US3371521A - Leak-testing apparatus for either flush or shouldered pipe joints and packer therefor - Google Patents

Description

March 5, 1968 E. D. HAUK 3,371,521

LEAK-TESTING APPARATUS FOR EITHER FLUSH OR SHOULDERED PIPE JOINTS AND PACKER THEREFOR Filed April 1, 1966 5 Sheets-Sheet l 6 y mwJ W v a 4 1 H 1 ERNEST D. HAUK I xs ww v M M kw w a w 5 Mfl w. a @w xwww mfi 7. F J ,K 0% .39 w

fiTTOIeA/Eyi March 5, 1968 HAUK 3,371,521

7 LEAK-TESTING APPARATUS FOR EITHER FLUSH OR 'SHOULDERED PIPE JOINTS AND PACKER THEREFOR Filed April 1, 1966 5 Sheets-Sheet 2 INVENTOR. meme-5r 0. #40

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E. D. HAUK 3, LEAK-TESTING APPARATUS FOR EITHER FLUSH OR March 5, 19 68 SHOULDERED PIPE JOINTS AND PACKER THEREFOR Filed April 1, 1966 5 Sheets-Sheet 5 INVENTOR. 561/657 0. #40! March 5 1968 E. D. HAUK 3,371,521 LEAK-TESTING APPARATUS FOR EITHER FLUSH OR SHOULDERED PIPE JOINTS AND PACKER THEREFOR Filed April 1, 1966 5 Sheets-Sheet 4 F k a! 16-. 6.

10.4w T H a r0 o a/v r0 opav 98 INVENTOR. 679M557 0. HAUK WA TEE BY soueae Z 6%; Q

3,371,521 LEAK-TESTING APPARATUS FOR EITHER FLUSH OR SHOULDERED PIPE JOINTS AND PACKER THEREFOR Filed April 1, 1966 E. D. HAUK Mafch 5. 1 968 5 Sheets-Sheet 5 I INVENTOR. ff/VEST 0. HAL/K 4T70PA/Ey5:

United States Patent Ofiiice 3,371,521 Fatent'ed Mar. 5, 1968 3,371,521 LEAK-TESTING APPARATUS FOR EITHER FLUSH R SHOULDERED PIPE JOINTS AND PACKER THEREFOR Ernest D. Hauk, 1315 E. 23rd St.,

Signal Hill, Calir. 90806 Filed Apr. 1, 1966, S'er. No. 539,579 31 Claims. (Cl. 73--46) ABSTRACT (IF THE DISCLOSURE pressures of thousands of pounds per square inch.

This invention relates to an apparatus adapted to test for leaks in joints betwen connected pipe sections, whether the joints be of the flush or shouldered type. The invention further relates to the packer member incorporated in such leak-testing apparatus.

The invention will be described in particular relation to the testing of collared joints between adjacent tubing sections being run into (or drawn out of) an oil well. It is to be understood, however, that the apparatus is alsoapplicable to the testing of threaded, welded or other joints between any two connected pipe sections.

In accordance with one conventional method of testing pipe at the wellhead of an oil well, pipe sections are sealed off with internal packer means and then filled with water at high pressures. The indicated system has basic disadvantages, however, among which are the following:

(a) The water hoses connecting to the internal chamber are necessarily relatively long. Therefore, when internal pressure on the order of thousands of pounds per square inch is applied, these long hoses stretch (expand) considerably and this, in conjunction with the stretch or increase in chamber size responsive to the pressure, creates a large elastic or reserve load. The leakage of a small amount of water out of the chamber will not be sufiicient to remove such elastic or reserve load, and therefore will not produce (within a reasonable time period) an appreciable change in the gauge which senses the pressure in the chamber. Accordingly, the indicated method may not practically be employed to determine small leaks but instead only relatively large ones. The determination of small leaks is vital because such leaks gradually increase (due to erosion) into large leaks and wash-outs.

(b) The use of internal packers in oil well pipe is undesirable because the scale, wax, plastic linings, etc., present in the pipe create problems relative to wear, sealing, etc.

For the above and other reasons, attempts have been made to test pipe joints by applyingexternal fluid pressure (US. Patent 2,587,192, issued to H. Meyer for Leak-age Tester for Threaded Pipe Couplings). Such attempts. were impractical, however, for various reasons including the following:

(a) It was necessary to mount the leak-testing apparatus fixedly at the wellhead, in pipe-supporting relationship, instead of in a movable position suspended above the wellhead.

URE 1,

(b) The testing required relative longitudinal movement between the pipe and the leak-testing apparatus.

(c) The leak-testing apparatus could not be employed in those numerous instances when two or more strings of pipe were being run into or withdraw from a well.

(d) It was difiicult or impossible to determine whether or not the lower one of the packer members was leaking, thus making it impractical to determine whether the leak was in the pipe itself or in the packer of the testing apparatus.

(e) The testing apparatus required a separate set of slips,

which were normally manually operated, thus rendering usless the automatic slips already present at the wellhead.

(f) The apparatus involved the use of many parts, and

was dilficult and slow to put into operation and operate.

(g). It was difficult or impossible to change the packers in the field, it instead being necessary to remove the apparatus to the shop.

(i) An experienced operator was required to efiect satisfactory testing operations.

(j) The apparatus was not effective in achieving sealing at very high fluid pressures, such as 6,000 pounds per square inch.

In view of the above and other factors characteristc of conventional leak-testing apparatus, it is an object of the present invention to provide a leak-testing apparatus, and packer means therefor, wherein a compact, self-contained unit is suspended in adjustable relationship above. the Wellhead of an oil well and is adapted to effectively and externally test pipe joints without the necessity for any relative longitudinal movement between the pipe and the test r, and without the necessity of feeding the pipe through any object whatsoever.

A further object is to provide a leak-testing apparatus which is readily and economically operated by unskilled personnel, and which incorporates a packer means which may be readily changed in the field and in a short period of time.

