Alloy K-500 (Monel K-500) Flanges

Ultra-High Strength (Three Times Alloy 400): Precipitation-hardenable through aluminum and titanium additions (γ' phase Ni₃(Al,Ti) precipitates), Alloy K-500 flanges offer approximately three times the yield strength (≥690 MPa aged) and double the tensile strength compared to Alloy 400, making them the strongest commercially available nickel-copper alloy flanges.

Exceptional Seawater and Brine Resistance: Outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking in high-velocity seawater, brine, and marine environments, with excellent erosion-corrosion resistance for pump and propeller applications.

Non-Magnetic Properties: Low magnetic permeability (<1.005) at temperatures down to -101°C (-150°F), making Alloy K-500 flanges ideal for degaussing systems, naval vessel components, sensitive instrumentation, and applications where magnetic interference must be avoided.

No Ductile-to-Brittle Transition: Maintains excellent toughness and ductility from cryogenic temperatures (-200°C / -328°F) up to 480°C (900°F), suitable for low-temperature and elevated-temperature service.

Excellent Resistance to Reducing Acids and Caustics: Good corrosion resistance in deaerated hydrochloric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, alkaline solutions, and organic acids, with performance comparable to Alloy 400.

High Erosion and Wear Resistance: Superior resistance to erosion-corrosion, galling, and wear, making K-500 flanges suitable for high-velocity seawater, slurry, and abrasive service where standard nickel alloys suffer from mechanical degradation.

Precipitation-Hardenable (Age-Hardening): Ultimate strength achieved through controlled heat treatment (solution anneal + age hardening), allowing for optimized mechanical properties for specific high-stress applications.

NACE MR0175 / ISO 15156 Compliant: Fully qualified for sour service (H₂S) applications in oil and gas drilling and production equipment, with documented HIC and SSC test reports available.

Excellent Resistance to Biofouling: Natural resistance to marine biofouling, reducing maintenance requirements in seawater systems.

Good Weldability with Special Considerations: Can be welded using matching filler metals (ERNiCu-7), but post-weld heat treatment (solution anneal + age) is required to restore optimum mechanical properties and corrosion resistance.

Full Range of Types: Weld neck (WN), slip-on (SO), blind (BL), socket weld (SW), threaded (TH), lap joint (LJ), plate flanges, reducing flanges, long weld neck (LWN), orifice flanges, and custom forged flanges.

Pressure Ratings: Available in Class 150, 300, 400, 600, 900, 1500, and 2500 (PN6 to PN400 in metric equivalents).

High-Strength Fasteners and Bolting: Alloy K-500 flanges can be supplied with matching high-strength bolts, nuts, and studs for complete bolted connection systems.

International Certifications: Flanges can be certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK for marine and offshore applications, and comply with NACE MR0175/ISO 15156, NORSOK M-650, ASME, PED, and EN standards.

These standards ensure that our Alloy K-500 (Monel K-500) precipitation-hardenable nickel-copper flanges meet global requirements for chemical composition, mechanical properties, dimensional tolerances, and pressure-temperature ratings for high-strength corrosive service.

Alloy K-500 (UNS N05500) is a precipitation-hardenable nickel-copper alloy with controlled additions of aluminum (2.30-3.15%) and titanium (0.35-0.85%). These elements form coherent Ni₃Al (γ' phase) and Ni₃Ti precipitates during age hardening, providing approximately three times the yield strength and double the tensile strength of Alloy 400. The high nickel content (≥63%) provides excellent resistance to chloride stress corrosion cracking and alkaline environments, while copper (27-33%) provides outstanding resistance to seawater biofouling, hydrofluoric acid, and reducing acids.

Comparison of Alloy 400 vs Alloy K-500 for Flange Applications:

High-Temperature Tensile Properties (Aged Condition, Typical Values):

NACE MR0175 / ISO 15156 Compliance (Sour Service):
Alloy K-500 is qualified for sour service applications in oil and gas production equipment. Maximum sour service temperature: 232°C (450°F). Alloy K-500 flanges used in sour service must be in the age-hardened condition and heat treated per NACE requirements.

