US2973583A - Tube calipering device - Google Patents

Description

March 7, 1961 D E, STQLLE ET AL 2,973,583

TUBE CALIPERING DEVICE Inventors B J florney .D 0 .D u w E n m e &\ E E 6N t w am 2 \l .14, 6 4 6 \l fiZ /fl! w o 8 H; E z iZ \W Q v Q m. p a rl M m 3 n Donald E. Srolle Newbold 0. Cross FlG.-IA

Filed Sept. 12, 1958 March 7, 1961 D. E. STOLLE ETAL 2,973,533

TUBE CALIPERING DEVICE Filed Sept. 12, 1958 2 Sheets-Sheet 2 FIG-3 Donald E. Srolle N b Cross Inventors Y Attorney TUBE CALIPERING DEVICE Donald E. Stolle, White Plains, N.Y., and Newhold 0. Cross, Berkeley Heights, N..l.; said Stolle assignor to Standard-Vacuum Oil Company, a corporation of Delaware, and said Cross assignor to Esso Research and Engineering Company, a corporation of Delaware 'Filed Sept. 12, 1958, Ser. No. 760,797

2 Claims. (Cl. 33-178) The present invention relates to an improved-device for calipering the internal surface of tubular conduits. The invention particularly relates to a device for cating and measuring surface irregularities such as are produced by erosion, corrosion, and especially that resulting from mechanical damage of the internal walls of conduit tubes such as employed in heat exchangers, tubular reactors, furnaces and the like.

Such tubes are usually of small diameter, and in addition to damage resulting from normal service, may develop internal accumulations of carbonaceous deposit. In reactor tubes, where the tubes are packed with solid catalysts, the catalyst particles may become so coated with reaction products as to completely block the tube. In any event, the deposits and other obstructions usually require removal by drilling and wire brushing. This must be done by means of a drill head or brush mounted on a rotatable shaft which can be extended for the length 7 of the tube. Due to the length of shaft required, it tends to develop a whipping motion, causing the drill head or brush to deviate from a path concentric with the tube, and thereby to strike against and damage the tube inner surface. On occasion such damage, termed gun cuts, may be severe enough to render a tube unsafe.

It is an object of the present invention to provide means whereby the location and depth of such gun cuts and other irregularities in the inner surface of tubular conduits may be determined. It is a particular object of the invention to provide such a means, wherein determination is accomplished by a unitized feeler and transmission assembly which is quickly and easily replaceable in the main body of the caliper unit. A further object of the invention is to provide a calipering device, employing an electrical indicating system, and suitable for use in the presence of potentially explosive atmospheres.

The invention and its objects may be more fully understood from the following description, when it is read in conjunction with the accompanying drawings, where- 1n:

Figs. 1A and 1B illustrate opposite end portions of the device arranged to show their assembled relationship and disposition in a tubular conduit. Each figure provides a view in longitudinal section diametrically of the device and conduit, with a portion of the device shown in elevation by Fig. 1A;

Fig. 2 is a view in cross section, taken along the line II--II of Fig. 1B;

Fig. 3 is an exploded view of the feeler and transmission mechanism according to the present invention; and

Fig. 4 is a perspective view of an instrument case adapted to contain means for exhibiting electrically the irregularities encountered by passage of the device through a tubular conduit.

Referring now to the apparatus components as illustrated by Figs. 1A, 1B, 2, and 3, the numeral 1 desiginserts for the head and tail portions 201 and 20.

2,973,583 Patented Mar. 7, 1961 nates a tubular conduit, such as heat exchanger, or a reactor tube. The numeral 1a designates a pit in the internal surface of the tube, and the numeral 2, a caliper device according to the present invention, wherein the portion designated 2a in Fig. 1A is the head portion of the device, the portion 2b in Fig. 1B is the central portion and the portion 2c is the tail portion. In Fig. 1A the head portion 2a is shown partly in longitudinal section and partly in elevation, while in Fig. 1B, the central portion and tail portion are illustrated in longi tudinal section. A part of the head portion 2a as shown in Fig. 1A, including the externally threaded coupling end 3, also is shown in Fig. 1B. As shown, the end 3 of portion 2a is adapted for threaded engagement in the internally threaded coupling end 4 of the central portion 2b, as shown in Fig. 1B.

The head and tail portions 2a and 2c separated by central portion 2b form a tubular housing adapted to contain a caliper mechanism, including means for centering the housing in a conduit tube. Caps 5 and 6 provide end closures for the head and tail portions respectively of the housing.

At each end of the housing, the respective portions 2a and 2c define a circumferential series of longitudinally extending slots such as the slots 7 in portion 2a, and the slots 8 in portion 20. These slots 7 and 8 provide for extension therethrough of a corresponding series of centering wheels or rollers 9 and 10, adapted to engage the inner surface of the conduit 1, in the manner shown, whereby to center the housing in the conduit.

