ASTM B165 (also known as ASME SB-165) covers nickel-copper alloy UNS N04400 (commonly known as Monel 400) in the form of cold-worked seamless pipe and tube. Monel 400 is renowned for its excellent corrosion resistance in seawater, hydrofluoric acid, sulfuric acid, and alkalies. This specification provides materials for the most demanding marine, chemical processing, and offshore applications.
Quick Specifications
Material: UNS N04400 (Monel 400)
Nominal Composition: 67% Ni, 30% Cu, 1.3% Fe, 1% Mn
Product Forms: Seamless Pipe, Seamless Tube
Applications: Seawater, hydrofluoric acid, chemical processing, offshore
Chemical Composition (ASTM B165 - UNS N04400)
| Element |
UNS N04400 (Monel 400) % |
Limits |
| Nickel (Ni) |
Balance (≥63%) |
63.0 min |
| Copper (Cu) |
28.0 - 34.0 |
28.0 - 34.0 |
| Iron (Fe) |
≤2.5 |
2.5 max |
| Manganese (Mn) |
≤2.0 |
2.0 max |
| Carbon (C) |
≤0.30 |
0.30 max |
| Silicon (Si) |
≤0.5 |
0.5 max |
| Sulfur (S) |
≤0.024 |
0.024 max |
Mechanical Properties (Annealed Condition)
| Property |
Annealed |
Stress Relieved |
| Tensile Strength, min (MPa) |
480 |
515 |
| Yield Strength (0.2% offset), min (MPa) |
195 |
345 |
| Elongation in 2 in. (50 mm), min (%) |
35 |
15 |
| Rockwell Hardness, max (HRB) |
68 |
- |
Mechanical Properties (Cold Worked Conditions)
| Condition |
Tensile Strength (MPa) |
Yield Strength (MPa) |
Elongation (%) |
| Annealed |
480-585 |
195-290 |
35-50 |
| 1/4 Hard |
550-690 |
380-520 |
20-30 |
| 1/2 Hard |
620-760 |
450-620 |
12-20 |
| 3/4 Hard |
690-825 |
550-690 |
8-12 |
| Hard |
760-895 |
620-760 |
3-8 |
Physical Properties (Monel 400)
| Property |
Value |
| Density |
8.80 g/cm³ (0.318 lb/in³) |
| Melting Point |
1300-1350°C (2370-2460°F) |
| Thermal Conductivity |
21.8 W/m·K (150 BTU·in/hr·ft²·°F) |
| Electrical Resistivity |
0.547 μΩ·m (at 21°C) |
| Coefficient of Thermal Expansion |
13.9 μm/m·°C (7.7 μin/in·°F) |
| Modulus of Elasticity |
179 GPa (26,000 ksi) |
Available Products (ASTM B165)
Monel 400 Seamless Pipe
Size Range: 1/2" - 12" (OD 21.3mm - 323.8mm)
Wall Thickness: SCH 5S - SCH 160
Length: Random or Fixed lengths
Surface: Annealed & pickled, or bright annealed
Monel 400 Seamless Tube
Size Range: 1/4" - 4" (OD 13.7mm - 114.3mm)
Wall Thickness: 0.5mm - 10mm
Heat exchanger tubes available
U-bend tubes for heat exchangers
Special Configurations
Boiler tubes
Condenser tubes
Heat exchanger tubes
Instrumentation tubes
Key Features of Monel 400
Excellent Seawater Resistance: Outstanding corrosion resistance in both flowing and stagnant seawater
Hydrofluoric Acid Resistance: Excellent resistance to hydrofluoric acid at all concentrations and temperatures
High Strength: Higher strength than nickel 200/201 at room temperature
Non-Magnetic: In annealed condition, essentially non-magnetic
Good Fabricability: Can be readily hot and cold worked, forged, and machined
Weldability: Good weldability with proper procedures
Corrosion Resistance
ASTM B165 Monel 400 provides excellent resistance to:
Seawater and Brackish Water
Excellent resistance to pitting and crevice corrosion
High velocity seawater service acceptable (up to 30 ft/s)
Resists biofouling
Preferred material for seawater condensers and heat exchangers
Acids
Hydrofluoric Acid: Excellent at all concentrations and temperatures
Sulfuric Acid: Good resistance below 85°C (185°F)
Phosphoric Acid: Good resistance
Hydrochloric Acid: Limited to low temperatures, dilute solutions
Alkalies
Excellent resistance to sodium hydroxide and potassium hydroxide
Suitable for caustic soda and potash handling
Limitations
Not recommended for strongly oxidizing acids (nitric acid)
Susceptible to stress corrosion cracking in certain conditions
May be attacked by acidic chlorides
Temperature Service Ratings
| Service |
Max Temperature |
Notes |
| Seawater |
300°C (570°F) |
Excellent resistance |
| Steam |
450°C (840°F) |
Good strength |
| Hydrofluoric Acid |
550°C (1020°F) |
All concentrations |
| Caustic Alkalies |
400°C (750°F) |
Excellent resistance |
| General Service |
450°C (840°F) |
Good mechanical properties |
Applications
Marine and Offshore
Seawater condensers
Seawater cooling pipes
Offshore platform piping
FPSO vessels
Propeller shafts
Ship hull fittings
Chemical Processing
Hydrofluoric acid production and handling
Sulfuric acid plants
Phosphoric acid processing
Chlor-alkali cells
Caustic soda evaporators
Oil and Gas
Offshore oil and gas processing
Produced water handling
Desalination plants
Wellhead piping
Power Generation
Surface condensers
Feedwater heaters
Steam condensate lines
Aerospace
Aircraft fuel tanks
Hydraulic systems
Manufacturing Process
Melting: AOD (Argon Oxygen Decarburization) or VOD (Vacuum Oxygen Decarburization)
Hot Extrusion: Form mother tube from cast ingot or electrode
Cold Drawing: Multiple passes with intermediate annealing to achieve final dimensions
Solution Annealing: 870-980°C (1600-1800°F), rapid cooling
Pickling: Remove oxide scale
Testing: Hydrostatic, eddy current, dimensional inspection
Heat Treatment
Solution Annealing:
Temperature: 870-980°C (1600-1800°F)
Cooling: Rapid cooling (water quench for critical applications)
Purpose: Optimize corrosion resistance and ductility
Stress Relieving:
Temperature: 540-600°C (1000-1110°F)
Purpose: Reduce residual stresses from cold working
Welding
ASTM B165 Monel 400 is readily weldable:
Gas Tungsten Arc Welding (GTAW): Use ERNiCu-7 (or Monel 60) filler wire
Gas Metal Arc Welding (GMAW): Use ERNiCu-7 or RNiCu-1 filler
Shielded Metal Arc Welding (SMAW): Use ENiCu-7 (or Monel 190) electrodes
Submerged Arc Welding (SAW): Use matching composition flux
Welding Notes:
Cleanliness is critical - remove all oils, grease, sulfur compounds
Use copper backing bars or fixtures (to prevent contamination)
No preheat required for thin sections
Post-weld heat treatment not required for corrosion service
Interpass temperature should be controlled (max 150°C/300°F)
Testing Requirements
Tensile Test: One per lot
Flattening Test: Seamless pipe - one per end
Flange Test: For pipe
Hardness Test: Rockwell or Brinell
Hydrostatic Test: 100% of pipes and tubes
Eddy Current Test: For tubes (when specified)
Chemical Analysis: Heat analysis
Dimension Tolerances
| Parameter |
Seamless Pipe |
Seamless Tube |
| Outside Diameter |
±0.5% (min ±0.05mm) |
±0.5% (min ±0.05mm) |
| Wall Thickness |
+20% / -0% |
+22% / -0% |
| Length |
+5mm / -0mm |
+3mm / -0mm |
Monel 400 vs. Stainless Steel Comparison
| Property |
Monel 400 (N04400) |
316L Stainless |
| Tensile Strength |
480 MPa min |
485 MPa min |
| Yield Strength |
195 MPa min |
170 MPa min |
| Seawater Resistance |
Excellent |
Good (limited velocity) |
| HF Acid Resistance |
Excellent |
Poor |
| Cost |
Higher |
Lower |
Related ASTM Standards
ASTM B163 - Heat Exchanger Tubes (all nickel alloys)
ASTM B164 - Nickel-Copper Alloy Rod and Bar
ASTM B127 - Nickel-Copper Alloy Plate, Sheet, and Strip
ASTM B564 - Nickel Alloy Forgings
Frequently Asked Questions (FAQ)
Q: What is the difference between ASTM B165 and ASME SB-165?
A: ASTM B165 and ASME SB-165 are essentially the same specification. ASME adopts ASTM standards with the SB designation for use in the ASME Boiler and Pressure Vessel Code. The technical requirements are identical.
Q: Can Monel 400 be used in seawater service?
A: Yes, Monel 400 is one of the best materials for seawater service. It offers excellent resistance to pitting, crevice corrosion, and erosion-corrosion. It can handle seawater velocities up to 30 ft/s (9 m/s), significantly higher than stainless steel.
Q: Why is Monel 400 preferred for hydrofluoric acid applications?
A: Monel 400 has excellent resistance to hydrofluoric acid at all concentrations and temperatures because the copper content forms a protective film that resists HF attack. This makes it the material of choice for HF production, handling, and storage equipment.
Q: Is post-weld heat treatment required for Monel 400?
A: No, post-weld heat treatment is not required for corrosion resistance. However, for stress relief in thick sections or complex welds, stress relieving at 540-600°C (1000-1110°F) may be beneficial.
Q: What are the magnetic properties of Monel 400?
A: Monel 400 is essentially non-magnetic in the annealed condition (permeability < 1.01). Cold working will introduce some magnetic response, but it remains low compared to ferromagnetic materials.
Q: How does Monel 400 compare to Nickel 200 for chemical applications?
A: Monel 400 has higher strength than Nickel 200 and superior seawater resistance. However, Nickel 200 is preferred for caustic alkali service and high-temperature applications (>315°C/600°F) due to its lower carbon content preventing graphitization.
Request a Quote — ASTM B165 Monel 400 Seamless Pipe and Tube
Zhengzhou Huitong (HT Pipe) supplies ASTM B165 compliant Monel 400 (UNS N04400) pipes and tubes with full EN 10204 3.1 CMTRs and competitive lead times from affiliated mills in China.
