CA1200436A - Sucker rod coupling - Google Patents
Sucker rod couplingInfo
- Publication number
- CA1200436A CA1200436A CA000478526A CA478526A CA1200436A CA 1200436 A CA1200436 A CA 1200436A CA 000478526 A CA000478526 A CA 000478526A CA 478526 A CA478526 A CA 478526A CA 1200436 A CA1200436 A CA 1200436A
- Authority
- CA
- Canada
- Prior art keywords
- wheel
- slot
- pin
- coupling
- wheel member
- 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.)
- Expired
Links
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
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Earth Drilling (AREA)
Abstract
"SUCKER ROD COUPLING"
ABSTRACT OF THE DISCLOSURE
An improved sucker rod coupling is provided for use in a rod string in a pumping oil well. An elongate, cylindrical body member is utilized. This member has internally threaded, longitudinal bores at each end thereof, for connection with the sucker rods which it is to join.
Transversely extending, substantially diametric, longitudinally spaced apart, vertical slots are formed in the mid-portion of the body member.
A wheel is mounted on a horizontally extending pin within each slot, for rotation therein. A portion of the wheel protrudes beyond each side of the body member, to thereby provide an anti-friction roller for the coupling when it contacts and slides against the surrounding tubing wall during reciprocation of the rod string. Preferably the wheel is spaced from the side walls of the slot, so as to be movable laterally within the slot.
This arrangement permits the wheel to shift back and forth on its pin, to thereby expel sand and wax building up between the wheel and the slot walls.
Additionally, the wheel is preferably manufactured of a lubricious material, such as nylon, so as not to score the tubing, and is formed with a lenticular configuration. This configuration appears to have the benefit of assisting in expelling sand and wax from the wheel slot. The coupling is effective to provide a long-lasting, anti-friction, centralizing means, which means are self-cleaning and thus do not readily seize up by clogging with sand and wax in the oil.
ABSTRACT OF THE DISCLOSURE
An improved sucker rod coupling is provided for use in a rod string in a pumping oil well. An elongate, cylindrical body member is utilized. This member has internally threaded, longitudinal bores at each end thereof, for connection with the sucker rods which it is to join.
Transversely extending, substantially diametric, longitudinally spaced apart, vertical slots are formed in the mid-portion of the body member.
A wheel is mounted on a horizontally extending pin within each slot, for rotation therein. A portion of the wheel protrudes beyond each side of the body member, to thereby provide an anti-friction roller for the coupling when it contacts and slides against the surrounding tubing wall during reciprocation of the rod string. Preferably the wheel is spaced from the side walls of the slot, so as to be movable laterally within the slot.
This arrangement permits the wheel to shift back and forth on its pin, to thereby expel sand and wax building up between the wheel and the slot walls.
Additionally, the wheel is preferably manufactured of a lubricious material, such as nylon, so as not to score the tubing, and is formed with a lenticular configuration. This configuration appears to have the benefit of assisting in expelling sand and wax from the wheel slot. The coupling is effective to provide a long-lasting, anti-friction, centralizing means, which means are self-cleaning and thus do not readily seize up by clogging with sand and wax in the oil.
Description
1 A_K ROUND OF T~IE INVENTION
2 Oil is commonly produced from a subterrarlean Formation
3 through a string of tubing extendlng to -the sur-Face. The oil is commonly
4 lifted through the tubing by the action oF a downhole pump actuated by a sucker rod string which is reciprocated at surface by a pump jack.
6 A sucker rod string is made up of a multiplicity of 7 individual sucker rods threaded together end to end to form the string.
8 Each sucker rod comprises a main stem, typically having a length of about 9 30 feet and a diameter of 3/4 inches. ~t one end, the sucker rod has an enlarged coupling member having an externally threaded pin; at its outer 1l end, it has a second enlarged coupling member having an internally 12 threaded box. These coupling members -typically have a diameter of 1-7/8 3 inches. The tubing in which the rod string moves typically has an 4 inside diameter of 2-1/2 inches.
