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Monel K500 Stud Bolt
QS Fastener: Monel K500 Stud Bolt
Name: Monel K500 Stud Bolt
Material: Monel K500, UNS N05500/2.4375
Hardness: 140-315 HB
Size: 2 inch
Length: 150 mm
Application: For strong acid, strong alkali and high temperature, high pressure
Feature: nonmagnetic, high strength, corrosion resistance
Material: Monel K500, UNS N05500/2.4375
Hardness: 140-315 HB
Size: 2 inch
Length: 150 mm
Application: For strong acid, strong alkali and high temperature, high pressure
Feature: nonmagnetic, high strength, corrosion resistance
Quantity
The Monel K500 Stud Bolt is manufactured from high-strength nickel-copper alloy (UNS N05500), with a hardness range of 140-315 HB. It combines exceptional corrosion resistance with high-temperature and high-pressure performance, making it the ideal fastener for strong acids, alkalis, and harsh environments. Its non-magnetic properties and high precision make it the preferred choice in chemical processing, marine, and energy applications.
1. Corrosion Resistance in Acidic Environments
(1) H₂S Tolerance & Hydrogen Embrittlement Resistance
The Monel K500 Stud Bolt performs exceptionally in H₂S-containing acidic environments due to its nickel-based microstructure and passive film properties.
(1) H₂S Tolerance & Hydrogen Embrittlement Resistance
The Monel K500 Stud Bolt performs exceptionally in H₂S-containing acidic environments due to its nickel-based microstructure and passive film properties.
Key Test Data (NACE MR0175 / ISO 15156-3 Standard):
- Test Conditions: 0.1 bar H₂S partial pressure, pH 2.7, 5000 ppm Cl⁻.
- Results: After 30-day sustained load testing (90% AYS), the Monel K500 Stud Bolt showed no sulfide stress corrosion cracking (SSCC), while AISI 4340 (1000 MPa yield strength) failed within 72 hours.
- Test Conditions: 0.1 bar H₂S partial pressure, pH 2.7, 5000 ppm Cl⁻.
- Results: After 30-day sustained load testing (90% AYS), the Monel K500 Stud Bolt showed no sulfide stress corrosion cracking (SSCC), while AISI 4340 (1000 MPa yield strength) failed within 72 hours.
Anti-Hydrogen Embrittlement Mechanisms:
- Low Hydrogen Diffusion Rate:
- Nickel matrix has lower hydrogen solubility (~0.03 wt%) compared to steel (~0.1 wt%).
- Hydrogen diffusion coefficient in nickel (10⁻¹⁴ m²/s) is 1/100 that of steel, reducing crack propagation risk.
- Low Hydrogen Diffusion Rate:
- Nickel matrix has lower hydrogen solubility (~0.03 wt%) compared to steel (~0.1 wt%).
- Hydrogen diffusion coefficient in nickel (10⁻¹⁴ m²/s) is 1/100 that of steel, reducing crack propagation risk.
- γ' Phase Inhibits Hydrogen Segregation:
- Nanoscale Ni₃(Al,Ti) precipitates pin grain boundaries, minimizing hydrogen accumulation (HEI = 5%, vs. 50% for 17-4PH stainless steel, per ASTM F1624).
- Nanoscale Ni₃(Al,Ti) precipitates pin grain boundaries, minimizing hydrogen accumulation (HEI = 5%, vs. 50% for 17-4PH stainless steel, per ASTM F1624).
- Stable Passive Film:
- Forms nickel-rich sulfide (NiS₂) passive layer in H₂S environments, with breakdown potential >0.5 V (SCE) (vs. <0.1 V for carbon steel).
- Forms nickel-rich sulfide (NiS₂) passive layer in H₂S environments, with breakdown potential >0.5 V (SCE) (vs. <0.1 V for carbon steel).
Case Study:
- A high-sulfur gas field (0.3 bar H₂S) replaced Super 13Cr bolts with Monel K500 Stud Bolt (ASTM F468)—zero stress corrosion failures over 5 years, compared to the previous 8-month average lifespan.
