US2836251A - Casing scraper - Google Patents

Description

May 27, v195s Filed Nov. 22, 1954 3 Sheets-Sheet 1 5) gm ATTORNEY May 27, 1958 R. M. cLAYPooL ETAL 2,836,251

CASING SCRAPER 3 Sheets-Sheet 2 Filed Nov. 22, 1954 R m w @L o V0 H WM A www af/ @j 5M w@ @WM 0A R0 w n w May 27, 1958 R. M. cLAYPooL ETAL 2,836,251

cAsING SCRAPER Filed Nov. 22, 1954 s sheets-sheet s 04 lla /04 @La 104 IN VENTOR l l /14 M57 7N H BY ww s/ Ja ATTORNEY IUnited tates Patent 'i i CASHIG SCRAPER Robbins M. Ciaypool, Bellaire, and David M. Best, Houston, Tex.; said Best assignerV to said Claypool Application November 22, 1954, Serial No. 470,342

16 Ciaims. (Cl. 16d- 173) The present invention relates to cleaning means; and more particularly to scraping type cleaning means for tubular members.

Tubular members, such as pipes, conduits, and the like, over a period of time develop interior conditions which materially impair their etiiciency of function or operation. These interior conditions usually are brought about or develop due to the usage to which the member is put, as, for example, the formation of lilms or caking resulting from greases, synthetic resins, mud or sludge, and cement that may be passed through conduits; or burrs that may be raised within the interior of tubes or the like. it is readily appreciated lby those skilled in the art that if such conditions are allowed to develop over a long period of time the tubular member may become totally useless and beyond reclamation by ordinary cleaning methods. Additionally, in the case of tubular members such as conduits that carry semi-liquid substances, the film or cake formed by these substances often becomes extremely hard, which not only creates a serious cleaning problem, but also results in a number of broken or damaged cleaning tools before the cleaning job is satisfactorily accomplished.

Many prior art efforts have been made to devise a rugged, simple cleaning tool capable of coping with the aforedescribed cleaning problem, no matter how hard the film or cake has formed within the tubular member. Typical of such prior art efforts and representative of considerable advance in providing an etiicient cleaningV means for tubular members are United States Letters Patents No. 2,667,930, issued to Dean F. Saurenman, et al., and No. 2,667,931, issued to Reuben C. Baker. A salient feature common vto both of the aforedescribed cleaners or Scrapers is the use of keeper members removably secured to the basic mandrel member by a plurality or" screws for holding the scraper elements on the mandrel which serves as the support for the scraper elements.

The present device embodies improved details of construction and function over the Saurenrnan and Baker patents to provide a rugged, simple, inexpensively rmanufactured, etiiciently functioning tool that solves heretofore deficiencies in prior art tools of the same nat-ure. The tool of the present invention embodies a novel disposition of improved scraper elements for efficient cleaning action, retained on an improved rugged mandrel member in a novel manner by non-removable retention means which eliminates the use of screws and like retention elements which are relatively weak and can easily fail under the severe shear loads imposed thereon during operation. Additionally, the novel non-removable retention means assures a compact assembly that -can be easily and quickly assembled or disassembled with maximum ease and etiiciency with a minimum opportunity of losing or misplacing a number of small parts, as in prior art devices. The present tool also embodies novel details of construction that not only assure aA-rugged tool of maximum strength, but also one of simple con- 2,836,25i Patented May 27, 19,58

fice

2 struction readily adapted to inexpensive high speedmanu- -facturing techniques.

It is therefore a primary object of the present invention to provide novel cleaning means.

Another object of the present invention is to provide a novel scraping tool.

A further object of the` present invention is to provide novel tool means for cleaning the interior of tubular members.

A still'further object of the present invention is to provide a novel scraping tool with an improved rugged,

' to provide an improved scraping tool with a unique rugged support mandrel mounting novel non-removable scraper element retention means that require no screws, rivets, pins, or the like in their assembly.

Still a further object of the present invention is to pro.- vide a scraping tool comprising a rugged elongate support mandrel having a plurality of spaced slots serving to mount novel scraper elements retained on the mandrel by novel retention means non-removably mounted on the mandrel and retained in locked position by novel split lk rings.