Maximum Recommended Service Temperatures:

Critical Note: Alloy K-500 achieves its optimum mechanical properties through controlled precipitation hardening (age hardening). The heat treatment sequence is critical: Solution anneal (980°C / 1800°F) + water quench, followed by age hardening at 580–590°C (1075–1095°F) for 8-10 hours, then air cool. Welded components must be solution annealed and aged after welding to restore mechanical properties and corrosion resistance. Aging in free air may adversely affect corrosion resistance in certain environments.

Heat Treatment Condition:

Alloy K-500 flanges are supplied in one of the following conditions:

Delivery Condition: Flanges can be supplied in solution annealed condition (for subsequent forming/welding) or solution annealed and aged condition (ready for high-strength service). Upon request, centerless ground finishes can be provided for high-precision rotating applications.

*Reference: Based on ASME B16.5 for nickel alloys. These ratings are similar to Alloy 400, but Alloy K-500 offers significantly higher mechanical strength at equivalent pressure ratings.*

Standard Dimensions: ASME B16.5 for sizes up to 24″, and ASME B16.47 Series A/B for large diameters up to 60″. EN 1092-1 dimensions available upon request.

Raw Material Selection: High-quality Alloy K-500 (UNS N05500) nickel-copper billets from certified premium mills (Special Metals, VDM Metals, Carpenter) with certified chemical composition (Ni 63-70%, Cu 27-33%, Al 2.3-3.15%, Ti 0.35-0.85% verification) and traceability.

Cutting & Heating: Material is cut to precise weight using band saws, then induction-heated to forging temperature (1100–1200°C). Temperature control is critical for precipitation-hardenable alloys.

Forging: Hot forged using hydraulic presses (3000–8000 tons) with strict temperature control. Alloy K-500 has good forgeability in the solution annealed condition.

Heat Treatment – Solution Annealing: Heat treatment at 980°C (1800°F) followed by water quenching to put aluminum and titanium into solution for subsequent age hardening.

Aging (Precipitation Hardening): For aged condition flanges, age hardening at 580–590°C (1075–1095°F) for 8-10 hours followed by air cooling to develop γ' (Ni₃Al/Ni₃Ti) precipitates for maximum strength.

Machining: CNC lathes and milling machines produce precise dimensions, bolt holes, and facing surfaces. Alloy K-500 requires proper tooling and cooling due to work hardening tendency.

Surface Finishing: Raised face serration, flat facing, or RTJ groove machining per ASME B16.5 requirements.

Marking: Laser engraving or stamping with grade (K-500/N05500), size (NPS), class, heat number, heat treatment condition (SA or SA+A), manufacturer identification, and standard.

Inspection & Testing: Dimensional check, PMI, hardness test, and NDT as required.

Surface Treatment: Pickling and passivation using specialized pickling acids optimized for nickel-copper alloys; thorough rinsing required.

Each Alloy K-500 flange face is inspected for surface roughness, concentricity, and absence of defects.

Chemical Analysis: PMI 100% verification using handheld XRF spectrometer for Ni (63-70%), Cu (27-33%), Al (2.3-3.15%), Ti (0.35-0.85%).

Mechanical Testing: Tensile strength (≥690 MPa aged), yield strength (≥655 MPa), elongation (≥15%), hardness (255–370 HBW).

Precipitation Hardening Verification: Hardness testing to confirm proper aging (25-40 HRC typical).

Dimensional Inspection: OD, ID, bolt circle, bolt hole alignment, thickness, flatness using calibrated gauges and CMM.

Thread Inspection: NPT thread verification using GO/NO-GO gauges per ANSI B1.20.1.

NDT – Liquid Penetrant Testing (PT): 100% for surface defects.

NDT – Ultrasonic Testing (UT): For internal flaws upon request.

NDT – Magnetic Permeability Test: Per customer request for non-magnetic verification (<1.005).