A further object is to provide a leak-testing apparatus which will quickly detect very small leaks, which will contain pressures of many thousands of pounds per square inch, which may be employed in conjunction with parallel strings of pipe being run into or out of a well, which is self-verifying in that any leakage therefrom may be visual.- ly observed, which may be employed in conjunction with the automatic slips already present at the wellhead, and which is not subject to the effects of the scale, wax, etc., within oil well pipe.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a perspective view illustrating a leaktesting apparatus, constructed in accordance with the present invention, in fully-open condition adapted to laterally receive or discharge a pipe section;

FIGURE 2 is a top plan view of the apparatus of FIG- illustrating the same in fully-closed condition in solid lines, and in fully-open condition in phantom lines;

FIGURE 3 is a longitudinal sectional view taken generally on line 33 of FIGURE 2;

FIGURE 4 is an exploded perspective view illustrating the upper back-up assembly for the packer. (the lower back-up assembly being identical but inverted);

FIGURE 5 is a top planview ofthe packer, illustrating the same in closed condition;

FIGURE 6 is a horizontal sectional view taken on line 6-6 of FIGURE 3, and showing (in phantom lines) the pivoted jaw in open condition;

FIGURE 7 is a fragmentary vertical sectional view taken along line 7--7 of FIGURE 2, and showing only the upper end region of the apparatus,

FIGURE 8 is an enlarged vertical sectional view of an area illustrated at the upper left portion of FIGURE 3;

FIGURE 9 is an isometric view illustrating the packer, the rubber portion of the packer being illustrated in phantom lines and the metal portion thereof in solid lines;

FIGURE 10 is a fragmentary sectional view taken generally along line 10- 10 in FIGURE 2; and

FIGURE 11 is a schematic diagram of the neumatic and hydraulic portions of the apparatus.

The leak-testing apparatus will be described as employed to test for leaks the threaded joints between two pipe (tubing) sections 10 and 11 and a collar 12.

Stated generally, the apparatus comprises clamping-j aw means formed by a back-up jaw 13 and a pivoted jaw 14, the latter being pneumatically actuated by cylinders 15. Latch means 16 are provided to effect an additional clam-ping operation and also a latching or locking operation, such latch means comprising hook means 17 and cranks 18. Cranks D8 are operated by cylinders 19 which, like cylinders 15, are provided on a body or housing portion 20 to which the back-up jaw 13 is fixedly connected. The term cylinders, as employed herein, denotes cylinder and piston assemblies (rams).

Very importantly, the apparatus comprises a molded rubber packer 21 having molded therein mounting, preloading (compressing), stretching and extrusion-prevention elements. A detailed description of the packer and the associated embedded elements, and also of the adjustment means and back-up elements associated with the upper and lower ends of the packer, will be given subsequently. There will also be described the means for passing water to and from the pressure chamber which is de'fined within packer 21 and around the pipe section.

Detailed description of the mechanical jaw and latching means 13-20, inclusive It is pointed out that the expression back-up jaw is not necessarily intended to denote the absence of any movement, the expression being employed because the jaw 13 is shown as being fixedly related to the body portion 20 of the apparatus.

Each of the clamping jaws 13 and 14 is illustrated to comprise a semi-cylindrical casing member 23, being preferably approximately one-half of a hollow cylinder. A semi-annular internal collar 24 is welded or otherwise fixedly secured at the inner surface of each member 23 at the upper and lower end thereof. When the elements 23 and 24 are in the closed positions represented in FIG- URE 3, members 23 provide back-up support for the vertical walls of packer 21, whereas the internal collars 24 provide back-up support for the extrusionprevention retaining assemblies which form part of the end-seal means for the packer.

A substantial number of vertically spaced, generally semi-annular exterior ribs 25 are welded or otherwise fixedly secured to each of the semi-cylindrical members 23, providing a bracing function against the great internal pressures contained within the packer. In the illustrated embodiment, eight ribs 25 are provided on each of the casing sections 23.

The upper and lower ribs 25 on the back-up jaw 13 have welded thereto suitable upper and lower horizontal plates 27 which form major components of the body 20 of the apparatus. Such plates 27 extend radially outwardly from the jaws and provide mounting means for the various cylinders 15 and 19 and associated valving, pumping and other means incorporated in the self-contained leak-testing unit.

There will next be described the means for effecting pivotal mounting of jaw 14 in such manner that it may be opened to a widely-spaced position relative to back-up jaw 13 in order to permit lateral reception and discharge of the tubing sections 10 and 11 and the collar 12. Such pivotal mounting means comprises a strong vertical pin or pintle 29 (FIGURE 6) which extends through housing plates 27 and through end regions of all of ribs 25 on jaw 13 adjacent one side of what may be termed the rear gap 30 between the jaws. A plurality of strong, thick, short links 31 are pivotally connected to pin 29 between various ones of ribs 25 as indicated in FIGURES 3 and 6. The ends of the short links 31 remote from pin 29 extend between corresponding ribs 25 of pivoted jaw 14, so that such link ends and the vertically adjacent regions of the ribs 25 of the pivoted jaw may receive a second vertical pin or pintle which has been given the reference number 32. A compound pivotal movement is thus effected, upon shortening of actuating cylinders 15, which causes a wide, spacing between the jaws at the rear gap 30 and thus at the diametrically opposite front gap 33 through which the pipe section is laterally received and discharged.

The actuating cylinders 15 for jaw 14 are pivotally connected to a vertical pin 34 at the end of body 20 remote from the jaws. The piston-rod portions of the cylinders are pivotally connected to an additional pin 35 which is associated with the pivoted jaw 14 by means of suitable lugs 36.

A gripping handle 37 is welded to the pivoted jaw 14, relatively adjacent the lugs 36, to facilitate manipulation of the leak-testing apparatus by an operator. It is emphasized that the entire apparatus is freely suspended (as from the derrick) by means of a helical spring 38 (FIG- URE 1) in order to permit manual vertical (and horizontal) adjustment of the position of the apparatus to correspond with the location of the collar 12. This is a great advantage in comparison to apparatus in which the entire pipe string, not just the tester, must be moved.

The latch means 16, which cooperates with cylinders 19 in closing the jaws, and which also effects locking of the jaws in closed condition against the enormous forces of the contained fluid, comprises an additional vertical pin or pintle 40 which extends through all ribs 25 of back-up jaw 13 on one side of the front gap 33. As best shown in FIGURE 1, the previously-indicated cranks 18 are pivotally connected to the pin 40 in the gaps which are provided between alternate sets of ribs 25. Stated more definitely, one crank is located above the upper rib 25, a second crank is located below the lower rib 25, and two adjacent cranks 18 are located between the alternate remaining sets of ribs.

