CA1236007A - Sucker rod scraper method and device - Google Patents

Abstract

"SUCKER ROD SCRAPER METHOD AND DEVICE"

ABSTRACT OF THE DISCLOSURE

A plurality of sucker rod scrapers are securely attached in spaced apart relationship to a length of sucker rod for scraping paraffin deposits from the interior of a tubing string, thereby ob-viating obstruction to the flow of oil therethrough by maintaining a satisfactory effective flow area within the tubing string. The scrapers each have a spiraled scraping surface wound helically about the sucker rod and attached at each opposed end thereof by the provision of a clamping member which includes a U-band and a heat shield. The U-band has confronting marginal edge portions which overlap the edge portions of the heat shield. The heat shield has a slot formed centrally therein for receiving a tab located at either of the opposed ends of the spiraled scraper. The confront-ing edges of the U-band are welded to one of the marginal opposed ends of the scraper, while the heat shield prevents the metal of the sucker rod being elevated to a temperature which changes the characteristics thereof.

Description

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BACKGROUND OF THE INVENTION

Attachment of a spiraled paraffin scraper to a sucker rod is generally known in the art as evidenced by U.5. Patents tO
Troutman, 3,41Q,349; Polson 2,772,741; Triplehorn 2,733,768 and

2,928,473; Neumeyer 1,639,660; Winegar 2,979,133; and Crayel 2,453,199.
In Txoutman, the~scrapers are attached to the rod by a U-band having tabs placed through slots and bent back to mechani-1~ cally secure the ~craper and U-band ~o one another and to the rod.
In Polson the scraper and the U-band are directly welded to one another, with there being no provision for protec~ing th~ under-lying suxface of the ~ucker rod, and accordingly, the hardness`as well as the alloy composition might be changed as the temperature of the rod surface exceeds a certain known value.
Schellsted et al 3,499,210 tèaches a method of mounti~g a protector on a drill pipe. The protector i8 in the form of a split sleeve 20 having a ~lot 34 formed internally thereof within which a back-up strip 35 is received; and thereafter a bead 44 of ~0 welding then reattaches the confronting ends 31 of the sleeve 20 together. As the sleeve cools, it is heat ~hrunk about the drill pipe. "~ , .
Re~erence is made to these previously~issued patents for further background of the present invention, as well as to the ref-erences cited therein.
The present invention differs from the above cited art of record in that a sucker rod and paraffin scraper combination, sometime ref~rred to as a paraffin scraper and rod guide, is ar~
ranged in spaced xelationship along a string of sucker rod, in alternating relationship with respect to one another, so that ,:~r~

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adjacent scrapers may be provided with a right handed and left handed pitch spiral about the rod axis, thereby eliminating any tendency of the rods ~o unscr~w respective ~o oné another, and thereby providing a balanced rod string. More distinctly, each scraper assembly is provided with a spiral blade having opposed ends which ter~inate in projecting tabs. The tabs are formed 4y cut-outs. A U-band of limited longitudinal le~gth is bent about the rod surface with the confronting edges thereof being placed closely adjacent to one o the tabs located on the ~craper. A
heat shield underlies both the confronting edge portions of the U-band and further in~ludes a slo~-within which the tab o~ the scraper is received. The confronting ~nds of the U-band are welded to the scraper at a location adjacent to the tabs, while th~ heat shield isolates and prevents damage to the undexlying surface of the sucker rod.

