US3171889A

US3171889A - Electric cable clamp and protector

Info

Publication number: US3171889A
Application number: US160082A
Authority: US
Inventors: Patrick B Mccarthy
Original assignee: Individual
Current assignee: J STANSBURY
Priority date: 1961-12-18
Filing date: 1961-12-18
Publication date: 1965-03-02
Anticipated expiration: 1982-03-02

Description

March 1965 P. B. MCCARTHY 3,171,889

ELECTRIC CABLE CLAMP AND PROTECTOR Filed Dec. 18, 1961 INVENTOR.

Pare/cg B McC en/r firramvey.

United States Patent ELECTRIC CABLE CLAMP AND PROTEXITGR Patrick E. McCarthy, Van Nuys, Qalih, assignor, by

direct and mesne assignments, of forty percent to Burton J. Stansbnry, Newport Beach, twenty percent to Paul F. Loveridge, Santa Ana, and twenty percent to Ernest T. Saftig, Bakersfield, Calif., and twenty percent to Peggy Lee Mcarthy Filed Dec. 18, 1961, Ser. No. 166L082 8 Claims. (Cl. 174-136) The present invention relates to subsurface apparatus for oil, water, sulphur, and similar well bores, and more particularly to electric cable apparatus adapted to be secured to tubular strings disposed in the well bores and to conduct current to electrically operated equipment associated with the tubular strings, such as electric heaters and electric motor driven pumps.

Insulated electric cables have been clamped on the exterior of tubing strings disposed in well bores to conduct current to apparatus associated with the tubing strings. Tightening of the clamps on the tubing string oftentimes causes excessive compression of the cable and its internal short circuiting. Such short circuiting is also caused by the clamps imposing sharp bends on the cable at the couplings securing tubing sections together, resulting in embedding of the coupling ends or shoulders in the cable insulation. The undesirable embedding action is enhanced by reliance on the ends or shoulders of the couplings to support the weight of the cable. In addition to the hazard of causing short circuiting, prior clamp arrangments employed centralizers mounted on the tubing string to protect the cable by preventing the tubing strings from forcing the cable against the casing during running of the tubing string and cable in the latter. Otherwise, dam age to the cable could occur. Even after the apparatus has been installed in the casing, breathing of the tubing string, resulting from operation of a reciprocating pump therein, can cause the cable to be rubbed against the easing in the absence of a centralizer.

An object of the present invention is to provide apparatus for properly clamping electric cable to a tubing string to be disposed in a Well bore, without imposing excessive compressive forces on the cable, and without bending the cable around the end shoulders of the couplings securing tubing sections together.

Another object of the invention is to provide an apparatus for clamping electric cables to a tubing string to be disposed in casing in a well bore, which protects the cables in the region of the tubing couplings or collars and prevents contact of the cable with the casing, both in the regions of the couplings and between the couplings themselves. Thus, the apparatus serves the purposes of clamping the cable to the tubing string and protecting it against damage, without the necessity for mounting centralizers on the tubing strings.

A further object of the invention is to provide an apparatus for clamping an electric cable to a tubing string to be disposed in casing within a well bore, in which any tendency for the apparatus to be shifted longitudinally of the tubing string results in its automatically tightening on the tubing string to prevent such shifting.

An additional object of the invention is to provide an electric cable clamp and protector which can be installed rapidly and securely on the tubing string along which the cable is arranged, which is of strong and sturdy construction, well able to withstand relatively large forces encountered in the casing, as when running the tubing string and cable combination in the well casing, and, accordingly, possessing a long and useful life.

This invention possesses many other advantages, and has other objects which may be made more clearly ap- 'ice parent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a side elevational view of an apparatus embodying the invention disposed in a well casing;

FIG. 2 is an enlarged cross-section taken along the line 2-2 on FIG. 1;

FIG. 3 is an enlarged longitudinal section taken along the line 3-3 on FIG. 2;

FIG. 4 is a cross-section taken along the line 4-4 on FIG. 3.

