Blind disk, also called flange cover, is a flange with no holes in the middle and is used to seal the pipe mouth. The function is the same as the head and cap, but the blind seal is a detachable sealing device, and the seal of the head is not ready to open again. There are many types of sealing surfaces, such as plane, convex, concave and convex, tenon and groove surface and ring connection surface. Materials include carbon steel, stainless steel, alloy steel, copper, aluminum, PVC and PPR.

From the appearance of blind board, it is generally divided into plate blind board, 8-character blind board, plug board, and gasket ring (plug board and gasket ring are blind to each other). Blind plate plays the role of isolation and cutting off, as well as sealing head, pipe cap and welding plug. Because of its good sealing performance, it is generally used as a reliable means of isolation for systems requiring complete isolation. Plate blind plate is a solid circle with a handle, which is used in isolation system under normal conditions. The shape of 8-character blind plate is like 8-character, one end is blind plate, the other end is throttle ring, but the diameter is the same as the pipe diameter, and does not play a throttling role. The 8-character blind plate is easy to use. When isolation is needed, the blind end is used. When normal operation is needed, the throttle ring end is used. It can also be used to fill the installation gap of the blind plate in the pipeline. Another feature is that the logo is clear and easy to identify the installation status.