The wheels 9 and 10 are parts of an identical pair of The insert for the head portion includes inner and outer cylindrical plug portions 11 and 12, respectively, each having obverse and reverse surface portions 11a and 11b, and 1242' and 12b. The plug portions 11 and 12 are joined and spaced in coaxial relation by means of a tube 13 which is disposed in parallel eccentric relation to the axis common to each plug portion. The tube 13 is frictionally engaged at each end. in passageways 14 and 15 defined in and opening through the obverse and reverse surfaces of the respective plug portions. A series of paired spring supports 16 are mounted in vertical receiving recesses or passageways 17 defined in the plug portion 11, each pair of spring supports being adapted to provide a mount for the wheels 9 audit), and to extend the wheel outwardly and radially of the insert. The pairs of recesses 17 are disposed in spaced relation peripherally of the plug portion obverse surface 11a, so as to correspond with the spacing of the slots 7, whereby the' wheels may extend therethrough. The insert, .in-

eluding plug portions 11 and I2, is adapted for slidable insertion into the housing head end portion 2a, and is retained therein as by means of set screws 18 and 19.

When thus inserted, and the cap 5 applied, a chamber 20 is formed between the cap and the obverse surface 12a of the plug 12. The reverse surface 12b defines a series of recesses 21 which are arranged so as to correspond with the slots 7 in the housing of head portion 2a, and adapted to serve as wheel guides for the wheels 9.

The insert provided for the opposite end of the housing, and adapted for slidable insertion in the tail end portion 20, is shown in Fig. 1B. As noted, this insert is identical with that for the head end portion 2a. In Fig. 1B, the several parts of the tail end insert are designated by numerals corresponding to those for the parts of the head end insert shown in Fig. 1A, except that in Fig. 1B such numerals are all in the series.

In addition to the slots 8 defined in the wall of the tail portion 20, the threaded coupling end also defines a second circumferential series of slots which extend longitudinally through the central portion 2b; these slots are designated in Figs. 18 and Fig. 2 by the numeral 30. Preferably the slots 36 are arranged as diametrically opposed pairs. As shown in Fig.2, three such pairs are provided.

The coupling end of the central housing portion 212 also is adapted to receive the feeler and signal transmission unit including a cylindrical plug 31 having obverse and reverse surface portions 31a and 31b, which plug is insertable in the central portion for a sliding fit therein. A set screw, not shown, is provided through the wall the central portion 2b to retain the plug. In the assembled housing, the plug 31 divides the housing as a partition, to form a chamber 32 between the plug portion surface 11b and the reverse surface portion 3112. This chamber 32 communicates with the chamber '26, by way of the tube 13.

The plug 31 is provided with a concentric passageway 33 opening at the ends thereof through the obverse and reverse surface portions of the plug, 31a and 31b, respectively. That portion of the passageway which opens through the obverse surface portion 31a is enlarged to provide an outwardly facing internal annular shoulder 34. The enlarged portion of the passageway 33 is designated in the drawings by the numeral 33a. The passageway is provided to receive a plunger element having a shaft 35 and a head portion 36, the shaft and head portions together being slightly longer than the passageway, with the shaft disposed for sliding reciprocal movement in the passageway and the head portion 36 similarly disposed in the enlarged portion 33a. A helical expansion spring 37 is disposed between the head portion 36 and the annular shoulder 34, being adapted to bias the plunger in the direction of the plug obverse surface portion 31a.

The plug 31 defines a series of slotted portions 38 disposed in spaced relation circumferentially of the plug. The spacing of these slotted portions conforms to the spacing of the slots 30 in the housing portion 2b of Fig. lB. Each slot opens through the obverse and reverse surface portions 31a and 31b and extends inwardly into spaced relation to the wall of the passageway 33 adjacent the reverse surface portion, and opens through the wall of the enlarged passageway portion 33a. Between slotted portions the peripheral edge of the obverse surface portion is chamfered as at 39 providing a series of paired ear portions 40 each of which is drilled to receive a retainer pin 41. In addition, the plug 31 defines a series of recesses 42 of substantially circular cross section, each having an axis centered on the center line of a slotted portion 38 and extended inwardly toward the axis of the plug 31 into spaced relation to the passageway 33 defined therein. Each such recess provides a receptacle for an expansion spring such as designated in Figure 1B by the numeral 43. A second passageway 44 is defined in the plug 31 eccentrically thereof so as to open through the respective surface portions thereof.

