MELCO's ANUFLEX Annular Packing Unit has a group of patented metal segments, spaced apart at regular intervals imbedded in the unit, instead of the conventional one piece segments furnished by other manufacturers. MELCO's unique hinge design allows the unit to conform and flex with a lessor amount of resistance than conventional units, which allows for more opens and closures, and a longer life cycle.

The pivotability of the upper portion of each segment, relative to the base plate, limits the force exertable by the element on a drill string component.

The upward, pivotal motion of the heel portion of the base plate feeds rubber upward and radially inward to compensate for wear of rubber in the bore walls of the unit where most conventional units begin to fail.

Other annular units have fixed metal segments molded into the rubber in a circular hemispherical cavity. The segments are pushed upwards by hydraulic piston pressure in a spherical cavity forcing rubber to cold flow inward effecting a seal around the drill pipe. Since the metal segment is fixed, the upper, inner edge of the fixed segment can make contact with the drill pipe and can damage it in certain conditions.

MELCO's Anuflex segment is made of two parts which are moveable with respect to one another. The freedom of one part with respect to the other limits the force which the metal segments may exert on drill pipe as the hydraulic piston moves the sealing element into a closed position. MELCO's ANUFLEX units function particualy well during stripping operations. The hinged segments allow the rubber to cold flow more freely than conventional segments.

The design of the segment allows the smaller protion of each segment base plate to pivot, functioning as a toe plate, supporting and directing the cold flow of rubber upward toward the sealing bore of the element. This action increases the longitudinal length of the seal, greatly improving the capability of the seal to contain higher pressures than standard segmented units.