US3223425A - Slush pump piston rod packing assembly and packing - Google Patents

Description

A. L. LEMAN Dec. 14, 1965 SLUSH PUMP PISTON ROD PACKING ASSEMBLY AND PACKING Original Filed Feb. 19, 1959 F|G 4 fi INVENTOR.

ARTHUR L. LEMAN ATTOR N EYS FIGr5 United States Patent Ofitice 3,223,425 Patented Dec. 14, 1965 3,223,425 SLUSH PUMP PISTON R01) PACKING ASSEMBLY AND PACKING Arthur L. Leman, R0. Box 24068, Houston, Tex.

Original application Feb. 19, 1959, Ser. No. 794,429, new

Patent No. 3,076,658, dated Feb. 5, 1963. Divided and this application Apr. 5, 1965, Ser. No. 445,682

3 (Ilaims. (Cl. 277-115) This application is a continuation-in-part of my application Ser. No. 253,703, filed January 24, 1963, now abandoned, as a division of my application Ser. No. 794,- 429, filed February 19, 1959, Patent No. 3,076,658 dated February 5, 1963.

This invention relates to reciprocating piston pumps, especially those handling fluids likely to contain abrasive matter, such as slush pumps employed in the oil fields. Among its objects are to provide for such pumps an improved piston rod packing assembly adapted to maintain an eflective seal despite variation in the piston rod diameter at the packing region such as caused by Wear, and especially to provide an integral one-piece but laterally separable packing unit readily applicable to and removable from the rod with minimal time loss in pump operation yet constructed and arranged to effect said sealing action mechanically and apart from reliance on fluid .pressure on circumferential terminal lips liable to sealing failure especially at the ends of the longitudinal zone of lateral jointure of the unit.

In the drawing illustrating one exemplary embodiment of the invention:

FIG. 1 is a longitudinal section at the power end of a pump cylinder having a stufiing box and packing unit of the invention operatively installed, with a portion being broken away for clarity;

FIG. 2 is a perspective view of the packing unit of FIG. 1 unlocked and partly opened laterally along the longitudinal joint formation;

FIG. 3 is an enlarged longitudinal section taken centrally along the closed packing joint as on the line 3-3 of FIG. 1;

FIG. 4 is a view corresponding to FIG. 3 but in elevation looking at one margin of the interlocking joint structure as when held in open position such as in FIG. 2; and

FIG. 5 is a detail transverse section as on the line 5-5 of FIG. 4.

In reciprocating slush pumps and others handling fluids containing abrasives the piston rods become worn to a reduced diameter. This diameter-reducing Wear generally is greatest at an intermediate or substantially midlength part of the rod and merges into less worn end por- Lions. To continue to seal off the fiuid effectively the packing must be in adequately tight easement with the rod section of minimum diameter. But in the conventional stuffing box if the packing is made sufiiciently tight for a worn rod section, it is subjected to abnormally high compression at the less Worn and hence larger rod diameters. There usually being no place for the packing to escape when entered by a larger-diameter rod portion, an excessive bearing pressure builds up, causing rapid erosion of the packing as Well as further wear of the rod.

Under the invention special provision is made for relative relief of the packing at the larger rod portions while at the smaller sections sealing engagement with the worn rod is maintained, so that at all times during an extended useful life of the parts efiicient scaling is maintained even with a worn rod section. At times in the operation, as at the end of a stroke, with a rod portion of normal or but relatively little reduced diameter at the stufiing box, the packing elongates axially, substantially as in the full-line showing in FIG. 1 of the drawing, where the dotted-line position diagrams that of the packing element at other times.

Further in accord with the invention the desired sealing maintenance is had mainly mechanically and without resort to annular recessing at the packing end such as to form lips thereat for subjection to fluid pressure radially as proposed for example in Patent No. 2,896,980 to Dicky. Such proposal for hydraulically supplemented sealing is unsuited to applicants purposes of high-pressure abrasure fluid pumping and maintenance of efiicient sealing at the ends of the axially extending packing joint.