As disclosed in the drawings, a tubing string A is disposed in a well casing B within a well bore. This tubing string may be associated with a reciprocating pump (not shown) operated by a string of sucker rods (not shown) adapted to be moved in the tubing string for the purpose of elevating well production in the latter to the top of the hole. If it is desirable to elevate the temperature of the well production for the purpose of reducing its viscosity and facilitating its flow into the well bore, an electric heater (not shown) may be suitably secured to the tubing string at a desired point, current to the electric heater being supplied through a cable 10 having appropriate insulation 11 therearound, which cable is clamped to the exterior of the tubing string A by means of a clamp device 12., there being a clamp device located at suitable intervals, such as at each coupling 13, along the length of the entire string of tubing. The electric cable may have any desired number of

conductors

14, 15 therein. As shown by way of example, two conductive lines 14 are embedded in the cable for supplying current to the electric heater, or other device disposed in the well bore; Whereas, two other conductors 15 are illustrated, which may be part of a thermally responsive system for controlling the supply of current to the electric heater in order to maintain the temperature of the production in the well bore within predetermined temperature limits.

The tubing string A illustrated in the drawings is internally flush and is composed of sections of a suitable length, the upper and lower ends of which are externally upset. Thus, an upper joint or section of tubing 16 will have a lower threaded pin 17 threadedly connected within a coupling or collar 13. The lower portion of the coupling or collar 13 is threadedly secured to an upper threaded pin 18 of a lower tubing section 19. Thus, each joint or section of tubing will have upper and lower threaded

pins

18, 17 threadedly secured to companion coupling members 13. Disposed between each threaded

17, 18 and the main pipe body 20 of each tubing joint is an externally

tapered portion

21 or 22, the taper extending from the threaded

17, 18 to the main body 20. Thus, the tapered portion 21 at the lower end of each tubing joint or section will converge in an upward direction; whereas the tapered portion 22 at the upper end of each joint or section of tubing will converge in a downward direction.

The electric cable 10 extends from the top of the well bore down along the tubing string A to the electric device to which it is supplying current. It is preferably clamped in a protective manner to the tubing string at each coupling or collar 13. As shown, each clamp and protector device 12 includes an elongate protector strip 25 extending from an upper tubing section 16 at the upper end of its tapered portion 21, along such tapered portion, the coupling 13, and the lower 3 tapered portion 22, just beyond the end of the latter. The protector strip is substantially semicylindrical in cross-section and has a relatively heavy wall thickness so as to resist deformation. The radius of curvature of its inner wall 26- conforms substantially to the external radius of the electric cable 11; itself, so that the outer portion of the cable is received within the protector strip, the opposed, inner portion of the electric cable bearing against the periphery of the collar 13 substantially along its entire length and also bearing against the cylindrical pipe body portion 20 of the upper tubing joint 16 and also the cylindrical pipe body portion 26) of the lower tubing joint 19.

The protector strip 25 includes a central portion 27 parallel to the axis of the tubing string and extending along the entire length of the coupling 13. This central portion merges into an upper inclined, intermediate or interconnecting portion 28 above the upper end or shoulder 29 of the coupling, and also into a lower inclined, interconnecting or intermediate portion 3% below the lower end or shoulder 31 of the coupling or collar. The upper intermediate portion 28 is inclined in an upward and inward. direction along the tapered portion 21 of the upper tubing joint or section 16, being integral with an upper end portion'or terminal 32 located immediately above the upper end of the tapered portion 21, and which is substantially parallel to the axis of the tubing string A. The lower inclined, interconnecting portion 3% is inclined in a downward and inward direction, lying along the lower tapered portion 22 of the lower tubing, section 19 and merging and being integral with a lower end portion 33 adjacent to the lower end of the lower tapered portion 22, and which is substantially parallel to the axis of the tubing string A.