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

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

Marine Propulsion & Pump Systems: Centrifugal pump flanges, propeller shaft flanges, seawater pump impeller connections, high-speed marine pump flanges, pump wear ring flanges (ABS, BV, DNV, LR certified).

Oil & Gas Drilling (High-Strength): Drill collar flanges, kelly bushing connections, rotary table flanges, blowout preventer (BOP) flanges, wellhead flanges, choke and kill line flanges (API 6A compliant, NACE MR0175 sour service certified).

Fasteners & Bolting Systems: High-strength bolt flanges, stud bolt flanges, nut flanges, threaded rod connections for critical bolting applications.

Naval Vessels & Degaussing Systems: Non-magnetic flange connections, degaussing system flanges, mine countermeasure vessel flanges, submarine component flanges, low-magnetic signature connections.

Pump & Valve Components (High-Stress): Valve body flanges, bonnet flanges, stem flanges, pump casing flanges, high-pressure valve flanges, cryogenic valve flanges.

Springs & Control Components: High-strength spring flanges, actuator flanges, control valve flanges, pressure regulator flanges.

Chemical Processing (High-Strength): High-pressure reactor flanges, caustic evaporator flanges, HF alkylation flanges (limited), heat exchanger flanges (high-pressure).

Aerospace & Defense: Hydraulic system flanges, fuel system flanges, actuation system flanges, missile component flanges, aircraft high-strength connections.

Subsea & Deepwater Equipment: Subsea control system flanges, umbilical termination flanges, high-pressure seawater injection flanges, ROV component flanges.

Cryogenic Service: LNG plant flanges, liquid oxygen flanges, liquid nitrogen flanges, cryogenic transfer line flanges (maintains toughness to -200°C).

Instrumentation & Control Systems: High-pressure instrument flanges, gauge connection flanges, transmitter connection flanges, hydraulic control line flanges.

Small flanges (≤4″): Heavy-duty cartons with moisture barrier paper on pallets, individual plastic bagging.
Medium flanges (6″–12″): Wooden crates with foam padding dividers, each flange wrapped in VCI paper.
Large flanges (≥14″): Individual wooden crates or steel-framed pallets with foam padding.

All shipments:

VCI paper interleaving between flanges

Plastic end caps for bore protection

Bolt hole protectors for RTJ facings

Individual tagging: Grade (Alloy K-500/N05500), size, class, heat number, heat treatment condition (SA or SA+A), manufacturer identification, standard, PO number

Waterproof shipping marks for export containers

Moisture barrier wrapping for sea freight

Womic Steel's Delivery Strengths:

Ready stock: Class 150 and 300 Alloy K-500 flanges in sizes 1/2″–12″ (aged condition) – dispatch within 48–72 hours.

Direct cooperation with global shipowners for the most competitive freight rates.

Professional loading by in-house teams using padded slings.

Complete documentation package including EN 10204 3.1 MTR, PMI reports, heat treatment charts (aging curves and furnace records), hardness test reports, and inspection certificates.

Continuous cargo tracking and after-sales follow-up.

1. What is the difference between Alloy 400 and Alloy K-500 flanges?
Alloy K-500 contains aluminum (2.3-3.15%) and titanium (0.35-0.85%) to create γ' precipitates (Ni₃Al, Ni₃Ti) during age hardening, providing approximately three times the yield strength (690-1103 MPa vs 170 MPa) and double the tensile strength (935-1275 MPa vs 480-580 MPa) compared to Alloy 400. The heat treatment is more complex, and K-500 has higher cost.

2. Can Alloy K-500 flanges be welded?
Yes, but with special considerations. Welding must be performed in the solution annealed condition, followed by full solution anneal and age hardening after welding to restore mechanical properties and corrosion resistance. Aging in free air may adversely affect corrosion resistance – controlled atmosphere heat treatment is recommended.

3. Are Alloy K-500 flanges magnetic?
No. Alloy K-500 has low magnetic permeability (<1.005) at temperatures down to -101°C (-150°F), making them suitable for degaussing systems, mine countermeasure vessels, sensitive instrumentation, and applications where magnetic interference must be avoided.

