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ASTM B564 UNS N08825 Spectacle Line Blinds Flanges Raised Face: Technical Specifications and Applications

1. Introduction

ASTM B564 UNS N08825 Spectacle Line Blinds Flanges with Raised Face (RF) are critical components in industrial piping systems, designed to isolate sections of pipelines for maintenance or safety purposes. These flanges, made from Incoloy 825 (UNS N08825), combine superior corrosion resistance with mechanical durability, making them ideal for harsh environments such as chemical processing, oil and gas, and marine applications .

2. Material Properties

• UNS N08825 (Incoloy 825):
  • Composition: Nickel (38–46%), Chromium (19.5–23.5%), Molybdenum (2.5–3.5%), Copper (1.5–3.0%), and Iron (balance) .
  • Corrosion Resistance: Excellent resistance to sulfuric acid, phosphoric acid, chloride stress corrosion, and marine environments due to high nickel and molybdenum content .
  • Temperature Tolerance: Suitable for temperatures up to 550°C (1,022°F) with maintained mechanical strength .

3. Design Features

• Spectacle Line Blinds:
  • Consist of two metal discs (a "spade" for flow blocking and a "spacer" for flow continuity) connected by a handle, ensuring safe pipeline isolation .
  • Compliant with ASME B16.48 standards for dimensions and pressure ratings (150–2500#) .
• Raised Face (RF):
  • A machined surface (typically 1.6–6.3 μm roughness) around the flange bore to enhance gasket sealing under high-pressure conditions .

4. Manufacturing and Standards

• ASTM B564 Compliance: Specifies the requirements for nickel-alloy forgings, ensuring material integrity through rigorous chemical, mechanical, and non-destructive testing .
• Surface Finish: Polished or machined surfaces to meet NACE MR0175 standards for sour gas service .
• Sizes: Available in diameters from 1/2" to 48", with custom thickness and bolt-hole configurations .

5. Applications

• Chemical Processing: Used in sulfuric acid reactors, phosphoric acid evaporators, and nuclear waste handling systems 
• Oil and Gas: Deployed in offshore platforms, subsea pipelines, and sour gas environments due to resistance to hydrogen sulfide (H₂S) .
• Power Generation: Suitable for flue gas desulfurization (FGD) systems and heat exchangers .

6. Advantages Over Alternatives

• Superior to Carbon Steel: Enhanced resistance to pitting, crevice corrosion, and oxidation in acidic or saline environments .
• Cost-Efficiency: Reduced maintenance and replacement costs due to long-term durability .

7. Procurement and Customization

• Packaging: Bulk orders typically use wooden crates or pallets, with lead times of 10–25 days from certified manufacturers 
• Custom Options: Available in alternative finishes (e.g., electro-polished), non-standard sizes, or modified RF heights .

Conclusion

ASTM B564 UNS N08825 Spectacle Line Blinds Flanges with Raised Face are indispensable in industries demanding reliability under extreme conditions. Their compliance with international standards, robust material properties, and adaptability to customization make them a preferred choice for engineers prioritizing safety and longevity in pipeline systems.

References

• Incoloy 825 chemical composition and corrosion resistance.
• ASME B16.48 standards and RF flange design.
• ASTM B564 material testing and NACE MR0175 compliance.
• Sizing and procurement details.