Referring to the drawing in more detail, the reciprocating piston rod is indicated at 5, extending through a portion of a pump cylinder wall 6 at the power end of the pump. The cylinder wall 6 is apertured for reception of the piston rod stuffing box designated generally at 110. The piston end of the rod 5 is toward the right.

The stufling box comprises a generally cylindrical body 111 having at the outer end an external circumferential mounting flange 112 and at the opposite or inner end an internal flange or annular shoulder 13 surrounding a central aperture 14 dimensioned for free reciprocating passage of the piston rod 5. The box is anchored on the cylinder wall as by a plurality of studs 112' through the mounting flange 112, again later referred to in connection with the gland 130.

Under the invention the stufiing box is novelly adapted for cooperation with a wedge-ring packing elment by provision of inclined wall means 115 carried internally of and herein as an integral portion of the stufiing box 110. The inner circumferential surface of said wall means 115 is formed along a prominent incline over a major portion of its length and at an acute angle relative to the axis of piston rod 5. Such angle of wall inclination as shown is in the range of about 8 to 15, being approximately 11 in the illustrated example. Thus in elfect there is provided an inwardly tapering main wall portion for the stufiing box bore, extending toward the inner end of the box and there preferably terminating in a relatively short cylindrical wall portion 118. At said inner end the minimum bore diameter of the inclined Wall means 115 and of the box bore is still substantially greater than the maximum diameter of the piston rod 5, providing annular space thereat including a tapered portion S in continuation of the inclined wall means 115 and an inner terminal cylindrical portion S.

In the presently illustrated example the stufiing box 110 is cast, machined or otherwise formed to carry said inclined wall means 115 in the box bore and as an integral portion of the box, and having the low angle of inclination as stated.

For cooperation with the inclined wall means 115 of the stuffing box, and with the rod 5, a one-piece packing unit is provided in the form of an annular sleeve-like body or ring 20 of rubberous or like elastomeric composition of substantial resiliency and capacity to expand and contract and in effect to flow under application of external force and resiliently to return toward normal free shape and dimension upon release of such force. Similarly as in my said prior application and patent this packing ring 20 in longitudinal section is of predominant wedge form. It has an outer wall 21 molded to taper toward the inner end of the stufling box over a major axial extent of the packing from a point beyond mid-length toward the outer end and continuing to the inner end in conformity with the degree of incline of the stufiing box inner Wall means 115, i.e. at an approximate angle of 11 to the piston rod axis in the given example. While in some instances the taper at 21 may begin at or substantially at the outer end of the packing ring 20 preferably a relatively short outer terminal portion as at 24 is made cylindrical and of a diameter to seat snugly in an outer cylindrical part of the bore of stuffing box 110.

The described stufling box structure presents an inwardly tapering packing recess or cavity in the stuffing box 110 defined, at the radially outer side of the packing, by an integral wall of the stufl'lng box including the inclined wall means 115 thereof, and defined at the radially inner side of the packing by the piston rod 5. The inner end wall of this packing recess or cavity is defined by the mentioned internal annual shoulder 13 of the box. The length of this packing recess of the stufling box in the direction of taper is markedly greater than the length of the packing ring 20 therefor in the normal initial or free form of the latter. As shown, the total cavity or recess includes a normally open space S with a tapering outer circumferential wall in continuation of the inclined wall 115 of the box 110, and inwardly beyond said tapering space S an inner end portion S with a substantially cylindrical outer wall. Thus the integral inclined wall 115 of the stuffing box extends at S somewhat beyond the initial position of the inner end of the conical packing ring 20 and merges into a substantially cylindrical terminal cavity at S extending to the stuffing box inner end shoulder 13.

The packing ring 20 and associated parts including the stuffing box 110 and the piston rod 5 are so constructed, proportioned and arranged that when installed in operative position in the pump the packing ring 20 as shown in full line on the drawing is under a degree of axial elongation and radial compression as compared to the wholly free form of the ring as it comes from the mold. Thus in said free form the ring 20 measures somewhat less in axial length and somewhat greater in transverse width than under operating conditions even including those which develop under diameter-reducing wear of the piston rod and wherein said ring is still sufficiently stressed mechanically to maintain an effective seal at any reduceddiameter rod section, even under the high pressure conditions frequently encountered in slush pump operation. On FIG. 1 of the drawing the mentioned dotted lining and the numeral 20 with dotted lead-line is diagrammatically indicative of less elongated and less compressed conditions of the packaging, as when opposite a reduced or worn piston rod portion when the packing more nearly approaches but does not reach free form during continued useful life ofthe parts.

