ASTM B574 Ni-Mo Binary Alloy Octagonal Ring Gasket Non-Magnetic
Hastelloy B2 (UNS N10665) is a nickel-molybdenum binary alloy with outstanding resistance to strong reducing media. It is specifically designed for manufacturing octagonal ring gaskets (ORG) used in highly corrosive environments. As a critical sealing component for high-pressure flange connections, this gasket ensures the tightness and reliability of flange joints in harsh working conditions, widely applied in the chemical, petroleum, and hydrometallurgical industries.
I. Core Basic Information
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Item
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Details
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Alloy Grade
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Hastelloy B2, UNS N10665, ASTM B574
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Core Composition
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Ni (balance, ~60–65%), Mo (28–33%), Fe (≤2.0%), C ≤ 0.15%, Mn ≤ 1.0%
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Microstructure
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Single-phase austenite, non-magnetic, excellent formability, suitable for cold/hot forming
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Gasket Type
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Octagonal ring gasket (ORG), part of the metal ring gasket series
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Standard Compliance
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ASTM B574 (Hastelloy B2 alloy standard), ASME B16.20 (flange sealing surface and gasket standards)
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II. Core Performance Advantages (Tailored for ORG Working Conditions)
The performance characteristics of Hastelloy B2 alloy determine that the octagonal ring gasket made from it can operate stably in highly corrosive environments. Its core advantages are as follows:
1.Exceptional Resistance to Reducing Media
▶Exhibits excellent corrosion resistance to strong reducing acids such as hydrochloric acid, sulfuric acid, and phosphoric acid (including reducing media containing chlorine and sulfur). It resists corrosion, pitting, and crevice corrosion from the media.
▶Particularly suitable for working conditions involving wet chlorine, hydrogen chloride, and other mixed media with both oxidizing and reducing properties. It is the ideal material for pickling and hydrometallurgical processes in the chemical industry.
2.Good High-Temperature Mechanical Properties
▶Can be used continuously within the temperature range of -200°C to 540°C. It maintains high strength and creep resistance even at high temperatures, preventing gasket deformation and leakage under high pressure and temperature.
▶Tensile strength ≥ 690 MPa, yield strength ≥ 276 MPa, hardness (HB) ≤ 200, meeting the sealing load requirements of high-pressure flanges.
3.Excellent Processability and Sealing Performance
▶Features good cold and hot formability, enabling precise processing into an octagonal ring structure to ensure tight contact between the gasket and the flange sealing surface.
▶Strong elastic recovery ability: Under flange preload, it deforms elastically to fill gaps on the sealing surface effectively.
4.Resistance to Stress Corrosion Cracking (SCC)
▶Exhibits good resistance to stress corrosion cracking caused by chloride ions, maintaining structural stability even in high-concentration chloride environments.
Ⅲ. Typical Application Scenarios
Hastelloy B2 octagonal ring gaskets are mainly used in highly reducing, highly corrosive, and high-pressure-high-temperature working conditions. Their typical application fields include:
1.Chemical Industry
▶Sealing flanges of reaction kettles and storage tanks handling strong acids such as hydrochloric acid, sulfuric acid, and phosphoric acid.
▶Sealing flanges of equipment in hydrometallurgical processes (e.g., leaching tanks, extraction towers).
▶Sealing of high-pressure pipelines in pickling production lines and wastewater treatment systems.
2.Oil and Gas Industry
▶Sealing flanges of wellhead equipment and separators in sulfur-containing and chloride-containing oil and gas fields.
▶Sealing of high-pressure pipelines in sour gas wells (mixed media of H₂S/CO₂).
3.Nuclear Power and Environmental Protection Industry
▶Sealing of high-corrosion media transportation pipelines in nuclear chemical engineering.
▶Sealing of flanges in acidic wastewater treatment systems of waste incineration power plants.
IV. Comparison with Other Nickel-Based Alloy Octagonal Ring Gaskets
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Alloy Material
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Core Advantages
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Applicable Working Conditions
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Limitations
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Hastelloy B2 (Nickel-Molybdenum Alloy)
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Excellent resistance to strong reducing acids; anti-pitting performance
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Strong reducing media such as hydrochloric acid and sulfuric acid
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Slightly lower high-temperature stability compared to Inconel series
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Hastelloy C276 (Nickel-Chromium-Molybdenum-Tungsten Alloy)
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Resistance to both strong oxidizing and reducing media
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Mixed media of strong acids and alkalis
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Higher cost than B2
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Inconel 625 (Nickel-Chromium-Molybdenum Alloy)
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Resistance to strong oxidizing media; high high-temperature strength
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High-temperature oxidation environments
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Poor resistance to reducing acids
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Monel 400 (Nickel-Copper Alloy)
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Resistance to seawater corrosion; low cost
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Medium and low-pressure seawater environments
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Poor resistance to strong acids
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V. Installation and Usage Notes
1.Sealing Surface Matching: The gasket must precisely match the roughness and size of the flange sealing surface to avoid leakage caused by uneven sealing surfaces.
2.Installation Specifications: Avoid twisting or scratching the gasket during installation. The preload force must be evenly distributed to prevent local overload and gasket deformation.
3.Temperature Control: Avoid long-term use at temperatures exceeding 540°C or below -200°C, as this will degrade the alloy’s performance.
4.Maintenance and Inspection: Regularly check the surface condition of the gasket. Replace it promptly if corrosion or deformation is detected.
DINGSCO Complete Production Chain:
SMELTING → FORGING → HEAT TREATMENT → MACHINING → HOT EXTRUSION
①Foundational Assurance in Smelting and Forging:
VIM furnaces ensure alloy purity; ESR furnaces further optimize internal structure. Forging yields diverse billets, laying a defect-free foundation for downstream processing and controlling material properties at the source.
②Precision Control in Intermediate Processing:
Heat treatment is customized for alloys. CNC machining enables high-precision forming, yielding semi-finished parts to ensure pre-extrusion billets meet forming specs.
③Synergistic Value of Hot Extrusion with Full Process:
The new hot extrusion press is part of an integrated system: High-purity alloys (VIM/ESR), dense forging microstructures, and heat-treated performance collectively enable stable extrusion of hard-to-form alloys. Produced complex components: seamless pipes, profiles; material utilization up 15-20%. Full-process efficiency cuts standard model lead times to 5-10 days.
④Quality and Delivery Assurance:
Every batch comes with EN 10204 Type 3.1 certification, inspected by our internal QC team. We support third-party audits (BV, SGS, etc.), and offer custom manufacturing per drawings with sample testing available.
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