The longitudinal protector strip 25 is radially disposed relative to the tubing string, with its convex portion facing outwardly toward the wall of the casing B. It is clamped to the tubing string A to force the electric cable 16' against the periphery of the tubing string joints or sections 16, 19 and the coupling 13. A clamp strap 35 is spot welded or otherwise secured to each of the upper and

lower end portions

32, 33 of the protector strip. Each clamp strap extends around an

end portion

32 or 33 of the protector strip 25 and around the tubing joint 16 or 19' immediately adjacent to its

tapered portion

21 or 22, the clamp strap 35 being suitably tightened against the joint of tubing 16 or 19 and also against the

end portion

32 or 33 of the protector strip, forcing the protector strip inwardly and compressing the insulation 11 of the cable partially against the periphery of the tubing joint to effect the flattened condition 36. The extent of inward compression is limited by the engagement of opposed inwardly extending fingers 37 integral with each

end portion

32, 33 with the exterior of the tubing joint. The fingers 37 are of such length as to engage the exterior of the tubing string A when the cable insulation 11 is partially flattened, such as shown most clearly in FIG. 2. Further tightening of the clamp strap 35 cannot deform the inner portion 36 of the cable insulation to any further extent, in view of the limitations imposed by the contact of the stop fingers 37 against the periphery of the associated tubing joint.

Boththe upper and the lower clamp straps 35 are appropriately tightened to the extent that the upper and lower fingers 37 engage the'upper and lower tubing joints or sections 16, 19. The cable is not only flattened to the controlled extent against the upper and lower joints, as disclosed in FIG. 2, but the central portion 27 of the protector strip will also be shifted inwardly toward the coupling 13, so that the length of the cable along the coupling is also flattened to a controlled extent, which, for example, may be of the same extent that the cable insulation is flattened in the regions 36 of the

end portions

32, 33. Such flattening of the cable insulation securely clamps the cable 10 between the protector strip 25, on the one hand, and the upper and lower tubing joints 16, 19 and the intervening coupling 13, on the other hand, preventing longitudinal movement of the cable along, the tubing string A. The mode of clamping the electric cable 19 to the tubing string provides a large area of frictional engagement between the electric cable and the tubing string itself, and also between the electric cable and the protector strip 25, which is capable of supporting the weight of the electric cable between couplings 13 with a very high factor of safety.

Any suitable mechanism for clamping the straps 35 around the tubing joints can be used. As shown, one end 40 of the strap extends through a support or housing 41 to which it is suitably secured, as by spot welding. The other end portion 4 2 of the strap is inserted through this same housing portion 41 in overlapping relation to the other end it) of the strap. The lastnientioned portion of the clamp strap has a plurality of teeth or grooves 43 therein adapted to mesh with the threads of a screw 44 suitably rotatably mounted in the housing 41. The screw has an external thumb piece as attached thereto. By rotating the thumb piece, the screw 44, because of its meshing with the teeth 43 on the clamp strap, will move the toothed portion 42 of the strap along and into further overlapping relation to the other fixed end portion it of the strap, thereby effecting a shortening of the strap and its secure and firm tightening around a tubing joint, forcing the protector strip 25 inwardly to the extent limited by engagement of its fingers .37 with the periphery of the tubing joint. The pitch of the threaded screw 44 is such that it is self-locking and will not inadvertently turn to effect loosening of the clamp strap 35.

The tubing string A is run in the well casing B with the cable 10 disposed therealong. The cable is clamped to the tubing string, preferably at each coupling 13, in the manner illustrated in the drawings, insuring a controlled compression and frictional holding of each cable to the tubing joints 15, 19 and the coupling collars 13 without there being any abrupt bends imposed on the cable, as is evident from FIGS. 1 and 3. The upper and lower ends or

shoulders

29, 31 of. the coupling 13 cannot embed themselves in the cable 11 since the latter is not abruptly forced around such shoulders and against the adjacent exterior of the tubing. Instead, the inclined, interconnecting or