At points relatively remote from pin 40, cranks 18 receive a further vertical pin 41 adapted to effect mounting of the above-indicated hooks 17. Such hooks are disposed at elevations which correspond to the crank-free gaps between various ribs 25 of jaw 13, having hook ends 42 which are shaped to fit around a vertical latch pin 43. Pin 43 extends through the ends of ribs 25 of pivot jaw 14 (on the opposite side of front gap 33).

The various hooks 17 are fixedly connected to each other by a vertical bar 44 having a handle 45 thereon. The upper and lower ones of cranks 18 have extension portions which extend in a direction away from pin 40 and are pivotally connected at their free ends to the pistonrod portions of actuating cylinders 19. For the purpose of such pivotal connection, a vertical pin 46 is connected between such crank extensions.

Referring particularly to FIGURE 2, let it be assumed that the cylinders 19 are in their extended conditions illustrated in phantom lines. The operator may then readily manually (or by suitable pneumatic or hydraulic apparatus, if desired) effect clockwise pivoting of books 17 from the illustrated phantom-line positions to positions (unshown) adjacent latch pin 43. The operator then causes retraction of cylinders 19 to the illustrated solidline positions, thus etfectingpivotal movement of the hooks 17 to the illustrated solid-line positions. The locations of the various pins, the sizes of the various elements,

etc., are such that the last-mentioned pivotal movement of the hooks l7 first effects an additional closing (clamping) movement of the jaws 13 and 14 and then effects a locking action.

When fully locked, as shown in solid lines in FIGURE 2, pin 41 is over center relative to a plane intersecting the axes of pins 40 and 43, being on the side of such plane adjacent body 20. Accordingly, the mechanism 16 will remain locked, when high-pressure fluid is present within the packer, in the absence of any fluid pressure in cylinders 19. It will even remain locked despite an attempt made by the operator to extend the cylinders 19. This is a safety feature since the operator may not open the jaws until the fluid pressure in the packer has been relieved.

All of the enormous pressure contained within the packer-lined casing 23 is held solely by the hooks 17, pins 40, 41 and 43, the portions of cranks 18 between pins 46 and 4-1, the ribs 25, pins 29 and 32, and short links 31. None of the pressure is borne by the cylinders and 19, and none by the body portion of the apparatus. It is emphasized that the ribs 25, links 31, hooks 17 and cranks 18 form an encircling cage around the casing portions 23 of jaws 13 and 14, such cage having great strength.

Similarly to the case of the cylinders 15, the latch cylinders 19 are pivotally connected to the body 20 by means of a pin 47 mounted through plates 27 at a location remote from the jaws.

Detailed description of the packer 21 and associated back-up and seal-adjustment means Packer 21 comprises, as best illustrated in FIGURE 9, a molded rubber body 48 shaped to conform to the interior wall defined by easing sections 23 and also shaped, at its ends, to conform closely to the exterior surfaces of tubing 10 and 11. The term rubber, as employed in the present specification and claims, denotes not only natural and synthetic rubbers but also various deformable equivalents thereof formed of suitable plastics.

It is an important feature of the invention that the entire casing 23 is lined by the rubber body 48 of the packer, the relationship being such that the pressurized fluid only sees rubber except at the water-inlet and water-outlet lines. The sealing means for preventing escape of water at such lines, at the longitudinal slit in the packer, and at the ends thereof, are critical to the invention and are described in detail hereinafter.

The packer has a cylindrical external wall 49 and a cylindrical internal wall 50, as shown in FIGURE 3, the latter having suficient diameter at its central portion to receive the collar 12. At its upper and lower end portions, the packer is necked down at 51 for purposes including decreasing the size of the defined pressure chamber and increasingthe packer wall thickness whereby fluid connections may more readily be made to the chamber. At its extreme end portions, the packer is further necked down at 52 to diameters substantially smaller than the outer diameter of tubing 10-11.

At one point about its circumference, the molded rubber packer is slit (split) at 53, such slit 53 being located relatively adjacent the front gap 33 (FIGURE 6) whereby the leak-testing apparatus may 'be opened for lateral reception and discharge of the tubing. By lateral reception and discharge it is meant that the tubing does not (necessarily) rnove axially, but instead toward and away from the longitudinal axis of the leak-testing apparatus.

Molded into the rubber body 48 of packer 21, in spaced relationship from the slit 53 and on opposite sides thereof, are vertical bars 55 and 56 which provide extremely important functions relative to effecting compression and stretching of certain regions of the rubber and also relative to mounting of the packer in the casing sections 23. The bars 55 and 56 should be completely embedded in the rubber body 48, as illustrated, there being suitable washers 57 associated with the outer surfaces of the bars at apertured regions thereof. Such washers. extend outwardly to, and are flush with, the external cylindrical packer surface 49. Bars 55 and 56 are formed of steel or other suitable rigid material.

The mounting function of the bars 55 and 56 will first be described, with particular reference to index screws 58 which are provided at each end of each bar 55 and 56. Each screw 58 extends threadedly through a casing section 23 and into a rounded or conical recess in an associated bar 55 or 56. The inner end of each screw 58 is correspondingly rounded or conical, the relationship being such that radial-inward threading of each screw creates a cam-like indexing action which positively locates the packer 21 in the casing. Thus, after all four index screws 58 are in position, it is known that other openings in the bars 55 and 56 will be in position for reception of mounting and conduit members next to be described.

Referring particularly to FIGURES 3 and 8,, combina tion water-conduit and mounting elements 59 are extended through openings in casing sections 23 and into packer 21 at the upper and lower neck regions 51 thereof. Such elements 59 have externally-threaded inner ends which are received in corresponding internally-threaded regions of the bar 55. Thus, and because elements 59 have shoulders which bear against the outer casing surface, such elements 59 provide a positive mounting function relative to bar 55. The sealing and fluid-conducting functions of elements 59 will be described hereinafter.

Referring next to FIGURE 10, upper and lower mounting screws 61 are shown as extending through a casing section 23 into bar 56. Such screws 61 are adapted to provide the same mountin function performed by conduit elements 59.

It is emphasized that mounting screws 61, index screws 58, etc., do not penetrate to the interior surface 50 of the rubber body 48 of the packer. Thus, there is no sealing problem relative to these elements. The only elements which penetrate to the interior surface of the packer are the conduit elements 59, which should have special seals associated therewith as will be descri ed relative to FIGURE 8.

