A516 Spectacle Blind Flange

QS Flange: Jiaxing Spectacle Blind Flange

A516 Gr.70+S5 carbon steel spectacle blind flange, 0.75 inch Class 1500LB RF per ASME B16.5, for positive isolation of high-pressure lines.

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One-Minute Overview

Figure-8 plate combining a solid blind and an open ring to isolate or restore flow in one motion.
Rotating the unit 180 degrees switches the joint between blocked and open without extra parts.
A516 Gr.70+S5 carbon steel, ASME B16.5 dimensions, RF face, 0.75 inch, Class 1500LB.
Black anti-rust coating protects the plate during storage, transport and service.

The A516 spectacle blind flange is a pipeline isolation device that combines a solid blind plate and a ring spacer in a single figure-8 unit. Swinging the assembly 180 degrees lets operators positively isolate a line or return it to flow without cutting the pipe or adding components. For high-pressure joints where a valve cannot guarantee absolute shutoff, the figure-8 plate is the permanent barrier of choice.

Name: A516 Spectacle Blind Flange
Size: 0.75 Inch
Pressure: Class 1500LB
Material: A516 GR.70+S5
Flange Face: RF
Standard: ASME B16.5
Coating: Black Anti-rust Coating

The plate is crafted from ASTM A516 Gr.70+S5 carbon steel, a pressure vessel plate grade with a minimum tensile strength of 70 ksi and excellent weldability. The normalized condition refines the grain structure and keeps mechanical properties stable in high-pressure service at temperatures down to -20°F. Manufacturing to ASME B16.5 for dimensions and tolerances makes the blind interchangeable with existing piping systems, and the raised face concentrates gasket pressure to achieve a superior seal. Spectacle blinds provide positive isolation — a physical barrier that valves cannot guarantee — which is essential where safety and absolute shutoff are critical.

In power generation the blind isolates sections of steam lines, boiler feedwater systems and turbine bypasses during maintenance. Petroleum and chemical plants rely on spectacle blinds in lines carrying hydrocarbons and other hazardous fluids to comply with lock-out/tag-out (LOTO) protocols, and water conservancy facilities use them to isolate equipment in pumping stations and treatment plants. Strong stiffness and good sealing keep the joint tight in every position of the plate.

FAQ

Q1. How does the figure-8 design actually switch a line on and off?

The plate joins a solid blind and an open ring with a steel web. Loosen the bolting, swing the unit 180 degrees and retighten: the solid end blocks the joint for positive isolation, the ring end lets flow pass. You never remove the plate, so no part gets lost mid-job.

Q2. Which material and pressure class does this spectacle blind use?

It is crafted from ASTM A516 Gr.70+S5, a carbon steel pressure vessel plate with at least 70 ksi tensile strength and excellent weldability. The unit is sized 0.75 inch at Class 1500LB with a raised face, so it suits high-pressure joints where a dependable seal matters.

Q3. Why choose a spectacle blind instead of just closing a valve?

A valve can leak or be misoperated; a spectacle blind is a physical barrier. For lock-out/tag-out work on hazardous hydrocarbon lines, maintenance teams trust the solid plate because positive isolation can be seen and verified. Valves isolate for convenience, spectacle blinds isolate for safety.

Q4. What is the smallest order I can place?

Standard flange insulation gasket kits start at one set, and standard gaskets, studs, washers and sleeves start at one piece. Parts made to your drawing or to a non-standard bolt pattern are quoted one by one, because the minimum really depends on the material and the tooling involved.

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