The use of sucker rod strings in directional or slanted 16 wellbores has been attended with problems. The steel rod string tends 7 to lie along the low side of the tubing string and, with time~ recipro-18 cation of the rod string tends to wear away the wall of the tubing 19 string.
This problem has been comprehendecl and grappled with in 21 the prior art. One concept which has been explored involved incorpora-22 ting centralizing anti-friction means into the rod string7 to space the 23 rods from the tubing and reduce wear of the tubing wall. Patents which 24 exemplify the prior art solutions based on this concept are: U.S.
2,198,720 (Edgecomb et al); U.S. 1,5087845 (Giles); U.S. 2,783,028 26 (Jamison), UOS. 2,601,478 (Weir); U.S. 1,541~791 (Christofferson); and 27 U.S. 1,507,972 (Loop).
28 The present invention gre~ out of a series of different 29 embodiments which ~ere built and tried.
~f~6~
l The First embodiment involved cut-ting a circumferential 2 slot in the surface of each rod string coupling. This slot was filled 3 with a wrapping of rawhide. The rawhtde had two desirable qualities:
4 it was slippery and, if it separated from the coupling and dropped down the tubing, it did not cause damage (as would be the case with steel 6 'junk'). However the rawhide would s~ell and restric-t clearance needed 7 for the movement of oil between the rod and tubing strings.
8 The next version tried involved using a split ring 9 plastic sleeve in place of the rawhide. eut these sleeves came off easily and dropped down the annulus between the strings and interfered with the ll proper operation of the rod string and downhole pump.
12 Consideration was then given to mounting small~ protruding 13 wheels in the coupling body. The concept considered was to cut slots 14 partway into the body, in the manner shown by Edgecomb, and mount the wheels on pin axles. However this approach was discarded for the 16 following reasons:
17 - the wheels and axles would be small in dimension, due 18 to space limitations, and thus would be liable to fail 19 and drop out of the slot;
- and, because these components would be made of steel, 21 such failure would result in steel junk dropping to the 22 base of the tubing string onto the pump, which is 23 undesirable.
24 Another problem~ which was making itself apparent during this design and testing stage, had to do with the nature of the produced 26 oil stream being dealt with. The couplings were being used in slanted, 27 shallow wells producing heavy oil conta1ning much sand. Parrafin wax 28 is commonly associated with such heavy oil. The combination of wax and 29 sand would readily clog up moving parts.
1 SUMMARY OF_rllE I_V ~lrI0~l 2 At this point in the evolution of the invention, it ~as 3 decided to form substantially diametrical slots which extended right -through 4 the coupling body. This meant tha-t larger wheels and pins could be used within the constraints of the space limitations involved. These larger 6 wheels and pins would be less likely to fail. In addition, the wheels 7 would project out each side of the coupling and contact the tubing wall.
8 If a pin failed, the wheel and pin would tend to remain in place within 9 the slot, because the wheel would be held there by the bracketing surfaces of the tubing wall. In addition, it was hoped that the slot, which was 11 open on both sides, would permit of ejection of collecting wax and sand, 12 thereby reducing likelihood of the wheel seizing up due to the slot 13 becoming clogged with the wax and sand.
14 When this version of the device was -tes-ted~ it was found that mechanical failure of the wheel and pin was not a significant 16 problem. However, seizing up of the wheel with wax and sand was not 17 eliminated - it typically occurred within a rnonth in the wells in which 18 the device was tested.
19 This initial "diametrical"-version had wheels which had close clearances (about .01") from the adjacent slot walls.
21 A coupling was then made and tried having diametrical 22 slots, but the wheels had a "sloppy fitl' ~ that is, there was provided 23 a clearance of about .1" between each side of the wheel and the 24 adjacent surface of the slot side wall, when the wheel was centrally positioned on the pin.
26 When tested, it was found that this "sloppy fit" version 27 gave much improved performance, with respect to seizure of the wheels.
28 Tests showed that the wheels were still rotating freely several months 29 after insertion in wells in which the initial diametrical couplings had been seized up in about a month.
1 It is believed that the use of an open-ended slot and 2 provision of the transverse movement capability of the wheel along the 3 pin axis combine to provide an assembly which in use is characterized 4 by the slot being cleared of the wax and sand that would otherwise clog it and seize up the wheel.