In addition to their mounting function, the bars 55 and 56 provide very important functions relative to effecting preloading of the interfacial region at slit 53, in order that the contained water will not commence to escape therethrough prior to the time that dynamic loading (effected by the extremely high internal fluid pressures) becomes operative. Such preloading is achieved by causing the distance between each bar and the slit 53 to be very substantially less when the apparatus is in fully-closed condition than the distance between each bar and the associated slit end (which cooperates with the other slit end to define the interfacial region) when the device is in open condition. The bars 55 and 56 are spaced sufficiently far from slit 53 to permit such preloading of the interfacial region, and are also (as will be described hereinafter) spaced sufliciently far from the packer portion diametrically opposite slit 53 to provide the optimum stretching action as the packer is shifted to open condition.

It has been found that a desired degree of preloading or compression between bars 55 and 56 and slit 53 is on the order of 25%, that is to say that the regions of the packer rubber 48 between bars 55 and 56 are compressed approximately 25% in response to shifting of the apparatus from its open condition to its closed condition. In the illustrated packer, the angle defined by adjacent surfaces of bars 55 and 56 (those bar surfaces adjacent slit 53) is on the order of about 40 to 60 degrees when the leak-testing apparatus is fully closed.

As a specific example of one method of achieving the desired preload at the interface 53, let it be assumed that the inner diameter of the casing 23 is, when the casing is in the fully-closed position shown in solid lines in FIG- URE 2, 5 /8 inches. The packer 21 is then so molded that its outer diameter will be, when in the closed condition shown in FIGURE 9 but prior to any compressing action, approximately inches. The difference between the: circumference of the interior casing surface and the circumference of the exterior packer surface will then be a little more than inch. Accordingly, the bores which. receive index pins 58 and mounting elements 59 and 611'. are so located that all of such 4 inch difference will be present in the lower region illustrated in FIGURES 5 and. 6, that is to say in the region directly between the bars. 55 and 56. Thus, when the leak-testing apparatus is. shifted from its open to its fully-closed condition, such 4 inch will necessarily be taken up in the form of compression between the bars 55 and 56, and will effect a very substantial preloading of the interfacial region 53..

The stated preloading of the interface will exist despite the fact that some stretching of the casing occurs when thousands of pounds per square inch pressure is created within the packer. It is pointed out that the precise location of the slit 53 is not of the essence, the important thing being the distance between the bars 55 and 56. It is. also pointed out that the above-stated example is given by way of illustration only, and not limitation.

From the above it will be understood that the two bars 55 and 56 should lie, respectively, in the two quadrants of the circle (FIGURES 5 and 6) which are relatively adjacent the front gap 33 and remote from rear gap 30, the distance between the bars being selected to effect preloading of the packer regions therebetween, There will next be discussed the distances between bars 55 and 56 and the packer region which is adjacent rear gap 30, in particular relation to the stretching of the packer (the stretching function of bars 55 and 56) which occurs when the same is shifted from its closed position to the open position shown in FIGURE 1. It is emphasized that the bars 55 and 56 could each be located much closer to rear gap 30 than in the illustrated embodiment, but that this would produce the undesirable result of decreasing the amount of rubber which is adapted to be stretched when the packer is opened. This, accordingly, would provide additional wear in the form of strain on the bars 55 and 56, stretching of the rubber, etc., which would shorten the packer life. For these and other reasons it is desirable to locate the bars 55 and 56 in the circle quadrants adjacent slit 53, as indicated above, and as far from rear gap 30 as is commensurate with adequate preloading of the packer regions on opposite sides of slit 53.

Bars 55 and 56 should extend for the full length of the packer body, and should be at least substantially continuous.

It is pointed out that the slit 53 does not, at least at the outer region thereof, coincide with the front gap 33. Instead, an extrusion-prevention bar 62 (formed of steel or other suitable rigid material) is molded into the packer 21 at the region thereof adjacent front gap 33, the outer surface of such bar being flush with outer surface 49 of the rubber packer body. The bar 62 is sufficiently wide that its outer surface will be in bridging contact with the interior surfaces of easing sections 23 when the device is fully closed as shown in FIGURE 6. Thus, bar 62 effectively prevents extrusion of rubber through the front gap 33 despite stretching of the casing in response to insertion of fluid therein. An additional and corresponding extrusion-prevention' bar 63 is molded into the packer 21 at rear gap 30, as shown in FIGURES 5, 6 and 9.

There will next be specifically described those portions of the packer 21, and cooperating elements, which relate primarily to sealing of the upper and lower packer ends as distinguished from sealing the region at the slit 53.

Arcuate compression members 65 are molded into the upper and lower packer ends on opposite sides of bars 62 and 63 (which, in turn, are located at the front and rear gaps as stated heretofore). Similarly to the case of the extrusion- prevention bars 62 and 63, and the vertical bars 55 and 56, the arcuate members 65 are formed of metal (such as steel) or other strong and rigid material. The end regions of members which are relatively adjacent slit 53 are indented to receive the extreme ends of vertical bars 55 and 56. Furthermore, such end regions are spaced sufficiently far from slit 5; to permit the aboveindicated preloading of the rubber at such slit. The ends of elements 65 are spaced on opposite sides of a diametral plane which contains the longitudinal axis of the apparatus, and which extends adjacent slit 53.

Members 65 are preferably rectangular in section, having outer cylindrical surfaces 66 which are flush with packer surface 49 and abut the interior surfaces of easing sections 23. Such members also have interior cylindrical surfaces 67 which are concentric with the casing 23 and are spaced radially outwardly from tubing sections 10 and 11 when the apparatus is in fully-closed condition. The precise radial distances between surfaces 67 and the extreme inner (tubing contacting) regions of the packer rubber are selected to effect preloading of the neck regions 52 in response to closing of the packer. Stated more definitely, such preloading should be on the order of about 25%.

As an example, let it be assumed that the inner diameter of each packer neck region. 52 is A inch less than the outer diameter of each tubing section 10 and 11. There, fore, each diametrically-opposite region of the packer will necessarily be shifted outwardly (compressed) A; inch when the apparatus is closed. Since such A; inch is approximately 25% of /2 inch, it follows that the radial distance between each surface 67 and the outer surface of each section 10 and 11 should be approximately /2 inch, when the apparatus is closed.