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~5 ~Z:36~7 SUMMARY OF T~E INVENTION
This invention relates to a paraf~in scraper and xod guide which is securely mounte~ to a sucker rod ~y a novel clamp-ing member which enables the blade of the paraffin scraper to bs welded to the clamping member b~ a method set ~orth hereinbelow.
The paraffin scraper has a spiral blade concentrically dispose~
about the rod, with the clamping members located at each oppo~ed end of the~blade each having a U~band, the confronting ed~e~ of which are weldedly attached to one of the oppos~d.marginal ends lD of the blade, with there being a heat shield underlying the mar- :
ginal confronting edge portions of the U-band, ~o that whén the adjacent U band and blade ends are.welded together, the underlying rod surface is protected from the radiant and conve~tive heat re-sulting from the welding process.
Thè heat shield extends up to 90 about the circumferen-tially extending outer surface area of the rod, and preferably is provided with a slot within which there is received a tab asso-ciated with and forming an integral part of the bladeO The tab pre~erably is made by spaced cutouts arranged in a manner whi~h ~0 c~uses the tab to be perpendicularly aIigned r`espective to the longitudinal axis of the sucker rod.
The sucker rod scrapers preferabl~ are ~paced ~rom one another, with there being both right and lèft hand pi ~hed spiral~
located adjacent to one another, so tha~ alternate pitched ~pirals are disposed along the rod length, th~reby precluding axial xot~
tion of the rod lengths during the pumping action of the rod ~tring.
In carrying out the method of the present invention, the slotted heat shield i5 curved to conform to the curvature of the rod surface. The tab formed at each and of the scraper blade i~
positioned within the slot. The U-band i5 next bent about the rod `J

~3~ 7 surface with the marginal confronting ends thereof overlapping the marginal edge portions of the heat shield. A welding bead is then laid down or executed to thereby weld the confronting edge portions of the U-band to the opposed sides of the scraper, with the underlying heat shield preventing the rod surace fxom being elevated to a temperature level which changes the chara-cteristics of the rod surface. As the combination rod and par-affin scraper cools, the U-band contracts, thereby holding the scraper assembly with great friction to the rod surface.
The interconnected slot and tab provide a mechanical connection which enhances the structural integrity of the final rod and scraper combinatlon~ The heat shield provides a barrier which prevents the alloy of the rod from changing from i~s de-signed characteristics. The overall combination provides a clam~-ing member which rigidly affixes the blade to the rod surface in a new and unexpected manner.
Accordingly, a primary object of the present invention is the provision of an improved paraffin scraper and rod guide affixed to the outer surface of a sucker rod by high frictional ~0 force and in a manner which precludes damage to the underlying rod surface.
Another object of the invention is to provide an improved paraffln scraper rigidly clamped to a sucker rod by we~ding the component parts of the scraper device together without any resul tant damage to the rod surface.
A further object of the ~resent invention is the provi-sion of an improved paraffin scraper securely clamped to a sucker rod by an improved clamping member which is welded while positioned about the rod, but without changin~ the characteristics of the rod alloy.

~LZ36~7 A still further object of this invention is to provide a method of a~taching a paraffin scraper to a sucker rod which includes placing a heat shield~in underlying relationship respec-tive to a U-shaped clampin~ member and the free ~arginal ends of the scraper blade in a manner which pxecludes damage to the un derlying sucker rod.
Thèse and various other objects and advantages o the invention will become readily apparen~ to those skilled in the art upon reading the following detailed description and claàms and by referring to the accompanying drawings.
The above objects are attained in acco~dance with the present invention by the provision of a method for use with ap-paratus fabricated in a manner substantially as described in the above abstract and summary.

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~5 ~:36~7 BRIEF DESCRIPTION OF THE DRAWINGS
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Figure 1 is a broken! ~ide elevational.view of a sucker rod and scraper combination made in accordance with the present invention;
Fi~ure 2 is a fragmented view of a length of sucker rod having a paraffin scraper and rod guide mounted thereto in accox-dance with the present invention;
Figure 3 is a cross-sectional view taken along line 3-3 of Figure l;
- Figures 4, 5, and 6, respectively, are detailed views of t~e various components used in fabricating the paxaffin scraper and rod guide o Figures 1, 2, and 3, and, Figure 7 is a part diagrammatical, part ~chematical, part c~os5-sectional representation of a pxoce~s for building and attaching a sucker rod scraper to a sucker rod, in accordance with the present invention~

