US2728096A - Tube cleaning tool - Google Patents

Description

Dec. 27, 1955 R. s. FAHLE TUBE CLEANING TooL Filed May 7, 1952 OR NEYS m R om TF. N. Nm IB O R .Qu- ATT United States Patent() TUBE CLEANING TOOL Robert S. Fahle, Seattle, Wash. Application May 7, 1952, Serial No. 286,593 4 Claims. (Cl. 15-104.G4) (Granted under Title 35, U. S. Code (1952), sec. 266) This invention may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The invention relates to tube cleaning apparatus and more in particular to tools for cleaning or scraping scale and other incrustations from the exterior surfaces of tubes that are held in a symmetrical or evenly-spaced nested relationship; such symmetrical arrangements commonly being employed in heat-exchange apparatus, such as evaporators and boilers.

As is well known, the cleaning or scraping oit of scale and other foreign matter which forms on such tubing has presented a diiicult problem and many different types of tools have been devised in an effort to facilitate and expedite the operation. It, of course, is possible to dismantle the nest or bundle of tubes and remove each tube for individual cleaning but, as may be appreciated, such a procedure is extremely ineicient since the apparatus is put out of use during the period of time required for such removal and cleaning. The diiculties and time involved in such removal are readily apparent when it is considered that most such tubes are press-rolled into their supporting tube sheets.

To avoid this tube removal, various cleaning means have been devised, some of these including the pulling of steel chains through the nest, the pounding of the tubes with suitable tools, and the use of acids or kerosene torches, as well as attempts at cracking the scale by alternately heating and chilling of the tubes. So far as is known, none of these procedures have proven to be as satisfactory as could be desired principally because of an inability to achieve and maintain a positive, effective and constant engagement between the cleaners and the tubes.

Some attempts have been made to avoid this particular diculty by mounting pivotal cleaners or scrapers on the body of the tool and using springs or other resilient means to press the Scrapers outwardly into a tube-engaging position. However, the perfomance of these springpressed tools depends upon an ability to correctly apply the spring pressure and also upon maintenance of a constant spring force and, in practice, this particular type of tool has not provided a suitable answer.

Accordingly, one of the objects of the present invention is to provide a tool for cleaning the exterior surface of tubes, the tool being so arranged that a positive cleaning contact is maintained at all times during cleaning operation. As a corollary to this object, another object is to assure such cleaning contact without dependence upon resilient means for pressing the Scrapers into tube engagement.

A more specific object is to provide a cleaning tool for cleaning nests of tubes, the cleaners of the tool being xedly mounted for unyieldable engagement with the exterior surfaces of the tubes.

A further object is to provide a tube cleaning tool capable of being moved through laterally spaced rows of nested tubes, the cleaners of the tool positively engag ing the surfaces of the tubes during such movement and further acting as guiding means for movement through the rows.

Other objects are to provide a tube cleaning tool which is simple, relatively inexpensive and capable of effective and raipd cleaning operations upon nests of symmetrically arranged tubes in situ.

One of the more basic advances of the present invention resides in the concept of using the natural resiliency of the laterally spaced tubes as a means for assuring an effective cleaning contact and this is accomplished by assuring that the tool has an effective working width (width between outermost working surfaces) which is as great as, and preferably slightly greater than, the spacing between the rows of tubes to be cleaned. With such arrangement, as the tool is moved into the space between the rows, the tool cleaners engage and exert a spreading pressure upon the tubes and the tube resiliency insures Contact between the cleaners and the tube surfaces. As may be surmised, this resilient engagement results even when the so-called eective working width of the tool is the same as the distance between the rows because the presence of any layer of scale on the tubes induces the spreading so that the resilient engagement persists so long as scale is' present.