Conversely stated, the wedge ring or tapered packing 20 in the practice of the invention has a free form and dimensioning such that it is of distinctly less length axially than the receiving recess therefor and is of greater thickness radially than the radial dimension of the annular space constituting such recess, having reference to the maximum expectable radial dimension of said space at the smallest or most worn diameter of the piston rod of the given pump installation.

Thus as noted the axial and radial dimensioning of the box bore including the inclined wall means 115 and the dimensioning of the wedge pack-ing ring 20 are so correlated that the inwardly tapering cavity within the integral inclined-wall bore of the stuffing box 110 has a length in the axial direction greater than that of the packing 20 in the free form of the latter, again noting the recess inner end portions S and S respectively with tapering and with substantially cylindrical circumferential walls.

Further, in the preferred embodiment illustrated, the wedge packing ring 20 is shaped, proportioned and arranged to be compressed into sealing easement with the reciprocable rod 5 in a positive mechanical fashion such as to avoid reliance on fluid pressure upon lengthwise protruding terminal lips at either the outer conical wall or the inner cylindrical wall of the packing, such for example as resorted to in the Dicky patent mentioned where reentrant recessing at the inner terminus forms bevelled outer and inner edges respectively adjacent the bore wall of the stuffing box and the cylindrical surface of the piston rod. Such lips or edges of progressively thinning component material as they approach coincidence with said adjacent box and rod walls are found to be incompatible with effective sealing of surfaces of longitudinal surfaces of separation needed for lateral application of the packing to the rod and in the presence of high-pressure abrasive fluids are subject to rapid breaking away and attendant production of leakage.

In contrast to such bevel-lipped formations the unitary packing ring of the instant invention both at the outer end wall 22 and at the inner end wall 23 flat faces of substantial radial extent and disposed wholly or substantially entirely in planes perpendicular to the axis of the packing and of the rod 5 which it surrounds.

At the same time the radial extent of said flat terminal faces, which is to say the radial thickness of the packing wall, and the stated taper of the outer wall are in the present invention so correlated with the axial length of the packing unit 20 that the radial wall thickness thereof at the outer or large end is more than twice the radial wall thickness at the inner or small end. Yet the length along the rod is made at least three times the maximum radial wall thickness at the larger outer end. By thus utilizing a solid but relatively narrow wholly radial inner end wall face, less than one-half that of the similarity radial outer wall face, in conjunction with the stated overall length-to-outer end-wall-thickness ratio had by means of the stated average 11 taper, the mechanical compression capacity is drastically improved. Resultantly there is for the first time provided an efiiciently sealing yet laterally installable packing for high-pressure slush pump use such as for current deep well operations.

Thus in accordance with the invention the rod packing assembly not only provides for mechanically squeezing the rubber or rubberous composition of the packing ring 2% into sealing accommodation to the reciprocating piston rod operating under high pressure conditions and in the pumping of abrasive fluids such as the slush for oil wells drilling, but also accomplishes this improved sealing while affording to the packing ring 20 the ability to be installed on and removed from the rod 5 without having to unscrew or disconnect the rod from the crosshead.

Such lateral applicability and removability for the packing ring requires that the wall thereof be separably split longitudinally from end to end, so that the opposed ring portions at longitudinal zone of division or split path may be resiliently spread apart laterally sufliciently to he slipped onto and off from the rod transversely thereof; see particularly FIG. 2 where the split or longitudinal joint formation is designated generally at 25.

An important aspect of the illustrated embodiment of the invention resides in the novel structure and arrangement of this separable joint formation or interlocking jointure 25 and the combination thereof with the externally conical packing ring 20 having the described radial flat end wall faces.

