CA2284380C - Top coupling arrangement for a reciprocating pump - Google Patents
Top coupling arrangement for a reciprocating pump Download PDFInfo
- Publication number
- CA2284380C CA2284380C CA 2284380 CA2284380A CA2284380C CA 2284380 C CA2284380 C CA 2284380C CA 2284380 CA2284380 CA 2284380 CA 2284380 A CA2284380 A CA 2284380A CA 2284380 C CA2284380 C CA 2284380C
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- Canada
- Prior art keywords
- plunger
- coupling
- leading edge
- barrel
- annulus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/14—Pistons, piston-rods or piston-rod connections
- F04B53/144—Adaptation of piston-rods
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B47/00—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps
- F04B47/02—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps the driving mechanisms being situated at ground level
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Details Of Reciprocating Pumps (AREA)
Abstract
An improved coupling arrangement is provided for coupling connected to the top of a plunger which reciprocates in a pump barrel. The coupling provides fluid ports for discharging fluid from the bore of the plunger and coupling to the annulus between the coupling and pump barrel. The lower edge of the ports is positioned below the leading edge of plunger, or conversely the leading edge of the plunger is re-formed above the lower edge; of the coupling's ports. Accordingly, solids cannot be trapped between the leading edge of the plunger and barrel and pump live is markedly improved. Preferably the plunger's leading edge is formed by the novel coupling so that industry standard plunger's can be used. Further, the plunger's leading edge is preferably fitted with a wiper which is even more preferably backed by a stack of seals fitted into a pressure-equalized annulus located below the wiper.
Description
1 "TOP COUPLING ARRANGEMENT FOR A RECIPROCATING PUMP"
3 F'IELD OF THE INVENTION
4 The invention relates to improvements to the coupling between the reciprocating driver and the reciprocating portion of a reciprocating plunger and 6 barrel pump used in wells which produce a large fraction of granular solids.
9 Throughout North America, oilwells and gas-producing water wells are often associated with sand production. In some geographical locations such as 11 Southern Alberta, Ceinada, heavy oil is sometimes recovered from unconsolidated 12 sandstone formations using a technique called cold production. The operator of the 13 well aggressively perforates the well and purposefully produces formation sand 14 along with the heavy oil. This technique pulls sand from the formation, increasing oil mobility and formation permeability for improving the flow of viscous oil to the 16 well. Typically sancl production is high upon well completion and for a period 17 thereafter.
18 Reciprocating rod pumps can be used with varying success in lifting 19 sand concentrations of 20% or more. Progressive cavity pumps (PCP) are more tolerant than most reciprocating pumps of sand but are generally limited to sand 21 concentrations of less than 20%.
22 Pump failures can halt production until an expensive and time-23 consuming workover clears the sand. A workover usually entails calling in an 1 expensive service rig to pull the pump or flush a PCP implementation. It is even 2 more costly to maintErin a service rig at the well.
3 Converitional rod-actuated reciprocating pumps comprise a cylindrical 4 barrel housing a recilprocating piston or plunger. Sand is very damaging to such reciprocating pumps, particularly at the interface between the plunger and the 6 barrel.
7 In both light or heavy oil production, sand is present but in varying 8 degrees and in varying gravity weights of fluid. With low concentrations of sand in 9 viscous oil, the sand tends to stay in suspension and does not readily settle and accumulate in the purnp. Conversely, higher concentration of sand in light or thin oil 11 settles out quickly and readily accumulates to a point where abrasion damage 12 occurs. As well, even in heavier oils of in the presence of water, high 13 concentrations of sarid result in quick and damaging accumulations which causes 14 rapid damage to the plunger, barrel and can seize the plunger in the pump.
If sand is allowed to accumulate between any part of the plunger and 16 or any of it's components and the barrel wall abrasion damage will occur either 17 quickly or over a period of time. With reciprocating rod pumps, the upstroke or 18 pressure stroke traps sand accumulation under pressure at pressures which are 19 typically 2 - 3000 pounds per square inch.
More particularly, the barrel is anchored in a well. Generally, a 21 reciprocating driver such as a string of rods or a tubing string is coupled to the 22 plunger. Plungers can be made by different manufacturers but have standard 23 dimensions and conriections. The plunger is hollow and has a travelling check 1 valve adjacent its bottom end. A coupling is provided which connects 2 the rod string to the connection on the top of the plunger and permits the exit of fluid 3 from the hollow plunger. The barrel has a standing check valve at its bottom end.
4 The barrel is anchored within the well so that relative movement between the reciprocating plunger and the stationary barrel results in a cyclical filling of the barrel 6 and emptying into the plunger for lifting to the surface.
7 Sand from the above-described wells is very fine and tends to pack up 8 in any small spaces or clearances rendering piston rings, grooves and seals 9 ineffectual. The sand may be likened to a lapping compound, causing high wear and ultimately resulting in seal, ring or barrel failure. Seals are used at the bottom of the 11 plunger. In U.S. Patent No. 6,099,274 issued on August 8, 2000, applicant has 12 disclosed improved seals which are more tolerant of sand. Conventionally, merely 13 close tolerances are provided at the top of the plunger to exclude debris with more 14 substantial seals being adjacent the travelling valve.
During the plunger downstroke, fluid exiting the hollow plunger is 16 routed through the top of the plunger and through the coupling to reach the annular 17 space outside of the reciprocating drive or rod string. This brings any solids into 18 direct proximity and contact with the interface of the top of the plunger and the pump.
19 Specifically, having reference to Figs. 1 a and lb and so as to define the basic conventional components, a prior art pump is shown comprising a conventional 21 plunger A, barrel B, coupling C and rod D. Industry standards specify the overall 22 dimensions of most components A,B,C,D and connections to ensure 1 consistency and compatibility. Accordingly a variety of prior art couplings C can be 2 fitted to prior art plungers A. The top end of the plunger A is closely fitted to the 3 barrel B and has a'top male threaded connection. The coupling C comprises a 4 hollow body having a lower threaded connection for coupling with the plunger's threaded connection. Coupling C has a smaller diameter than plunger A, forming 6 an annular gap E so as to avoid contact with the barrel B. The coupling's hollow 7 body forms a bore contiguous with that of the plunger A. A plurality of ports F are 8 formed in the periphery of tf ie coupling C for flow passageways to pass well fluid 9 from the plunger A to the barrel B for discharge from the pump.
