Eddy current testing equipment and related methods

Abstract

An eddy current testing apparatus and associated method for performing nondestructive testing of heat exchanger tubes accessible through the tubesheet. The apparatus includes a motor-driven drive pulley and one or more idler pulleys that engage a test cable of a test probe, feeding the test cable and test head into and retrieving the test cable and test head from within the heat exchanger tube under test. The apparatus' support bracket includes a manually expandable tube clamp operated by an actuation lever. The clamp includes a tubular locking sleeve with an expandable portion that inserts into and releasably locks onto an anchor tube in the tubesheet, thereby cantilevering the apparatus from the tubesheet. The idler pulley is attached to a motor-driven pivot arm, which is movable between an inward position that presses the test cable against the drive pulley and an outward position that releases the cable for easy setup or removal.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application No. 63 / 422,174, filed November 3, 2022, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present invention relates to the inspection of metallic materials for defects, and more particularly to an improved eddy current testing apparatus and associated method suitable for inspecting cylindrical conduits such as heat exchanger tubes. [Background technology]

[0003] With increasing demands on the global power grid, it is more important than ever to keep power plant condensers, feedwater heaters, and other plant-wide heat exchangers operating at peak efficiency. While keeping these units clean is well-known to be crucial for maximizing power output, it is equally important to monitor the health of each unit's tubes and take corrective action to prevent tube failure, including identifying incipient defects that could lead to impending tube leaks. Nondestructive testing (NDE) is one method for monitoring the health of heat exchanger unit tubes, detecting patterns of wear and damage caused by tube-side and shell-side fluid flow, and identifying specific wear and damage on specific tubes. Depending on the tube material used, NDE can include eddy current testing, remote field testing, or other variations of these electromagnetic inspection techniques.

[0004] In eddy current testing, an eddy current testing unit generates an electromagnetic field in a metal structure, such as a heat exchanger tube, and measures the field to identify deformations or defects such as cracks, abrasion-induced wall thinning caused by fluid flow on the tube side and / or shell side, and other damage. The testing unit can also measure physical properties of the tube structure or component, such as metal wall thickness, hardness, and electrical conductivity.

[0005] Eddy current testing of heat exchanger tubes is typically performed by accessing the open ends of the tubes through the heat exchanger's thick tubesheet. The tubes penetrate the tubesheet and are typically densely packed in a staggered array. The test probe, consisting of a test head and a length of power / control cable, is typically manually inserted into the tube and manually advanced along its entire length. The tubes used in power plant feedwater heaters (heat exchangers) can often be 30 feet (approximately 9 meters) long or longer. A single tube bundle in a typical power plant high- or low-pressure feedwater heater can contain hundreds or even over 1,000 tubes. This inspection is typically a two-person job: one technician slowly and manually inserts the test probe into the tube, while the other monitors the test equipment's monitor / screen to read the signal generated by the probe and identify potential tube defects. Therefore, eddy current testing of such tubes is very time-consuming and cumbersome, and is not suitable for testing multiple tubes simultaneously.

[0006] In light of these circumstances, improvements in eddy current testing are required. Summary of the Invention

[0007] The present disclosure provides an eddy current testing apparatus and associated methods that overcome the drawbacks of conventional manual heat exchanger tube testing. The testing apparatus is configured and operable to be removably connected to a heat exchanger seat to access the tube to be tested. While installation and removal of the apparatus are performed manually, the performance of the eddy current testing can be automatically controlled by a servo motor-driven cable feeding mechanism operatively connected to a programmable controller. The drive mechanism includes a drive pulley connected to the motor and one or more driven pulleys operatively engaging the test cable of the eddy current test probe, thereby automatically feeding or retracting the cable and attached test head via the controller. In another embodiment, the motor can be manually controlled to feed or retract the cable. The test head and cable are inserted into the heat exchanger tube under test and incrementally advanced longitudinally while the controller receives and measures changes in voltage or impedance of a test coil within the test head to detect defects in the tube. The controller can include a visual display viewable by a single test equipment operator or technician. Therefore, a single operator or technician can perform the entire eddy current tube test, including setting up the test equipment and monitoring the electrical measurements transmitted from the test head to the controller. This is because, unlike the conventional method of manually inserting the test head and cable into the tube, the controller operates and controls the motor to advance the test head and cable. Depending on the equipment configuration, it is also possible to test multiple heat exchanger tubes in parallel simultaneously using several eddy current testing equipment functionally connected to the controller.

[0008] In some embodiments, the servo motor may be a stepper motor combined with an encoder. The stepper motor can incrementally advance the test head and cable into the tube under test using a step-by-step feed or indexing motion. The stepper motor and encoder combination can pinpoint the exact location of defects or anomalies within the heat exchanger tubes, allowing for corrective action to be considered.

