Sucker rod coupling tool and method

A sucker rod coupling tool and method for either breaking or tightening the threaded joint between a sucker rod and the coupling that joins the sucker rod to the next sucker rod. A base plate has a backup wrench mounted to one end and a friction wrench actuated by a hydraulic piston pivotally affixed to the base plate at the other end. An inversion loop is affixed to the base plate and rotatably suspended below a control platform to accommodate inversion of the base plate along with the backup wrench and the friction wrench. The control platform also supports the control levers and can be raised and lowered to allow the backup wrench to engage the sucker rod.

BACKGROUND 
1. Field of the Invention 
This invention relates to rod coupling tools and, more particularly, to a 
hydraulic tool apparatus for breaking and/or tightening the couplings in a 
sucker rod string. 
2. The Prior Art 
A producing oil well includes a number of systems for pumping the oil from 
the bottom of the oil well to the surface. The oil well itself is defined 
by a steel casing extending from the surface through the production zone. 
The purpose of the casing is to protect the integrity of the hole bored 
into the earth and to provide the basic unit of the production string. The 
production string consists of a production tubing, a tubing anchor, a 
seating nipple, a rod pump, and a sucker rod string. The production tubing 
is secured to the casing by the tubing anchor while the rod pump is set in 
the seating nipple and actuated by the sucker rod string to pump oil 
upwardly through the production tubing. 
The sucker rod string is interconnected between the walking beam of a pump 
jack located at the wellhead and the rod pump at the bottom of the oil 
well. The sucker rod string is moved in a reciprocatory manner to actuate 
the rod pump. Various devices are used on the production string to assure 
the proper tensile forces are imposed on the production tubing to minimize 
undue stresses and wear on the sucker rod string during this reciprocatory 
motion. Further, a rod rotator is mounted to the walking beam to impart a 
rotational force on the sucker rod string each time the sucker rod string 
is moved downwardly. This rotational force is directed to the right so as 
to apply a continuous tightening effect on the couplings between the 
individual sucker rods in the sucker rod string. 
Each sucker rod is about 25 feet long and is configured with a 
male-threaded, pin end at each end and is coupled to the next sucker rod 
by a rod coupling. The rod coupling is fabricated as a cylindrical length 
of hardened steel about 3 to 4 inches long with a female thread coaxially 
located in each end. The foregoing rotational force imposed on the sucker 
rod string is designed to impose a continual tightening force on the 
threaded joints between each sucker rod and its respective coupling. 
Periodically, it becomes necessary to remove the sucker rod string from the 
oil well for servicing. A workover rig is brought to the well head and 
serves as the support structure to accommodate removal and servicing of 
the sucker rod string and the associated elements in the production 
string. The sucker rod string is pulled from the production string one 
sucker rod at a time. As each rod coupling is brought to the surface, one 
of the joints between the rod coupling and the sucker rod at each end of 
the rod coupling is uncoupled using the rod tongs of the workover rig. The 
rod tongs are designed to engage the respective ends of the sucker rod at 
each end of the rod coupling and cause one or the other sucker rod to 
become uncoupled from the rod coupling. At this point the rod coupling 
must than be removed from the other sucker rod in order to allow it to be 
replaced with a new rod coupling. As each rod coupling is replaced, it is 
reassembled to the same sucker rods to assure that each sucker rod is 
returned to its original position in the sucker rod string. Three lengths 
of the reassembled sucker rod are then stacked sequentially in the rod 
basket of the workover rig and held there until reassembled and lowered 
into the production tubing in the exact sequence as they were originally. 
Each length of three sucker rods is referred to in the industry as a pull 
and each pull may have an interconnecting rod coupling on either the 
bottom or top of the pull, depending on how that particular joint broke 
when uncoupled using the rod tongs. 
The foregoing sequence of uncoupling the sucker rods from the rod coupling 
using the rod tongs and then a friction wrench to remove the rod coupling 
from the remaining sucker rod would appear to be a fairly routine 
procedure. However, the foregoing rotational forces imposed on the sucker 
rod string during the pumping action create a very tight engagement 
between the coupling and the respective sucker rods. Further, since the 
rod tongs will inherently have uncoupled the easier of the two joints 
between the respective sucker rods and the rod coupling, one on each end 
of the rod coupling, it necessarily means that the most difficult of the 
two joints must now be uncoupled by hand using the foregoing friction 
wrench. 