As shovvn in more detail in Fig. 1 b, fluid-borne solids, carried through 11 ports, can settle out aind pack in the dead area G of the annular gap E, below ports 12 F. The high pressure of the next lifting stroke tightly packs the solids into the gap.
13 Continued reciprocation of the plunger A with packed solids in the gap E
results in a 14 high rate of wear and eventual failure of the barrel B.
Applicarit has determined that even by fitting applicant's improved 16 seals to the top of the plunger has not resulted in significantly improved wear 17 resistance at the barrel - plunger interface.
18 Having determiried that mere substitution of improved seals between 19 the top of the plunger= and the pump barrel were not the solution to pump failures, other innovations are requireci. Accordingly, there is a demonstrated need for other 21 solutions if the mean t.ime between failures is to be extended and pumping of sand-22 laden fluids is to be economical.
2 The present invention uses a novel arrangement of the coupling and 3 plunger connection to prevent the damaging accumulation of solids between the 4 pump plunger and barrel. lt was determined that there was a need to remove cavities and dead areas which collect solids adjacent the barrel and even to actively 6 flush the areas with fluid.
7 Applicant recognized that industry standards for connection of the 8 plunger to the reciprocating driver caused an unfortunate physical configuration, 9 guaranteed to result in premature wear and ultimately failure. The novel arrangement provides a retrofit solution for both conventional plungers and solution 11 using a custom plunger.
12 Briefly, in a simplified form, the invention comprises altering the 13 arrangement of the fluid ports in the coupling and the leading edge of the plunger.
14 By positioning the ports below the leading edge of the plunger, then solids settling from the fluid (such as during the upstroke) are diverted inwardly into the bore of the 16 plunger and cannot be trapped against the barrel. Further, during fluid flow (such 17 as during the downstroke) the fluid flushed solids from the leading edge of the 18 plunger.
19 Accordingly, iri a broad apparatus aspect of the invention, an improved coupling is provided for a reciprocating pump which co-produces fluids 21 containing entrained solids. The pump has a cylindrical barrel within which a 22 cylindrical plunger is slidably movable, the plunger fitting closely within the barrel, 23 and a reciprocating string o-f rods for connection to the top of the plunger for 1 reciprocating the plunger within the pump barrel whereby fluid travels through a 2 bore through the plunger. The improved arrangement for coupling the plunger to 3 the string of rods comprises a coupling and a leading edge for the plunger.
The 4 coupling is connecteci at its lower end to the top of the plunger and at its upper end to the string of rods for reciprocating the plunger.
9 Throughout North America, oilwells and gas-producing water wells are often associated with sand production. In some geographical locations such as 11 Southern Alberta, Ceinada, heavy oil is sometimes recovered from unconsolidated 12 sandstone formations using a technique called cold production. The operator of the 13 well aggressively perforates the well and purposefully produces formation sand 14 along with the heavy oil. This technique pulls sand from the formation, increasing oil mobility and formation permeability for improving the flow of viscous oil to the 16 well. Typically sancl production is high upon well completion and for a period 17 thereafter.
18 Reciprocating rod pumps can be used with varying success in lifting 19 sand concentrations of 20% or more. Progressive cavity pumps (PCP) are more tolerant than most reciprocating pumps of sand but are generally limited to sand 21 concentrations of less than 20%.
22 Pump failures can halt production until an expensive and time-23 consuming workover clears the sand. A workover usually entails calling in an 1 expensive service rig to pull the pump or flush a PCP implementation. It is even 2 more costly to maintErin a service rig at the well.
3 Converitional rod-actuated reciprocating pumps comprise a cylindrical 4 barrel housing a recilprocating piston or plunger. Sand is very damaging to such reciprocating pumps, particularly at the interface between the plunger and the 6 barrel.
7 In both light or heavy oil production, sand is present but in varying 8 degrees and in varying gravity weights of fluid. With low concentrations of sand in 9 viscous oil, the sand tends to stay in suspension and does not readily settle and accumulate in the purnp. Conversely, higher concentration of sand in light or thin oil 11 settles out quickly and readily accumulates to a point where abrasion damage 12 occurs. As well, even in heavier oils of in the presence of water, high 13 concentrations of sarid result in quick and damaging accumulations which causes 14 rapid damage to the plunger, barrel and can seize the plunger in the pump.
If sand is allowed to accumulate between any part of the plunger and 16 or any of it's components and the barrel wall abrasion damage will occur either 17 quickly or over a period of time. With reciprocating rod pumps, the upstroke or 18 pressure stroke traps sand accumulation under pressure at pressures which are 19 typically 2 - 3000 pounds per square inch.
More particularly, the barrel is anchored in a well. Generally, a 21 reciprocating driver such as a string of rods or a tubing string is coupled to the 22 plunger. Plungers can be made by different manufacturers but have standard 23 dimensions and conriections. The plunger is hollow and has a travelling check 1 valve adjacent its bottom end. A coupling is provided which connects 2 the rod string to the connection on the top of the plunger and permits the exit of fluid 3 from the hollow plunger. The barrel has a standing check valve at its bottom end.
4 The barrel is anchored within the well so that relative movement between the reciprocating plunger and the stationary barrel results in a cyclical filling of the barrel 6 and emptying into the plunger for lifting to the surface.
7 Sand from the above-described wells is very fine and tends to pack up 8 in any small spaces or clearances rendering piston rings, grooves and seals 9 ineffectual. The sand may be likened to a lapping compound, causing high wear and ultimately resulting in seal, ring or barrel failure. Seals are used at the bottom of the 11 plunger. In U.S. Patent No. 6,099,274 issued on August 8, 2000, applicant has 12 disclosed improved seals which are more tolerant of sand. Conventionally, merely 13 close tolerances are provided at the top of the plunger to exclude debris with more 14 substantial seals being adjacent the travelling valve.