Another object of the present invention is to provide an improved scraping tool for tubular members that is simple, rugged, and inexpensively manufactured, involving a minimum of parts.

These and other objects will appear from the following Fig. 2 is an elevational View, partially in section, ofV

thenovel support mandrel of the present invention showing the novel mounting slots, grooves, and threaded portions thereon;

Fig. 3 is an enlarged exploded perspective view of one of the'novel non-threaded end keeper rings of the present invention;

Fig. 4 is an enlarged sectional view of one of the novel threaded imer retention rings of the present novel mvention;

Fig. 5 is an enlarged exploded perspective view of one of the novel split lock rings of the present invention;

Fig. 6 is an enlarged perspective view of one ofthe novel lett-hand helically toothed scraper elements ofthe present invention;

Fig. 7V is a fragmentary sectional View of one of the novel teeth of the scraper elements of the present invention showing the unique construction thereof.

Fig.v S is `an elongated fragmentary sectional vieur showing the assembly of the scraper elements on `the support mandrel and their relation to the novel keeper ring and retention rings and the assembly of theV novel split locktring;

the line 9-9 of Fig. 8;

plurality of novel scrapingV ywhich comprises a novel elongate rugged mandrel member generally indicated 22, whichserves to mount three spacedA groups of scraper elements generally indicated 24, to'be more particularly described hereinafter.

'Permanently mounted on mandrel 22 adjacent 'the outermost ends of the upper and lower groups of scraper elements l24, as viewed in Fig. l, are a pair of nonthreaded, Vnon-removableV keeper rings 26 which serve to retain'the ends of the adjacent groups of scraper elements 24, as willbe more particularly Vdescribed here' inafter. Adjacent the inner ends of the upper and lower groups of scraper elements and the intermediate group of scraper elements are two pairs of novel threaded nonansetzenV cleaned, as will hereinafter be more particularly described.

As fragmentarily shown in Fig. 2, an axially extending opening 55 extends through the entire length of mandrel 22 to permit circulation. A iluid such as water may be passed through the mandrel 22 into the interior of the tubular member being cleaned or scraped for purposes of lubrication and flushing of therloosened scrapings therein, as is well known in the art.

Turning now to Figs. 3 through' in conjunction with Fig. 8, the details yof the novel keeper rings, retention rings, split lock rings and scraper elements and their mounting on support mandrel22 will now be .particularly described.

As shown in Fig. 3 non-threadedkeep'er rings 26 are plain cylindrical rings having smooth internal and external surfaces 68 and 70 andrhaving a thickness equal to the depth of grooves 56.

removable retention rings 2S each spaced by intermediate split lock rings 30, whichserve to lock Vthe entireV assem-` bly. Split lock rings 30 are secured in place by cap It 'will be readily appreciated from the foregoing brief Ydescription of the scraping tool 20 that the tool ofk the present invention is extremely simple, rugged, and uses no weak securing members, such as screws orthe like to carry the extremely high shearing forces imposed on the scraper elements, as in prior art devices.

l Turning now tol-lig. 2, lthe novel detailsY of construc-V Ytion of the unique supporting mandrel 22 will now be Vparticularly described. Y

As clearly seen in Fig. 2,- the upper end of mandrel 22 'is formed with an integral, externally pipe-threaded portion 38 for connection to pulling means, suchV as a Vdrillrsti'ing, for pulling, pushing, lor rotating the 'tool 20 through'tubular members to be cleaned. The inner end of portion 38 is integrally connected to enlarged barrel portion 40.` The lower end of mandrel 22 is also provided with an elongate, barrel portion 42 having an internally pipe-threaded portion 44, as clearly seen in Fig. 2, for connection to operating Vmeans (not shown).V

