Spectacle Blind（SB)
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A spectacle blind flange (also known as a figure-8 blank) is a pressure-retaining industrial fitting used in piping systems for positive isolation and flow control. It is a single-piece metal component shaped like the number 8 or a pair of spectacles. It consists of two discs connected by a narrow web: Solid Disc (Blind End): A fully sealed plate that blocks fluid flow when positioned in the pipeline.Open Disc (Spacer End): A ring with a bore matching the pipe's inner diameter, allowing unobstructed flow when in place. Function & Operation Installed between two flanges, it is manually rotated 180 degrees to switch between two states: OPEN (Flow): The spacer ring is aligned with the pipe bore for normal operation.CLOSED (Isolation): The solid plate is inserted to provide a leak-proof seal for maintenance, testing, or safety shutdowns. Key Features Positive Isolation: Provides a physical, visual barrier superior to valves.Interlocked Design: The two ends are permanently connected, preventing loss or misplacement.Standards: Manufactured per ASME B16.48 and other international specifications.Materials & Ratings: Available in carbon steel, stainless steel, alloys; sizes 1/2" to 48" (DN15 to DN1200); pressure classes from 150# to 2500#. Applications Widely used in oil & gas, petrochemical, power generation, and refinery industries where absolute flow separation is critical.
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Main products: WN, SO, PL, BL flanges, elbows, tees, reducers, caps. Materials: carbon steel, stainless steel, alloy steel. Standards: ASME, ANSI, EN, JIS, DIN. Export to global pipeline projects. Contact Us