During the plunger downstroke, fluid exiting the hollow plunger is 16 routed through the top of the plunger and through the coupling to reach the annular 17 space outside of the reciprocating drive or rod string. This brings any solids into 18 direct proximity and contact with the interface of the top of the plunger and the pump.
19 Specifically, having reference to Figs. 1 a and lb and so as to define the basic conventional components, a prior art pump is shown comprising a conventional 21 plunger A, barrel B, coupling C and rod D. Industry standards specify the overall 22 dimensions of most components A,B,C,D and connections to ensure 1 consistency and compatibility. Accordingly a variety of prior art couplings C can be 2 fitted to prior art plungers A. The top end of the plunger A is closely fitted to the 3 barrel B and has a'top male threaded connection. The coupling C comprises a 4 hollow body having a lower threaded connection for coupling with the plunger's threaded connection. Coupling C has a smaller diameter than plunger A, forming 6 an annular gap E so as to avoid contact with the barrel B. The coupling's hollow 7 body forms a bore contiguous with that of the plunger A. A plurality of ports F are 8 formed in the periphery of tf ie coupling C for flow passageways to pass well fluid 9 from the plunger A to the barrel B for discharge from the pump.
As shovvn in more detail in Fig. 1 b, fluid-borne solids, carried through 11 ports, can settle out aind pack in the dead area G of the annular gap E, below ports 12 F. The high pressure of the next lifting stroke tightly packs the solids into the gap.
13 Continued reciprocation of the plunger A with packed solids in the gap E
results in a 14 high rate of wear and eventual failure of the barrel B.
Applicarit has determined that even by fitting applicant's improved 16 seals to the top of the plunger has not resulted in significantly improved wear 17 resistance at the barrel - plunger interface.
18 Having determiried that mere substitution of improved seals between 19 the top of the plunger= and the pump barrel were not the solution to pump failures, other innovations are requireci. Accordingly, there is a demonstrated need for other 21 solutions if the mean t.ime between failures is to be extended and pumping of sand-22 laden fluids is to be economical.
2 The present invention uses a novel arrangement of the coupling and 3 plunger connection to prevent the damaging accumulation of solids between the 4 pump plunger and barrel. lt was determined that there was a need to remove cavities and dead areas which collect solids adjacent the barrel and even to actively 6 flush the areas with fluid.
7 Applicant recognized that industry standards for connection of the 8 plunger to the reciprocating driver caused an unfortunate physical configuration, 9 guaranteed to result in premature wear and ultimately failure. The novel arrangement provides a retrofit solution for both conventional plungers and solution 11 using a custom plunger.
12 Briefly, in a simplified form, the invention comprises altering the 13 arrangement of the fluid ports in the coupling and the leading edge of the plunger.
14 By positioning the ports below the leading edge of the plunger, then solids settling from the fluid (such as during the upstroke) are diverted inwardly into the bore of the 16 plunger and cannot be trapped against the barrel. Further, during fluid flow (such 17 as during the downstroke) the fluid flushed solids from the leading edge of the 18 plunger.
19 Accordingly, iri a broad apparatus aspect of the invention, an improved coupling is provided for a reciprocating pump which co-produces fluids 21 containing entrained solids. The pump has a cylindrical barrel within which a 22 cylindrical plunger is slidably movable, the plunger fitting closely within the barrel, 23 and a reciprocating string o-f rods for connection to the top of the plunger for 1 reciprocating the plunger within the pump barrel whereby fluid travels through a 2 bore through the plunger. The improved arrangement for coupling the plunger to 3 the string of rods comprises a coupling and a leading edge for the plunger.
The 4 coupling is connecteci at its lower end to the top of the plunger and at its upper end to the string of rods for reciprocating the plunger.
6 The coupling has 7 = a bore contiguous with the bore of the hollow plunger;
8 = a cylindrical wall forming an annulus between the coupling and 9 the barrel;
= a plurality of ports formed in the cylindrical wall of the coupling for 11 forniing fluid passages between the contiguous bore and the 12 annulus, the ports having lower edges; and 13 The leading edge for the plunger is formed by the connection of the 14 coupling and the plunger, the plunger's leading edge fitting closely within the barrel and positioned so that the lower edge of the ports is below the plunger's leading 16 edge, the result being that eritrained solids settling downwardly in the annulus are 17 directed radially inwardly frorn the leading edge and downwardly into the plunger 18 without accumulating adjacent the barrel.
19 Preferably, the leading edge of plunger is formed by the lower portion of the coupling which fits closely to the barrel, replacing the plunger's own top edge.
21 More preferably, the plunger's leading edge is formed by a non-22 metallic wiper, the leading edge of the wiper being above the lower edge of the 23 coupling's ports.
1 Even more preferably, the wiper leading edge of the plunger is backed 2 by a stack of seals fitted into a pressure-equalized annulus located below the wiper.
Figure 1 a is partial cross-sectional view of the top end of a prior art 6 reciprocating pump plunger;
7 Figure lb is an enlarged view of the prior art pump plunger and 8 coupling arrangement according to Fig 1 a;
9 Figure 2a is a partial cross-sectional view of the top end of an improved pump plunger according to the fourth embodiment of the invention;
11 Figure 2b is an enlarged view of the pump plunger of Fig. 2a;
12 Figure 3 is a partial perspective view of the coupling and plunger of 13 Fig. 2a. A portion of the punip barrel is cutaway to illustrate the coupling and fluid 14 flow;
Figures 4a - 4c illustrate views of the coupling and plunger 16 arrangements accorcling to the first through third embodiments of the invention.