Each end of the sucker rod is provided with a wrench engagement surface 
configured with a square external profile that is easily and securely held 
by the rod tongs or a dimensionally configured wrench. The rod coupling, 
on the other hand, is a cylindrical surface so that it requires a special 
friction wrench that grips the coupling more tightly as more force is 
applied to the wrench. In practice, it is customary for the oil field 
workers to slip a length of pipe (called a "cheater pipe") over the handle 
of the friction wrench in order to increase the leverage on the friction 
wrench. Generally, two or even three workers will grasp the cheater pipe 
in order to impose sufficient force to break the threaded joint between 
the sucker rod and the coupling. Not only does this procedure require 
extra time, but it frequently results in injury to the workers if the 
friction wrench slips or the threaded joint breaks unexpectedly. 
In view of the foregoing, it would be an advancement in the art to provide 
a rod coupling tool for easily and safely opening as well as tightening 
the threaded joint between a coupling and a sucker rod. It would also be 
an advancement in the art to provide a hydraulic rod coupling tool wherein 
all the forces imposed on the threaded joint are applied using a hydraulic 
system. Another advancement in the art would be to provide a hydraulic rod 
coupling tool that can be readily inverted to adapt the rod coupling tool 
to a change in the orientation between the rod coupling and the sucker 
rod. It would also be an advancement in the art to provide a rod coupling 
tool for tightening the threaded joint between a rod coupling and a sucker 
rod. Such a novel apparatus and method is disclosed and claimed herein. 
BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
The present invention is a novel, hydraulic system for either breaking or 
tightening the threaded joint between a rod coupling and a sucker rod. A 
backup wrench for releasably engaging the square profile on the shank of 
the sucker rod is mounted to a base plate and serves to securely affix the 
sucker rod against rotation. A friction wrench is releasably engaged to 
the rod coupling and is actuated by a wrench hydraulic piston mounted at 
one end to the base plate at a position spaced from the backup wrench. The 
base plate with the backup wrench, the wrench hydraulic piston, and the 
friction wrench can be readily inverted to accommodate other rod 
coupling/sucker rod orientations. The entire assembly can be raised and 
lowered by an elevational hydraulic piston. The hydraulic controls are 
mounted to the base of the elevational hydraulic piston where they are 
readily accessible and are not affected by inversion of the base plate and 
its associated equipment. 
It is, therefore, a primary object of this invention to provide 
improvements in rod coupling apparatus. 
Another object of this invention is to provide improvements in the method 
of either breaking or tightening the threaded joint between a rod coupling 
and a sucker rod. 
Another object of this invention is to provide a hydraulic system for 
either breaking or tightening the threaded joint between a rod coupling 
and a sucker rod. 
Another object of this invention is to provide a hydraulic system for 
either breaking or tightening the threaded joint between a rod coupling 
and a sucker rod wherein the entire actuator assembly can be inverted in 
order to accommodate a reversed orientation between the rod coupling and 
the sucker rod. 
Another object of this invention is to provide a hydraulic system for 
either breaking or tightening the threaded joint between a rod coupling 
and a sucker rod wherein the entire assembly is suspended from an 
elevational system. 
Another object of this invention is to provide a hydraulic piston for 
raising and lowering the hydraulic mechanism. 
These and other objects and features of the present invention will become 
more readily apparent from the following description in which preferred 
and other embodiments of the invention have been set forth in conjunction 
with the accompanying drawing and appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention is best understood by reference to the drawing wherein like 
parts are designated by like numerals throughout in conjunction with the 
following description. 
GENERAL DISCUSSION 
This invention is a portable, hydraulically powered tool for use in either 
breaking or tightening the threaded joint between a rod coupling and a 
sucker rod. The hydraulic power is supplied from any suitable source such 
as a conventional hydraulic pump powered by an internal combustion engine. 
The tool is configured to be suspended from the overhead derrick structure 
of the workover rig with the suspension point being an upper end of an 
elevational hydraulic piston. This elevational hydraulic piston enables 
the operator to easily adjust the operating height of the tool. 
The tool itself includes two basic components, a control platform and a 
base plate to which the various operative elements of the tool are 
attached, These operative elements include a backup wrench, a guide, and a 
hydraulically powered friction wrench. The guide controls the lateral 
movement of the friction wrench and supports the same when the base plate 
is inverted. The base plate is suspended below the control platform by a 
rollover bar engaged to a roller under the control platform. The rollover 
bar is configured with a triple lobe configuration to allow the base plate 
to be selectively inverted to reverse the relative orientation of the 
backup wrench and the friction wrench with respect to the sucker rod and 
the rod coupling. An intermediate lobe orients the base plate in the 
vertical plane to enable the tool to be used on a sucker rod and rod 
coupling combination oriented horizontally. 
The ability to easily invert the tool is important since it is uncertain 
whether the rod coupling will break from the upper sucker rod or the lower 
sucker rod when the each joint is broken by the rod tongs. Advantageously, 
the rod coupling tool can also be used during reassembly of the sucker rod 
string to assure that each of the reset joints between the pulls in the 
sucker rod string are suitably tightened prior to the sucker rod string 
being lowered into the production string. 