The innerv ends of barrel portions 4t) and 42 are integrally connected to `enlarged cylindrical shoulder por- A tions 46 and 48, respectively, `by means of conical con-Vv necting charnfer portions 5t? and 52,'respectively. Intermediate cylindrical shoulders 46 and 48 are three spaced enlarged integral bosses, generally indicated at 54, of the same diameter as the diameter of cylindrical shoulders 46 and 48. Smooth bottomed peripheral keeper ringV grooves V56 are disposed'intermediate shoulders 46 and 48 vand the adjacent bosses 54, while intermediate adjacent pairs Yof bosses 54 is aperipherally grooved portion generally indicated by the reference numeral 58 and comprising two threaded portions'G/adjacent eachY of the bosses 54 and spaced fromeach other by inter- Afterbeing formed, keeper rings 26 are split Yonira diameter to form a pair of semi-circular rings 72 and 74 for purposes of assembly which will appear hereinafter. The semi-circular portions 72 Yand 74a're placed around mandrel 22 with their internalsurfaces 68 in contact with the bottom of grooves 56 and with their sides 76 and 78 V25 screws 32 threadedly engaging eachhalf of split lock l Vrings through aligned threaded openings 34 and 36, Vas will hereinafter be more particularly described.

in contact with the adjacent sides of cylindrical shoulders. 46 and 48 and bosses 54, respectively. The ends 80 andi 82, of the semi-circular portions 72 and 74, respectively Y of rings 26 are in abutting contact in their assembled position. Once semi-circular portions 72 and 74 have mediatesmooth bottomed peripheral groove 62 having a slightlygreater depth Vthanthe threads on portions 60.

Each of the bosses V54 is provided withV four equally 'spaced axially extending atfbottomedfslots 64, which Y extend partially into the adjacent grooves 56 or'threadedV portions 60 and` terminateina Vgradual slope upwardlyl at the peripheral surface of 'the adjacent grooves Vor threaded portions, as indicated at 66, for aV purpose which Vwill hereinafter appear. Voiset 36 with respect to the slots'on an yadjacent boss 54 Theslots 64 of eachboss are so that- Vscraper elements V24 will overlap each Yother in their scraping action to assure 160% cleaning actionby A the scraper'elements within the Vtubular member to be been properly placed on mandrel 22, they are welded to each other along abutting ends 8i) and 82, to form a com plete integral ring again, and also to mandrel 22 along Vshoulders 46 and 48 and the adjacent ends of bosses 54 between the slotsk andthe adjacent side of ring 26, as indicated at 84 andl85, respectively, in Figs. l and'8. Thus, once ring 26 is completely assembled on mandrel 272, it forms an integral part thereof andalso forms a simple rugged keeper means for theV adjacent scraper elements 24 as will hereinafter appear. Attention is also called to Fig. 8 wherein it is clearly seen that slots 64 in end bosses 54 extend under rings 26 for a purpose to be described.

Turning now to Fig. 4, the details of the novelthreaded retention rings 28 Ywill now be particularly described. These retention rings are initially formed as a full ring and then cut to form two halves as shown in Fig. 3. As clearly seen in Fig. 4, retention rings 28 are provided with a smooth Vexternal surface 86 having a diametery equal tothe diameter of bosses 54, and a threaded insideV surface 88 for mutual threaded engagement with threadedV portions 60 ofmandrel 22. Extending inwardly from one side of retention rings 28 is a smooth counterbore 90 equal in diameter to the depth of threads S8 and equal in axial length to the portion ofV slots 64 extending into threaded portion 60 forV purposes of overlying andV retaining scraper elements 24, as will hereinafter appear. The

Vtwofhalvesrof threaded retention rings 28VV are Aassembled on threaded portion Y60 and are welded to each other or together along adjacent abutting edges to'form integraly retention'rings 28 non-removably threadably adjustably mounted on mandrel 22, somewhat similar to the mannerV of mounting keeper rings 26. Y The axial length of retention rings V28 is exactly the sameras the axial Vlength of threaded portions 60, for a purpose which will hereinafter v Ybe more particularlyV described. Y

Y' In Fig.` 5 there'fa're shown the details i Y rings 30 which comprise halves 94 and 96',V eachhaving smooth inside and`outside `surfaces"98 and 108, 4respec'- tively,'t he diameters of which Vare substantialiy equaltoy the diameters of slots 62 and bosses 54, respectively, fora purpose whichV will appear. VHalves 94 and 96 Vof lock."V Y rings30 abut along'faces 102 in their-V` assembled posif tions and are each'provided withdiametrically opposed pairs of threaded apertures 34 land 36 yas *heretofore described which'are in alignment inV their assembled posi` of novel split lock aasaae 1 tion for the reception of a pair of securing cap screws 32, which fixedly join halves 9d and 95. The axial length of lock rings 30 is equal to the ividth of slotsv 62.

