Monel 400 Lined Stainless Steel Pipes

Premier Hydrofluoric Acid (HF) Resistance: 

Standard material for HF alkylation service piping, handling HF across all concentrations up to 150°C (302°F), making Monel 400 the preferred lined pipe material for refinery HF transfer lines and process piping.

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.

Cost-Effective Alternative to Solid Monel 400: 

Reduces material cost by 60-80% compared to solid Monel 400 pipe while providing equivalent internal corrosion protection.

Good Weldability: 

Matching filler metal ERNiCu-7 for weld overlay. Weld zones retain corrosion resistance comparable to the base metal.

Weldable End Preparation: 

Available with weld overlay transition (butter layer) using ERNiCu-7 filler metal.

Full Range of Sizes: 

Available from 2″ to 48″ (DN50 to DN1200) with lining thickness from 2mm to 6mm.

International Certifications: 

Lined pipes 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 for Lining Materials:

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

Base Pipe Selection: Carbon steel or low-temperature steel base pipe selected based on service pressure, temperature, and mechanical requirements.

Base Pipe Preparation: Base pipe is cleaned (shot blasting to SA 2.5), inspected for surface defects, and prepared for lining application.

Lining Tube Fabrication: Monel 400 nickel-copper alloy sheet is rolled and welded into a tube slightly smaller than the base pipe ID using ERNiCu-7 filler metal.

Lining Insertion: The Monel 400 lining tube is inserted into the base pipe.

Hydraulic Expansion: High-pressure water (up to 5000 psi) expands the lining tube against the base pipe inner wall, creating a tight mechanical bond.

Annealing: Lining material is in annealed condition (700–800°C) for optimal corrosion resistance.

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

Weld Overlay (Butter Layer): Pipe ends are prepared with Monel 400 weld overlay using ERNiCu-7 filler metal.

Hydrostatic Testing: Each lined pipe is hydrostatically tested to verify bond integrity and pressure rating.

NDT Inspection: Ultrasonic testing (UT) and eddy current testing (ECT) verify lining thickness and bond quality.

End Finishing: Pipe ends are beveled per ASME B16.25 and prepared for field welding.

Marking & Coating: Pipes are marked with grade, size, lining thickness, heat number, and standard. External coating applied upon request.

Base Pipe Inspection: Chemical analysis, mechanical testing, dimensional check, hardness test.

Lining Material Verification: PMI 100% for Monel 400 lining material – verification of Ni (≥63%), Cu (28-34%).

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

Bond Integrity Testing: Ultrasonic test (UT) to verify bond between lining and base pipe – 100% coverage.

Lining Thickness Check: Ultrasonic thickness measurement at multiple points.

Hydrostatic Test: Each pipe tested at 1.5× design pressure.

Surface Inspection: Internal and external surface inspection.

Dimensional Check: OD, ID, wall thickness, length, straightness.

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) transfer lines, acid cooler piping, regenerator column feed lines, HF storage tank connections, alkylate product transfer lines, acid settling drum piping.

Marine & Shipbuilding (Seawater Systems): 

Seawater cooling piping, propulsion cooling water lines, ballast water treatment system piping, fire main system piping, sanitary seawater lines (ABS/BV/DNV/LR certified, classification society certified).

Naval Vessels (Military Applications): 

Non-magnetic piping systems for mine countermeasure vessels, submarine hydraulic lines, degaussing system piping, low-magnetic signature vessel piping.

Desalination Plants: 

Brine heater feed lines, brine preheater piping, multi-stage flash (MSF) evaporator connections, high-velocity brine handling lines, chemical injection lines.

Chemical Processing (Brine & Chlor-Alkali): 

Brine heater piping, chlor-alkali plant brine transfer lines, salt evaporator connections, caustic service lines (deaerated conditions), sodium chloride brine handling piping.

Offshore Platforms (Limited): 

Seawater intake piping, firewater system headers, cooling water lines, chemical injection lines (limited sour service).

Power Generation (Coastal): 

Seawater-cooled condenser circulating water lines, auxiliary cooling water piping, intake structure piping.

Cryogenic Service (LNG): 

LNG plant auxiliary piping – maintains good toughness down to -196°C.

Chemical Brine Lines: 

Brine transfer piping for chemical manufacturing, salt processing lines.

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

2. Can Monel 400 lined pipes 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 hydrochloric acid service, Hastelloy C276 lined pipes are recommended.

4. What is the maximum temperature for HF service?
Approximately 150°C (302°F). Above this temperature, other materials may be required. The carbon steel base pipe can handle higher temperatures, but the Monel 400 lining limits HF service to 150°C.

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 system piping on naval vessels and for sensitive instrumentation where magnetic fields could interfere.

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

7. Can Monel 400 lined pipes be welded in the field?
Yes, with proper weld overlay (buttering) at pipe ends using ERNiCu-7 filler metal. The overlay provides a transition layer allowing welding between carbon steel base pipes.

Premier HF Acid Material: Standard material for hydrofluoric acid alkylation transfer lines – 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 piping systems

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

Cost-Effective: 65-88% cost savings compared to solid Monel 400 pipe

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

Complete Size Range: 2″ to 48″ (DN50 to DN1200) – standard and custom sizes

Multiple Base Pipe Grades: API 5L X42-X60, A106 Gr B, A333 Gr 6

Lining Thickness Options: 2mm to 6mm – tailored to your service requirements

Weld Overlay Ready: Pipe ends prepared with ERNiCu-7 butter layer for field welding

Non-Magnetic Testing: Magnetic permeability verification upon request

Third-Party Inspection: SGS, BV, DNV, ABS, TUV, LR available

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

Website: www.womicstainless.com

E-mail: info@womicstainless.com

Tel / WhatsApp / WeChat:

Victor: +86 15575100681

Jack: +86 18390957568

Womic Steel – Your reliable partner for high quality stainless steel products, precision machined components, and custom solutions for corrosion resistant applications.

Stock Examples (Monel 400 Lined Pipes – A106 Gr B Base – 3mm Lining – Weld Overlay Ends – HF Alkylation Service):

Stock Examples (Monel 400 Lined Pipes – A106 Gr B Base – 3mm Lining – Marine Grade – ABS/DNV/LR Certified):

Stock Examples (Monel 400 Lined Pipes – A333 Gr 6 Base – 3mm Lining – Naval Non-Magnetic – Degaussing System):

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