17 More specifically, 18 Figure 4a is a partial cross-sectional view of a male coupling threaded 19 into a female top end of a plunger according to the first embodiment;
Figure 4b illustrates a partial cross-sectional view of male top end 21 plunger fitted with a three piece arrangement on the left section and a two piece 22 arrangement on the right section according to the second embodiment;
1 Figure 4c is a partial cross-sectional view of a male coupling threaded 2 into a pup connector integrating a wiper therein according to a third embodiment;
3 and 4 Figure 5)a and 5b are cross sectional views of the seal assembly of the fourth embodiment demonstrating plunger upstroke and downstroke actions 6 respectively, the action being illustrated separately in the left and right sections 7 about the centerline. Fig. 5a illustrates the seal assembly during the upstroke and 8 Fig. 5b illustrates the seal assembly during the downstroke.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
11 Turning now to the present invention, and having reference to Figs.
12 2a-4c, a rod-actuatecl pump is shown having a conventional cylindrical barrel 10. A
13 coupling 11 connects a string of rods 12 to a plunger 13 (the rod string 12 is shown 14 exploded from the coupling 11). The plunger 13 has a bore 14 for passing fluid 18.
The coupling 11 and plunger 13 reside in the bore 15 of the barrel 10. An annulus 16 16 is formed betweeri the upper end of the coupling 11 and the barrel 10.
The rod 17 string 12 reciprocates, causing the plunger 13 to reciprocate up and down, pumping 18 fluids 18 containing entrained solids 19 from the plunger's bore 14 and into the 19 annulus 16.
In several embodiments, the coupling 11 is shown having a male 21 threaded connection 21 at its lower end. The embodiments described below 22 illustrate a variety of means of connection, ranging from connecting directly to a 23 plunger, or to a pup connector provided intermediate the plunger and the coupling.
1 Providing a pup conriector or integrating the pup connector with the coupling itself 2 makes it easier to retrofit conventional American Petroleum Institute (API) spec 3 plungers to conform to the present invention.
4 In all embodiments, and having reference to Figs. 4a,4b illustrating the first, second and third embodiment and Figs. 2a,2b,3 and 4c illustrating the fourth 6 embodiment, the coupling 11 is a tubular body having a cylindrical wall 20 and a 7 bore 22 contiguous vvith the plunger's bore 14. A plurality of slot-like ports 23 are 8 formed in the cylindrical wall 20 for enabling the passage of fluid 18 from the 9 plunger's bore 14 in1;o the annulus 16. The ports 23 have top and lower edges 24,25, spaced sufficiently to provide sufficient flow area to pass the fluid 18 and 11 solids 19.
12 The arrangement of the lower edges 25 of the coupling's ports 23 and 13 the leading edge 26 of the plunger 13 cooperate to prevent the accumulation of 14 solids 19 adjacent thie damage-sensitive barrel 10. In the present invention, the lower edges 25 are Icicated below the plunger's leading edge 26.
16 It is unclerstood that normally the top of the plunger forms the leading 17 edge of the plunger. However, in some embodiments described herein, the 18 plunger's leading ecige 26 is provided or replaced by independent structure 19 positioned between the plunger 13 and the coupling's ports 23. As the leading edge of the plunger's purnping action is now replaced by other structure, this other 21 structure now forms a new plunger leading edge 26.
22 Accordiingly, during the downstroke of the plunger 13, the flow of fluid 23 18 and entrained solids 19 is upwardly from plunger's bore 14, sweeping through 1 the ports 23, upwardly past the plunger's leading edge 26 and outwardly into the 2 annulus 16. Thus, no dead space or gap can exist between the coupling 11 and the 3 plunger's leading edge 26, thereby avoiding trapping damaging solids 19 against 4 the barrel 10.
On the upstroke, the fluid 18 is substantially stationary at the top of the 6 plunger 13 and entrained solids 19 can settle. Therefore, according to the 7 arrangement taught by the present invention, during the plunger's upstroke, settling 8 solids 19 are guided inwardly by the plunger's leading edge 26 and away from the 9 barrel 10, through the ports 23 and downward into the plunger's bore 14.
Having reference to a first embodiment shown in Fig. 4a, the top of the 11 plunger has been modified to incorporate a female threaded connection 30.
The 12 male threaded connection 21 of the coupling 11 threads directly into the plunger 13.
13 The connection 21,30 is such that the lower edges 25 of the ports 23 are located 14 below the leading edge 26 of the plunger 13. The plunger's leading edge 26 acts as the seal between the plunger 13 and barrel 10.
16 Additiorial embodiments are possible, each of which varies the 17 configuration of leading edge 26 of the plunger to add additional functionality and 18 efficiency to the plunger but not to alter its location relative to the lower edge 25 of 19 the ports 23.
Referririg next to the second embodiment shown in Fig. 4b, the 21 plunger 13 is formeci with a male threaded connection at this top end per API
22 specifications.
1 On the left section of Fig. 4b, the coupling is connected to the plunger 2 using an intermediate a pup connector or pup 31. On the right section of Fig. 4b, 3 the pup is integrated into a uriitary coupling.
4 Simply, described in terms of an independent pup 31, the pup 31 obviates the need t.o modify off-the-shelf API plungers having male threaded 6 connections. The pup 31 acts as a union having opposing top and bottom female 7 threaded connections 32,33 for mating a male threaded connection 34 at the top of 8 the plunger 13 and the male threaded connection 21 of the coupling 11. The pup 9 31 has an upper end 35 and a upper edge 36 which slidably seals against the barrel 10. The pup 31 thereby forms part of the plunger 13.
= a plurality of ports formed in the cylindrical wall of the coupling for 11 forniing fluid passages between the contiguous bore and the 12 annulus, the ports having lower edges; and 13 The leading edge for the plunger is formed by the connection of the 14 coupling and the plunger, the plunger's leading edge fitting closely within the barrel and positioned so that the lower edge of the ports is below the plunger's leading 16 edge, the result being that eritrained solids settling downwardly in the annulus are 17 directed radially inwardly frorn the leading edge and downwardly into the plunger 18 without accumulating adjacent the barrel.
19 Preferably, the leading edge of plunger is formed by the lower portion of the coupling which fits closely to the barrel, replacing the plunger's own top edge.
21 More preferably, the plunger's leading edge is formed by a non-22 metallic wiper, the leading edge of the wiper being above the lower edge of the 23 coupling's ports.
1 Even more preferably, the wiper leading edge of the plunger is backed 2 by a stack of seals fitted into a pressure-equalized annulus located below the wiper.