intermediate portions

28, 30 of the protector strap or strip deflect the cable at a relatively shallow angle toward the tubing A, from which is runs along the main cylindrical body 20 of the tubing parallel to its axis. The relatively steep inclination of the interconnecting or

intermediate portions

28, 30 causes them to function as a protective guide in moving the cable through any restrictions, obstructions or bends encountered in the well casing B. The lower intermediate portion 3th, for example, will deflect the tubing string, so that the protector device and the tubing string itself can move past any obstructions, or the like, encountered in the well casing. Any such obstructions or restrictions cannot shift the protector strip 25 upwardly along the tubing string, since any tendency for the strip and the lower clamp 35 to shift upwardly will cause the lower clamp to move upwardly along the tapered portion 22 of its associated tubing joint, which will further automatically increase the clamping force exerted by this clamp strap 35 against the tubing string, preventing upward movement of the longitudinal protector strip 25. Similarly, any tendency of the upper clamp strap 35 to shift downwardly, as might result through the engagement of the upper portion 32 of the protector strip with a restriction or obstruction in the well casing during upward movement of the tubing string in the casing, will result in the upper clamp strip tending to move down along the downwardly diverging tapered portion 21 of its associated tubing joint 16, which will further increase the clamping force of the strap 35 on the tubing joint and preclude its downward movement, as well as the downward movement of the longitudinal protector strip to which it is secured. Thus, it is apparent that the clamp force of the clamp straps 35 against the tubing A is automatically increased in the event relative movement in either direction between the straps and tubing string tends to occur, precluding longitudinal shifting of the protector strip 25 along the tubing string. The entire clamp apparatus 12 remains in the position on the tubing string A to which it has been secured, the upper and lower intermediate portions 28, of the protector strip 25 serving as guides to cause appropriate lateral shifting of the tubing string in the well casing to insure that the tubing string is not caused to hang up on obstructions, or the like, in the casing during its lowering in the latter, as well as during its upward movement in the latter.

The longitudinal protector strips 25 not only protect the cable 10 in the region of the couplings 13, but also between the couplings, inasmuch as the cable 10 is maintained snugly against the intervening cylindrical body portion 20 of the tubing string by the clamp devices 12 themselves. The central portions 27 of each protector strip extend outwardly beyond the coupling or collar 13 to a sufiicient extent as to engage the wall of the well casing, and prevent the intervening part of the electric cable from coming in contact with the wall of the well casing B. Thus, the assemblage of electric cable clamp and protector devices 12 mounted on tubing string A serves to protect the entire length of the electric cable 10 mounted on the tubing string.

Because of the clamp devices 12, and their guiding and protecting functions with respect to the electric cable 10, it is not necessary to use separate centralizers on the tubing, which has heretofore had the purpose of preventing the cable from engaging the wall of the casing and being damaged thereby. The clamp apparatus 12 provides all of the protection that is necessary.

Each clamp device 12 can be installed in a rapid manner merely by placing the straps around the upper and lower joints 16, 19 of tubing, inserting the free ends 42 of the straps 35 into their associated housing 41 in overlapping relation with the other end portions of the straps, and then by turning the thumb screws 44, in the proper direction. If desired, a suitable tool (not shown) can be connected to the thumb elements 45 to secure enough turning force on the screws 44 for the purpose of securely tightening the straps 35 on the tubing joints closely adjacent to their

tapered portions

21, 22.

It is, accordingly, apparent that an electric cable clamp and protector apparatus 12 has been provided, which prevents shorting of the cable 10, in view of the limitation on the degree of compressive force than can be applied to the cable as the clamps 35 are tightened on the tubing string. The cable is not subjected to any embedding action of the ends or

shoulder

29, 31 of a coupling 13 in the insulation 11, which could also cause a shorting of the

conductive members

14, 15 within the cable. The controlled deformation of the cable insulation 11 against the exterior of the tubing joints 16, 19 and of the coupling collars 13 insures the presence of a large friction holding force capable of supporting the weight of the cable 10 and preventing its slipping along the tubing string A. Any tendency for any clamp apparatus 12 to shift longitudinally on the tubing string automatically efiects its tightening to prevent such shifting. The apparatus is capable of supporting large loads and of withstanding substantial forces in a safe manner while running the tubing string A and cable apparatus in the well casing, or elevating it therewithin. The parts of the apparatus 12 are of strong and sturdy construction, and possessed of a long and useful life.