Novel scraper elements 2d are generally rectangular blocks, as clearly seen in Fig. 6, having a main body portion ille surmounted by integral square type left-hand helically cut teeth "idd 1aving integral end tongues 03. The up er surfaces 1M of tongues i633 are curved to conform to the curvature of the retention rings While the lower surfaces lll?. of each of the entire scraper elements 2Q are flat, as seen in Fig. 6, to conform to the llat bottom of slots 6d of mandrel Z2. As shown in Fig. 7, the longitudinal sides of teeth Mld are cut away along the lines .M3-E3, and a very hard composition, indicated at li, such as stellite or other composition combinations like the cobalt-chromium-tungsten alloys, is allixed by suitable means, in place of the removed material, to provide a keen abrasive resistant scraping edge for maximum operating efficiency and extended service life. The undersides of scraper elements 24 are provided with three equally spaced blind apertures lilo, as best seen in Fig. S, for the reception of biasing means as will be hereinafter described.

Turning now to Fig. 8, the novel manner of assembling the scraper elements on mandrel T12 will now be particularly described. As heretofore described, non-threaded keeper ring halves 72 and 74 are assembled into grooves 56 of mandrel 22. and are then welded to each other along abutting edges Si) and S2 and to mandrel 22 along joint or junctures .Se and S5, as heretofore described. All of the threaded retention rings 23 are similarly assembled on mandrel Z2 to form retention means that are nonremovable from but adjustable axially on the mandrel. With reference to Fig. 8, lock ring Si) is not assembled on mandrel Z2 and the leftmost retention ring 2g is unthreaded or moved to the right away from its adjacent boss 515 exposing the portion 56 of slot 64 which extends into threaded portion Springs 11S are mounted in blind apertures llb on the underside of scraper elements 24, and four of the scraper elements are mounted on mandrel 22 by slipping end tongues 1&8 into slot portions 66 beneath keeper ring 26. The four scraper elements in this group are then all pressed into slots 64 toward mandrel 22 compressing springs lid, and leftmost threaded retention ring Z8 is threaded toward its adjacent boss 54 until it abuts the end of its boss 54, so that counterbored portion 9% of retention ring 2b overlies the righthand tongues itl@ of scraper elements 2:4. The axial length of body portion ldd of he scraper elements is slightly less than the axial length of boss Se so that the ends of keeper ring Ze and retention ring 23 will not bind the scraper elements 24, and they thus will be freely biased outwardly by springs lib.

Turning now to Figs. l and 2, one method of assembling the middle group of scraper elements will now be described, remembering that split lock rings Sil are not in their assembled positions. FEhe two retention rings 28 adjacent to opposite sides of the intermediate boss 54 may be threaded and thus capable of being moved away from boss d, exposing end portions 66 of slots 64. Pour scraper elements 24 with their springs llllS are then mounted in slots o4 with their end tongues 163 extending into portions d6 of slots ed. The two retention rings 28 are then threaded back toward middle boss 54 until the adjacent ends of retention rings 2S abut the adjacent sides of middle boss 54,. in this position the counterbores (it) Will completely overlie tongues M28 and will retain scraper elements 24 in slots 64 against the biasing force of springs M3. It will also be emphasized here that retention rings 28 abut the adjacent sides of boss 'Sli while the axiallength of body portion lil-@l of scraper elements is slightly less than the length of boss Se 'to permit free action of scraper elements 2d in slots 64% under the biasing force of springs 118 for maximum freedom of action and operation.