Figure 1 a is partial cross-sectional view of the top end of a prior art 6 reciprocating pump plunger;
7 Figure lb is an enlarged view of the prior art pump plunger and 8 coupling arrangement according to Fig 1 a;
9 Figure 2a is a partial cross-sectional view of the top end of an improved pump plunger according to the fourth embodiment of the invention;
11 Figure 2b is an enlarged view of the pump plunger of Fig. 2a;
12 Figure 3 is a partial perspective view of the coupling and plunger of 13 Fig. 2a. A portion of the punip barrel is cutaway to illustrate the coupling and fluid 14 flow;
Figures 4a - 4c illustrate views of the coupling and plunger 16 arrangements accorcling to the first through third embodiments of the invention.
17 More specifically, 18 Figure 4a is a partial cross-sectional view of a male coupling threaded 19 into a female top end of a plunger according to the first embodiment;
Figure 4b illustrates a partial cross-sectional view of male top end 21 plunger fitted with a three piece arrangement on the left section and a two piece 22 arrangement on the right section according to the second embodiment;
1 Figure 4c is a partial cross-sectional view of a male coupling threaded 2 into a pup connector integrating a wiper therein according to a third embodiment;
3 and 4 Figure 5)a and 5b are cross sectional views of the seal assembly of the fourth embodiment demonstrating plunger upstroke and downstroke actions 6 respectively, the action being illustrated separately in the left and right sections 7 about the centerline. Fig. 5a illustrates the seal assembly during the upstroke and 8 Fig. 5b illustrates the seal assembly during the downstroke.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
11 Turning now to the present invention, and having reference to Figs.
12 2a-4c, a rod-actuatecl pump is shown having a conventional cylindrical barrel 10. A
13 coupling 11 connects a string of rods 12 to a plunger 13 (the rod string 12 is shown 14 exploded from the coupling 11). The plunger 13 has a bore 14 for passing fluid 18.
The coupling 11 and plunger 13 reside in the bore 15 of the barrel 10. An annulus 16 16 is formed betweeri the upper end of the coupling 11 and the barrel 10.
The rod 17 string 12 reciprocates, causing the plunger 13 to reciprocate up and down, pumping 18 fluids 18 containing entrained solids 19 from the plunger's bore 14 and into the 19 annulus 16.
In several embodiments, the coupling 11 is shown having a male 21 threaded connection 21 at its lower end. The embodiments described below 22 illustrate a variety of means of connection, ranging from connecting directly to a 23 plunger, or to a pup connector provided intermediate the plunger and the coupling.
1 Providing a pup conriector or integrating the pup connector with the coupling itself 2 makes it easier to retrofit conventional American Petroleum Institute (API) spec 3 plungers to conform to the present invention.
4 In all embodiments, and having reference to Figs. 4a,4b illustrating the first, second and third embodiment and Figs. 2a,2b,3 and 4c illustrating the fourth 6 embodiment, the coupling 11 is a tubular body having a cylindrical wall 20 and a 7 bore 22 contiguous vvith the plunger's bore 14. A plurality of slot-like ports 23 are 8 formed in the cylindrical wall 20 for enabling the passage of fluid 18 from the 9 plunger's bore 14 in1;o the annulus 16. The ports 23 have top and lower edges 24,25, spaced sufficiently to provide sufficient flow area to pass the fluid 18 and 11 solids 19.
12 The arrangement of the lower edges 25 of the coupling's ports 23 and 13 the leading edge 26 of the plunger 13 cooperate to prevent the accumulation of 14 solids 19 adjacent thie damage-sensitive barrel 10. In the present invention, the lower edges 25 are Icicated below the plunger's leading edge 26.
16 It is unclerstood that normally the top of the plunger forms the leading 17 edge of the plunger. However, in some embodiments described herein, the 18 plunger's leading ecige 26 is provided or replaced by independent structure 19 positioned between the plunger 13 and the coupling's ports 23. As the leading edge of the plunger's purnping action is now replaced by other structure, this other 21 structure now forms a new plunger leading edge 26.
22 Accordiingly, during the downstroke of the plunger 13, the flow of fluid 23 18 and entrained solids 19 is upwardly from plunger's bore 14, sweeping through 1 the ports 23, upwardly past the plunger's leading edge 26 and outwardly into the 2 annulus 16. Thus, no dead space or gap can exist between the coupling 11 and the 3 plunger's leading edge 26, thereby avoiding trapping damaging solids 19 against 4 the barrel 10.
On the upstroke, the fluid 18 is substantially stationary at the top of the 6 plunger 13 and entrained solids 19 can settle. Therefore, according to the 7 arrangement taught by the present invention, during the plunger's upstroke, settling 8 solids 19 are guided inwardly by the plunger's leading edge 26 and away from the 9 barrel 10, through the ports 23 and downward into the plunger's bore 14.
Having reference to a first embodiment shown in Fig. 4a, the top of the 11 plunger has been modified to incorporate a female threaded connection 30.
The 12 male threaded connection 21 of the coupling 11 threads directly into the plunger 13.
13 The connection 21,30 is such that the lower edges 25 of the ports 23 are located 14 below the leading edge 26 of the plunger 13. The plunger's leading edge 26 acts as the seal between the plunger 13 and barrel 10.
16 Additiorial embodiments are possible, each of which varies the 17 configuration of leading edge 26 of the plunger to add additional functionality and 18 efficiency to the plunger but not to alter its location relative to the lower edge 25 of 19 the ports 23.
Referririg next to the second embodiment shown in Fig. 4b, the 21 plunger 13 is formeci with a male threaded connection at this top end per API
22 specifications.
1 On the left section of Fig. 4b, the coupling is connected to the plunger 2 using an intermediate a pup connector or pup 31. On the right section of Fig. 4b, 3 the pup is integrated into a uriitary coupling.
4 Simply, described in terms of an independent pup 31, the pup 31 obviates the need t.o modify off-the-shelf API plungers having male threaded 6 connections. The pup 31 acts as a union having opposing top and bottom female 7 threaded connections 32,33 for mating a male threaded connection 34 at the top of 8 the plunger 13 and the male threaded connection 21 of the coupling 11. The pup 9 31 has an upper end 35 and a upper edge 36 which slidably seals against the barrel 10. The pup 31 thereby forms part of the plunger 13.