6 In accordance with the invention~ therefore, there is 7 provided an improved anti-friction sucker rod coupling for connecting a 8 pair of sucker rods and centralizing -them in a tubing string. The 9 coupling comprises: an elongate, rigid, substantially cylindrical body member, having means at each end of said body member for connection with 11 a sucker rod, said body further forming a plurality of transversely 12 extending, substantially diametric, generally vertical slots extending 13 there-through, said body further defining a plurality of pin bores, each 4 such pin bore extending transversely through the body member so as to intersect one of said slots substantially perpendicularly; a plurality 16 of wheel members, each such wheel member being positioned within one 17 of said slots to rotate in a generally vertical plane, each wheel member 18 having a portion thereof extending beyond the periphery of said body 19 member to engage the inner surface of the tubing string and centrali~e the coupling; and a plurality of pins, one mounted in each of said pin 21 bores and supporting a wheel member thereon, whereby the wheel member is 22 rotatable within said slots; each such wheel member having a clearance 23 between its side surface and the wall surface of the slot, when the wheel 24 member is centered on the pin, where~y the wheel member may shift slightly along the pin, to assist in ejecting sand and oil from the slot.
~Q~
2 Figure 1 is a side viéw of the coupling; and 3 Figure 2 is a side view showing a wheel pos;tioned 4 in a slot of the coupling.
DESCRIPTION OF'THE PREFE~ED EMBODIMENT
____ ___ _ __ 6 The anti-frictional, central'izing sucker rod coupling A
7 comprises a body member 1. This body menlber 1 is solid, rigid, elongate 8 and cylindrical. An internally threaded bore 2 extends longitudinally 9 into each of its endsg for connection with the threaded pin ends of the sucker rods 3 which it joins together.
11 A plurality of diametric and Yertically directed slots 4 12 extend transversely through the body member 1. As shown, the slots 4 are 13 spaced one above another around the circumference of the body member.
14 A plurality of horizontally directed pin bores 5 extend through the body member 1. Each such pin bore 5 intersects one of the 16 slots 4 perpendicularly.
17 A plurality of wheel members 6 are mounted on pins 7 in 18 the slots 4 and pin bores 5. More particularly, a wheel member 6, ha~ing 19 a diameter selected to just fit into the tubing which is to receive the rod string, is positioned longitudinally in each slot 4. A pin 7 21 extends through the bore 5 and the wheel member 6. The pin 7 is press 22 fit in the body member'l. The wheel member 6 is thus adapted to rotate 23 within a vertical plane and projects beyond the periphery of the body 24 member, whereby it is functional to engage the inner surface of the tubing string (not shown) and centralize the coupling.
26 Since the wheel member 6 substantially corresponds in 27 diameter with the inside diameter of the tubing string, the tubing wall 28 will retain said wheel member in the s'lot, should the pin break. Thus~
29 the danger of junk falling to the base of the well bore is reduced.
l As shown in Figure 2~ the thickness of the wheel member 6 2 is less than the width of the slot 4.; Thus there is a clearance between 3 each side surface 8 of the wheel member 6 and the adjacent wall surface 9 4 of the slot 4, when the whee1 member is centered on the pin, as shown.
Typically, for a wheel member having a d1ameter and maximum thickness of 6 2.36" and .45" respectively, I provide a slot having a length and width 7 of 2.75" and .550" r~spectively. The slot remains constant in dimension, 8 although the diameter of the wheel will vary with differing tubing sizes.
9 As previously stated, the provision of clearance as aforesaid permits the wheel member 6 to shuttle back and forth a short ll distance within the confines of the slot walls - this movement assists 12 in clearing wax and sand out of the slot~
3 In a preferred design, I provide wheel members 6 having a 4 lenticular configuration, as illustrated in Figure 2. It is my belief that this design is particularly conducive to the ejection of wax and 16 sand from the slot.
17 The wheel members 6 are formed of a hard, non-abrasive 18 material, to minimize the possibility of scoring the tubing wall. I
19 have found hard nylon to be suitable for most applications.