DETAILED DESCRIPTION 
Referring now to FIG. 1, the novel rod coupling tool of this invention is 
shown generally at 10 and in the environment of a fragmentary portion of a 
conventional sucker rod string shown generally at 20. Sucker rod string 20 
includes an upper or first sucker rod 22 and a lower or second sucker rod 
24 with a rod coupling 26 interposed between first sucker rod 22 and 
second sucker rod 24. Second sucker rod 24 is shown uncoupled from rod 
coupling 26 to reveal pin 27 which is threaded with male threads 
configured to threadedly engage corresponding female threads (not shown) 
formed coaxially in the abutting end of rod coupling 26. Each of first and 
second sucker rods 22 and 24 include a wrench shank 23 and 25, 
respectively, for engagement of the respective sucker rod by the 
conventional rod tongs (not shown) as well as by a backup wrench 50 as 
will be discussed more fully hereinafter. 
Wrench shanks 23 and 25 are each configured with a square profile for 
secure engagement with backup wrench 50. Rod coupling 26 is fabricated 
from a specially hardened steel and provided with a cylindrical profile 
since rod coupling 26 is designed to act as the wear surface rather than 
sucker rod string 20 during its aforedescribed reciprocatory action in the 
event problems are encountered downhole causing sucker rod string 20 to 
abrade the production string (not shown). 
Rod coupling tool 10 consists of two basic components, control platform 12 
and base plate 14. Control platform 12 is mounted on the lower end of an 
elevational hydraulic piston 16. Base plate 14 is suspended below control 
platform 12 by a rollover bar 18 engaged in a roller 30. Roller 30 is 
mounted on the bottom of control platform 12 and acts as a single point 
suspension for rollover bar 18 and base plate 14 to which rollover bar 18 
is mounted. 
With further reference to FIGS. 3 and 4, two of the three possible 
orientations of rollover bar 18 and base plate 14 are shown in these 
fragmentary, cross-sectional end views. Rollover bar 18 is configured with 
three lobes 18a-18c any one of which can be received in roller 30 to 
achieve the desired orientation of base plate 14. FIG. 3 shows base plate 
14 in the orientation shown in FIGS. 1 and 2 with lobe 18a engaged in 
roller 30 whereas FIG. 4 shows base plate 14 in its inverted orientation 
with lobe 18c engaged in roller 30. Engagement of lobe 18b in roller 30 
suspends base plate 14 in a vertical orientation (not shown). Importantly, 
regardless of whether base plate 14 is suspended from any of lobes 
18a-18c, the functioning of rod coupling tool 10 remains the same. The 
particular orientation of baseplate 14 is determined by the particular 
configuration encountered in the sucker rod/rod coupling sequence 
encountered in sucker rod string 10. For example, as shown in FIG. 1, 
sucker rod string 20 is shown having the threaded joint break between 
lower sucker rod 24 and rod coupling 26. In the event rod coupling 26 is 
retained on the upper end of lower sucker rod 24 with the break being made 
between rod coupling 26 and upper sucker rod 22, base plate 14 will be 
inverted from the configurations shown in FIGS. 1-3 to that illustrated 
schematically at FIG. 4. Even though base plate 14 is inverted, all of the 
operative elements to be discussed more fully hereinafter operate in the 
same manner regardless of the particular orientation of base plate 14. 
Referring again to FIGS. 1 and 2, base plate 14 has a wrench hydraulic 
cylinder 32 pivotally mounted thereto at pivot 34. A bracket 36 aligns 
wrench hydraulic cylinder 32 in a plane parallel to the plane of base 
plate 14 while permitting a limited degree of lateral movement while 
working with rod coupling tool 10. Bracket 36 is particularly designed to 
hold wrench hydraulic cylinder 32 in place when base plate 14 is inverted 
as described hereinbefore. A wrench piston 38 operates telescopically in 
wrench hydraulic cylinder 32 and terminates in a pivotal coupling 39. A 
hollow, tubular wench receiver 40 is pivotally mounted at one end to 
pivotal coupling 39 and serves as a receiver for the handle of a friction 
wrench 42. A pin 41 releasably engages the end of the handle of friction 
wrench 42 inside wrench receiver 40. Pin 41 is removable to allow friction 
wrench 42 to be rotated to face the other direction when changing friction 
wrench 42 from an uncoupling mode to a coupling mode. Friction wrench 42 
is a commercially available friction wrench and includes a grasping 
channel 43 therein for frictionally engaging rod coupling 26. 
