Unloading apparatus

An apparatus for unloading a stuffing box is formed from a resiliently deformable material. It features a base and a plurality of elongate finger elements. The finger elements are supported about the periphery of the base, and define outer boundaries of a hollow interior region. Each finger element supports an externally projecting lip. In the relaxed position of the apparatus, the lips project outside the cross-sectional profile of the base. In a compressed configuration, the lips are fully contained within the base's cross-sectional profile. When the apparatus is inserted into a stuffing box loaded with coaxially aligned annular packing elements, it assumes a compressed configuration until the lips clear the lowermost packing element to be removed. The apparatus then assumes a relaxed position with the lips engaging the underside of the lowermost packing element. The apparatus and the engaged packing elements are then withdrawn from the stuffing box.

SUMMARY OF THE INVENTION

An apparatus for unloading a stuffing box features a first end and an opposed second end. The apparatus is formed from a base and a plurality of elongate finger elements. The base is situated at or adjacent the first end. The finger elements are supported by the base and disposed about its periphery, and define the outer boundaries of a hollow interior region. Each finger element supports an externally projecting lip at or adjacent the second end.

DETAILED DESCRIPTION

FIGS. 1-5show a apparatus10that may be used to unload a stuffing box having an internal chamber. A stuffing box12suitable for use with the apparatus10is shown inFIGS. 6-11. The stuffing box12is preferably part of a pump14, and features an internal chamber16.

As shown inFIG. 1, the apparatus10is characterized by a first end18and an opposed second end20. It includes a base22that is situated at or adjacent the first end20of the apparatus and is symmetric about a longitudinal axis24. Preferably, the base22is characterized by a circular cross section and outer surfaces26that define a cylindrical shape.

The apparatus10further comprises a plurality of elongate finger elements28. The finger elements28are spaced apart from one another and are supported by and joined to the base22. Preferably, the finger elements are joined to the base22about its periphery.

The finger elements28define outer boundaries of a hollow interior region30that is coaxial with the base22. In the embodiment shown in the Figures, the apparatus10includes four finger elements28. An elongate slot32is formed between each adjacent pair of finger elements28.

Preferably the external shape and dimensions of each finger element28conform to the external shape and dimensions of that portion of the base22that is offset axially from that finger element28. The outer surface34of each finger element28thus joins smoothly with the outer surface26of the base22. When the outer surface26defines a cylindrical shape, the outer surface34of each finger element28forms a curved shape with the same radius and axis as the outer surface26of the base22.

At or adjacent the second end20of the apparatus, the extremity of each finger element28supports an externally projecting lip36having a free end38. As shown inFIG. 5, each lip36is characterized by an outward-extending first surface40. The first surface40is planar, and disposed in orthogonal relationship to the outer surface34of the supporting finger element28. Joining the first surface40at free end38is a convexly-shaped second surface42, which may be smooth and curved. The second surface42of the lip36is situated at an axial extremity of the apparatus10, and functions to guide the finger element28toward axis24, as the apparatus10is pushed axially against a surface.

The apparatus10should be formed from a strong and durable material that is both deformable and sufficiently resilient that it can fully recover its shape after deformation. A preferred material is spring or tool steel that has been tempered. Preferably, the apparatus10is formed from a single piece or unit of material.

In a preferred embodiment, the apparatus10is formed from a single solid bar of steel that is machined to the required shape. Webs that interconnect adjoining finger elements28at the second end20are left in place. The machined shape is then subjected to heat treatment to increase its hardness. Following heat treatment, the connecting webs are cut away to form the finished apparatus10.

The apparatus10is characterized by a relaxed configuration and a compressed configuration. The relaxed configuration is shown inFIGS. 1,2and3. In this configuration, the lips36at least partially project outside the cross-sectional profile44of the base22, as shown inFIG. 3.

The compressed configuration is achieved when the lips36are fully contained within the cross-sectional profile44of the base, as shown inFIG. 4. To achieve this compressed configuration, a deforming forced is applied to the apparatus10. Preferably, this deforming force is a laterally compressive force.

The deforming force causes the lips36and finger elements28to move toward the axis24. Because interior region30is hollow, the apparatus20provides sufficient space for this internal movement. When the deforming force is removed or relaxed sufficiently, the apparatus10returns to its relaxed configuration.

The base22should feature a planar surface46at its lower extremity. Surface46is disposed in orthogonal relationship to the axis24. An axially disposed threaded shaft48may be installed in the base22, such that it projects at one end from surface46.

One embodiment of the apparatus10is used to unload annular packing elements having central openings with a diameter of 0.875 inches. In this embodiment, the maximum end-to-end length of the apparatus, excluding the projecting threaded shaft, is 3 inches. The diameter of the cylindrical base is 0.865 inches. The maximum width of the apparatus adjacent second end20is 1.02 inches.

FIG. 6shows a portion of a pump14with which the apparatus10may be used. The pump14includes a reciprocating rod assembly50formed from a first rod52, which may comprise a pony rod, and a second rod54. The first and second rods52and54are releasably joined in end-to-end relationship, preferably by mating threads.

During normal operation of the pump14, the second rod54extends through and reciprocates within a stuffing box12having an open first end56and an open second end58. Typically, the stuffing box12is permanently secured to the body of the pump14.