In summary, the wheel members function as an anti-21 frictional centralizing means, to minimize wear of the tubing by the 22 rod string reciprocating therein. The provision of wheel members having 23 approximately the same diameter as the tubing safeguards against the 24 possibility of broken parts dropping down the hole. In combination, the slot, the lenticular configuration of the wheel member, and the 26 lateral movement of the wheel member in the slot function to prevent 27 wax and sand build up in the slot.
6 A sucker rod string is made up of a multiplicity of 7 individual sucker rods threaded together end to end to form the string.
8 Each sucker rod comprises a main stem, typically having a length of about 9 30 feet and a diameter of 3/4 inches. ~t one end, the sucker rod has an enlarged coupling member having an externally threaded pin; at its outer 1l end, it has a second enlarged coupling member having an internally 12 threaded box. These coupling members -typically have a diameter of 1-7/8 3 inches. The tubing in which the rod string moves typically has an 4 inside diameter of 2-1/2 inches.
The use of sucker rod strings in directional or slanted 16 wellbores has been attended with problems. The steel rod string tends 7 to lie along the low side of the tubing string and, with time~ recipro-18 cation of the rod string tends to wear away the wall of the tubing 19 string.
This problem has been comprehendecl and grappled with in 21 the prior art. One concept which has been explored involved incorpora-22 ting centralizing anti-friction means into the rod string7 to space the 23 rods from the tubing and reduce wear of the tubing wall. Patents which 24 exemplify the prior art solutions based on this concept are: U.S.
2,198,720 (Edgecomb et al); U.S. 1,5087845 (Giles); U.S. 2,783,028 26 (Jamison), UOS. 2,601,478 (Weir); U.S. 1,541~791 (Christofferson); and 27 U.S. 1,507,972 (Loop).
28 The present invention gre~ out of a series of different 29 embodiments which ~ere built and tried.
~f~6~
l The First embodiment involved cut-ting a circumferential 2 slot in the surface of each rod string coupling. This slot was filled 3 with a wrapping of rawhide. The rawhtde had two desirable qualities:
4 it was slippery and, if it separated from the coupling and dropped down the tubing, it did not cause damage (as would be the case with steel 6 'junk'). However the rawhide would s~ell and restric-t clearance needed 7 for the movement of oil between the rod and tubing strings.
8 The next version tried involved using a split ring 9 plastic sleeve in place of the rawhide. eut these sleeves came off easily and dropped down the annulus between the strings and interfered with the ll proper operation of the rod string and downhole pump.
12 Consideration was then given to mounting small~ protruding 13 wheels in the coupling body. The concept considered was to cut slots 14 partway into the body, in the manner shown by Edgecomb, and mount the wheels on pin axles. However this approach was discarded for the 16 following reasons:
17 - the wheels and axles would be small in dimension, due 18 to space limitations, and thus would be liable to fail 19 and drop out of the slot;
- and, because these components would be made of steel, 21 such failure would result in steel junk dropping to the 22 base of the tubing string onto the pump, which is 23 undesirable.
24 Another problem~ which was making itself apparent during this design and testing stage, had to do with the nature of the produced 26 oil stream being dealt with. The couplings were being used in slanted, 27 shallow wells producing heavy oil conta1ning much sand. Parrafin wax 28 is commonly associated with such heavy oil. The combination of wax and 29 sand would readily clog up moving parts.
1 SUMMARY OF_rllE I_V ~lrI0~l 2 At this point in the evolution of the invention, it ~as 3 decided to form substantially diametrical slots which extended right -through 4 the coupling body. This meant tha-t larger wheels and pins could be used within the constraints of the space limitations involved. These larger 6 wheels and pins would be less likely to fail. In addition, the wheels 7 would project out each side of the coupling and contact the tubing wall.
8 If a pin failed, the wheel and pin would tend to remain in place within 9 the slot, because the wheel would be held there by the bracketing surfaces of the tubing wall. In addition, it was hoped that the slot, which was 11 open on both sides, would permit of ejection of collecting wax and sand, 12 thereby reducing likelihood of the wheel seizing up due to the slot 13 becoming clogged with the wax and sand.