- A high-sulfur gas field (0.3 bar H₂S) replaced Super 13Cr bolts with Monel K500 Stud Bolt (ASTM F468)—zero stress corrosion failures over 5 years, compared to the previous 8-month average lifespan.
(2) Resistance to Sulfuric & Hydrofluoric Acid Mixtures
The Monel K500 Stud Bolt exhibits outstanding corrosion resistance in hot sulfuric acid environments (e.g., petrochemical reactors).
The Monel K500 Stud Bolt exhibits outstanding corrosion resistance in hot sulfuric acid environments (e.g., petrochemical reactors).
Test Data (ASTM G31 Immersion Test):
- Conditions: 70°C, 20% H₂SO₄ + 2% HF.
- Corrosion Rate: 0.03–0.05 mm/year (vs. >0.5 mm/year for 316L stainless steel).
- Conditions: 70°C, 20% H₂SO₄ + 2% HF.
- Corrosion Rate: 0.03–0.05 mm/year (vs. >0.5 mm/year for 316L stainless steel).
Corrosion Resistance Mechanisms:
- Copper’s Protective Role:
- Forms Cu₂O/CuSO₄ composite film (solubility: 10⁻⁶ mol/L vs. Fe²⁺ at 10⁻⁴ mol/L).
- Corrosion current density (i_corr) = 1.2 μA/cm² (Tafel polarization), 1/20 that of 304 stainless steel.
- Copper’s Protective Role:
- Forms Cu₂O/CuSO₄ composite film (solubility: 10⁻⁶ mol/L vs. Fe²⁺ at 10⁻⁴ mol/L).
- Corrosion current density (i_corr) = 1.2 μA/cm² (Tafel polarization), 1/20 that of 304 stainless steel.
- HF Resistance:
- Forms NiF₂ layer (K_sp=10⁻¹²); Ti (0.35–0.85%) contributes TiF₃, sealing passive film defects.
- In 5% HF + 10% H₂SO₄ at 50°C, corrosion rate remains <0.08 mm/year.
- Forms NiF₂ layer (K_sp=10⁻¹²); Ti (0.35–0.85%) contributes TiF₃, sealing passive film defects.
- In 5% HF + 10% H₂SO₄ at 50°C, corrosion rate remains <0.08 mm/year.
Application Example:
- Alkylation reactor bolts (M24×120, 80 kN preload) in a refinery (65°C, 15% H₂SO₄ + 3% HF) showed after 3 years:
- No crevice corrosion (ASTM G48 Method A).
- Tensile strength retention >95% (ISO 6892-1).
- Passive film thickness maintained at 20–30 nm (XPS analysis).
- Alkylation reactor bolts (M24×120, 80 kN preload) in a refinery (65°C, 15% H₂SO₄ + 3% HF) showed after 3 years:
- No crevice corrosion (ASTM G48 Method A).
- Tensile strength retention >95% (ISO 6892-1).
- Passive film thickness maintained at 20–30 nm (XPS analysis).
2. Material Selection Guidelines & Limitations
While the Monel K500 Stud Bolt excels in acidic environments, consider these restrictions:
1) Oxidizing Acids:
- Avoid concentrated nitric acid (>50%) or oxidizing acids with Fe³⁺/Cu²⁺, where corrosion rates may exceed >1 mm/year (due to copper leaching).
While the Monel K500 Stud Bolt excels in acidic environments, consider these restrictions:
1) Oxidizing Acids:
- Avoid concentrated nitric acid (>50%) or oxidizing acids with Fe³⁺/Cu²⁺, where corrosion rates may exceed >1 mm/year (due to copper leaching).
2) Temperature Limit:
- Long-term use ≤150°C—higher temperatures cause γ' phase coarsening, reducing mechanical properties.
- Long-term use ≤150°C—higher temperatures cause γ' phase coarsening, reducing mechanical properties.
3) Sensitivity to Processing:
- Post-cold-working aging treatment (595°C×16h) is mandatory to prevent residual stress-induced localized corrosion.
- Post-cold-working aging treatment (595°C×16h) is mandatory to prevent residual stress-induced localized corrosion.
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