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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Figures l and 2 of th~ drawing disclos~ a sucker rod 10 of usual construction having a novel paraffin scraper and rod S guide 12, made in accordance with the present invention, attached thereto. A clamping member 14 is positioned at each opposed end of a blàde 16. The blade 16 therefore spirals about th~ rod sur-face from one to the other~clamping member. The marginal opposed ends of the blade are each attached to one of the illustr~ted clamping members in accordance with ~he method of thi~ invention, as will be more fully explained later on herein.
The inside diameter, or inside spiraled edge of-the blade, preferably lies adjacent to and contacts the outer periph-eral surface of the sucker rod. Each clamping member 14 includes the illustrated U-band 15. A heat shiel~ 18, the details of which will be more fully discussëd later on in this dis~losure, under-lies the marginal ends of the blade and the U-band.
As seen in Figures 2 and 3, together with other ~igures of the drawing, the U-band encompas5es the sucker rod an~ a medial length of the heat band, with a marginal terminal end of the heat shield`slightly extending from under the U-band. The heat shield has a width made complementary respective to the cuxvature of the sucker rod s~rface. The width of the heat shield pref~rably is not more than 90~ of circumferentially extending surface area of the rod. The U-band preferably has an inner peripheral surface having a curvature made complementary re~pective to the outer peripheral surface area of the ~ucker rod, at a location diamet-rically opposed to the heat shield. It will be not~d i~ Figure 3 that the U-band leaYes the rod surace and is brought into contact with the outer surface ~f the heat shield, thereby leaving the 11_ 36~:37 lustrated air spaces 19 which are formed between the rod surface, the inner surface of the U-band, and the opposed edge portions of the heat shield.
As seen in Figures 4, 5, and 6, togethe~ with other fig-ures of the drawing, the heat shield 18 has a slot 20 formed therein.As seen in Figures 2 and 3, welding 22 integrally attaches the ends of the U-band to one of the marginal ends of the blade. As seen in Figure 6, the blade is made from a discontinuou~ stamped wa~her having spaced cut-outs 24 and 2S, which leaves opposed tabs 28 at each marginal free end 30, 34 thereo~ The blade 16 of Figure 6 is bent into the illustrated spiral configura~ion seen in Figures 1, 2, and 3, which is concentrically arranged respective to the longitudinal axis of the sucker rod.
The method of the invention is carried out in accordance with Figures 4, 5, 6, and 7, wherein a flat piece of metal i~ bent into the illustrated U-band 15 having the illustrated opposed leg~
36 and 38. The hea~ shield 18 is apertured, then similarly bent, and thereafter positioned centrally between diametxi.cally position-ed movable dies 40 and 42. Means 44, preferably a lar~e hydraulic ~0 cylinder, is connected to move dies 40 and 42 towards o~e another, thereby bending legs 36 and 38 about the rod surface with great ~orce and causing the marginal ends of the }egs to overlap the marginal edges of the heat shield. The ends 36 and 38~of the U~and preferably are arranged ~lightly spaced from the opposed faces 32 at the marginai ends of the blade, thereby leaving approxim~tely 1/32 inch gap or accommodating the welding bead 22, thexeby assur-inq proper penetration of the bead.
The dies 40 and 42 hold the ends 36, 38 of th~ U-band against the heat shield with gr~at force while th~ bead 22 is formed along the elongated gap left between the ends 36, 38 of the U~band ` ~-r '~