The packer neck regions 52 should have substantial axial dimensions in order to aid in prevention of extrusion of rubber in response to the extremely high pressures. Preferably, circumferential annular grooves 68 and 69 are provided in each neck region 52.

It is pointed out that substantially the same packer molds can be employed to make packers for tubing sections 11 having somewhat different diameters. For example, if the packer is to be made for tubing having a diameter larger than that of tubing 10 and 11, the inner diameters of packer necks 52 are increased accordingly. Very importantly, however, the inner diameters (surfaces 67) of preloading members 65 are also increased accordingly, to thus maintain the desired degree of rubber compression or preloading.

The above-indicated spacing of the ends of elements 65 on opposite sides of the indicated diametral plane is desirable in the achieving of preloading of the packer rubber at slit 53, and in permitting the packer to open wide to the FIGURE 1 position. Very surprisingly, it has been found that such spacing does not adversely affect the preloading of neck 52. Thus, the preloading pressure effected by elements 65 bridges the end gaps.

The amount of wear effected at the neck regions 52 is necessarily substantial, because of the thousands of pounds pressure present within the packer. It is a feature of the invention that packer life may be considerably extended by use of the adjustment means indicated in FIGURE 6. Such adjustment means comprises a plurality of circumferentially-spaced screws '70 which are threaded through internally-threaded radial bores in casing sections 23 and abut against the exterior surfaces 66. When the packer regions adjacent grooves 68 and 69 wear substantially, it is merely necessary to effect radial-inward movement of screws 70, thus increasing the amount of loading of the rubber and lengthening packer life.

Self-adjusting, self-loading, extrusion-prevention (backup) means are provided for the neck regions 52 of the packer, and comprise outer and inner taper-related segmented rings 71 and 72, respectively. Each outer ring 71 is shown in FIGURE 4 as having two semi-circular segments or sectors, whereas each inner ring 72 is shown as r having six segments or sectors. In the showing of FIG- 9 URE 4, the radial dividing lines 73 register, respectively, with dividing lines 74. Each set of registered lines 73-74 is substantially registered with one of the front and rear gaps 33 and 30.

Each outer ring 71 has a radial (horizontal) outer surface which seats against a collar 24, and also has a generally frustoconical surface 76 (FIGURES 4 and 7) which converges in a direction away from the center of the apparatus. Each inner ring 72 has a radial inner surface which seats against the radial outer surface of neck 52 and of the associated arcuate members 65. Each inner ring also has a frustoconical surface 77 which engages surface 76 in such manner that a limited amount of radial movement of the segments or sectors is permitted. For this purpose, the taper angle of surface 76 (relative to a horizontal plane, perpendicular to the longitudinal axis of the apparatus) should be slightly smaller (one or two degrees) than the taper angle of surface 77 relative to such horizontal plane. It is to be understood that shapes other than generally frustoconical may be employed. Thus, for example, the cooperating surfaces of outer and inner members 71 and 72 may be generally spherical.

The surface regions of each inner ring 72 adjacent tube sections and 11 are also generally frustoconical, being steeply tapered relative to the above-indicated horizontal plane and converging toward the center of the leak-testing apparatus. Thus, the regions of each ring 72 closest to the adjacent packer neck 52 are caused to be in close metalto-metal contact with the exterior tubing surface regions, despite the fact that the tubing regions more remote from neck 52 may be somewhat protuberant.

Referring particularly to FIGURE 7, the central region of each half of each outer ring 71 is provided with a horizontal bore and counterbore 78 adapted to receive a mounting screw 79 which projects horizontally into an adjacent internally-threaded region of casing 23. A resilient element, for example a pad 81 of rubber, is interposed between the outer-central region of each sector of ring 71 and the adjacent cylindrical surface of casing 23. Thus, such pads 81 are diametrically opposite each other, at the central regions of the sectors of ring 71, each pad occupying, for example, approximately or degrees of the circle.

The two sectors of each outer ring 71 thus being mounted to the casing, such sectors may each support t-hree sectors or segments of the associated inner ring 72. In the case of those segments of inner ring 72 which are closest to the registered lines 73-74, FIGURE 4, support is effected by inserting screws 82 downwardly (as viewed in FIGURE 4) through oversize holes 83 in ring 71 for threaded reception into holes 84 in ring 72. In the case of the diametrically-opposite central sectors or segments of each inner ring 72, which are spaced from registered lines 73-74, support is elfected by providing horizontal lips 86 on such central sectors and causing such lips to hook horizontally over inwardly-projecting regions of outer ring 71. Two access holes 87 are provided in diametrically-opposite portions of each ring 72, in registry with bores 78, in order to permit threading of screws 79 into casing 23.

With the described construction, assembly is readily effected by connecting the segments or sectors of each ring 72 to the segments of ring 71, thereafter positioning the associated elements 71-72 in the position shown in FIGURES 2 and 7, and thereafter inserting screw drivers through access holes 87 to thread screws 79 into casing 23.

The holes 83 are oversize in radial directions, permitting the segments or sectors of each outer ring 71 to be shifted radially through substantial distances. The thicknesses of pads 81, the inner diameter of each ring 72, etc., are so selected that closing of the leak-testing apparatus onto the tube sections 10 and 11 causes a very considerable radially-inwardly directed preloading of each inner ring 72 against the tubing. Such preloading may total, for example, approximately 500 or 600 pounds at each end of the packer. This provides an effective back-up for packer neck regions 52, preventing initial extrusion there of as the pressure within the packer builds up.

As the fluid pressure within the packer increases, strong axial pressures are exerted against the inner radial surfaces of rings 72 but this, because of the taper relationship between surfaces 76 and 77, causes additional radialinward movement of the segments or sectors of each ring 72. Thus, the back-up assemblies 71-72 are self-energizing, after the initial preload is achieved, and effectively prevent extrusion of rubber from necks 52 despite the existence of thousands of pounds per square inch pressure within the packer.

The inner diameter (minimum) of each inner ring 72 corresponds approximately to the outer diameter of tubing 10-11. The gaps between adjacent sectors of each inne'. ring are caused to be very small when full pressure is present within the packer.