A preferable method of assembling the middle group or intermediate set of scraper elements 24 will now be described. Only one of the retention rings 2S adjacent the intermediate boss 54 is 4:hreadedly moved away from this boss exposinff circumferentially spaced end portions ed of slots de, while the other retention ring 28 remains in position against the other side of boss 54 in overlying relation to the other end portions 66 of slots 64. Scraper elements 2d, with their associated springs in place, are then placed in slots 64 and their end tongues lili.- are slipped under the retention ring that has not been threadedly moved away from boss 554i. Scraper elements 24 are then all pressed into slots 54 compressing springs HS, and the other retention ring 28 is then threadedly moved into abutting relation with its adjacent end of boss Se to overlie the adjacent tongues lll of scraper elements lt will readily be appreciated that no matter what method of assembly is employed the scraper elements are easily assembled with a minimum amount of effort and adjustment.

The lower group of scraper elements as viewed in Fig. l, are assembled in the same manner in which the group of scraper elments described in connection with Fig. 8 were assembled. Once all of the scraper elements 24 have been assembled and all the retention rings have been threaded into abutting engagement with their adjacent bosses 54, the splitL locl; rings 3i? are interposed between pairs of retention rings 2S and threadedly connccted together by means of recessed head cap screws 32 to completely loci. the assembly in a compact rugged unit.

It will be readily appreciated from the foregoing detailed description of the novel cleanino tool of the present invention that it is of relatively simple rugged construction and that the relatively high shear forces imposed on the scraper element are not carried by a plurality of relative weak screws, rivets, or pins as in prior art devices, but are carried by relatively large rugged .keeper or retention rings in pushing and pulling action and by the sides of bosses 54 in rotation which are capable of carrying such loads with little ill effect.

It frequently happens that it is necessary or desirable to rotate the tool as distinguished from pushing or pulling the same, and since the teeth lilo are of a curved formation, such rotation provides an excellent cutting action. ln addition to the fact that the tool will cut very well, it will be noted that the parts are so assembled that a rugged construction results which is not prone to become disassembled in use. Rotative force is transmitted from the drill string or the like down into the mandrel and then from the inner face of the slot 64 in the bosses 54 directly to the rather lengthy sides of the scraper bloclis generally indicated at 24. The retention rings furnish the drive when going in or coming out of the hole; that is, when pushing or pulling, but the sides of the slots 64 drive the scraper elements while rotating, as rotation is frequently employed, since this permits tivo operations at one time. For example, it frequently happens that a bit is connected to the lower threaded end 44 of the mandrel and scraping operations are carried on simultaneously with the drilling of a cement plug in the casina.

Further, it will be readily appreciated that the novel mandrel 22, the keeper, retention rings, lock rings, and the novel scraper elements are all formed by means of simple lathe and milling operations which result in a simple rugged tool that is easily manufactured by means of high speed inexpensive manufacturing methods.

The Ypresent invention may be embodied in other specidc forms without departing from the spirit or essential scope or characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the forev going description, and all changes which come Within the meaning and range of equivalency of the claims are therefore intended to be included therein.

. rrn assembled relation. Y

7 We claim:

1. Ink a casing scraper, an elongate support member,

connecting means on said elongate support member for attachment to a pipe string, aY plurality ofslots in said support member for removably receiving a plurality of scraper elements, a plurality of scraper elements, for scraping the inner walls of ytubular members, removably mounted in said slots, and a plurality of pairs of retention means non-removably mounted on said member and each of said pairs being cooperative with the adjacent ends of said scraper elements for'iixedly securing said scraper elements in mounted position on said support member.

V2. In ka casing scraper, an elongate support member, integral connecting means on said support member for attachment to a pipe string, a plurality of axially extending slots in said support member for mounting a plurality of scraper elements, a plurality 'of scraperjelements resiliently removably mounted in said slots on said elongate support member, and pairs of retention means non-removably mounted on said support member partially overlying adjacent ends of said scraper elements and cooperative with said scraper elements for securing said scraper ele- Y ments in their mounted position on said support member.