In the packing unit 20 of the present example longitudinal series of round-headed button-like members or lugs alternating with like-shaped sockets are formed on the ring wall at the joint 25 in longitudinally offset relation at the two sides thereof, so that the lugs 30 on one wall of the joint individually stand opposite the sockets 40 of the opposite wall in opposed mating relation; see FIGS. 1 and 2. In the closed position of the installed ring these members 30 of the two series mutually interlock resiliently and compressively, interengaging along curved surfaces providing for mutual overlapping of the adjointed members 30 circumferentially, longitudinally and also radially of the packing wall at the joint 25 and particularly including overlapping formations at the extremities of the joint at the described radial end wall faces of the packing unit 20. Thus positive closure of the joint is assured and especially against endwise seepage at the smaller as Well as the larger end of the packing ring unit 20 and in a manner not satisfactorily obtainable in high-pressure operations with prior packings of the terminal lip form such as represented by the Dicky patent already menitoned.

The curvilinear locking lugs 30 each extend for the full radial thickness of the packing wall at their respective positions lengthwise along it; see FIG. 3. As best seen in FIGS. 1 and 2 each such lug 30 has a rounded head portion 31 with parti-circular end faces 32, 33 at the exterior and interior surfaces of the packing. Said lug end faces and the lug body portions between them are of something in excess of semi-circular extent approaching or equalling the three-quarter round. Said lug head portions 31 are carried by reversely curved lug neck portions 34 merging into the packing wall at the side of the joint at which the given lug is supported.

The lugs 30 and the intervening sockets 40 along one margin of the joint are similarly shaped, spaced and arranged for snugly conforming matching interfit with the sockets 40 and lugs 30 respectively of the opposite margin, noting the closed position of the joint in FIG. 1, also FIG. 3. Thus there is positive interlocking of the jointforming elements 30, 40 in the directions lengthwise and also extensively circumferentially of the packing ring.

Additionally the heads 31 of the lugs 30 are formed with concavities and the sockets 40 with matching convexities in the direction radially of the packing, giving them a bowed and general hour-glass conformation as seen in section in FIGS. 3 and 5 and in edge elevation in FIG. 4 and designated as at 35, 36 therein. Said radial curvature, in effect creating flared portions 37 at the radially outer and inner ends of the lugs 30, affords a positive interlocking for the joint in the third or radial direction of the ring packing unit 20. It is noted that such three-way interlocking and sealing overlap of the joint-forming elements is carried out over the full length of the joint zone 25, including partial lug and socket formations 30 40 at the smaller end of the conical packing ring and 30 40 at the larger end.

From the foregoing it is apparent that by reason of the deeply interengaging lugs and sockets 30, 40 with approximately three-quarter round lug heads seating in conformant inner socket portions and the associated concave, convex and flaring formations such as shown and described the total longitudinal zone of jointure 25 is enabled to be compacted into assured sealing closure primarily under mechanical pressure alone.

In installation such mechanical pressure of a high order is applied at the respective flat radial end faces 22 and 23 of the conical packing ring unit 20, consequent to setting up of the installed packing by means of the action of the gland 130 at the larger end and as opposed by the inclined wall 115 of the stufling box engaging the conical portion of the packing including the smaller flat radial end thereof. The initial forming of the packing ring with terminal end faces wholly in radial planes perpendicular to the rod axis over substantially the entire radial extent of said packing ends insures security of complete sealing along the jointure zone and especially at the ends, thus avoiding the difficulties heretofore experienced in that regard where eiforts at augmented hydraulic sealing pressure have been attempted as by inwardly annularly recessing the ends of packing collar elements and there forming circumferential lengthwise protruding lips, bevelled rims or the like.

In operation, with the packing ring 20 laterally applied about the rod in the pump said packing element is set up into wedging engagement with the inclined Wall 115 of the stufiing box and is locked up in such operative position as by the gland 130. The anchoring of the stufling box 110 upon the pump cylinder wall 6 and the adjustable securement of the gland may be variously provided for. In the illustrated example there is employed for the purpose the series of threaded studs 112 earlier mentioned, these being tapped into the pump cylinder wall and extending commonly through the stufling box external flange 112 and the lateral flange 133 of the gland.

