Blind disk is formally known as Flange cover, sometimes also referred to as Blind Flange or Pipe Plug. It is a flange without a hole in the middle, used for sealing pipe openings. It serves the same function as a cap or pipe end, but the blind disk sealing is a removable sealing device, whereas the cap sealing is not intended to be reopened. There are various types of sealing surfaces, including flat, convex, concave, tenon and groove, and annular connection. Materials include carbon steel, stainless steel, alloy steel, copper, aluminum, PVC, and PPR.