US2574550A - Polished rod insulation - Google Patents

Description

Nov. 13, 1951 w. H. EDWARDS 2,

POLISHED ROD INSULATION Filed Nov. 10, 1949 Patented Nov. 13, 1951 POIiISHED ROD INSULATION William H. Edwards, Houston, Tex., assignor to The Texas Company, New York, N.- Y., a corporation of Delaware Application November 10, 1949, Serial N0. 126,498

Claims. (Cl. 103--205) The present invention-relates to the pumping of-wells, and more specifically is concerned with overcoming the electrolytic corrosion ofsubsurface equipment used in a pumping welLfor voir,*not shown, at apoint below the surface of 'the 'ground, which is represented by the reference numeral l2.

' A'polished or sucker rod 14 extends vertically the production of petroleum, which results from 6 axially down the well casing it connecting at its the flow of electrical surface energy through the lowerextremity with the piston of well pump, :sucker'or polished rod. not shown, which is disposed within the petro- The invention particularly contemplates the leum reservoir. disposition -of compact electrical insulating Thesucker rod 14 is continually reciprocated means between the =polished'rod and its source in an axial direction by any driving and transof actuation at the polished rod cross. More spemission mechanism, as for example, a pumping cifically, aninsulatingsleeve or bushing-is disjack not shown comprising a pivoted lever-or posed between-the polished rod of the pumping walking beam oscillated by a driving motor about assembly and-the hangeror polished rod cross, its fulcrum or pivot point in'a vertical plane .andan insulating collar or washer is caused to and suspending from its extremity, a pair of separate the upper surface of the hanger from driving cables or rods 16. Both cables [3, as the-polished rod clamp. 'As a result, a compact shown in Figure l, are connected as at IT with a and. relatively permanent mechanical connecpolished rod cross, yoke or hanger 18, which actionjoins the polished rod to its driving instrucordingly is continually lifted and lowered mentalities, and simultaneously prevents the flow through the desiredreciprocating path. vof electricity down the polished rod. Mechanical connection between the polished A particular feature of this arrangement rerod is and the polished rod cross I8 is eifected sides in the elimination of cumbersome insulatbypassing the extremity of the polished rod cening couplings by electrical insulating members trally through an aperture or cylindrical paswhich remain essentially a fixed relationship if) sageway in the red cross or hanger 8, and atwith respect to the parts which they electrically taching a hanger clamp 2| thereabove. The separate. As a result of the absence of relative hanger clamp 2| shown in the drawing is promovement, frictional wear as well-as tensile vided with set screws 22 for rigid attachment stressing of the insulating-members is essentially to the rod M although any other equivalent faseliminated. Therefore, continuous and permateni-ng-or-locking means for interconnecting the nent insulation of the polished or sucker rod is clamp and the rod 14 against relative movement continuously realized without the deterioration are obviouslycontemplated. which would be expected under the high me- -In accordance with the present invention, it'is chanical stresses and loads usually encountered to be particularly'noted that the cylindrical pasin pumping assembliesof this character. sageway 20 is of substantially greater diameter Obviously-there is a complete suppression of than therod 14 in order to accommodate an inelectrolytic corrosion, due to electrical surface terposed electrical insulating sleeve, tube or colcurrents passing through the sucker rod, curlar 23 which therefore embraces the rod 14 and rents which otherwise reach substantial maglines the bore or aperture 20. r The sleeve 23 exnitude and are highly destructive of the sucker 40 tends completely'throughthe aperture and prefrods, pump, casing, tubing and the like. erably' a short distance therebeyond, as at 24, In order to describe the invention in greater to positively prevent electrical contact between detail, reference is had to the attached drawing the d' a 't e h e wherein: As is particularly shown in Figure 2, an insu- Figure 1 is 9, ertical elevation, partially in lating disc, 0011341, 01 washer 25 extends radially section, showing one embodiment thereof as apoutwardly from the upper portion of'the sleeve plied to a um ing et 1eu 311 23,-occupying the space between the lower sur- Figure 2 is a sectional detail view taken 'verface of the clamping cOHar 2| d the upper tically and centrally through the embodiment of face of the'polished rod cross l8. In the embodi- Figure l in the region where the sucker rod m t w Sleeve 23 an Wa er 26 are passes through the hanger; and threadedly interen a ed as at 27.