Another important feature is that the cleaning is facilitated by a particular arrangement of the tools cleaners which results in a steady support and guide for the tool during its cleaning movements. Tous, in the preferred form, the tool includes plural pairs of cleaners each pair of which is made up of cleaners projecting outwardly from opposite sides of the support a sufcient distance to engage and exert the previously described spreading pressure. ln addition, the pairs of cleaners are spaced longitudinally along the extent of the support in suitable positions for engaging a plurality of tubes in each row or,

more specifically, in such position that, if there are two pairs of cleaners, the cleaners extending outwardly on one side of the support are spaced one from another to engage adjacent tubes in the row being cleaned. Similarly, the two cleaners projecting from the other side engage two adjacent tubes in the other row so `that a fourpoint support is formed for the tool by its four cleaning members and such a support not only assures the spreading action desired, but also guides the tool so that it can be moved backwardly and forwardly in horizontal directions across the surface of the tubes being cleaned. In practice, it has been found desirable to perform the cleaning by reciprocating the tool transversely across the engaged tubes and continuing this reciprocation along their longitudinal extent.

Preferably, the cleaners are roller Scrapers which are formed with serrated or threaded worlring surfaces and successive pairs of these rollers are oppositely threaded or the serrations are so inclined that they exert opposite cutting action on the tube scale.

ln the accompanying drawings Fig. l is a somewhat diagrammatic illustration of the form of the tool particularly adapted for cleaning a tube nest in which the tubes all are equidistantly spaced one from the other; Figs. 2 and 3 are plan and side views respectively of the tool shown in Fig. l; Fig. 4 a view similar to Fig. l showing a modied tool adapted to clean nests or" tubes disposed and held in a rectilinear array, and Figs. 5 and 6 plan and side views of the tool shown in Fig. 4.

Before commencing the detailed description of the present invention, it might be noted that there are several manners in which the nests of tubes can be arranged, and that the tools provided by the invention must be adapted for each separate arrangement, although, of course, tools incorporating the principles of this invention could be made adjustably adaptable for most all uses. Fig. l is Vdilerent tube arrangement in which the tubes are disposed in a rectilinear fashion the diagonal spacing of which is greater than the side spacing'. Forthe purposes of this invention, the evenly spaced arrangement of Fig. l has some advantages because longitudinalpathsthrough the array are provided in three different directions, designed by the arrows A-A, l- B and C-C of Fig. l, as cornpared with the two paths A-A and B-B of Fig. 4.

The tool itself is of rather simple construction, it being formed ofan elongate support 3 formed of a handle portion 4v and a yoke portion 6, the handle being` used to manually move the tool through the rows and the yoke providing bearings for the cleaning elements to be described. Preferably, these cleaning elements are roller Scrapers 7, the shafts of which are journaled in bearings provided in yofre portion 6, the rollers being formed with threadedV working surfaces S that maybe case-hardened to insure` adequate scraping, cutting and shearing action.

However, for other cleaning purposes, the cleaner design can be varied considerably in that they might be formed of wire brush, libre, non-ferrous metal, hard rubber or suchv other material as may be considered best suited for the particular cleaning job.

. In cleaning operations, the tool is inserted longitudinally between laterally spaced rows of tubesalong a path, such as the path indicated by arrows A-A of Fig. l, and, with the cleaners engaging the tube surfaces, the tool' then is reciprocated horizontally along the longitudinal extent of thel engaged tubes until all scale is removed. The effectiveness of the cleaning is insured by the fact that the rollers are so mounted and sized as to engage and exert a row-spreading pressure on the tubes, this pressure causing the tubes to bow or spread a slight distance to permit'pas.

sage of the tool. Generally, the row-spreading action is achieved by assuring that the etfective width of the tool, or, in other words, the transverse distance between the threaded working surfaces at each side of the tool, is at least as great, and preferably greater than, the row spacing, which spacing, for purposes of description, may be considered as the perpendicular distance between tangents common to laterally adjacent tubes in the rows to be cleaned.