Each of the slots 38 is adapted to receive a feeler element 4S pivotally mounted therein by means of a pin 41. Each feeler element is formed and mounted so as to provide a finger portion 45a adapted for extension from a slot under pressure of spring 43 against the inner edge of the feeler and a plunger-head, bearing lip 45b extending inwardly from the feeler inner edge, and adapted to engage the outer surface of the plungncr head portion 36. The springs 43 and 37 are compressed so that the pressure exerted by any one of the springs 43 will exceed the pressure exerted by the spring 37. When the plug 31 is inserted in the slotted end of the central housing portion 2b, the fingers 45a are adapted for extension through the respective slots 30 under pressure of the springs 43. A sleeve 52 on the central housing portion 2b is provided for reciprocal movement thereon to engage the feeler fingers 45a, whereby to retain them in at least a partly retracted position.

The reverse surface portion 31b of plug 31 provides a mounting surface for a support member 61 mounted thereon, as by means of screws 61a, in perpendicular relation to the surface 31b. The outer end of the support 61 is adapted to receive a rotatable shaft 62 on which is a pinion 63. The support 61 is also provided rotatably to receive a shaft 64 carrying a sector gear 65 in meshing relation to the pinion 63. The shaft 64 also carries in fixed relation thereto a crank arm 66. A link 68 is pivotally connected to the crank arm 66 and shaft 35 respectively substantially as shown. The relationship of these parts is particularly illustrated by the exploded view of Figure 3. In this view the support for the outer ends of the shafts 62 and 64 have been omitted for better illustration of the parts themselves. In Figure 18, however, the numeral 67 designates a plate support member mounted in spaced relation to the support 61, and secured thereto by means such as spacer bolt 67a, whereby to engage and support the outer ends of the shafts 62 and 64. The plate support 67 also provides a mount for a voltage divider resistance element 71 having wire connections 71a and 71b, respectively. A voltage divider slider element 72 is mounted on the outer end of the shaft 62 for arcuate movement thereby over resistance element 71. The slider 72 also is provided with a wire connection 72a.

The wire connections 71a, 71b, and 72a are extended from their voltage divider connections through the passageway 44 and tube 113 toward the tail end of the housing. The three connections form part of a 3-wire conductor 81 extended through a passageway 6a in the cap 6. A coupling 6b provides means whereby the conductor 81 is fixedly associated with the cap and thereby with the housing.

Referring now to Figure 4, the numeral 90 designates an instrument case having an internal partition 92 dividing the case into chamber portions 90a and 90b. The partition 92 defines a series of passageways 92a communicating between the respective chamber portions. The case 96 provides a housing for a voltmeter 82, battery 83, and resistance elements 84, 85, and 86, all connected in the voltage divider circuit through a switch 87. The resistance element 86, as indicated, is a variable resistor.

Although not shown in Figure 4, the case would be provided with a pair of cover plates adapted to be mounted on case rim portions 91 and engaged therewith in substantially sealed relation by means such as stud bolts 91a. The wire connections 71a, 71b, and 72a are brought into the chamber portion 90a by means of the conductor 81 which is extended through a coupling device, designated by the numeral 93, which is adapted to hold the conductor in fixed and fluid tight relation to the case. Preferably the voltmeter 82, switch 87, and the variable resistor element 86 will be mounted on the cover plate provided for the chamber 90a whereby they may be available for observation or actuation. The connections to these elements and the remainder of the wiring circuit may be loosely disposed within the chamber. The threewire conductor cable 81 may be provided with suitably spaced marks indicating progressively from a line adjacent cap 6 the total distance from the feeler elements 45 to and point along the cable. Preferably such marking will be in feet and inches.

In the voltage divider circuit as shown, the resistor 84 is disposed in series with the voltage divider resistance to simulate infinite resistance whereby to decrease current consumption. The variable resistor 86 is shunted across the internal resistance of the voltmeter 82 whereby to regulate the sensitivity thereof, to permit initial adjustment of the meter to a zero reading, and to compensate for feeler finger wear.