Figure 3 is a sectional detail view taken on a y, e insulating he 2 ext nds the lines 3-3 of Figure 2, radially outwardly beyond the margins of the In Figure 1, the numeral l0 represents a well collar to positively assure interruption of all eleccasing leading to a petroleum producing resertrical current flow between the parts but also to provide a substantial and adequate contact surface for transmitting the mechanical stresses encountered in actuation of the sucker rod l4.

Preferably, also, additional washers 28 and 29, formed of some material of good structural properties such as steel, iron or the like, are disposed respectively above and below the insulating washer to distribute these stresses uniformly through the insulating washer.

As above intimated, the interconnection between the tubular sleeve 23 and the insulating washer 26 may take any conventional form. For example, these parts may be joined by any desired fastenings or may be molded as an integral unit as a sleeve having a radial flange projecting from its upper extremity.

On the other hand, direct mechanical connection of these parts is not necessary where other provision is made to permanently hold the sleeve 23 in the position shown between the polished rod M and the hanger l8. For example, the sleeve may be held in position by clamps, setscrews or the like joining it to either the hanger or the rod, or may be fastened by any suitable means to either or both of the washers 28 and. 29.

As a result, however, of the arrangement of the tubular insulating member 23 in cooperation with the insulating flange 26, it .is obvious that the polished rod remains electrically separate from its driving means so that the usual current of relatively strong, solid, electrical insulating material. However, it will be apparent from what has been said before that the substantial stresses normally encountered in pumping petroleum wells dictate the use of materials having substantial resistance to compressive stress and impact.

To this end, therefore, it is preferred to employ some relatively rigid insualting material of high compressive strength, such as, for example, the following; polystyrene resins; vinyl acetate; pressed fiber; rubber; and the phenol-formaldehyde resins, for instance, Bakelite, or the linen base molded product Micarta. In general, plastics of substantial compressive strength and electrical insulating properties are suitable.

It is important to note that this structure adds subsantially nothing to the bulk of the assembly by way of eliminating the electrolytic destruction of subsurface equipment attributable to sucker rod conductors. In other words, this result is realized in a simple manner which obviates the use of undesired, cumbersome insulating couplings which would impair the vital strength and permanence of the assembly.

Obviously, many other modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. In a well pumping apparatus in which a well pump is actuated by a string of polished rods suspended in the well from a vertically reciprocating driving mechanism at the surface, said mechanism including a cross member and means for suspending the cross member from said mechanism, the polished rod extending vertically through an aperture in said cross member and having a clamp afiixed to the rod above the cross member, the improvement which comprises means for electrically insulating said polished rod from said cross member comprising a sleeve embracingthe polished rod and disposed within the said aperture of the cross member, and a projecting collar extended radially outwardly from the upper extremity of the sleeve and separating the upper surface of said cross member from said polished rod, said sleeve and collar being formed of electrically insulating material.

2. The combination called for in claim 1 wherein said insulating sleeve is attached to said insulating collar, thereby continuously locating the sleeve within the aperture in said polished rod cross member.

3. Means for electrically insulating the polished rod from a positively reciprocated polished rod cross member of a petroleum pumping well, wherein said polished rod extends vertically and axially of a petroleum well casing from a subsurface reservoir to the surface of said well, said polished rod passing through an opening in said polished rod cross member in the vicinity of its upper extremity and being provided above said aperture with a rigidly attached polished rod clamp projecting over the upper surface of the cross member to thereby suspend the polished rod, said insulating means comprising a cylindrical sleeve having an internal and an external diameter permitting said sleeve to fit coaxially about the polished rod and within the said aperture in said polished rod cross member, and an annular collar interengageable with the upper extremity of said sleeve and extending radially outwardly therefrom a substantial distance to lie 1 between said polished rod clamp and the upper surface of said cross member, said sleeve and collar being formed of electrically insulating material.

4; The apparatus according to claim 3 wherein the upper extremity of said sleeve is provided with a screw thread on its outer surface and wherein said collar is provided with a mating thread, permitting the sleeve and collar to be threadedly interengaged against relative axial movement.

5. The apparatus according to claim 3, having in combination therewith a pair of rigid metallic washers having annular faces substantially coextensive with the annular surfaces of said collar and adapted to oppositely engage said faces to distribute compressive stress through the collar.

WILLIAM H. EDWARDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,038,527 Eaton Apr. 28, 1936 2,230,029 Eaton Jan. 28, 1941 2,237,303 Calhoun Apr. 8, 1941

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