11 The leading edge 26 of the plunger 13 is now formed by the pup's 12 upper edge 36.
13 In the unitary arrangement of this embodiment, shown in the right 14 section of Fig. 4b, the couplirig now has a small diameter upper cylindrical wall 20a for forming the annullus 16. The lower cylindrical wall 20b, has a larger diameter 16 than the upper wall 20a and, like the pup 31, is fitted closely to the barrel 10.
17 Accordingly a shoulaler 37 is formed which becomes the leading edge 26 of the 18 plunger 13.
19 In the third embodiment shown in Fig. 4c, a non-metallic top wiper ring 40 is set into the second embodiment's plunger to form the plunger's leading edge 21 26 and provide a superior seal between the plunger 13 and the barrel 10.
22 In a fourth erribodiment shown in Figs. 2a, 2b, 5a and 5b, the 23 performance of the ttiird embodiment is enhanced further by the introduction of an 1 entire seal assembly 50 below the wiper ring 40. The wiper ring is now illustrated 2 as a composite of ari elastorneric leading edge component 41 glued into a shape-3 retaining metal cup 42 therebelow.
4 The seal assembly 50 is fitted to the upper end of the pup 31. The upper end 35 of the pup 31 forms a cylindrical sleeve portion 51 having an outer 6 diameter less than the inner diameter of the barrel 10, and forming a seal annulus 7 52 therebetween. The seal assembly 50 is fitted to the sleeve 51 within the seal 8 annulus 52. A lower retaining shoulder 48 is formed at the bottom of the seal 9 annulus 52 to support the seal assembly 50 during the upstroke.
The seal asserribly 50 is best shown in Figs. 5a,5b. As stated, Fig. 5a 11 illustrates a plunger upstroke (left section) and Fig. 5b the downstroke (right 12 section). The operation of the seal assembly 50 changes whether the plunger 13 is 13 moving up or down.
14 Seal assembly 50 comprises a plurality of seal rings 53 which are installed as stacks 54 on the sleeve 51. At the lower end of the coupling, an upper 16 retaining shoulder 49 is provided to engage and retain a complementary shoulder 17 55 on the wiper ring 40 which in turn retains the stack 54 on the sleeve 51. Each 18 individual seal ring :53 is a hydraulic seal such as those available as "Polypak"
19 (trademark) model #: 461525003250-375 from Parker Seal Group of Lexington, Kentucky, USA.
21 Each seal ring 53 has a leading face 56 which is oriented to maintain 22 a pressure differential in one direction. The leading face 56 of each seal ring 53 23 faces the surface (upwardly) and is effective to both lift fluid above the plunger and 1 draw a suction in the barrel 13 as the plunger strokes upwardly (Fig. 5a).
On the 2 plunger downstroke (Fig. 5b), seals of the stack 54 are less effective. The precise 3 action is described in more detail as follows.
4 The cross-section of each seal ring 53 is substantially rectangular with the leading face 56 being radially flared inwardly and outwardly. An inner radially-6 extending lip 57 of each seal ring alternately engages and disengages from 7 corresponding grooves 58 in the sleeve 51 on each downstroke and upstroke 8 respectively. Each seal ring 53 also has an outer radially-extending lip 59 for 9 engaging the barrel 10. Accordingly, there is an alternating increase and decrease in seal performance cluring the reciprocating plunger cycle.
11 On the downstroke, the stack 54 shifts upwardly on the sleeve 51 and 12 the inner lip 57 engages the grooves 38, the stack 54 being arrested from further 13 upward movement by bearing against the upper retaining shoulder 49. By engaging 14 each groove 58, preload of a seal's outer lip 59 on the barrel 10 is lessened, resulting in a lessening of the sealing action. On the fluid-lifting upstroke, the stack 16 54 shifts downwardly, the stack 54 being arrested from further downward movement 17 by bearing against the lower shoulder 48. The seal's inner lip 57 is compressed 18 radially outwardly as it is forced out of or disengages the groove 58, increasing the 19 preload of the outer lip 59 on the barrel and improving the sealing action.
The height of the stack 54 is less than free axial distance between the 21 upper and lower retaining shoulders 49,48, forming a gap 61 and permitting the 22 stack 54 its reciprocaiting movement.
1 Each sisal ring 53 is shown as incorporating an additional 0-ring 62 2 located midpoint of the ring's cross-section and along the leading edge 56.
The 3 additional radial area formed by the 0-ring cavity aids in hydraulically driving the lips 4 57,59 radially into stronger engagement with their respective sealing surfaces 51,10. Not all seal ring manufacturers utilize the additional 0-ring concept but most 6 provide the inward and outward lips 57,59. Aligned channels 70,71 are formed 7 through the coupling 11 and sleeve 51 respectively for equalizing pressure in the 8 seal annulus 52 and i:he plunger's bore 14.
17 Accordingly a shoulaler 37 is formed which becomes the leading edge 26 of the 18 plunger 13.
19 In the third embodiment shown in Fig. 4c, a non-metallic top wiper ring 40 is set into the second embodiment's plunger to form the plunger's leading edge 21 26 and provide a superior seal between the plunger 13 and the barrel 10.
22 In a fourth erribodiment shown in Figs. 2a, 2b, 5a and 5b, the 23 performance of the ttiird embodiment is enhanced further by the introduction of an 1 entire seal assembly 50 below the wiper ring 40. The wiper ring is now illustrated 2 as a composite of ari elastorneric leading edge component 41 glued into a shape-3 retaining metal cup 42 therebelow.
4 The seal assembly 50 is fitted to the upper end of the pup 31. The upper end 35 of the pup 31 forms a cylindrical sleeve portion 51 having an outer 6 diameter less than the inner diameter of the barrel 10, and forming a seal annulus 7 52 therebetween. The seal assembly 50 is fitted to the sleeve 51 within the seal 8 annulus 52. A lower retaining shoulder 48 is formed at the bottom of the seal 9 annulus 52 to support the seal assembly 50 during the upstroke.