Referring particularly to FIGURES 3 and 8, there will next be described the means for sealing the ends of conduit and mounting elements 59 to the neck regions 51 of the packer. As best shown in FIGURE 8, each conduit and mounting element 59 has a threaded portion 88 which is received in a corresponding internally-threaded opening in bar 55. For-med adjacent such threaded portion of the conduit element is a necked-down end region (head) 89 having an annular groove therein for reception of an O- ring 91. Head region 89 is inserted into a cylindrical opening 92 which is formed in the packer body 48, inwardly adjacent bar 55. Spaced radially-outwardly from opening 92, and embedded within the packer rubber concentrically of the opening, is a metal back-up ring 93. Such back-up ring being completely embedded in rubber, pressurized liquid may not reach any portion of the ring 93.

In the operation of the sealing means, the outer region of O-ring 91 is caused to bear forcibly against the cylindrical wall defining opening 92, so that the O-ring 91 is somewhat preloaded. Therefore, the combination of the O-ring and the adjacent regions of the packer rubber effectively prevent outward passage of liquid around any portion of conduit 59. The back-up ring 93 insures that adequate radial-inward pressure will be exerted against the O-ring 91, despite the outward forces exerted by the contained fluid.

It has been found that the O-ring 91 greatly increases the life of the sealed fluid coupling in comparison to those constructions wherein an O-ring is not employed. It is to be understood, however, that adequate sealing may be achieved, over a shorter useful life, by constructions wherein the head region 89 contacts only a necked-down region of the packer rubber.

Description of hydraulic and pneumatic circuits, and brief summary of operation Referring particularly to FIGURES 1 and 11, the upper conduit and mounting element 59 connects through a suitable pressure-resistant hose 96 and a valve 97 to a drain or discharge region. The lower conduit and mounting element 59 connects through a hos-e 98 to a suitable high-pressure injection pump 101 which is supplied with water (through a valve 102) from a suitable source. A gauge 103 communicates with line 98 and registers the pressure therein and thus within the packer. Such gauge should be capable of reading pressures in'excess of 6,000 pounds per square inch.

Pump 101 may be a conventional air-operated type, known as a Sprague pump, which is adapted to inject small amounts of liquid at very high fluid pressures in response to shifting of an air-operated piston or other element. Such piston has a large diameter, and operates a small-diameter piston in a water chamber having springpressed ball-check inlet and outlet means. The air side of pump 101 communicates through a line 134 and regulator 105 to a suitable source of air pressure, there being a valve 106 interposed in line 104 to control air flow. The air pressure source also communicates through a control valve 107 with cylinders 15, and through a control valve 108 with cylinders 19.

Let it be assumed that the leak-testing apparatus is suspended by spring 38 above the wellhead of an oil well, and is initially in the fully-open condition shown in FIG- URE 1. Assuming, as but one of numerous examples, that the tubing sections and 11 are being run into the well, such sections are lowered until the collar 12 is generally adjacent the testing apparatus. The testing apparatus is then moved laterally until collar 12 is received within packer 21, as shown in phantom lines in FIGURE 1, the spring 38 being utflized to permit the desired degree of vertical movement of the testing apparatus to permit the same to be vertically adjusted relative to the collar.

Valve 107 is then operated to extend the cylinders 15 and thus partially close the pivoted jaw 14. This effects a substantial amount of preloading engagement between the packer body sections adjacent slit 53, and between packer neck regions 52 and the external tubing surfaces. Thereafter, the operator grasps handle 45 and pivots the hook members 17 until they are shifted from the positions shown in phantom lines in FIGURE 2 to positions (unshown) at which latch pin 43 is engaged. Valve 108 is then operated to retract the cylinders 19 and thus shift cranks 18 from the positions shown in phantom lines in FIGURE 2 to those shown in solid lines therein. This effects, as described in detail, a very strong compression action between pivoted jaw 14 and back-up jaw 13, and also effects positive locking of the apparatus in closed condition. The aboveindicated preloading of the packer rubber at slit 53 is thus considerably augmented, and is also substantially augmented at the neck regions 52 at opposite ends of the packer. Furthermore, and as described above relative to FIGURE 7, the assemblies 71 and 72 at opposite ends of the packer are preloaded into close pressure engagement with the external tubing surfaces. Thus, substantial seals and back-up or retaining means are provided at all points.

The operator then opens valve 102 to effect flow of water through hose 98 and the lower conduit and mounting element 59 into the lower end of the annulus (pres sure chamber) defined between the tubing and packer. The pressure annulus is thus completely filled with water, the air therein discharging through the upper element 59 and through the valve 97 which is then in open condition. As soon as the operator sees water commence to discharge through the outlet from valve 97, he closes such valve and operates valve 106 to effect flow of air from the air source to the pump 101. The pump is then caused to operate until the water pressure within the packer builds up to the desired value which may be, for example, about 5,000 or 6,000 pounds per square inch. Because of the very small volume of the pressure annulus and connecting hoses, such pressure buildup occurs in only a few seconds.

After the desired operating pressure level is achieved, the operator stops operation of pump 101 and watches gauge 103 for a short period of time, such as 10 seconds. If the water pressure within the packer holds steady, it is known that there is no leak between the collar 12 and either tubing section 10 or 11. If the observed pressure commences to fall, and if the operator visually ascertains that there is no leakage of water through any of the seal points, it is known that there is a leak between collar 12 and one or both of the tubing sections. Of course, the gauge 103 may be any pressure-responsive means which visually or audibly indicates a pressure drop.

Valve 97 is then opened to relieve the fluid pressure in the packer, following which valves 107 and 108 are operated to open the clamping jaws. The apparatus is then ready for a new testing operation.

Because the volume of the chamber defined between the packer and the collar 12 is extremely small, for example one cup, and because the connecting hoses 96 and 98 are very short, the leakage of only a very small amount of water will be registered by gauge 103 as a very substantial pressure drop which is readily observable to the operator. Such leakage will, because of the extremely high water pressures employed, occur in only a few seconds. Thus, the entire testing operation for a single joint may be completed within twenty or thirty seconds.

Although the hoses 96 and 98 are shown as being flexible pressure hoses associated with pivoted jaw 14, it is to be understood that such hoses may be thick-walled metal pipes associated with back-up jaw 13. In the latter event, there is relatively little stretching or expansion of the hoses, despite fluid pressures on the order of 6,000 pounds per square inch and above.

