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BL Flange
SDFL
This ASME B16.5 blind flange stands as a versatile isolation solution for pipeline maintenance, shutdowns, and system modifications. Constructed from high-grade F304/F316 stainless steel—known for their excellent corrosion resistance and mechanical strength—it provides a secure seal for pipe ends while withstanding the demands of high-pressure industrial environments. Unlike welded caps, its bolted design allows for easy access during inspections, making it a cost-effective choice for critical systems requiring frequent maintenance.
Parameter | Details |
Standard | ASME B16.5 (Class 150–2500) with full compliance to dimensional and material requirements |
Material | F304 (304SS, 18Cr-8Ni), F316 (316SS, 18Cr-10Ni-2Mo) with optional F316L for low-carbon applications |
Seal Type | Raised Face (RF) for general service, Ring Joint (RJ) for high-pressure Class 600+ systems |
Temperature Range | -20°C to 450°C (F304, suitable for ambient to moderate heat), -20°C to 600°C (F316, ideal for high-temperature steam) |
Quick Isolation: Bolt-on design enables tool-free disassembly during routine inspections, reducing downtime by up to 30% compared to welded alternatives. The flange’s flat sealing surface ensures uniform gasket compression for reliable isolation.
Heavy-Duty Construction: F316 grade incorporates molybdenum (2-3% content) to resist chloride stress corrosion cracking, making it indispensable in marine or brine systems where salt concentrations exceed 35,000 ppm.
Precision Machining: ASME B16.5 mandates ±1.6mm bolt hole diameter tolerance and Ra 12.5 surface finish on sealing faces, guaranteeing consistent gasket contact and minimizing leak paths.
Multi-Industry Approval: Certified to API 605 standards for large-diameter flanges (NPS 26"–60") and compliant with ASME BPVC Section IX for welding procedures, meeting safety requirements in pressure vessel and pipeline codes.
Refineries: Class 300 RF blind flanges isolate reactor sections during scheduled turnarounds, preventing hydrocarbon leakage in catalytic cracking units operating at 3 MPa pressure.
Water Treatment: F304 blind flanges with flat face (FF) seals are used in chlorinated water lines, where their non-reactive surface resists degradation from chlorine levels up to 5 ppm.
LNG Terminals: RJ-sealed F316 flanges maintain integrity in cryogenic LNG storage tanks, withstanding temperatures as low as -162°C while preventing cold gas leakage.
Q: How to test the flange’s seal integrity?
A: Perform hydrostatic testing at 1.5x the rated pressure (e.g., 4.5 MPa for Class 300) using a non-asbestos spiral-wound gasket; hold pressure for 30 minutes with no visible leakage or pressure drop exceeding 5%.
Q: Can it handle vacuum conditions?
A: Yes. Select Class 1500+ flanges paired with copper-asbestos or PTFE gaskets to maintain airtight seals in vacuum-rated systems (down to -1 bar), commonly used in chemical distillation columns.
Q: What bolt materials are recommended?
A: Use ASTM A193 B8 (stainless steel) bolts for F304 flanges and ASTM A193 B8M for F316 flanges to ensure material compatibility and corrosion resistance.
