Abstract: A highly efficient packing material is provided in the form of a flexible, corrugated expanded graphite ribbon or tape, which material can be used to pack the stuffing box assembly of any pump or valve, or like structure, regardless of the dimensions of the shaft and stuffing box of such pump or valve. The use of corrugated ribbon or tape of expanded graphite as a packing material eliminates the former requirement for pre-made rings which had to be sized to conform precisely to the dimensions of the stuffing box and shaft of such pump or valve, and vastly broadens the applicability and use of this highly efficient packing material to many field operations where such use was formerly impossible.