I claim:

1. In combination: a tubing string adapted to be dis posed in a well bore and including tubing sections connected together by coupling means; an electric cable ex tending along said tubing string; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower elongate end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined in a downward and inward direction toward said lower end portion; and means securing said upper and lower end portions to tubing sections above and below said coupling means to compress said cable against said tubing sections and coupling means without abruptly bending said cable around the upper and lower ends of said coupling means.

2. In combination: a tubing string adapted to be disposed in a well bore and including tubing sections connected together by coupling means; an electric cable extending along said tubing string; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward direction toward said lower end portion; and upper and lower strap means spaced from said coupling means and secured to said upper and lower end portions and extending around and tightened against upper and lower tubing sections above and below said coupling means to compress said cable against said tubing sections and coupling means without abruptly bending said cable around the upper and lower ends of said coupling means.

3. In combination: a tubing string adapted to be disposed in a well bore and including tubing sections connected together by coupling means; an electric cable extending along said tubing string; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at -a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward direction toward said lower end portion; means spaced from said coupling means securing said upper and lower end portions to tubing sections above and below said coupling means to compress said cable against said tubing sections and coupling means without abruptly bending said cable around the upper and lower ends of said coupling means; and means on said upper and lower end portions engageable with said tubing sections to limit the extent of compression of said cable against said tubing sections.

4. In combination: a tubing string adapted to be disposed in a well bore and including tubing sections connected together by coupling means; an electric cable extending along said tubing string; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward direction toward said lower end portion; upper and lower strap means spaced from said coupling means and secured to said upper and lower end portions and extending around and tightened against upper and lower tubing sections above and below said coupling means to compress said cable against said tubing sections and coupling means without abruptly bending said cable around the upper and lower ends of said coupling means; and means on said upper and lower end portions engageable with said tubing sections to limit the extent of compression of said cable against said tubing sections.

5. In combination: a tubing string adapted to be disposed in a well bore and including tubing sections connected together by coupling means, said tubing sections having tapered portions adjacent to said coupling means and tapering longitudinally away from said coupling means; an electric cable extending along said tubing sections; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward direction toward said lower end portion; and meansspaced from said coupling means securing said upper and lower end portions to tubing sections above and below said coupling means adjacent to said tapered portions to compress said cable against said tubing sections and coupling means without abruptly bending said cable around the upper and lower ends of said coupling means; movement of said securing means longitudinally along said tapered portions more firmly securing said securing means and end portions to said tubing sections.

6. In combination: a tubing string adapted to be dis posed in a well bore and including tubing sections connected together by coupling means, said tubing sections having tapered portions adjacent to said coupling means and tapering longitudinally away from said coupling means; an electric cable extending along said tubing sections; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, ot said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward direction toward said lower end portion; and upper and lower strap means spaced from said coupling means and secured to said upper and lower end portions and extending around and tightened against upper and lower tubing sections above and below said coupling means adjacent to said tapered portions to compress said cable against said tubing sections and coupling means Without abruptly bending said cable around the upper and lower ends of said coupling means; movement of said upper and lower strap means along said tapered portions and toward said coupling means more firmly said cable against said tubing sections and coupling means 7 securing said strap means and end portions to said tubing sections.