3. A casing scraper assembly comprising an elongate support member, connecting means on said elongate support member for attachment to a pipe string, a plurality of scraper elements mountedfon said'support member, a plurality of pairs of retention means non-removably mounted on said support member in encircling relation to said support member and in partial overlying relation to the adjacent ends of said scraper elements Vtoretainthe means are operatively interposed between said support member and said scraper elements. Y

- 5. A casing scraperassembly comprising an elongate, hollow support member, a plurality of scraper elements mounted onV said support member, a plurality of pairs of retention means non-removably mounted on said support member in encircling relation thereto and in partial overlying relation to the adjacent ends of said scraper elesupport member, a plurality of axially extending slots in said support member for mounting a plurality of scraper elements, a plurality of scraper elements removably resiliently mounted in said slots on said elongate support member, V'a plurality of pairs of annular retention means non-removably mounted on said support member partally overlappingrthe adjacent endsV of said scraper elements and cooperative withsaid slots Vfor Vsecuring-said scraper elements in their mounted position on said support member, and lock means. cooperative with'sat least some ofsaid retention means `to lock said scraper assembly in Y '7.- A casing scraper .assembly comprising an elongate support member, a fluid passage extending through Vsaid support member, Yspaced shoulders on said support'me'mgate support member, pairs of Yannular retention means non-removably mounted on said support member partially overlapping the adjacent ends of said scraper elements and cooperative with said slots and shoulders for Vsecuring said scraper elements in their mounted position on said support member, and lock means cooperative with at least some of said retention means to lock said scraper assembly in firm assembled relation. v

8. A'casing scraper assembly comprising an elongate support member, integral connecting means on said support member for attachment to a pipe string, spaced shoulders on said support member, a plurality of axially extending slots in'said support member intermediate said shoulders for mounting a plurality of scraper elements, a plurality `of scraper elements removably resiliently mounted in said slots on saidv elongate support member, a plurality of annular iirst retention means permanently tixedly mounted on said support member, a plurality of annular second retention means non-removably adjustably mounted on said supportrmember, said ViirstV and second retention means partially overlapping said scraper elements and cooperative with said slots for securing said scraper elements in-their mounted position on said support member, and lock means cooperative with said second retention means to lock said scraper assembly in firm assembled relation.

9. A casing scraper assembly comprising an elongate support member, an axially extending duid passage therethrough, integral connecting means on said support member for attachment to a pipe string, spaced circumferential shoulders on said support member, a plurality of axially extending slots in said supportmember. intermediate said shoulders for mounting a plurality of scraper elements, a plurality of scraper elements resiliently removably mounted in said'slots on said elongate support member, a plurality of rst circumferential retention means permanently iixedly mounted on said support member, a plurality of second circumferential retention means non-removably adjustably mounted on said support member, a pair of said iirst and second retention means partially overlapping each of said scraper elements and cooperative with said slotsfor securing said scraper elements in their mounted position on said support member, and lock means cooperative with said second retenl tion means to lock said'scraper assembly in firm assembled relation. Y

10. A casing scraper assembly comprising an elongate Y support member, integral connecting means on said supi port member for attachment to a pipeV string, Vspaced shoulders'k on'. said support membena pluralityrof axially extending circumferentially and axially spaced mounting slots forV mounting a plurality of scraper elements,`V a` plurality of scraper elements mounted in said -slots on said support member, a plurality of annular rst retention means permanently fixedly secured onsaid support member, a plurality of` annular second retention means non-removably adjustably mounted on said support mem-` ber, a pair of said rstand second retention means partially overlapping each of said scraper elementsand cooperative with said slots for securing said scraperV elements in their mounted position, and lock means cooperative with said second retentionV means to lockY said scraper assembly in firm assembled relation. Y n

l1. The device as set forth in claim 10 wherein spring meansare operatively interposed between the underside YVof Vsaidrscraper elements and the bottomof said slots to resiliently mount said scraper elements. Y s

l2; A casing scraper assembly comprising an elongate support member, integral connecting meansA on saidrsup` r port means for attachmentV to aV piperstring', spaced cir- Vcumferential shoulders on'said support member, al plu-vsV rality of axially extending'circumferentially spaced mount-V ing slots intermediate said shoulders for mounting a plurality of scraper elements onV said support member, 'a

plurality of scraper elements removably resiliently mounted in said slots, a plurality of rst circumferential retention means permanently iixedly mounted on said support member, a plurality of second circumferential retention means non-removably adjustably mounted on said support member, a pair of said irst and second retention means partially overlapping e ch of said scraper elements and cooperative with said slots for securing said scraper elements in their mounted position on said support member, and loci; means cooperative with said second retention means to loci. said scraper assembly in rm assembled relation.