14 When this version of the device was -tes-ted~ it was found that mechanical failure of the wheel and pin was not a significant 16 problem. However, seizing up of the wheel with wax and sand was not 17 eliminated - it typically occurred within a rnonth in the wells in which 18 the device was tested.
19 This initial "diametrical"-version had wheels which had close clearances (about .01") from the adjacent slot walls.
21 A coupling was then made and tried having diametrical 22 slots, but the wheels had a "sloppy fitl' ~ that is, there was provided 23 a clearance of about .1" between each side of the wheel and the 24 adjacent surface of the slot side wall, when the wheel was centrally positioned on the pin.
26 When tested, it was found that this "sloppy fit" version 27 gave much improved performance, with respect to seizure of the wheels.
28 Tests showed that the wheels were still rotating freely several months 29 after insertion in wells in which the initial diametrical couplings had been seized up in about a month.
1 It is believed that the use of an open-ended slot and 2 provision of the transverse movement capability of the wheel along the 3 pin axis combine to provide an assembly which in use is characterized 4 by the slot being cleared of the wax and sand that would otherwise clog it and seize up the wheel.
6 In accordance with the invention~ therefore, there is 7 provided an improved anti-friction sucker rod coupling for connecting a 8 pair of sucker rods and centralizing -them in a tubing string. The 9 coupling comprises: an elongate, rigid, substantially cylindrical body member, having means at each end of said body member for connection with 11 a sucker rod, said body further forming a plurality of transversely 12 extending, substantially diametric, generally vertical slots extending 13 there-through, said body further defining a plurality of pin bores, each 4 such pin bore extending transversely through the body member so as to intersect one of said slots substantially perpendicularly; a plurality 16 of wheel members, each such wheel member being positioned within one 17 of said slots to rotate in a generally vertical plane, each wheel member 18 having a portion thereof extending beyond the periphery of said body 19 member to engage the inner surface of the tubing string and centrali~e the coupling; and a plurality of pins, one mounted in each of said pin 21 bores and supporting a wheel member thereon, whereby the wheel member is 22 rotatable within said slots; each such wheel member having a clearance 23 between its side surface and the wall surface of the slot, when the wheel 24 member is centered on the pin, where~y the wheel member may shift slightly along the pin, to assist in ejecting sand and oil from the slot.
~Q~
2 Figure 1 is a side viéw of the coupling; and 3 Figure 2 is a side view showing a wheel pos;tioned 4 in a slot of the coupling.
DESCRIPTION OF'THE PREFE~ED EMBODIMENT
____ ___ _ __ 6 The anti-frictional, central'izing sucker rod coupling A
7 comprises a body member 1. This body menlber 1 is solid, rigid, elongate 8 and cylindrical. An internally threaded bore 2 extends longitudinally 9 into each of its endsg for connection with the threaded pin ends of the sucker rods 3 which it joins together.
11 A plurality of diametric and Yertically directed slots 4 12 extend transversely through the body member 1. As shown, the slots 4 are 13 spaced one above another around the circumference of the body member.
14 A plurality of horizontally directed pin bores 5 extend through the body member 1. Each such pin bore 5 intersects one of the 16 slots 4 perpendicularly.
17 A plurality of wheel members 6 are mounted on pins 7 in 18 the slots 4 and pin bores 5. More particularly, a wheel member 6, ha~ing 19 a diameter selected to just fit into the tubing which is to receive the rod string, is positioned longitudinally in each slot 4. A pin 7 21 extends through the bore 5 and the wheel member 6. The pin 7 is press 22 fit in the body member'l. The wheel member 6 is thus adapted to rotate 23 within a vertical plane and projects beyond the periphery of the body 24 member, whereby it is functional to engage the inner surface of the tubing string (not shown) and centralize the coupling.
26 Since the wheel member 6 substantially corresponds in 27 diameter with the inside diameter of the tubing string, the tubing wall 28 will retain said wheel member in the s'lot, should the pin break. Thus~
29 the danger of junk falling to the base of the well bore is reduced.
l As shown in Figure 2~ the thickness of the wheel member 6 2 is less than the width of the slot 4.; Thus there is a clearance between 3 each side surface 8 of the wheel member 6 and the adjacent wall surface 9 4 of the slot 4, when the whee1 member is centered on the pin, as shown.