6 Each stud in this instance receives a pair of lock-up nuts 113, 114 individually engaging the respective flanges 112 and 133. While the gland may engage the resilient packing 20 direct preferably a fibrous or other substantially rigid intermediary collar 134, which may be divided for lateral installation, is interposed between the gland and the resilient wedge ring 20.

The invention is not limited to the particular embodiment thereof illustrated and described herein, its scope being set forth in the following claims.

I claim:

1. In a piston rod packing assembly for a reciprocating piston slush pump having a cylinder with an end wall, and a piston rod for operatively entering therethrough, the combination comprising a rod stufiing box for mounting on and entry through said wall, the box having a central bore coaxial with the piston rod path, an inner end wall providing an internal annular shoulder about the rod path and an external radial mounting flange,

the stufling box bore including internal relatively large and relatively small cylindrical portions at the outer and at the inner ends respectively and a major intermediate portion continuously tapering between the outer and the inner cylindrical portions, said box bore portions defining an annular packing recess to surround the piston rod,

and a resilient integral one-piece packing ring unit with a rod-receiving internal cylindrical bore and an external circumferential face presenting a major conical portion and a relatively short cylindrical portion at the larger outer end,

said packing ring unit having an initial longitudinal cross-sectional shape similar to that of the stuffing box bore wall including part of the cylindrical outer end portion thereof but with an initial free axial length short of the inner cylindrical end portion of said bore wall and further having an initial free radial wall dimension at all points along it greater than that of said annular packing recess at the corresponding point and to an extent greater than maximum expected variation in piston rod diameter under operative wear,

said packing ring unit having outer and inner end faces of substantial radial extent and disposed substantially entirely in planes perpendicular to the piston rod axis and having from end to end thereof a single longitudinal zone of separable jointure for lateral application and removal of the packing unit relative to the rod,

said jointure zone comprising along each opposed longitudinal margin thereof a series of alternating lugs and sockets similarly spaced at the two margins and longitudinally staggered for entry of the lugs of one margin into the sockets of the opposite margin, said lugs presenting at the free ends rounded heads of greater than half-round body and being bowed and terminally flared radially of the packing whereby three-dimensional interlocking of the lugs and sockets is afforded along the full extent of the jointure zone,

and a gland and associated threaded means at the outer end of the stufling box for applying to the packing unit axial thrust of a high order eflFective at the respective flat radially disposed end faces of the packing unit in a manner insuring secure sealing fully along and at the ends of the longitudinal jointure zone primarily under mechanical pressure alone.

2. For use in packing the rod of a reciprocating-piston slush pump,

a resilient integral onewpiece packing ring of truncate conical external form, said unit having at the respective ends flat terminal faces in planes perpendicular to the ring axis,

said ring having a longitudinal zone of separate jointure whereat it is openable for lateral application to and removal from a pump piston rod to be packed,

said jointure zone comprising along each opposed 7 8 longitudinal margin thereof a series of alternating of the ring is at least three times said maximum radial lugs and sockets similarly spaced at the two margins Wall thickness.

and longitudinally staggered for entry of the lugs of one margin into the sockets of the opposite margin, References Cited by the Examiner said lugs presenting at the free ends rounded heads 5 UNITED STATES PATENTS of greater than half-round body and being bowed 755 3 4/1930 Faudi 5 and terminally flared radially of the packing whereby 2,464,653 :3/1949 Phipps 277. 221 three-dimensional interlocking of the lugs and sockets 2,896,980 7/ 1959 Dicky 27 7-1 19 is afforded along the full extent and at the ends of the jointure zone. 3. A packing ring in accordance with claim 2 wherein the maximum radial wall thickness at the outer end is LAVERNE 11 GEIGER, P i E more than twice that at the inner end, and the axial length I MEDNICK A t an t Examiner 1o FOREIGN PATENTS 965,545 6/1957 Germany.