A guide assembly 44 is mounted to base plate 14 and includes a basal guide 
plate 46 with raised end plates 47a and 47b at each end. A retaining rod 
48 is removably mounted between end plates 47a and 47b in spaced 
relationship to basal guide plate 46. Retaining rod 48 holds wrench 
receiver 40 in a plane parallel to the plane of base plate 14 when base 
plate 14 is inverted as discussed hereinbefore. A first handle 49 extends 
outwardly from the end of guide assembly 44 and serves as one handle for 
the manipulation of rod coupling tool 10. The location of first handle 49 
at the end of guide assembly 44 provides the operator (not shown) with 
sufficient leverage to adequately manipulate rod coupling tool 10. A 
second handle 13 cooperates with first handle 49 to accommodate 
manipulation of rod coupling tool 10. 
Referring now also to FIG. 5, backup wrench 50 is releasably engaged to the 
end of base plate 14 by being slidingly received in an anchor bracket 52 
mounted to one face of base plate 14 and held therein by a pin 54. Backup 
wrench 50 is configured with a fixed slot or jaw 56 cut in one side. The 
dimensions of jaw 56 are designed to receive wrench shanks 23 or 25 of 
sucker rod string 20. Backup wrench 50 is configured to be removed and 
either replaced or serviced when jaw 56 becomes worn as a result of usage 
particularly in light of the harsh usage to which it will be subjected 
during operation of rod coupling tool 10. 
It should be noted at this point that backup wrench 50 and base plate 14 
are shown in FIG. 5 as inverted from the their position shown in FIGS. 1 
and 2. This position is the position achieved when rollover bar 18 is 
rotated to the position shown in FIG. 4 with lobe 18c engaged in roller 
30. Accordingly, the orientation of backup wrench 50 shown in FIG. 5 is 
the orientation for backup wrench 50 if it were to be used to engage shank 
23 with friction wrench 42 being used to engage rod coupling 26. 
Control platform 12, as the name implies, serves as the platform for the 
hydraulic controls of rod coupling tool 10, that is, elevation control 60 
and wrench control 62. Elevation control 60 controls the extension and 
retraction of a piston 17 operable in vertical cylinder 16. A hanger 15 on 
the end of piston 17 is used to suspend rod coupling tool 10 from an 
overhead hook of the workover rig (not shown). 
Retracting and extending piston 17 raises and lowers, respectively, rod 
coupling tool 10. For example, pulling elevation control 60 allows 
pressurized hydraulic fluid to pass through a hydraulic line 64 into 
vertical cylinder 16 causing piston 17 to extend therefrom and thereby 
lowering rod coupling tool 10. Pushing elevation control 60 causes 
hydraulic fluid to pass through a hydraulic line 65 causing piston 17 to 
retract thereby raising rod coupling tool 10. 
Correspondingly, pushing wrench control 62 sends hydraulic fluid through a 
hydraulic line 66 causing piston 38 to extend from cylinder 32. Pulling 
wrench control 62 sends hydraulic fluid through a hydraulic line 67 
causing piston 38 to retract within cylinder 32. This linear movement of 
piston 38 creates a lever action against both wrench receiver 40 and 
friction wrench 42 engaged thereby. With shank 25 engaged by backup wrench 
50, friction wrench 42 can be used to securely grasp rod coupling 26 to 
either break or tighten the threaded joint between these two elements. For 
example, assuming that threads 27 are securely engaged in corresponding 
threads (not shown) in rod coupling 26, shank 25 is engaged in backup 
wrench 50 while grasping channel 43 of friction wrench 42 is securely 
engaged about rod coupling 26. Wrench control 62 is then pushed to cause 
piston 38 to extend creating a powerful, yet controlled, torque between 
rod coupling 26 and threads 27. The joint is thereby safely and easily 
broken to permit rod coupling 26 to be unscrewed from sucker rod 24. 
Tightening of this joint is accomplished by screwing rod coupling 26 
against threads 27 and then engaging friction wrench 42 to rod coupling 26 
while piston 38 is extended. Pulling wrench control 62 retracts piston 38 
creating leverage through wrench receiver 40 and friction wench 42 to 
securely tighten the joint between rod coupling 26 and sucker rod 24. 
The single point suspension of rod coupling tool 10 on hanger 15 allows it 
to be easily pivoted incrementally in order to bring backup wrench 50 into 
engagement with either of wrench shanks 23 or 25, depending upon the 
particular orientation of rod coupling tool 10. Further, this free 
swinging capability of rod coupling tool 10 allows it also to be easily 
swung outwardly away from sucker rod string 20 while sucker rod string 20 
is being raised and lowered as described hereinbefore. 
The present invention may be embodied in other specific forms without 
departing from its spirit or essential characteristics. The described 
embodiments are to be considered in all respects only as illustrative and 
not restrictive. The scope of the invention is, therefore, indicated by 
the appended claims rather than by the foregoing description. All changes 
which come within the meaning and range of equivalency of the claims are 
to be embraced within their scope.