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~ 3 and the faces 32 of the blade. After the weld 22 has been formed on either side of thP blade, thereby rigidly attaching the blade ;
and the end of the U-band together, the temperature of the U-band will be raised an average of 200-300 F., which is a significant amount so far as regards expansion and contraction of the metallic U-band, but which is far below the temperature required to effe~t any si~nificant change in the characteristics of the sucker rod ~lloy.
As noted in Figure 6, the tabs 28 located at the opposed marginal ends of the blade are locked into~the slot 20 of the heat shield. The tabs have an innermost edge portion whi~h lies against the outer surface of the sucker rod, thereby effectively "keeping"
or "locking" the heat shield to the blade and rod. Accordingly, no matter how much the scraper assembly is abused, the heat shield lS can never be loosened fxom the scraper assembly and fall downhole in the borehole.
Moreover, as noted in Figure 4, the heat shield is de-formed into a curve so that its innermost surface is made comple-mentary respective to the outermost surfaca of tht! sucker rod.
The U-band likewise is deformed about the outer surface of the sucker rod and has a curvature which is made complementary re~pac-tiv~ to the curvature of the rod for a circumferentially extending distance of ~pproximately 270 at a location on the rod which is opposed to the heat shield. As seen in Figure 3, the U-band curved inner surface leaves the sucker rod outer surface and joins to the heat shield outer surface, forming an air gap of progressive wid~h between the U-band and the sucker rod. Accordingly~ as the w~ld 22 is jointiy fo~med on the blade and the marginal ~erminal ends of the U-band, heat is radiated into the blade and into th~ U-bandc The heat shield isolates the hotest part o~ the U-band from the --10-- - , ~3~

outer surface of th~ sucker rod, with the U-band and blade each forming a heat sink so that the U-band is heated to approximately 200-300F. as a result of the welding process, while the blade is heated to an average which is much less than ~his value due to the difference in mass and the heat transfer cha~acteristics of the blade and the U-band. Of course~ the axea immediately adja~
cent to the weld 22 is instantaneously heated to several thousand degrees farenheit in order to effect a suitable joinder of ~he welding bead to both the U-band and the blade; however, the heat sink characteristics of the blade and U-band~ together with the novel air spaces and heat shield, prevent the rod sur~ace from ever r~aching a temperature elevation which can e~fect any signi~-icant change in the alloy composition of the sucker`rod.
The slot 20 can be formed through the heat shield, or alternatively, the slot can be left with a bottom, which provides a groove in contradistinction to a slot. In carrying out the meth-od of ~abricating the sucker rod scraper 12 of the present inven-tion, it is preferrad to deform the washer 32 into the spiral blade 16 seen in Figure l; and thereafter to utilize two sets of duel ~0 jaws ~0, 42 at apaced locations so that the U-bands can be simul-taneously deformed about the rod surface, and the welding 22 rapid-ly effected in~a sequential manner at the u~per and lower clamping members.
The pxesent invention provides a..method by which a scraper can rapidly be built in situ at spaced intervals along a sucker rod without injuring the characteristics of the rod alloy. The clamping members rigidly affix the opposed ends of the blade to the rod with great frictional forces. The method of the present invention pro-vides a means by which the scraper blade is rapidly and efficiently mounted to the sucker rod. The cost of the material, as well as ~:3~ 7 the labor, for fabricating the rod i~ nominal. The pxesent in-vention provides a clamping member a~ each end of a blade which will not loosen from the rod with use, and further provides ~
paraffin scraper and rod guide fabricated in a manner whereby none of the componen~ parts can hecome loosened and fall down-hole into the borehole.

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Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS: .
1. Claim 1. A method of making and attaching a spiral scraper assembly onto the exterior of a sucker rod comprising the steps of:
   (1) forming a blade into a spiral which is wound about the surface of the rod;
   (2) forming an inwardly directed tab at opposed mar-ginal ends of the blade;
   (3) placing a discontinuous band about the rod and at each marginal end of the spiral, and placing the confronting edges of the band closely adjacent to each of the tabs;
   (4) placing a heat shield under the confronting margin-al ends of the U-band; and, (5) welding the opposed ends of the blade to the margin-al ends of the U-bands.
2. Claim 2. The method of Claim 1 and further including the step of forming a slot centrally of the heat shield, placing the tab within the slot, and then carrying out step (5).
3. Claim 3. The method of Claim 2 and further including the step of forming the tab by spaced cut-outs placed at the mar-ginal ends of the blade to thereby leave said tab of a dimension to be received within the slot; and, resting the edge of the cut-out within the cavity formed by confronting edges of the band.
4. Claim 4. The method of Claim 2 and further including the step of holding the band against the rod surface during the welding step so that subsequent cooling shrinks the band into tight engagement with the rod.
5. Claim 5. The method of Claim 1 and further including the step of forming the tab by spaced cut-outs placed at the mar-ginal ends of the blade to thereby leave said tab of a dimension to be received within the slot; and, resting the edge of the cut-out within the cavity formed by confronting edges of the band.
6. Claim 6. The method of Claim 5 and further including the step of holding the band against the rod surface during the welding step so that subsequent cooling shrinks the band into tight engagement with the rod.
7. Claim 7. The method of Claim 1 and further including the steps of arranging adjacent scrapers into a right and left hand spiral.
   
