Product Overview
The ASME SB564 Monel 400 Flange is a flanged pipe connection component forged from the nickel-copper alloy Monel 400 (UNS N04400). With a nickel content of approximately 63% or higher and copper content of 28–34%, Monel 400 offers outstanding corrosion resistance in seawater, hydrofluoric acid, alkaline solutions, and high-temperature steam, and is virtually immune to chloride stress corrosion cracking.
Our Monel 400 flanges are strictly manufactured to ASTM B564 / ASME SB564 standards, with dimensions conforming to ASME B16.5. They are widely used in marine engineering, chemical processing, petrochemical, nuclear power, and seawater desalination piping systems.
Core Material Characteristics
Chemical Composition Design
The nickel-copper alloy system of Monel 400 is the foundation of its corrosion resistance:
| Element | Content Requirement |
|---|---|
| Nickel (Ni) | ≥ 63.0% |
| Copper (Cu) | 28.0% – 34.0% |
| Iron (Fe) | ≤ 2.50% |
| Manganese (Mn) | ≤ 2.00% |
| Carbon (C) | ≤ 0.30% |
| Silicon (Si) | ≤ 0.50% |
| Sulfur (S) | ≤ 0.024% |
The nickel content includes cobalt. Low carbon and low sulfur control ensure good weldability and processing performance.
Mechanical Properties
| Property | Typical Annealed Values |
|---|---|
| Tensile Strength | 550 MPa |
| Yield Strength (0.2% offset) | 240 MPa |
| Elongation | 48% |
| Density | 8.8 g/cm³ |
| Melting Point | 1300 – 1350°C |
| Hardness | 110 – 150 HB |
Monel 400 maintains good mechanical properties from sub-zero temperatures up to approximately 550°C. It can be strengthened by cold working when higher strength is required.
Key Corrosion Resistance Characteristics
Seawater and Chlorides: Extremely low corrosion rates in fast-flowing seawater and brackish water, virtually immune to chloride stress corrosion cracking
Hydrofluoric Acid: One of the few metallic materials capable of withstanding unaerated hydrofluoric acid
Alkalis and Salts: Excellent resistance to neutral and alkaline salt solutions; long the standard material for salt industry equipment
Limitations: Not suitable for nitric acid and ammonia systems; attacked in sulfur-containing gases above approximately 370°C (700°F)
Comparison with Other Common Flange Materials
Comparison with 316L Stainless Steel
| Comparison Dimension | Monel 400 | 316L |
|---|---|---|
| Chloride Stress Corrosion Cracking | Immune | Susceptible |
| Seawater Corrosion Resistance | Excellent | Moderate (prone to pitting) |
| Hydrofluoric Acid | Excellent | Poor |
| Cost | High | Low |
Selection Principle: For chloride-containing, seawater, or hydrofluoric acid service, Monel 400 is irreplaceable; for general chemical media, 316L is sufficient.
Comparison with Inconel 625
| Comparison Dimension | Monel 400 | Inconel 625 |
|---|---|---|
| Reducing Acids (HF, H₂SO₄) | Superior | Good |
| Oxidizing Acids (HNO₃) | Not suitable | Excellent |
| High-Temperature Strength (>550°C) | Moderate | Superior |
| Chloride Stress Corrosion | Immune | Excellent |
Selection Principle: Choose Monel 400 for hydrofluoric acid and reducing acid environments; choose Inconel 625 for high temperature, oxidizing acids, or when higher strength is required.
Comparison with CuNi 90/10 and CuNi 70/30
| Comparison Dimension | Monel 400 | CuNi 90/10 | CuNi 70/30 |
|---|---|---|---|
| Seawater Velocity Tolerance | Excellent | Moderate | Good |
| Pitting/Crevice Corrosion Resistance | Excellent | Moderate | Good |
| Hydrofluoric Acid Resistance | Excellent | Poor | Poor |
| Cost | High | Low | Medium |
Selection Principle: CuNi 90/10 is adequate for general seawater service; for hydrofluoric acid-containing, high-velocity seawater, or high-reliability applications, Monel 400 is the more reliable choice.