4. Is Alloy K-500 suitable for sour service (H₂S environments)?
Yes. Alloy K-500 is NACE MR0175 / ISO 15156 compliant for sour service up to 232°C (450°F). Flanges must be in the age-hardened condition and heat treated per NACE requirements. HIC and SSC test reports are available upon request.

5. What is the maximum service temperature for Alloy K-500 flanges?
480°C (900°F) for continuous service in reducing environments. Above 480°C, the γ' precipitates may overage and reduce strength. For seawater service, limit to 260°C (500°F).

6. What facing is recommended for high-pressure oil and gas flanges?
Ring Type Joint (RTJ) facing with octagonal ring gasket is recommended for high-pressure oil and gas service (Class 600-2500) to ensure leak-tight sealing under extreme pressure cycling and sour service conditions.

7. What heat treatment condition is recommended for high-strength service?
Solution annealed and aged (SA+A) is recommended for high-strength service. This includes solution annealing at 980°C + water quench, followed by age hardening at 580-590°C for 8-10 hours + air cool. This produces the γ' precipitate structure for maximum strength.

8. Can Alloy K-500 flanges be used in hydrofluoric acid (HF) service?
Yes, Alloy K-500 has similar HF resistance to Alloy 400. It is suitable for HF alkylation service, but the higher strength does not provide significant advantage over Alloy 400 in this application.

9. Are Alloy K-500 flanges resistant to galling?
Yes. Alloy K-500 has good galling resistance, making it suitable for threaded connections, valve stems, and pump shafts where galling is a concern with other nickel alloys.

10. What is the typical lead time for Alloy K-500 flanges?
Stock sizes (1/2″–12″, Class 150/300 WN RF, aged condition): 3–5 days. Non-stock or special facings: 4–6 weeks. Large diameter or custom forged flanges: 6–8 weeks. Heat treatment (aging) adds approximately 24 hours for the age-hardening cycle.

Complete Product Range: Weld neck, slip-on, blind, socket weld, threaded, lap joint, reducing, long weld neck – one-stop sourcing for high-strength corrosive service.

Strict Quality Control: ISO 9001:2015, PED 2014/68/EU, and API Q1 certified facilities.

Premium Mill Sources: Special Metals, VDM Metals, Carpenter certified raw materials – 100% traceable.

Precipitation Hardening Expertise: In-house heat treatment for solution annealing and age hardening with temperature-controlled furnaces and time-temperature recording.

NACE MR0175 / ISO 15156 Compliant: Full documentation for sour service applications with HIC/SSC test reports on request.

Non-Magnetic Verification: Magnetic permeability testing available (<1.005 at -101°C) for naval/degaussing applications.

Advanced Forging & Machining: 3000–8000 ton hydraulic presses and CNC machining centers.

Full Traceability: Heat number stamped on each flange – traceable back to original mill certificate.

Heat Treatment Certification: Complete heat treatment records (solution anneal + age) including temperature charts and time logs.

Flexible Customization: Special facing types (RTJ, T&G, M&F), custom bolt drilling, and non-standard sizes available.

Marine & Offshore Certified: ABS, BV, DNV, LR, GL, RINA, CCS, KR, NK certification available.

Global Delivery: Exported to major offshore drilling, marine propulsion, and naval 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 Alloy K-500 (Monel K-500) stainless steel flanges. We offer certified quality, precipitation-hardened material verification, NACE MR0175 compliance, non-magnetic testing, fast production lead times, and reliable global delivery to keep your marine propulsion, oil and gas drilling, and high-strength seawater projects running smoothly.

Stock Examples (Class 150 WN RF – Alloy K-500, Aged Condition):

Stock Examples (Class 300 WN RF – Alloy K-500, Aged Condition – High-Pressure Service):

Stock Examples (Class 600 and above – RTJ facing – Alloy K-500 for Oil & Gas Drilling):

Common Stock Examples for Marine Pump Flanges (Alloy K-500, Class 300, RF, Aged):

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