The seal asserribly 50 is best shown in Figs. 5a,5b. As stated, Fig. 5a 11 illustrates a plunger upstroke (left section) and Fig. 5b the downstroke (right 12 section). The operation of the seal assembly 50 changes whether the plunger 13 is 13 moving up or down.
14 Seal assembly 50 comprises a plurality of seal rings 53 which are installed as stacks 54 on the sleeve 51. At the lower end of the coupling, an upper 16 retaining shoulder 49 is provided to engage and retain a complementary shoulder 17 55 on the wiper ring 40 which in turn retains the stack 54 on the sleeve 51. Each 18 individual seal ring :53 is a hydraulic seal such as those available as "Polypak"
19 (trademark) model #: 461525003250-375 from Parker Seal Group of Lexington, Kentucky, USA.
21 Each seal ring 53 has a leading face 56 which is oriented to maintain 22 a pressure differential in one direction. The leading face 56 of each seal ring 53 23 faces the surface (upwardly) and is effective to both lift fluid above the plunger and 1 draw a suction in the barrel 13 as the plunger strokes upwardly (Fig. 5a).
On the 2 plunger downstroke (Fig. 5b), seals of the stack 54 are less effective. The precise 3 action is described in more detail as follows.
4 The cross-section of each seal ring 53 is substantially rectangular with the leading face 56 being radially flared inwardly and outwardly. An inner radially-6 extending lip 57 of each seal ring alternately engages and disengages from 7 corresponding grooves 58 in the sleeve 51 on each downstroke and upstroke 8 respectively. Each seal ring 53 also has an outer radially-extending lip 59 for 9 engaging the barrel 10. Accordingly, there is an alternating increase and decrease in seal performance cluring the reciprocating plunger cycle.
11 On the downstroke, the stack 54 shifts upwardly on the sleeve 51 and 12 the inner lip 57 engages the grooves 38, the stack 54 being arrested from further 13 upward movement by bearing against the upper retaining shoulder 49. By engaging 14 each groove 58, preload of a seal's outer lip 59 on the barrel 10 is lessened, resulting in a lessening of the sealing action. On the fluid-lifting upstroke, the stack 16 54 shifts downwardly, the stack 54 being arrested from further downward movement 17 by bearing against the lower shoulder 48. The seal's inner lip 57 is compressed 18 radially outwardly as it is forced out of or disengages the groove 58, increasing the 19 preload of the outer lip 59 on the barrel and improving the sealing action.
The height of the stack 54 is less than free axial distance between the 21 upper and lower retaining shoulders 49,48, forming a gap 61 and permitting the 22 stack 54 its reciprocaiting movement.
1 Each sisal ring 53 is shown as incorporating an additional 0-ring 62 2 located midpoint of the ring's cross-section and along the leading edge 56.
The 3 additional radial area formed by the 0-ring cavity aids in hydraulically driving the lips 4 57,59 radially into stronger engagement with their respective sealing surfaces 51,10. Not all seal ring manufacturers utilize the additional 0-ring concept but most 6 provide the inward and outward lips 57,59. Aligned channels 70,71 are formed 7 through the coupling 11 and sleeve 51 respectively for equalizing pressure in the 8 seal annulus 52 and i:he plunger's bore 14.
Claims (8)
1. In a rod-actuated pump for co-producing fluids containing entrained solids, the pump having a cylindrical barrel within which a cylindrical plunger is slidably movable, the plunger fitting closely within the barrel, a reciprocating string of rods for connection to the top of the plunger for reciprocating the plunger within the pump barrel whereby fluid travels through a bore through the plunger, an improved arrangement for coupling the plunger to the string of rods comprising:
(a) a coupling connected at its lower end to the top of the plunger and at its upper end to the string of rods for reciprocating the plunger and having i) a bore contiguous with the bore of the hollow plunger;
ii) a cylindrical wall forming an annulus between the coupling and the barrel;
iii) a plurality of ports formed in the cylindrical wall of the coupling for forming fluid passages between the contiguous bore and the annulus, the ports having lower edges; and (b) a leading edge for the plunger being formed by the connection of the coupling and the plunger, the plunger's leading edge fitting closely within the barrel and positioned so that the lower edge of the ports is below the plunger's leading edge, the result being that entrained solids settling downwardly in the annulus are directed radially inwardly from the leading edge and downwardly into the plunger without accumulating adjacent the barrel.
(a) a coupling connected at its lower end to the top of the plunger and at its upper end to the string of rods for reciprocating the plunger and having i) a bore contiguous with the bore of the hollow plunger;
ii) a cylindrical wall forming an annulus between the coupling and the barrel;
iii) a plurality of ports formed in the cylindrical wall of the coupling for forming fluid passages between the contiguous bore and the annulus, the ports having lower edges; and (b) a leading edge for the plunger being formed by the connection of the coupling and the plunger, the plunger's leading edge fitting closely within the barrel and positioned so that the lower edge of the ports is below the plunger's leading edge, the result being that entrained solids settling downwardly in the annulus are directed radially inwardly from the leading edge and downwardly into the plunger without accumulating adjacent the barrel.
2. In a rod-actuated pump as recited in claim 1 wherein:
(a) the coupling has male threads formed on the cylindrical wall at its lower end below the lower edges of the ports; and (b) the top end of the plunger is formed with female threads for threaded connection with the coupling, the threaded connection being such that the lower edge of the ports resides lower than the top edge of the plunger so that the plunger's leading edge is formed by the top edge of the plunger.
(a) the coupling has male threads formed on the cylindrical wall at its lower end below the lower edges of the ports; and (b) the top end of the plunger is formed with female threads for threaded connection with the coupling, the threaded connection being such that the lower edge of the ports resides lower than the top edge of the plunger so that the plunger's leading edge is formed by the top edge of the plunger.
