. ASME SB163 permits UNS N04400 tubing in either annealed or stress-relieved condition per Table 2 of the specification.
Q: What is the maximum recommended service temperature for Monel 400 tubes? Mechanical properties are retained from cryogenic temperatures up to approximately 1020°F (548°C), though design temperature limits should be evaluated against the specific operating environment.
Contact: For technical inquiries, dimensional requirements, or quantity requests, reach Yuhong Group at vladimir@steelseamlesspipe.com.