Another feature of the invention already considered in a general fashion is that the tool is steadied in its tube engaging and working position by a four-point support provided by its rollers, the tool most suitably being formed with at least four rollers 9, 11 and 12, 13, two of these rollers projecting outwardly from each side of the tool v body or support. To provide the four-point support, these are so carried that they simultaneously engage four of the tubes, such disposition being obtained when the lateral distance between the rotational aXes of the'rollers at each side of the support is equal to the lateral distance between the axes of adjacent tubes in the rows to be engaged. Stated in another manner, thedistance between rotational axes'or rollers 9 and 12 is equal to the distance-between the axes of tubes 14 and i6 (Fig. l).

With this arrangement, when the'tool is inserted into path A--A, the rollers engage their respective'tubes in the manner shown and, the perpendicular distance between working edges of rollers 9-11 and 12-13 being preferably greater than the tangential spacing of the rows, the tubes in the rows are spread slightly to set up a resiliency in the tubes that will assure a positive and eective cleaning engagement of the tube surfaces. The amount by which the tubes may be spread or, in other words, the permissible working width of the tool, is a functionof the maximum allowable stress atthe tubel joints'and also a function of the relative hardness of the; tubes andthe rollers. It, of course,.is mostdesi'rable to avoidinjury tov the tubes or their jointed connection in plates 2, although it has been found that no injury results from controlled bowing pressure exerted along the longitudinal center portions oi the tubes. For cleaning in the proximity of the tube joints, a tool having an eective working width just equal to the row spacingV is recommended. Such a tool also is advisable for general use in certain cleaning operations, and a more thorough scale removal is possible in the area of the tube joints if the rollers are so constructed and mounted as to overhang, or project outwardly beyond, one side of a leg yoke portion 6.

Another feature of the invention lies in the specific construction of the rollers which, as has been stated, are formed with threaded or serrated working surfaces. In this respect it has been found most suitable to alternate the pitch of the threads of these rollers so that the first two rollers, rollers J and 11, are formed with what may be considered as left-hand thread, while the second two rollers 12 and i3 are formed with a right-hand thread. This alternating of the pitch of the threads results in a shearing action on the scale and facilitates cleaning operations. if non-rotatable cleaning members are utilized, it, nevertheless, is desirable to alternate the serrations of these members so asto achieve a similar shearing yaction.

The modification illustratedv in Figs. 4 to 6 is one that is adapted for cleaning a nest of tubes in which the tube arrangement is rectilinear or quadrilateral. The tool is substantially the saine as that previously described with respect to Figs. l to 3 except that, as may be noted, the lateral spacing of the roller is varied to insure their desired simultaneous engagement of lateral spaced tubes of each adjacent row.. ln cleaning such a quadrilateral arrangement of tubes, it may benoted that the tool only can be passed through the tube nest in two different directions, these directions being indicated by the arrows AA and B--B. However, in practice, it has been found that cleaning performed in this manner is adequate. With the equidistant spacing of. Fig. l, the tool may be passed in the directions or paths indicatedv by arrows A-A, B-B and C-C', a conditionwhich assures a thorough cleaning.

One particular advantage of the present tool stems from the fact that its tube cleaners or rollers are fixed, instead of resiliently mounted on the tool support. As has been stated, prior tools required spring-pressed cleaning memberstand it was found that such springs were not effective and would not stand up under continued use. The present tool utilizes the natural resiliency of the tube and, in so doing, achieves a far more dependable action and'permits a much simpler structural arrangement. The tool also permits easier and quicker cleaning operations due to roller design andto the fact that the tool as a whole is steadiedand guided during its manipulations by its four-point support. As may be surmised, the tool may be reciprocatedeither manually, or if desired, it may be mechanically attached to a source of reciprocating drive. Although the cleaningaction of theftool has been stressed inv the above'descripti'on, it also should be noted that-the eiiiciency and speed'permitted by this particualr construc tion isl an important factor, since it reduces the time required for boiler or evaporator shutdowns for cleaning. In some instances it may be found possible to increase the speed of the cleaning operation by the use of three or moreipairs ofV rollers instead of the two pairs illustrated inV the drawings, although, in practice the two pairs of rollers have been found most suitable. However, even one pair of cleaners is advantageous providing they are adapted to exert the described spreading action.