It is desirable to maintain a coating of oil on the interfacial regions at slit 53, and on the pipe-engaging packer surfaces adjacent grooves 68 and 69.

The bars 55 and 56, elements and bars 62 and 63 may each be somewhat interrupted or discontinuous, although it is greatly preferred that such elements be continuous as shown. Similarly, and although a metal such as steel is greatly preferred, the various elements molded into the rubber packer body may in some cases be nylon or other plastic.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. A replaceable packer for the casing of a high-pressure leak-testing apparatus, said casing comprising jaws adapted to open for lateral reception of a pipe section, which packer comprises:

a generally cylindrical hollow body formed of molded rubber,

said body having end portions shaped to sealingly engage the exterior cylindrical surfaces of a pipe section,

the full length of said body being slit at one point about the circumference thereof whereby said body may be opened for lateral reception of a pipe section, and

mounting and compression means molded into said body on opposite sides of the slit therein,

said mounting and compression means being adapted to be connected to said jaws for opening and closing therewith, said mounting and compression means being adapted to effect, in response to closing of said jaws, substantial compression of the interfacial region of said body at said slit,

at least one of said mounting and compression means being spaced sufficiently far from said slit that a substantial segment or sector of said body will be compressed in response to said closing of said jaws.

2. The invention as claimed in claim 1, in which additional compression means are molded into said body at said end portions thereof, said additional compression means being adapted to effect, in response to closing of said jaws, substantial compression of the regions of said body adjacent the pipe-engaging surfaces thereof, said additional compression means being spaced a substantial distance radially-outwardly from said pipe-engaging surfaces.

3. The invention as claimed in claim 2, in which said additional compression means comprise two pairs of arcuate metal elements, one pair at each end of said body, the metal elements in each pair being generally coaxial with said body and being disposed on opposite sides of a 13 diametral plane containing the axis of said body and extending adjacent said slit, said elements in each pair lying generally in 'a plane whichfis perpendicular. to thelongitudinal axis of said body.

4. The inventionas claimed in claim 1, in which extrusion-prevention means are molded into the outer part of said body, said extrusion-prevention means being located to bridge gaps between said jaws. whensaid jaW are in closed condition. y

5. The invention as claimed in claim 4, in which said extrusion-prevention means and the region of said slit relatively adjacent the exterior surface of said body are located at different points about the circumference of said body, and in which said extrusion-prevention means are relatively rigid bars.

6. The invention as claimed in claim 4, in which said mounting and compression means comprises a pair of rigid bars extending for substantially the full length of said body and embedded'in said body, and in which said extrusion-prevention means comprises two rigid bars molded into said body relatively adjacent a diametral plane containing the axis of said body and extending adjacent said slit, said last-named bars being disposed on diametrically opposite sides of said body and being adjacent the exterior surface of said body, said last-named bars extending for substantially the. full length of said body.

7. The invention as claimed in claim 1, in which additional compression means are molded into said body at said end portions thereof, said additional compression means being adapted to effect, in response to closing of said jaws, substantial compression of the regions of said body adjacent the pipe-engaging surfaces thereof, and in which extrusion-prevention means are molded into said body, said extrusion-prevention means being located to bridge gaps between said jaws when said jaws are in closed condition.

8.' The invention as claimed in claim 1, in which said mounting and compression means comprises a plurality of elongated rigid elements extending generally parallel to the axis of said body, said elements being located in the quadrants of said body which are adjacent said slit.

9. The invention as claimed in claim 8, in which said rigid elements are embedded in said body inv spaced relatiicfmship from both the interior and exterior surfaces there- 10. The invention as claimed inclaim 8, in which said rigid elements comprise two bars each extending for substantially the full length of said body, said bars having 0penings therein for reception of mounting and fluidconducting means. 7

11. The invention as claimed in claim 1, in which said pipe-engaging portions of saidbody have annular grooves, said groves lying generally in planes which are perpendicular to the longitudinal axis of said body.

12. A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure, said casing means comprising two semi-cylindrical casing sections adapted to form a hollow cylindrical casing,

and further adapted to be opened tolaterally receive a pipe section,

'each of said casing sections having a substantial number of spaced parallel ribs provided on the exterior surface thereof,

each of said, sections further having a plurality of pins extending through said ribs. parallel to the axis of said casing and on opposite sides of the gaps between said sections,

a flexible packer mounted within said casingmeans and slit fonlateral reception of a pipe section,

the slit in said packer being generally registered with a gap between said two casing sections, said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closedv condition, fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid, and actuating means to effect opening and closing of said casing means and said packer,

at least some of said pins cooperating with said actuating means in effecting opening and closing of the jaws formed by said casing sections and said ribs. 13. The invention as claimed in claim 12', in which a plurality of short connecting links are pivotally connected between two of said pins which are located on opposite sides of one of the gaps between said sections, and in which an actuating and latch means is connected between two of said pins which are located on opposite sides of the other of the gaps between said sections.

14. A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure, said casing means being split into at least two casing sections .and in such manner that said casing means may be opened to laterally receive a pipe section,

said casing means comprising two jaws pivotally connected to each other adjacent a first gap between said jaws,

a flexible packer mounted within said casing means and slit for lateral reception of a pipe section,

the slit in said packer being generally registered with a second gap between said jaws, said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closed condition, fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid, and

actuating means to effect opening and closing of said casing means and said packer,

said actuating means including:

crank means pivotally connected to one of said jaws adjacent said second gap,

hook means pivotally connected to said crank means,

latch-pin means provided on the other of said jaws adjacent said second gap and positioned to seat hooked end portions of said said hook means, and

fluid-operated cylinders connected to said crank means to pivot the same to a position at which said hook means locks said said jaws in tightly-closed positions.

15. The invention is claimed in claim 14, in which said crank means is pivoted sufficiently far, when said jaws are in said closed positions, that said jaws will remain locked even in the absence of fluid pressure in said fluid-operated cylinders.

16. The invention as claimed in claim 14, in which additional fluid-operated cylinders are provided to pivot said other jaw between open and partially closed positions.

17., A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure,

said casing means being split into at least two casing sections and in such manner that said casing means may be opened to laterally receive a pipe section,

a flexible packer mounted within said casing means and slit for lateral reception of a pipe section,

the slit in said packer being generally registered with a gap between two casing sections,

15 said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closed condition, said packer having a molded rubber body, said packer further having mounting and compression means molded into said body on opposite sides of said slit,

said mounting and compression means being adapted to be connected to said two casing sections for opening and closing therewith, said mounting and compression means being adapted to effect, in response to closing of said two casing sections, substantial compression of the interfacial region of said body at said slit, fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid, and

actuating means to effect opening and closing of said casing means and said packer.

