The formal name for blind flanges is flange cover, and some are also called blind flanges or pipe plugs. It is a flange without a hole in the middle, used to seal pipeline openings. The function of the blind plate seal is the same as that of the head and pipe cap, except that the blind plate seal is a detachable sealing device, and the seal of the head is not intended to be opened again. There are various forms of sealing surfaces, including flat, convex, concave convex, mortise and tenon surfaces, and ring connection surfaces.