In operation, the chamber 90b is first filled with Dry Ice as is also the chamber 29 in the 'housing 2. This is done to provide a non-explosive atmosphere in the areas surrounding electrical connections such as those existing awaees in the chamber 99a and in the chamber 32. Transformation of the carbon dioxide from its solid form to its gaseous form produces a pressure which is transmitted from the chamber 90b to the chamber 90a by way of the passageways 92a, and from the chamber 20 to the chamher 32 by way of the passageway provided by means of the tube 13. in each instance an atmosphere of gaseous carbon dioxide is created in the vicinity of such electrical connections, which accomplishes exclusion of any combustible or explosive atmosphere existing within the tube 1, or adjacent areas. When thus prepared for use, the feeler elements 45 are at least partly retracted by moving the sleeve 52 toward the head end of the assembled housing whereby to engage the fingers 45a forcing them into the slots 38 against the pressure exerted by the springs 43. Retraction of the feeler elements permits the plunger head and shaft portions 36 and 35, respectively, to move outwardly toward the obverse portion surface 31a of the plug 31. In doing so, the crank 66 moves the sector gear 65 arcuately and in turn moves the slider 72 through the gear #33 and shaft 62. The slider 72 is moved toward the terminal connection of the wire connector 71b to the voltage divider resistor element 71. The housing may then be inserted in the tube to be calipered by depressing the wheel elements S and against the pressure of their respective spring supports. In any suitable fashion the housing is then passed entirely through the tube to the end opposite that of its insertion. The sleeve is then retracted to permit extension of the fingers. The housing is then drawn toward the insertion end of the tube while compressing feeler elements as required to permit re-insertion of the device in the opposite end of the tube. At this point, with the fingers 45a in engagement with the inner surface of the tube, the variable resistor 86 is adjusted to provide a zero reading on the meter. The housing is then drawn through the tube by means of the conductor 81. If any gun cuts or other irregularities are present, such as the pit 1:; shown in the drawing, one or more of the fingers will be extended to a degree greater than permitted by a regular tube surface. When thus extended, any one or more of the bearing lip portions 4517 will press against the plunger head portion 36 moving the shaft outwardly from the passage 33. Through the link 68 and crank arm 65, the sector gear 65, through pinion 63, translates this straight line motion into arcuate motion of the slider 72 on the resistor 71 thereby changing the voltage impressed on the meter 32. This change in voltage is readily translated into an indication of the depth of the irregularity encountered by the finger portions 45a. If the irregularity encountered by two or more finger portions is of varying depth, then the deepest portion encountered by any finger is that which will be shown by the meter. The meter reading may either be compared with a predetermined scale of readings indicating various pit or other irregularity depths, or preferably the meter may be calibrated and scaled to permit a direct depth reading in fractional inches. As previously stated, the housing is substantially centered in the tube being measured by means of the spring mounted wheels 9' and 10. The exact location of any irregularity indicated in this manner with reference to either end of the tube will be provided if suitably spaced marks or linear indicia are carried on the conductor cable 81.

What is claimed is:

1. A calipering device for measuring irregularities in the internal diameter of a tubular conduit, comprising a tubular housing adapted to fit said conduit freely, said housing including head, central, and tail sections, said head and tail sections having outer ends forming opposite ends of said housing, the head and tail section each containing a series of slots opening through said ends to extend longitudinally of said sections and disposed in spaced relation circumferentially thereof, a partition insert disposed intermediate the ends and within each of the head and tail sections, a removable cap for each outer end, the head section cap and the partition insert for this section defining a first chamber adapted to be charged with an inert gas forming material including solid carbon dioxide, an insert in said central section including a cylindrical solid body portion having obverse and reverse surface portions, said body portion coaxially defining a passageway opening through said surface portions and enlarged inwardly from said obverse surface portion to form an internal annular shoulder, a plunger element including substantially integral shaft and head portions disposed for reciprocal movement longitudinally of said passageway with said head disposed and slidably fitted in the passageway enlarged portion, said body portion containing a series of slots extending longitudinally thereof and in circumferentially spaced relation, the number and spacing of said slots corresponding to slots in the casing of said central section, said body portion slots opening through said obverse and reverse surface portions and through the wall of the enlarged passageway portion, a series of feeler elements pivotally mounted in said body portion slots, spring means biasing said feeler elements to extend them outwardly at one end through said slots in the housing of the central section and inwardly at the other end to engage the plunger head portion, a voltage divider means mounted on the reverse surface of said body portion, including a resistor and a slider movable thereover from end to end, means to move said slider including a link connection to the plunger shaft portion, the body portion reverse surface being disposed in spaced relation to the head section partition insert and defining therewith a chamber in said central section, said chamber adapted to contain said voltage divider means and mount therefor, with said central and tail sections in threaded engagement, a conduit communcating between the head section chamber and the central section chamber, meter means adapted to indicate the position of said slider and thereby the position of maximum extension of at least one of said feeler elements, conductor means for connecting said voltage divider and said meter means, including a conductor cable adapted to support and to draw said calipering device through a conduit to be calipered, and means to support and maintain said device in substantially coaxial reciprocally movable relation to said conduit.

2. A caliper device according to claim 1, wherein each of said partition inserts comprises a pair of cylindrical partition elements disposed in parallel, coaxial relation and in spaced relation longitudinally of their common axis, and said conduit communicating between said head section chamber and said central section chamber is in radially displaced parallel relation to said axis, said conduit being secured at the respective ends thereof in corresponding passageways defined in and opening through said respective partition elements.

References Cited in the file of this patent UNITED STATES PATENTS 2,150,070 Kregecz Mar. 7, 1939 2,324,865 Milligan July 20, 1943 2,518,663 Chaney et al. Aug. 15, 1950

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