18. The invention as claimed in claim 17, in which additional compression means are molded into said packer body at the end portions thereof, said additional compression means being adapted to effect, in response to closing of said two casing sections, substantial compression of the regions of said body adjacent the pipe-engaging surfaces thereof.

19. The invention as claimed in claim 17, in which extrusion-prevention means are molded into said packer body, said extrusion-prevention means being located to bridge a gap which is present between said two casing sections when said sections are in closed condition.

20. A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure,

said casing means being split into at least two casing sections and in such manner that said casing means may be opened to laterally receive a pipe section,

a flexible packer mounted within said casing means and slit for lateral reception of a pipe section,

the slit in said packer being generally registered with a gap between two casing sections, said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closed condition, an extrusion-preventing back-up assembly provided in said casing means at each end of said packer for close engagement with the exterior surface of said pipe section,

said back-up assembly comprising taper-related means to increase the radial-inward pressure against said pipe section in response to an increase in the fluid pressure contained within said pressure chamber, fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid, and

actuating means to eflect opening and closing of said casing means and said packer.

21. The invention as claimed in claim 20, in which means are provided to effect preloading of said back-up assemblies in response to closing of said casing and prior to the introduction of fluid pressure into said pressure chamber.

22. A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure,

said casing means being split into at least two casing sections and in such manner that said casing means may be opened to laterally receive a pipe section,

a flexible packer mounted within said casing means and slit for lateral reception of a pipe section,

the slit in said packer being generally registered with a gap between two casing sections,

said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closed condition,

said packer having a molded rubber body,

said packer further having compression means molded into said body radially-outward'y frcm said longitudinally spaced regions of said pipe sections,

fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid,

actuating means to effect opening and closing of said casing means and said packer, and

adjustment means provided in said casing means to augment the radial-inward shifting of said compression means in response to closing of said casing means,

said adjustment means being adjustable to increase the loading on said body and thus compensate for the effects of wear thereon. V 23. A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure,

said casing means being split into at least two casing sections and in such manner that said casing means may be opened to laterally receive a pipe section,

a flexible packer mounted within said casing means and slit for lateral reception of a pipe section,

the slit in said packer being generally registered with a gap between two casing sections, said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closed condition, said packer having a molded rubber body, fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid,

said fluid inlet means comprising a rigid element inserted into an opening in said body,

said rigid element having an annular groove therein and an O-ring provided in said annular groove, the eilterior region of said O-ring contacting the rubber wall of said opening, and actuating means to effect opening and closing of said casing means and said packer.

24. The invention as claimed in claim 23, in which a rigid back-up ring is molded into said packer in radiallyoutwardly spaced concentric relationship relative to said opening.

25. The invention as claimed in claim 23, in which said fluid inlet has a threaded portion which is threaded into a rigid insert molded into said packer.

26. A high-pressure leak-testing apparatus for pipe joints, which comprises:

casing means to contain fluid under high pressure,

said casing means being split into at least two casing sections and in such manner that said casing means may be opened to laterally receive a pipe section,

a flexible packer mounted within said casing means and slit for lateral reception of a pipe section,

the slit in said packer being generally registered with a gap between two casing sections, said packer being shaped to sealingly engage longitudinally spaced regions of said pipe section whereby to define a pressure chamber around said pipe section when said casing means is in closed condition,

said packer having a molded rubber body,

said packer further having relatively rigid mounting and compression means molded into said body on opposite sides of said slit,

fluid inlet means provided in said packer to admit fluid into said pressure chamber whereby to fill said chamber with high-pressure fluid,

said fluid inlet means including a threaded member threaded into said mounting and compression means to aid in the mounting and compressing function thereof, and

actuating means to effect opening and closing of said casing means and said packer.

27. The invention as claimed in claim 26, in which taper-ended index screws are threaded through said casing means and into tapered recesses in said mounting and compression means to thus locate said packer in said casing means.

28. A high-pressure leak-testing apparatus, which comprises:

a metal casing having jaws adapted to be shifted between a closed condition and an open condition at which a pipe section may be shifted laterally into and out of said casing,

a molded rubber packer disposed within said casing and having a slit so located that said packer may open and close with said jaws for lateral reception and discharge of said pipe section,

said packer having necked-down end portions adapted to sealingly engage longitudinally spaced regions of said pipe section,

a set of rigid mounting and compression elements molded into said packer on opposite sides of said slit,

at least one of said mounting and compression elements being spaced a substantial distance from said slit,

means to connect said mounting and compression elements to said jaws,

said last-named means being so located that closing of said jaws effects a very substantial compression of the packer region between said mounting and compression elements whereby to preload said packer at said slit,

a set of compression elements molded into said packer at said necked-down end portions thereof,

said last-named compression elements being spaced radially-outwardly from the pipe-engaging surfaces of said end portions, the diameters of said pipe-engaging surfaces being substantially smaller than the outer diameter of said pipe section whereby substantial compression of said end portions is effected in response to closing of said casing, and actuating means to effect forcible closing of said casing.

29. The invention as claimed in claim 28, in which said mounting and compression elements and said lastnamed compression elements are so related to said casing and to said pipe section that closing of said casing effects a compression of the associated packer rubber on the order of about 25%.

30. The invention as claimed in claim 28, in which said mounting and compression elements are so related to said casing that said packer is stretched when said casing is shifted to open condition.

31. The invention as claimed in claim 28, in which back-up assemblies are mounted in said casing at each end of said packer to prevent longitudinal extrusion of said end portions of said packer.

References Cited UNITED STATES PATENTS 2,255,921 9/1941 Fear 7346 2,571,236 10/ 1951 Hamilton 7346 2,587,192 2/1952 Meyer 7346 2,761,311 9/1956 Baker 73--46 2,817,230 12/ 1957 McCully 7346 2,981,331 4/ 1961 Arterbury 73405 X 3,034,339 5/1962 Gawlik 7346 LOUIS R. PRINCE, Primary Examiner.

J. NOLTON, Assistant Examiner.

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