Claims (1)

1. IN A PISTON ROD PACKING ASSEMBLY FOR A RECIPROCATINGPISTON SLUSH PUMP HAVING A CYLINDER WITH AN END WALL, AND A PISTON ROD FOR OPERATIVELY ENTERING THERETHROUGH, THE COMBINATION COMPRISING A ROD STUFFING BOX FOR MOUNTING ON AND ENTRY THROUGH SAID WALL, THE BOX HAVING A CENTRAL BORE COAXIAL WITH THE PISTON ROD PATH, AN INNER END WALL PROVIDING AN INTERNAL ANNULAR SHOULDER ABOUT THE ROD PATH AND AN EXTERNAL RADIAL MOUNTING FLANGE, THE STUFFING BOX BORE INCLUDING INTERNAL RELATIVELY LARGE AND RELATIVELY SMALL CYLINDRICAL PORTIONS AT THE OUTER AND AT THE INNER ENDS RESPECTIVELY AND A MAJOR INTERMEDIATE PORTION CONTINUOUSLY TAPERING BETWEEN THE OUTER AND THE INNER CYLINDRICAL PORTIONS, SAID BOX BORE PORTIONS DEFINING AN ANNULAR PACKING RECESS TO SURROUND THE PISTON ROD, AND A RESILIENT INTEGRAL ONE-PIECE PACKING RING UNIT WITH A ROD-RECEIVING INTERNAL CYLINDRICAL BORE AND AN EXTERNAL CIRCUMFERENTIAL FACE PRESENTING A MAJOR CONICAL PORTION AND A RELATIVELY SHORT CYLINDRICAL PORTION AT THE LARGER OUTER END, SAID PACKING RING UNIT HAVING AN INITIAL LONGITUDINAL CROSS-SECTIONAL SHAPE SIMILAR TO THAT OF THE STUFFING BOX BORE WALL INCLUDING PART OF THE CYLINDRICAL OUTER END PORTION THEREOF BUT WITH AN INITIAL FREE AXIAL LENGTH SHORT OF THE INNER CYLINDRICAL END PORTION OF SAID BORE WALL AND FURTHER HAVING AN INITIAL FREE RADIAL WALL DIMENSION AT ALL POINTS ALONG ITS GREATER THAN THAT OF SAID ANNULAR PACKING RECESS AT THE CORRESPONDING POINT AND TO AN EXTENT GREATER THAN MAXIMUM EXPECTED VARIATION IN PISTON ROD DIAMETER UNDER OPERATIVE WEAR, SAID PACKING RING UNIT HAVING OUTER AJD INNER END FACES OF SUBSTANTIAL RADIAL EXTENT AND DISPOSED SUBSTANTIALLY ENTIRELY IN PLANES PERPENDICULAR TO THE PISTON ROD AXIS AND HAVING FROM END TO END THEREOF A SINGLE LONGITUDINAL ZONE OF SEPARABLE JOINTURE FOR LATERAL APPLICATION AND REMOVAL OF THE PACKING UNIT RELATIVE TO THE ROD, SAID JOINTURE ZONE COMPRISING ALONG EACH OPPOSED LONGITUDINAL MARGIN THEREOF A SERIES OF ALTERNATING LUGS AND SOCKETS SIMILARLY SPACED AT THE TWO MARGINS AND LONGITUDINALLY STAGGERED FOR ENTRY OF THE LUGS OF ONE MARGIN INTO THE SOCKETS OF THE OPPOSITE MARGIN SAID LUGS PRESENTING AT THE FREE ENDS ROUNDED HEADS OF GREATER THAN HALF-ROUND BODY AND BEING BOWED AND TERMINALLY FLARED RADIALLY OF THE PACKING WHEREBY THREE-DIMENSIONAL INTERLOCKING OF THE LUGS AND SOCKETS IS AFFORDED ALONG THE FULL EXTENT OF THE JOINTURE ZONE AND A GLAND AND ASSOCIATED THREADED MEANS AT THE OUTER END OF THE STUFFING BOX FOR APPLYING TO THE PACKING UNIT AXIAL THRUST OF A HIGH ORDER EFFECTIVE AT THE RESPECTIVE FLAT RADIALLY DISPOSED END FACES OF THE PACKING UNIT IN A MANNER INSURING SECURE SEALING FULLY ALONG AND AT THE ENDS OF THE LONGITUDINAL JOINTURE ZONE PRIMARILY UNDER MECHANICAL PRESURE ALONE.

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