   Claim 8. A sucker rod having a paraffin scraper and rod guide mounted to the surface thereof, the improvement com-prising:
   said-scraper and guide comprises spaced clamping mem-bers; a spiral blade having the marginal ends thereof ridigly affixed to said clamping members;
   said clamping members each include a U-band which em-braces the rod surface, with the confronting edges thereof having
8. Claim 8 continued:
   the marginal end of the blade received therebetween; a heat shield underlying the marginal confronting ends of the U-band and separating said marginal confronting ends from the rod sur-face;
   a bead of welding attaching the ends of the U-band to the marginal end of the blade;
   so that the heat shield protects the rod surface dur-ing the welding operation while the U-band is being attached to the end of the blade.
9. Claim 9. The improvement of Claim 8 wherein said heat shield includes a slot formed therein, each said opposed end of the blade includes a tab formed thereon which extends radially towards the axial centerline of the rod, said tab is received within said slot and separates the marginal ends of the U-band from the rod surface so that the rod surface is protected from undue heat during the welding of the U-band and blade.
10. Claim 10. The improvement of Claim 9 wherein the inner surface of said heat shield is placed against the outer surface of said rod, and the opposed edges of said heat shield describe an arc of less than 90°.
11. Claim 11. The improvement of Claim 10 wherein there are a plurality of scrapers on each rod, and adjacent scrapers are spiraled one to the right and the other to the left, said U band is separated from said rod surface for a limited circumferential length at the termination of the heat shield.
12. Claim 12. The improvement of Claim 8 wherein said heat shield includes a slot formed therein, each said opposed end of the blade includes a tab formed thereon which extends radially towards the longitudinal axis of the rod; said tab is received within said slot and separates the marginal ends of the U-band from the rod surface so that the rod surface is protected from undue heat during the welding of the U-hand and blade.
13. Claim 13. The improvement of Claim 12 wherein the in-ner surface of said heat shield is placed against the outer sur-face of said rod, and the opposed edges of said heat shield de-scribe an arc of less than 90°;
    wherein there are a plurality of scrapers on each rod, and adjacent scrapers are spiraled in opposite pitch, said U-band is separated from said rod surface for a limited circumferential.
    length where the heat shield terminates.
14. Claim 14. In a paraffin scraper located at spaced in-tervals along and concentrically of a sucker rod, the combination of said rod and scraper of an improved attachment means by which each end of said blade is rigidly affixed to the rod surface;
    said blade has radial tabs aligned perpendicularly re-spective to the rod axis; said attachment means includes an aper-tured heat shield and a U-band, wherein the U-band has adjacent edges rigidly weldedly joined to the marginal ends of the blade, with said heat shield underlying the blade and the U-band; said tab is received within the aperture of said heat shield;
    whereby the heat shield protects the rod surface from undue heat during the joining of the blade to the U-band, and ef-fects an interference fit between the attachment means and the rod.
15. Claim 15. The combination of Claim 14 wherein said apertured heat shield includes a slot formed therein, each said opposed end of the blade includes said tab thereon which extends radially towards the axial centerline of the rod, said tab is re-ceived within said slot and separates the marginal ends of the U-band from the rod surface so that the rod surface is protected from undue heat during the welding of the U-band and blade.