Blind plate flange (blind flange) also known as blind plate, the correct name is called flange cover. Is a flange with no holes in the middle for sealing the pipe plug. There are many types of sealing faces, including plane, convex, concave, tenon, ring joint. One of its functions is to seal the end of the pipe, https://www.jiade-group.com/flange/ https://www.jiade-group.com/