Typically, for a wheel member having a d1ameter and maximum thickness of 6 2.36" and .45" respectively, I provide a slot having a length and width 7 of 2.75" and .550" r~spectively. The slot remains constant in dimension, 8 although the diameter of the wheel will vary with differing tubing sizes.
9 As previously stated, the provision of clearance as aforesaid permits the wheel member 6 to shuttle back and forth a short ll distance within the confines of the slot walls - this movement assists 12 in clearing wax and sand out of the slot~
3 In a preferred design, I provide wheel members 6 having a 4 lenticular configuration, as illustrated in Figure 2. It is my belief that this design is particularly conducive to the ejection of wax and 16 sand from the slot.
17 The wheel members 6 are formed of a hard, non-abrasive 18 material, to minimize the possibility of scoring the tubing wall. I
19 have found hard nylon to be suitable for most applications.
In summary, the wheel members function as an anti-21 frictional centralizing means, to minimize wear of the tubing by the 22 rod string reciprocating therein. The provision of wheel members having 23 approximately the same diameter as the tubing safeguards against the 24 possibility of broken parts dropping down the hole. In combination, the slot, the lenticular configuration of the wheel member, and the 26 lateral movement of the wheel member in the slot function to prevent 27 wax and sand build up in the slot.
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An anti-friction sucker rod coupling for connecting a pair of sucker rods and centralizing them in a tubing string, comprising:
an elongate, rigid, substantially cylindrical body member, having means at each end of said body member for connection with a sucker rod, said body further forming a plurality of transversely extending, substantially diametric, generally vertical slots extending therethrough, said body further defining a plurality of pin bores, each such pin bore extending transversely through the body member so as to intersect one of said slots substantially perpendicularly;
a plurality of wheel members, each such wheel member being positioned within one of said slots to rotate in a generally vertical plane, each wheel member having a portion thereof extending beyond the periphery of said body member to engage the inner surface of the tubing string and centralize the coupling;
and a plurality of pins, one mounted in each of said pin bores and supporting a wheel member thereon, whereby the wheel member is rotatable within said slot;
each such wheel member having a clearance between its side surface and the wall surface of the slot, when the wheel member is centered on the pin, whereby the wheel member may shift slightly along the pin, to assist in ejecting sand and oil from the slot.
an elongate, rigid, substantially cylindrical body member, having means at each end of said body member for connection with a sucker rod, said body further forming a plurality of transversely extending, substantially diametric, generally vertical slots extending therethrough, said body further defining a plurality of pin bores, each such pin bore extending transversely through the body member so as to intersect one of said slots substantially perpendicularly;
a plurality of wheel members, each such wheel member being positioned within one of said slots to rotate in a generally vertical plane, each wheel member having a portion thereof extending beyond the periphery of said body member to engage the inner surface of the tubing string and centralize the coupling;
and a plurality of pins, one mounted in each of said pin bores and supporting a wheel member thereon, whereby the wheel member is rotatable within said slot;
each such wheel member having a clearance between its side surface and the wall surface of the slot, when the wheel member is centered on the pin, whereby the wheel member may shift slightly along the pin, to assist in ejecting sand and oil from the slot.
2. An anti-friction sucker rod coupling as set forth in claim 1 wherein said wheel member has a substantially lenticular configuration, to thereby increase the open slot area in the proximity of the wheel periphery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000478526A CA1200436A (en) | 1985-04-04 | 1985-04-04 | Sucker rod coupling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000478526A CA1200436A (en) | 1985-04-04 | 1985-04-04 | Sucker rod coupling |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1200436A true CA1200436A (en) | 1986-02-11 |
Family
ID=4130205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000478526A Expired CA1200436A (en) | 1985-04-04 | 1985-04-04 | Sucker rod coupling |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1200436A (en) |
-
1985
- 1985-04-04 CA CA000478526A patent/CA1200436A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |