Monel 400 Stainless Steel Plates

Premier Hydrofluoric Acid (HF) Resistance: Standard material for HF alkylation service, handling HF across all concentrations up to 150°C (302°F), making Monel 400 the preferred plate material for refinery HF storage tanks and process vessels.

Exceptional Seawater Erosion Resistance: Handles velocities up to 10 m/s (33 ft/s) without impingement attack – significantly outperforms 316L, duplex, and titanium in high-velocity seawater applications.

Excellent Chloride SCC Resistance: High nickel content (≥63%) provides outstanding resistance to chloride-induced SCC, outperforming all austenitic stainless steel grades.

Superior Biofouling Resistance: Naturally resists marine biofouling, reducing maintenance requirements and preserving flow efficiency in seawater systems.

Non-Magnetic Properties: Low magnetic permeability (<1.005) for degaussing systems on naval vessels and sensitive instrumentation applications.

Good Resistance to Reducing Acids: Excellent performance in deaerated sulfuric acid, hydrochloric acid, phosphoric acid, and organic acids.

Good High-Temperature Strength: Maintains excellent mechanical properties up to 400°C (752°F) in non-oxidizing environments.

Good Weldability: Nickel-copper alloy offers good weldability with matching filler metals (ERNiCu-7). Weld zones retain corrosion resistance comparable to the base metal.

International Certifications: Plates can be certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK for marine and shipbuilding applications, and comply with NACE MR0175 (limited sour service) and ASME standards.

Monel 400 (UNS N04400) is a nickel-copper alloy with high nickel (≥63%) and copper (28-34%) content. The high nickel content provides excellent resistance to chloride stress corrosion cracking and caustic environments, while the copper content provides outstanding resistance to hydrofluoric acid, seawater biofouling, and reducing acids. Unlike precipitation-hardenable nickel alloys, Monel 400 is a solid solution strengthened alloy with no intentional precipitation hardening additions, making it exceptionally stable in marine environments and HF service.

Comparison of Seawater and Chemical Performance:

High-Temperature Tensile Properties (Typical Values):

NACE MR0175 / ISO 15156 Compliance (Limited Sour Service):
Monel 400 is compliant for sour service applications under specific conditions as defined in NACE MR0175/ISO 15156. Maximum sour service temperature: 232°C (450°F).

Maximum Recommended Service Temperatures:

Critical Note: Monel 400 is not recommended for service in oxidizing acids (e.g., nitric acid, chromic acid) as it will experience rapid attack. It should also not be used in sulfur-containing environments at high temperatures (above 450°C) due to susceptibility to sulfur attack (sulfidation).

Heat Treatment Condition:
Monel 400 plates are normally supplied in the annealed condition (heat treated at 700–800°C) followed by air cooling. This heat treatment relieves internal stresses from rolling, restores optimum ductility and corrosion resistance, and ensures a stable microstructure for marine and HF service.

Delivery Condition:
Plates are normally supplied in annealed and pickled condition, providing a clean, smooth surface and excellent corrosion resistance. Upon request, bright annealed finish can be provided for high-purity applications.

Thickness Tolerances (Hot-Rolled – ASTM A480):

Width and Length Tolerances (Hot-Rolled – ASTM A480):

Flatness Tolerances (Hot-Rolled – ASTM A480):

Monel 400 is inherently non-magnetic with magnetic permeability <1.005. For naval degaussing system components, Womic Steel offers magnetic permeability testing:

Chemical Analysis: PMI 100% verification using handheld XRF spectrometer for Ni (≥63%), Cu (28-34%), Fe (≤2.5%).

Mechanical Testing: Tensile strength (≥480 MPa), yield strength (≥170 MPa), elongation (≥35%), hardness (≤180 HBW) per ASTM A370.

Non-Magnetic Verification: Magnetic permeability testing (<1.005) upon request.

Dimensional Inspection: Thickness, width, length, flatness, squareness using calibrated instruments.

Surface Inspection: Visual check for surface defects, cracks, laminations, and consistency.

Ultrasonic Testing (UT): Per ASTM A435 for internal flaw detection (upon request).

Intergranular Corrosion Test: ASTM G28 – upon request.

Sour Service Qualification (limited, upon request): HIC per NACE TM0284, SSC per NACE TM0177.

Third-Party Inspection: SGS, BV, DNV, ABS, TUV, LR on customer request.

HF Alkylation Units (Petrochemical Refining): Hydrofluoric acid (HF) storage tank plates, acid cooler shells, regenerator column vessels, HF storage tank linings, alkylate product vessels, acid settling drum shells (NACE MR0175 limited sour service).