The stuffing box12is loaded with a plurality of coaxially disposed annular packing elements60. The packing elements include a plurality of contiguous seals62disposed in stacked relationship. In the embodiment shown in the Figures, three such seals62are provided. The packing elements may further comprise an adapter element64and a retainer element66, situated on opposite sides of the stacked seals62.

The adapter element64is situated immediately adjacent the first end56of the stuffing box12. The packing elements may further comprise a spring68, situated adjacent the retainer element66at the second end58of the stuffing box12.

The stuffing box12is releasably closed at its first end56by a nut70, such as a castle nut, which is preferably secured to the stuffing box12by mating threads. The packing elements62and the nut70are characterized by central axial openings72, preferably circular, that permit the second rod54to extend closely, but clearingly, therethrough.

During operation of the pump14, reciprocation of the rod assembly50causes the seals62to wear. In order to keep the pump14operating efficiently, these seals62must be removed and replaced periodically. A port74formed in a wall of the pump14provides access to the service area76around stuffing box12for this removal and replacement operation.

Because the seals62are tightly packed within the stuffing box12, their removal can be difficult. Removal is further complicated by the limited space available in the area around the stuffing box12, as shown inFIG. 6. As a result, manual and tool access to the stuffing box is highly restricted.

When conventional hand tools are used to remove seals, those tools can easily scratch or otherwise damage the inner surfaces of the stuffing box12, producing damage that can impair sealing and interfere with efficient pump operation. Moreover, in some instances, removal must be performed under challenging outdoor field conditions. All of these factors can make seal removal a difficult process that can easily result in damage to the stuffing box.

FIGS. 6-11show how the unloading apparatus10can be used to remove packing elements with greater speed and accuracy, and less risk of damage to the stuffing box. During the initial stage of replacement, shown inFIG. 7, the first and second rods52and54of the rod assembly52are disconnected. The pump mechanism is used to pull second rod54out of the stacked packing elements60. Similarly, the first rod52is drawn away from the stuffing box12.

In the next stage of replacement, shown inFIG. 12, the nut70is unthreaded from the stuffing box12. The unloading apparatus10, in its relaxed configuration, is then coaxially aligned with the aligned central openings72of the packing elements70within the stuffing box12. Preferably this aligned positioning is achieved by releasably connecting the apparatus10to first rod52and maintaining them in coaxial engagement. That coaxial engagement is maintained by mating the threaded shaft48supported on base22with internal threads formed within the end of first rod52.

Axial force is next applied to the apparatus10in the direction of the stuffing box12, preferably at the planar surface46of base22. Preferably, such axial force is applied by manually pushing the apparatus10toward the stuffing box12. The coaxial engagement of apparatus10with first rod52assures that apparatus10enters the stuffing box12in an axial direction.

The convex second surface42of each lip36contacts the uppermost packing element60at the edge of its central opening72. In the embodiment shown in the Figures, the uppermost packing element is adapter element64. Under axial force, the second surface42guides each lip36, and its attached finger element28, into the central opening72of the adapter element64.

As axial force continues to be applied, the apparatus10moves axially within the stuffing box12, through aligned central openings72of the stacked packing elements60. The lips36and finger elements28are compressed by the packing elements60, causing the lips36and finger elements28to move toward axis24and occupy a portion of the previously hollow interior region30. This causes the apparatus10to assume its compressed configuration, as shown inFIG. 9.

The external dimensions of the base22closely but clearingly match those of the central openings72of the packing elements60. Thus, in its compressed configuration, the apparatus10can be moved through the aligned openings72of the packing elements60.

As shown inFIG. 10, the apparatus10is preferably sized so that, at its point of maximal insertion into the stuffing box12, the lips36can closely but clearingly underlay the lowermost of those packing elements60that are to be removed from the stuffing box12. In the embodiment shown in the Figures, the lowermost packing element to be removed is the lowermost seal62. The retainer element66and spring68are not customarily removed when packing elements are replaced.

When the lips36of the apparatus10clear the lowermost of the seals62, the resiliently deformable construction of the apparatus10causes the finger elements28and lips36to return the apparatus to its relaxed configuration, as shown inFIG. 10. In that configuration, the planar first surfaces40of the lips36engage the underside of the lowermost seal62. At this stage, axial insertion of the apparatus10into the stuffing box12is stopped.

Axial force in the opposite direction is next applied to the apparatus10. Preferably, such axial force is applied by manually pulling the apparatus10from the stuffing box12. As shown inFIG. 11, this axial force causes the apparatus10, still in its relaxed configuration, to be withdrawn from the stuffing box12. The lowermost packing element60engaged by the lips36, and any packing elements60above it, are carried out of the stuffing box12as the apparatus10is withdrawn. Inasmuch as the apparatus10is inserted and withdrawn from the stuffing box12through application of purely axial forces, the internal sides of the stuffing box12are not scratched or otherwise damaged during the removal process.

Following removal of the apparatus10from the stuffing box12, the apparatus10is disengaged from the first rod52, and any used packing elements60are removed. Following replacement of the removed packing elements60with new packing elements, the first rod52and second rod54are reconnected. The reassembled pump14is now ready for use.

Changes may be made in the construction, operation and arrangement of the various parts, elements, steps and procedures described herein without departing from the spirit and scope of the invention as described in the following claims.