13. A casing scraper assembly comprising an elongate support member, integral connecting means on said support member for attachment to a pipe stringiapaced circumferential shoulders on said support member, spaced bosses on said support member intermediate said shoulders, a plurality of axially extending circumferentially spaced slots in said bosses for mounting a plurality of scraper elements on said support member, a plurality ot scraper elements removably resiliently mounted in said slots, a plurality of first circumferential retention means permanently xedly mounted on said support member, a plurality of second circumferential retention means nonremovably adjustably mounted on said support member, a pair of said first and second retention means partially overlapping each of said scraper elements and cooperative with said bosses to retain said scraper elements in their assembled position, and lock means cooperative with said second retention means to lock said scraper assembly in rm assembled relation.

14. A casing scraper assembly `comprising an elongate support member, integral connecting means on said support member for attachment to a pipe string, spaced circumferential shoulders on said support member, a plurality of spaced bosses on said support member intermediate said shoulders, a plurality of axially extending circumferentially spaced slots on said bosses for mounting a plurality of scraper elements, a plurality of scraper elements resiliently removably mounted in said slots having toothed scraping surfaces with hard a' rasive resistant auxiliary material attached to said teeth, a plurality of annular iirst retention means permanently iixedly mounted intermediate said shoulders and adjacent said bosses, a plurality of annular secc-nd retention means nonremovably and initially adjustably mounted intermediate successive bosses, a pair of said tirst and second retention means partially overlapping each of said scraper elements and cooperative with said bosses for retaining said scraper elements in assembled position, and lock means mounted intermediate successive bosses and second retention means to lock said scraper assembly in iirm assembled relation.

15. A casing scraper assembly ycomprising an elongate support member, spaced circumferential shoulders on said support member, a plurality of axially spaced bosses on said support member intermediate said shoulders, circumferential grooves intermediate said shoulders and the adjacent bosses, threaded portions intermediately disposed between mutually adjacent bosses, second circumferential grooves dividing said threaded portions, axially exten-ding circumferentially spaced slots in said bosses, a plurality of scraper elements resiliently removably mounted in said slots, scraping teeth on said scraping elements having auxiliary material liXedly attached to the sides of the teeth for maximum abrasion resistance, a plurality of annular first retention means permanently fixedly mounted in said rst grooves and partially overlapping some of said scraper elements, a plurality of annular second retention means non-removably and initially adjustably mounted on said threaded portions and also partially overlapping the scraper elements to retain them in said slots, and loclr means mounted in said second grooves to maintain said second adjustably mounted, retention means in adjusted non-removable retaining position to maintain said scraper elements in iirm assembled relation.

16. A casing scraper assembly comprising an elongate support member, spaced circumferential shoulders on said support member, a plurality of axially spaced bosses on said support member intermediate said shoulders, circumferential grooves intermediate said shoulders and adjacent bosses, threaded portions intermediately disposed between mutually adjacent bosses, second circumferential grooves dividing said threaded portions, axially extending circumterentially spaced slots in said bosses, a plurality of scraper elements resiliently removably mounted in said slots, tongue means on opposite ends of said scraper elements, scraping teeth'on an outer surface of said scraper elements having auxiliary extremely hard material affixed to the sides thereof to provide abrasion resistant scraping edges, a plurality of rst retention rings permanently iixedly mounted in said iirst grooves in encircling relation to said support member and in overlapping relation to the adjacent tongue means of adjacent scraping elements, a plurality of second re ention rings nonaremovably thre-adably mounted ou said threaded portions and in overlapping relation to the adjacent tongue means of adjacent scraping elements, split lock rings mounted in said second grooves to maintain said second retention rings in adjusted retaining position, and securing means fmedly securing the portions of said split lock rings together to loci; said scraping assembly in firm assembled relation.

References Cited in the file of this patent UNITED STATES PATENTS 96,552 Coyle Nov. 9, 1869 482,935 Willcoxon Sept. 20, 1892 2,275,939 Baker Mar. 10, 1942 2,667,930 Saurenman et al Feb. 2, 1954 2,667,931 Baker Feb. 2, 1954

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