Stainless Steel Blind Flange

Product Description

Stainless Steel Blind Flanges (often designated as BL, BLRF, or BLRTJ) are solid forged or plate discs without a central bore, used to blank off, cap, or isolate pipeline ends, pressure vessel nozzles, and valve outlets.

1. Operating Principle & Key Functions

• System Termination: Acts as a removable seal to cap off line ends, manifold branch headers, and pressure vessel openings.

• Maintenance & Inspection Access: Allows quick access into piping spools or vessels during maintenance, hydro-testing, or internal cleanouts when unbolted.

• Pressure Isolation: Withstands full system internal pressure and bending loads across the entire disc face, making it one of the highest-stressed flange configurations in a piping loop.

2. Sealing Face Configurations

• RF (Raised Face): Features a raised seating area with concentric serrations (125 to 250 AARH) for spiral wound or flat gaskets; standard for Class 150 through Class 600.

• RTJ (Ring Type Joint): Machined with an annular metallic groove to house solid oval or octagonal metal ring gaskets; mandatory for high-pressure, high-temperature lines (Class 600 and above).

• FF (Flat Face): Full flat contact surface; primarily used when mating against cast equipment, low-pressure stainless steel, or plastic-lined systems to prevent flange cracking.

3. Common Stainless Steel Material Specifications

Stainless steel blind flanges are specified under ASTM A182 (forged) or ASTM A240 (plate material):

4. Applicable Standards & Dimensional Specs

• ASME B16.5: Pipe Flanges and Flanged Fittings ($\text{NPS } 1/2 \text{ to } 24$, Class 150, 300, 400, 600, 900, 1500, 2500).

• ASME B16.47 Series A & B: Large Diameter Steel Flanges ($\text{NPS } 26 \text{ to } 60$).

• EN 1092-1 Type 05: European standard for blank / blind flanges (PN 2.5 through PN 400).

• JIS B2220 BL: Japanese standard blind flanges (5K through 30K).