Blind Flanges
Date:2026-08-21View:5Tags:Stainless steel pipe,ERW steel pipe,Sprial steel pipe
A blind flange (also called a flange cover) is a removable sealing device primarily used to seal pipe openings, isolating and cutting off the flow of media. Unlike welded end caps, its biggest advantage is its ability to be easily disassembled and installed.
Main Types and Characteristics
Based on structure and application, blind flanges can be mainly classified into the following categories:
1. Plate-type flat blind flange: A solid disc with a handle, typically used in systems requiring long-term isolation. It is the simplest type of blind flange.
2. Figure-8 blind flange: Shaped like the number "8," one end is a solid blind flange, and the other end is a hollow throttling ring (equivalent to a gasket). Isolation is achieved using the blind flange end; normal connection is achieved by rotating the flange to use the throttling ring end. A significant advantage is its clear visibility of the status—the shape exposed on the pipe allows for a very intuitive determination of whether the pipe is "open" or "closed," greatly reducing the risk of misoperation.
Core Uses and Key Application Scenarios
1. Piping System Isolation and Testing: For example, during pressure testing of equipment (such as compressors and reactors), it prevents high-pressure media from accidentally entering the equipment; or when the plant is shut down, it completely disconnects material pipelines that are still in operation.
2. Pressure Vessel Safety Interlocks: In the petroleum and chemical industries, quick-opening blind flanges (a type of pressure vessel end cover that can be opened quickly) use specially designed safety bolts as part of the safety interlock device. This ensures that "if the quick-opening blind flange is not fully closed, the vessel cannot be pressurized; if the internal pressure is not fully released, the blind flange cannot be opened," which is an important safety protection measure.
3. Application of Extended Bolts in Flange Connections: When installing figure-eight blind flanges, due to the thickness of the blind flange, longer bolts than usual are required for flange connections to ensure a good seal.
4. Key Technical Requirements and Parameters: Strict Sealing Performance: Blind flanges have various sealing surface forms (such as flat, raised face, recessed face, tongue and groove, etc.), which must perfectly match the sealing surface of the pipeline flange to ensure no leakage. Pressure and Temperature Resistance: Different pressure ratings (from 1.0 MPa to 16.0 MPa or even higher) and temperature ranges require different materials and structures for blind flanges. For example, heat-resistant alloy steel or stainless steel may be used under high-temperature and high-pressure conditions.
Materials and Processes: Blind flanges are made of various materials (carbon steel, stainless steel, alloy steel, etc.), and manufacturing processes include forging and casting. Generally, forging and plate cutting yield better quality than casting.