Marine & Shipbuilding: Seawater cooling heat exchanger plates, propulsion cooling water components, ballast water treatment system vessels, fire main system plates, shipboard sanitary system tanks, degaussing system structural plates (non-magnetic requirement) – ABS, BV, DNV, LR, GL, RINA, CCS, KR, NK certified.

Naval Vessels (Military Applications): Non-magnetic plate components for mine countermeasure vessels, submarine hydraulic system parts, degaussing system structural elements, low-magnetic signature vessel components.

Desalination Plants: Brine heater plates, brine preheater components, multi-stage flash (MSF) evaporator shells, high-velocity brine handling vessels, chemical injection tanks.

Chemical Processing (Brine & Chlor-Alkali): Brine heater plates, chlor-alkali plant brine tank linings, salt evaporator vessels, caustic service tanks (deaerated conditions), sodium chloride brine handling equipment.

Offshore Platforms: Seawater intake plates, firewater system tanks, cooling water heat exchanger shells, chemical injection vessels (limited sour service, NORSOK M-650 qualified upon request).

Power Generation (Coastal): Seawater-cooled condenser shells, auxiliary cooling water vessels, intake structure components.

Womic Steel offers precision cutting services for Monel 400 stainless steel plates:

Standard Packaging:

Plates wrapped with moisture-proof paper and VCI film

Edge protectors to prevent damage

Steel skids or wooden pallets for plate protection

Clear labeling with grade (Monel 400/N04400), heat number, dimensions, weight, magnetic permeability (if tested)

Womic Steel's Shipping Strengths:

Direct cooperation with global shipowners – competitive freight rates

Professional loading and securing teams prevent plate bending and damage

Efficient document preparation (EN 10204 Type 3.1 MTR, PMI reports, marine classification certificates, non-magnetic test reports) minimizes customs delays

Rapid delivery time – standard plates maintained in ready stock

Continuous cargo tracking and after-sales follow-up

1. What is Monel 400 best suited for in plate applications?
Monel 400 plates are primarily used for three key applications: (1) Hydrofluoric acid (HF) alkylation vessels in refineries (premier material), (2) High-velocity seawater handling equipment (excellent erosion resistance), and (3) Non-magnetic naval vessel components where magnetic signature must be minimized.

2. Can Monel 400 plates be used in seawater applications?
Yes, excellent resistance. Monel 400 handles high-velocity seawater (up to 10 m/s) without impingement attack – significantly better than 316L, duplex, or titanium. It also resists biofouling, reducing maintenance.

3. Is Monel 400 resistant to hydrochloric acid (HCl)?
Limited. Monel 400 has fair resistance to deaerated dilute HCl but is not recommended for concentrated or aerated HCl. For HCl service, Hastelloy C276 is the preferred material.

4. What is the maximum temperature for HF service?
Approximately 150°C (302°F). Above this temperature, other materials may be required.

5. Why is Monel 400 non-magnetic?
Monel 400 has a nickel-copper austenitic structure that is inherently non-magnetic with magnetic permeability <1.005. This property is critical for degaussing systems on naval vessels.

6. Are Monel 400 plates available with ASME certification?
Yes. Monel 400 plates can be supplied with ASME SB127 certification for pressure vessel applications.

Premier HF Acid Material: Standard material for hydrofluoric acid alkylation vessels – proven in refineries worldwide

Excellent Seawater Resistance: Handles high-velocity seawater up to 10 m/s without erosion

Non-Magnetic for Naval Applications: Magnetic permeability <1.005 for degaussing systems

ASME SB127 Certified: Pressure vessel grade plates available

Marine Classification Certified: ABS, BV, DNV, LR approvals available

Full Traceability: Heat number on each plate – traceable to original mill certificate

Complete Size Range: Thickness from 3mm to 60mm – standard and custom sizes

Cut-to-Size Services: Plasma, laser, waterjet, and shearing for custom dimensions

Non-Magnetic Testing: Magnetic permeability verification upon request

Global Delivery: Exported to major marine, naval, and refinery projects worldwide

Tel / WhatsApp:

Victor: +86 15575100681

Jack: +86 18390957568

E-mail: info@womicstainless.com

Website: www.womicsteel.com

Contact Womic Steel today for a competitive quote on Monel 400 stainless steel plates. We offer certified quality, marine classification society certification, HF alkylation expertise, non-magnetic verification, ASME SB127 certification, and reliable global delivery for your marine, naval, and refinery projects.

Stock Examples (Hot-Rolled Monel 400 Plates – No.1 Finish – HF Service Grade):

Stock Examples (Hot-Rolled Monel 400 Plates – No.1 Finish – Marine Grade):

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