3. In a rod-actuated pump as recited in claim 1 wherein the coupling has male threads formed on the cylindrical wall at its lower end below the lower edges of the ports and further comprises a pup connector, the pup connector comprising:
(a) a cylindrical wall fitting closely within the barrel and having a top end;
(b) a bore contiguous with the bore of the hollow plunger and having upper and lower ends, the pup's bore at the upper end being threaded for connection to the coupling's lower end so that, when connected to the coupling;
(c) the lower edges of the coupling's ports reside lower than the top edge of the plunger so that the plunger's leading edge is formed by the top edge of the pup connector.
(a) a cylindrical wall fitting closely within the barrel and having a top end;
(b) a bore contiguous with the bore of the hollow plunger and having upper and lower ends, the pup's bore at the upper end being threaded for connection to the coupling's lower end so that, when connected to the coupling;
(c) the lower edges of the coupling's ports reside lower than the top edge of the plunger so that the plunger's leading edge is formed by the top edge of the pup connector.
4. In a rod-actuated pump as recited in claim 1 wherein the plunger has a standard American Petroleum Institute threaded male threaded connection at its top end, and the coupling has a complementary female threaded connection in the bore at its lower end, the improvement further comprising:
(a) the cylindrical wall at the upper end of the coupling forms an annulus between the coupling and the barrel;
(b) the cylindrical wall at the lower end of the coupling fits closely to the barrel for forming the plunger's leading edge; and (c) the lower edges of the plurality of ports formed in the coupling's cylindrical wall are positioned so that they are below the plunger's leading edge.
(a) the cylindrical wall at the upper end of the coupling forms an annulus between the coupling and the barrel;
(b) the cylindrical wall at the lower end of the coupling fits closely to the barrel for forming the plunger's leading edge; and (c) the lower edges of the plurality of ports formed in the coupling's cylindrical wall are positioned so that they are below the plunger's leading edge.
5. In a rod-actuated pump as recited in claim 1 further comprising a barrel wiper positioned at the plunger's leading edge and above the lower edges of the plurality of ports.
6. In a rod-actuated pump as recited in claim 5 further comprising (a) an annulus formed at the plunger's leading edge, below the wiper and between a cylindrical portion of the plunger's leading edge and the barrel;
(b) a seal residing in the annulus to seal the plunger against the barrel;
and (c) a pressure-equalization port formed between the annulus and the plunger's bore.
(b) a seal residing in the annulus to seal the plunger against the barrel;
and (c) a pressure-equalization port formed between the annulus and the plunger's bore.
7. In a rod-actuated pump as recited in claim 6 wherein the seal further comprises:
(a) one or more hydraulic seal rings, each ring having a leading edge oriented towards the plunger's leading edge and which is radially flared, said seal ring or seal rings being stacked axially ring-to-ring in the annulus;
(b) upper and lower axially spaced retaining shoulders located above and below the seal rings for retaining the seals therebetween; and (c) the seal rings occupying the annulus so that the flared leading edges are compressed between the cylindrical portion of the plunger's leading edge and the barrel.
(a) one or more hydraulic seal rings, each ring having a leading edge oriented towards the plunger's leading edge and which is radially flared, said seal ring or seal rings being stacked axially ring-to-ring in the annulus;
(b) upper and lower axially spaced retaining shoulders located above and below the seal rings for retaining the seals therebetween; and (c) the seal rings occupying the annulus so that the flared leading edges are compressed between the cylindrical portion of the plunger's leading edge and the barrel.
8. In a rod-actuated pump as recited in claim 6 wherein the seal further comprises:
(a) one or more circumferential and axially spaced grooves formed in the cylindrical portion of the plunger's leading edge within the annulus, the grooves causing a localized widening of the annulus, the number of grooves corresponding to the number of seal rings, the profile of the grooves being matched to the relaxed profile of the flared leading edge of the seal rings, the spacing of the grooves corresponding to the axial spacing of the seal rings in the stack of seals, the grooves being axially offset slightly towards the plunger's leading edge;
(b) the axial height of the stack of seal rings being less than the spacing between the spaced retaining shoulders so as to form a gap and enable the seal stack to move between first and second positions (i) in the first position, the stack of seals shifts downward in the annulus to bear against the lower shoulder; and (ii) in the second position, the stack of seals shifts upward in the annulus to bear against the upper shoulder so that at the first position the flared portion of the seal rings engage the narrow cylindrical portion of the annulus and form an effective seal, and conversely at the second position the flared portions of the seal rings engage their respective annularly wider grooves, lessening the sealing action of the seal rings.
(a) one or more circumferential and axially spaced grooves formed in the cylindrical portion of the plunger's leading edge within the annulus, the grooves causing a localized widening of the annulus, the number of grooves corresponding to the number of seal rings, the profile of the grooves being matched to the relaxed profile of the flared leading edge of the seal rings, the spacing of the grooves corresponding to the axial spacing of the seal rings in the stack of seals, the grooves being axially offset slightly towards the plunger's leading edge;
(b) the axial height of the stack of seal rings being less than the spacing between the spaced retaining shoulders so as to form a gap and enable the seal stack to move between first and second positions (i) in the first position, the stack of seals shifts downward in the annulus to bear against the lower shoulder; and (ii) in the second position, the stack of seals shifts upward in the annulus to bear against the upper shoulder so that at the first position the flared portion of the seal rings engage the narrow cylindrical portion of the annulus and form an effective seal, and conversely at the second position the flared portions of the seal rings engage their respective annularly wider grooves, lessening the sealing action of the seal rings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2284380 CA2284380C (en) | 1999-10-01 | 1999-10-01 | Top coupling arrangement for a reciprocating pump |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2284380 CA2284380C (en) | 1999-10-01 | 1999-10-01 | Top coupling arrangement for a reciprocating pump |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2284380A1 CA2284380A1 (en) | 2001-04-01 |
| CA2284380C true CA2284380C (en) | 2009-09-29 |
Family
ID=4164272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2284380 Expired - Fee Related CA2284380C (en) | 1999-10-01 | 1999-10-01 | Top coupling arrangement for a reciprocating pump |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2284380C (en) |
-
1999
- 1999-10-01 CA CA 2284380 patent/CA2284380C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2284380A1 (en) | 2001-04-01 |
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| MKLA | Lapsed |