In cases Where the incrustation is of a viscous or gummy nature and not susceptible to cracking oft the tubes, it might be` desirable'to use rollers of different form or compostion'suchas wire brushes or serrated or fluted rollers of fibre, hard rubber, or. other "material, In such cases it.might1also bel more preferable to provide.l gearing, or the.: like, adapted tocausethe rollers to rotate counter to lth'eirlnormal f rollinglmovement over.v thetube surfaces, so as to produce a scraping action rather than a cutting and shearing action.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A tool for cleaning the exterior surfaces of laterallyspaced rows of evenly-spaced tubes, said tool comprising an elongate handle member, an elongate support member forming a continuation of said handle and being reciprocably insertable transversely of said tube axes in the space between laterally adjacent rows, and a plurality of parallel elongated cleaners mounted transversely to and along the elongate extent of the support member, said cleaners being arranged in a longitudinally staggered relationship one to the other to the extent that successive cleaners project outwardly from opposite sides of the support a sulcient amount for contacting the tubes of said laterally adjacent rows when said support is inserted between said rows, said cleaners further being spaced along said support for permitting the cleaner axes to simultaneously align with all of said contacted tubes, whereby constant self-alignment of said tool during said insertion and reciprocation is provided.

2. A tool for cleaning the exterior surfaces of laterallyspaced rows of evenly-spaced tubes, said tool comprising an elongate handle member, an elongate support member forming a continuation of said handle and being reciprocably insertable transversely of said tube axes in the space between laterally adjacent rows, and a plurality of parallel threaded roller cleaners mounted transversely to and along the elongate extent of the support member, said cleaners being arranged in a longitudinally staggered relationship one to the other to the extent that successive cleaners project outwardly from opposite sides of the support a sucient amount for contacting the tubes of said laterally adjacent rows when said support is inserted between said rows, the successive roller cleaners projecting outwardly on each side of the support being oppositely threaded for successively, during tool reciprocation, engaging each tube of each row with an oppositely threaded working surface, and said cleaners further being spaced along said support for permitting the cleaner axes to simultaneously align with all of said contacted tubes, whereby constant self-a1ignment of said tool during said insertion and reciprocation is provided.

3. A tool for cleaning the exterior surfaces of laterallyspaced rows of evenly-spaced tubes, said tool comprising an elongate handle member, an elongate support member forming a continuation of said handle and being reciprocably insertable transversely of said tube axes in the space between laterally adjacent rows, and an evennumbered plurality of parallel elongated cleaners mounted transversely to and along the elongate extent of the support member, said cleaners being arranged in a longitudinally staggered relationship one to the other to the extent that successive cleaners project outwardly from opposite sides of the support a sucient amount for contacting the tubes of said laterally adjacent rows when said support is inserted between said rows, said cleaners further being spaced along said support for permitting the cleaner axes to simultaneously align with all of said contacted tubes, whereby constant self-alignment of said tool during insertion and reciprocation is provided.

4. A tool for cleaning the exterior surfaces of laterallyspaced rows of evenly-spaced tubes, said tool comprising an elongate handle member, an elongate support member forming a continuation of said handle and being reciprocably insertable transversely of said tube axes in the space between laterally adjacent rows, and an even-num bei-ed plurality of parallel threaded roller cleaners mounted transversely to and along the elongate extent of the support member, said cleaners being arranged in a longitudinally staggered relationship one to the other to the extent that successive cleaners project outwardly from opposite sides of the support a suicient amount for contacting the tubes of said laterally adjacent rows when said support is inserted between said rows, the successive roller cleaners projecting outwardly on each side of the support being oppositely threaded for successively, during tool reciprocation, engaging each tube of each row with an oppositely threaded working surface, and said cleaners further being spaced along said support for permitting the cleaner axes to simultaneously align with all of said con tacted tubes, whereby constant self-alignment of said tool during said insertion and reciprocation is provided.

References Cited in the tile of this patent UNITED STATES PATENTS

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