Applicable Standards and Specifications
| Parameter | Standard/Range |
|---|---|
| Material Standard | ASTM B564 / ASME SB564 |
| Flange Standard | ASME B16.5 (NPS 1/2 – 24) / ASME B16.47 (NPS 26 – 60) |
| Pressure Class | Class 150 / 300 / 600 / 900 / 1500 / 2500 |
| Flange Types | Weld Neck (WN), Slip-On (SO), Blind (BL), Socket Weld (SW), Threaded (TH), Lap Joint (LJ) |
| Flange Face Type | Raised Face (RF) standard; Flat Face (FF) or Ring Joint (RTJ) customizable |
| Size Range | NPS 1/2 – NPS 60 |
Typical Application Scenarios
Marine Engineering: Seawater piping flanges, seawater valve connections, offshore platform process systems
Chemical and Petrochemical: Hydrofluoric acid alkylation units, sulfuric acid alkylation units, MEA reboiler connections
Power Generation and Nuclear: Feedwater heater connections, nuclear plant service water piping
Seawater Desalination and Salt Industry: Brine piping flanges, evaporator connections
Petroleum Refining: Crude tower overhead piping, sour gas service connections
Quality Assurance and Services
Standard Compliance: Strictly manufactured to ASTM B564 / ASME SB564; flange dimensions conform to ASME B16.5 / B16.47
Inspection Certification: EN 10204 3.1 material certificates available; third-party inspection supported including SGS, BV, TUV
Material Traceability: Each batch comes with heat number traceability and mechanical property reports
Customization Services: Drawing-based customization of non-standard sizes, special flange face types, and pressure ratings
Technical Support: Assistance with confirming Monel 400 applicability based on customer media conditions
FAQ
Q1: Are Monel 400, UNS N04400, and DIN 2.4360 the same material?
Yes. Monel 400 is the commercial trade name, UNS N04400 is the American unified numbering system designation, and DIN 2.4360 (Werkstoff Nr.) is the European material number. All three refer to the same nickel-copper alloy with essentially identical chemical composition. It is recommended to also specify UNS N04400 in orders for accuracy.
Q2: What is the maximum service temperature of Monel 400 flanges?
Monel 400 maintains good mechanical properties from sub-zero temperatures up to approximately 550°C. The recommended continuous service temperature in oxidizing atmospheres is approximately 400°C. Note that the material is attacked in sulfur-containing gases above approximately 370°C (700°F), and high-temperature use in such environments should be avoided.
Q3: Why can Monel 400 withstand hydrofluoric acid?
Monel 400 is one of the few metallic materials capable of withstanding unaerated hydrofluoric acid. Its nickel-copper matrix forms a stable protective fluoride film in hydrofluoric acid, preventing further corrosion. However, note that aerated (oxygen-containing) hydrofluoric acid accelerates corrosion, and the specific state of the medium should be confirmed before use.
Q4: What is the difference between ASTM B564 and ASME SB564?
The technical content is identical. ASTM B564 is the material standard body for nickel alloy forgings, while ASME SB564 is the corresponding version in the ASME Boiler and Pressure Vessel Code. Pressure equipment projects typically require compliance with ASME SB564.
Q5: What should be noted when welding Monel 400 flanges?
ERNiCu-7 filler metal is recommended, using GTAW (TIG) or GMAW processes with high-purity argon shielding (99.99% or higher). Oil and contaminants must be thoroughly removed before welding. Post-weld heat treatment is generally not required, but stress relief annealing is recommended if exposed to caustic soda, fluorosilicates, or certain mercury salts.
Q6: Does Monel 400 require passivation after machining?
No, and it is not recommended. Monel 400's corrosion resistance comes from the natural formation of a nickel-based oxide film. Nitric or citric acid passivation has limited effect, and strongly oxidizing nitric acid may actually cause localized corrosion. For weld cleaning, a pickling paste suitable for nickel-based alloys can be used to remove welding oxides.
Q7: Are custom flange types and pressure ratings supported?
Yes. We can provide Weld Neck (WN), Slip-On (SO), Blind (BL), Socket Weld (SW), Threaded (TH), and Lap Joint (LJ) flanges. Pressure ratings cover Class 150 to 2500, with Raised Face (RF), Flat Face (FF), or Ring Joint (RTJ) face types available.
Q8: What are the delivery lead time and minimum order quantity?
Delivery lead time and minimum order quantity are determined by specifications, quantity, and inspection requirements. Common specifications are available from stock; custom specifications typically require 15–30 working days. Please consult our sales team for details.