, 7. In combination: a tubing string adapted to be disposed in a well bore and including tubing sections con,- nected together by coupling means, said tubing sections having tapered portionsfadjacent to said coupling means and tapering longitudinally away from said coupling means; an electric cable extending along said tubing sections; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward directiontoward said lower end portion; means spaced from said coupling means securing said upper and lower end portions and tubing sections above and below said coupling means adjacent to said tapered portions to compress said cable against said tubing sections and coupling means without abruptly bending said cable around the upper and lower ends of said coupling means; movement of said securing means longitudinally along said tapered portions more firmly securing said securing means and end portions to said tubing sections; and means on said upper and lower end portions engageable with said tubing sections to limit the extent of compression of said cable against said tubing sections.

8. In combination: a tubing string adapted to be disposed in a well bore and including tubing sections connected together by coupling means, said tubing sections having tapered portions adjacent to said coupling means and tapering longitudinally away from said coupling means; an electric cable extending along said tubing sections; a longitudinal protector strip in which the cable is disposed and having a central portion extending along said coupling means, upper and lower end portions spaced substantially longitudinally from the upper and lower ends, respectively, of said coupling means, and upper and lower elongate intermediate portions interconnecting said central portion and said upper and lower end portions, respectively, said upper intermediate portion being inclined at a shallow angle in an upward and inward direction toward said upper end portion and said lower intermediate portion being inclined at a shallow angle in a downward and inward direction toward said lower end portion; upper and lower strap means spaced from said coupling means and secured to said upper and lower end portions and extending around and tightened against upper and lower tubing sections above and below said coupling means adjacent to said tapered portions to compress without abruptly bending said. cable around the upper and lower ends of said coupling means, movement of said upper and lower strap means along said tapered portions and toward said coupling means more firmly securing said strap means and end' portions to said tubing sections; and means on said upper and lower end portions engageable with said tubing sections to limit the extent of compression of said cable against said tubing sections.

References Cited by the Examiner UNITED STATES PATENTS 1,383,777 7/21 Stephens 174136 X 2,858,093 10/58 Knoll 174-136 X 3,007,534 11/61 Salnikov et al 174-l04 3,048,358 8/62 Raulins et'al 174136 X DARRELL L. CLAY, Primary Examiner.

JOHN P. WILDMAN, E. JAMES SAX, Exaliziners.

Claims

1. IN COMBINATION: A TUBING STRING ADAPTED TO BE DISPOSED IN A WELL BORE AND INCLUDING TUBING SECTIONS CONNECTED TOGETHER BY COUPLING MEANS; AN ELECTRIC CABLE EXTENDING ALONG SAID TUBING STRING; A LONGITUDINAL PROTECTOR STRIP IN WHICH THE CABLE IS DISPOSED AND HAVING A CENTRAL PORTION EXTENDING ALONG SAID COUPLING MEANS, UPPER AND LOWER ELONGATED END PORTIONS SPACED SUBSTANTIALLY LONGITUDINALLY FROM THE UPPER AND LOWER ENDS, RESPECTIVELY, OF SAID COUPLING MEANS, AND UPPER AND LOWERE INTERMEDIATE PORTIONS INTERCONNECTING SAID CENTRAL PORTION AND SAID UPPER AND LOWER END PORTIONS, RESPECTIVELY, SAID UPPER INTERMEDIATE PORTION BEING INCLINED AT A SHALLOW ANGLE IN AN UPWARD AND INWARD DIRECTION TOWARD SAID UPPER END PORTION AND SAID LOWER INTERMEDIATE PORTION BEING INCLINED IN A DOWNWARD AND INWARD DIRECTION TOWARD SAID LOWER END PORTION; AND MEANS SECURING SAID UPPER AND LOWER END PORTIONS TO TUBING SECTIONS ABOVE AND BELOW SAID COUPLING MEANS TO COMPRESS SAID CABLE AGAINST SAID TUBING SECTIONS AND TO COUPLING MEANS WITHOUT ABRUPTLY BENDING SAID CABLE AROUND THE UPPER AND LOWER ENDS OF SAID COUPLING MEANS.