Monel 400 Stainless Steel Coils

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 coil 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: Coils 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). For sour service applications, consult Womic Steel for specific requirements and documentation.

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 coils 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:
Coils 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 (Cold-Rolled – ASTM A480):

Thickness Tolerances (Hot-Rolled – ASTM A480):

Width Tolerances (Hot-Rolled – ASTM A480):

Flatness Tolerances:

Raw Material Selection: High-quality Monel 400 (UNS N04400) nickel-copper alloy slabs from certified premium mills (Special Metals, VDM Metals) with certified chemical composition (Ni ≥63%, Cu 28-34% verification) and traceability.

Reheating: Slabs heated to forging temperature (1100–1200°C). Temperature control is important for nickel-copper alloys.

Hot Rolling: Heated slabs passed through roughing and finishing stands to reduce thickness to 3-12mm (hot-rolled coils).

Laminar Cooling: Controlled water cooling to achieve desired microstructure.

Coiling: Hot-rolled strip coiled at approximately 600-700°C for hot-rolled coils.

Annealing: Hot-rolled coils undergo annealing at 700–800°C followed by air cooling to relieve stresses and restore ductility.

Pickling: Removal of oxide scale using specialized pickling acids optimized for nickel-copper alloys; thorough rinsing required.

Cold Rolling: For thicknesses below 3.0mm, hot-rolled coils further reduced through cold rolling passes.

Cold Rolling Annealing (Optional): Intermediate annealing for cold-rolled coils.

Non-Magnetic Verification (Upon Request): Magnetic permeability testing to verify <1.005 for naval degaussing applications.

Slitting (Optional): Wide coils cut into narrower strips per customer requirements (20mm to 600mm width).

Inspection & Testing: Dimensional check, PMI, mechanical testing, surface inspection, non-magnetic verification.

Coiling & Packaging: Coiled to specified ID/OD, wrapped with moisture barrier paper, steel strapped.

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.

Dimensional Inspection: Thickness, width, flatness, coil ID/OD using calibrated instruments.

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

Non-Magnetic Verification: Magnetic permeability testing (<1.005) upon request for naval degaussing applications.

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 shells, acid cooler shells, regenerator column vessels, HF storage tank linings, alkylate product vessels, acid settling drum shells, HF piping components (NACE MR0175 limited sour service).

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

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

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

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

Offshore Platforms: Seawater intake components, 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.

Cryogenic Service: LNG plant components – maintains good toughness down to -196°C.

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

Womic Steel offers precision slitting services for Monel 400 coils:

Standard Packaging:

Coils wrapped with moisture-proof paper and VCI (Vapor Corrosion Inhibitor) film

Outer steel strapping (4-8 straps per coil depending on weight)

Non-metallic spacers to prevent galvanic corrosion (for naval applications)

Wooden pallet or steel skid for coil protection during transport

Plastic edge protectors for slit coils

Clear labeling with grade (Monel 400/N04400), heat number, dimensions, coil weight, and order number

Womic Steel's Shipping Strengths:

Direct cooperation with global shipowners for competitive freight rates

Professional loading and securing teams using non-metallic slings and padded supports prevent coil damage

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

Continuous cargo tracking and after-sales follow-up

1. What is Monel 400 best suited for in coil applications?
Monel 400 coils 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 coils 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. For higher temperature HF service, consult corrosion data.

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 and for sensitive instrumentation where magnetic fields could interfere.

6. Can Monel 400 coils be supplied with marine classification society certification?
Yes. Womic Steel can supply Monel 400 coils certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK for marine and shipbuilding applications. Please specify your required classification society and class requirements.

7. What is the difference between Monel 400 and Monel K-500?
Monel K-500 is a precipitation-hardenable version of Monel 400 with aluminum and titanium additions, offering higher strength (YS ≥ 550 MPa vs 170 MPa). However, K-500 is more expensive and less weldable. For coil applications requiring high strength, Monel K-500 is available upon request.

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

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

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

Complete Size Range: Thickness from 1.0mm to 12.0mm – standard and custom sizes

Slitting Services: In-house slitting capability for narrow strips (20mm to 600mm)

Non-Magnetic Testing: Magnetic permeability verification upon request

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 coils. We offer certified quality, marine classification society certification, HF alkylation expertise, non-magnetic verification, fast production lead times, and reliable global delivery for your marine, naval, and refinery projects.

Stock Examples (Hot-Rolled Monel 400 Coils – Annealed & Pickled – HF Service Grade):

Stock Examples (Cold-Rolled Monel 400 Coils – 2B Finish – Marine Grade):

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