[0009] One embodiment of an eddy current testing apparatus according to the present disclosure includes a support bracket with a pair of manually expandable tube clamps configured to be removably secured within heat exchanger tubes accessible through the tubesheet that are not being tested. The tube clamps cantilever the testing apparatus from the tubesheet. Each tube clamp includes an actuating lever with a cam head at its distal end, configured to cam action to radially expand an extension of the clamp to frictionally engage the inner surface of each anchor tube. The extension may be formed by a slotted end of a retaining sleeve connected to a faceplate of the bracket. Each actuating lever is pivotable between a locked position and an unlocked position to engage or disengage the tube clamp from the anchor tube.

[0010] A tapered alignment ferrule located on the bracket contacts the tube under test to feed and center the test head and cable into the tube. This facilitates setup of the test equipment and allows the cable to move smoothly in and out of the tube during eddy current testing. Multiple alignment ferrules may be provided with central through-holes of different diameters. These alignment ferrules can be interchangeably mounted on the test equipment bracket to test heat exchanger tubes of different diameters using test heads and cables connected to them of different diameters. This configuration provides a modular test system.

[0011] The eddy current testing apparatus according to a preferred embodiment of the present invention further includes a pivotable pivot arm, which in one aspect facilitates manual threading of the test head and cable through the alignment ferrule and into the tube under test prior to initiating a test, and withdrawal of the test head and cable after the test. The pivot arm is coupled to a bracket of the testing apparatus about a pivot axis. One or more idler pulleys are rotatably mounted on the arm. The pivot arm is pivotable between an inwardly engaged position, in which the one or more idler pulleys press the test cable against the drive pulley to maintain contact and maintain proper contact during cable delivery or retraction, and an outwardly released position, in which the one or more idler pulleys are positioned distal to the drive pulley. The outward (released) position is used when initially threading the test head and cable through the apparatus into the tube under test, and when retracting the cable after the test is completed. In one embodiment, two idler pulleys are preferably provided to position the cable at approximately a 90 degree contact angle with the drive pulley, allowing for smooth and precise cable extension and retraction through motorized operation. A return spring biases the pivot arm to an inwardly engaged position, ensuring that the test cable is always engaged with the drive pulley.

[0012] According to one aspect, there is provided an eddy current testing apparatus, comprising: a bracket configured to be removably connected to a tubesheet of a heat exchanger; a rotatable drive pulley supported by the bracket and operatively connected to a motor; a pivot arm connected to the bracket and pivotable about a pivot axis, the idler pulley including a first idler pulley; an eddy current test probe comprising a test head and a test cable, the cable being disposed between and engageable with a first idler pulley and a drive pulley; Including, the first idler pulley presses the test cable against the drive pulley to maintain an engaged state between them; When the drive pulley rotates in a first rotational direction, the cable is advanced from the device, and when the drive pulley rotates in a second rotational direction, the cable is retracted toward the device.

[0013] According to another aspect, there is provided a method for conducting eddy current testing of a heat exchanger tube, comprising the steps of: providing an eddy current testing apparatus including a bracket with a pair of tube clamps, each tube clamp including a radially expandable portion operatively coupled to a pivotable actuation lever configured to actuate the radially expandable portion, wherein the actuation lever of each tube clamp is in an unlocked position; positioning a bracket adjacent to a tubesheet of a heat exchanger including a plurality of heat exchanger tubes coupled to the tubesheet; inserting the expandable portion of each tube clamp into a respective fixation heat exchanger tube accessible through the tubesheet; pivoting the actuation lever of each tube clamp to a locked position; radially expanding the expandable portion of each tube clamp into frictional engagement with the inner surface of a respective clamping heat exchanger tube; Including, The test device is cantilevered from the tubesheet. [Brief explanation of the drawings]

[0014] The present invention will become more apparent from the following detailed description and the accompanying drawings, in which like elements are numbered the same.

[0015] [Figure 1] 1 is a first front perspective view of an eddy current testing device according to the present disclosure. FIG.

[0016] [Figure 2] FIG. 2 is a second front perspective view of the device.

[0017] [Figure 3] FIG.

[0018] [Figure 4] FIG.

[0019] [Figure 5] FIG.

[0020] [Figure 6] FIG. 1 is a first side view of the device.

[0021] [Figure 7] FIG. 2 is a second side view of the device.

[0022] [Figure 8] FIG.

[0023] [Figure 9] FIG.

[0024] [Figure 10] FIG. 1 is a cross-sectional view of the test fixture taken through an alignment ferrule mounted on the faceplate of the support bracket.

[0025] [Figure 11A] FIG. 1 is a diagram of an eddy current testing apparatus shown with the pivot arm in an outward deflected position and the test head and cable of the test probe disengaged during installation or removal of the testing apparatus.

[0026] [Figure 11B]FIG. 1 is a diagram of an eddy current testing apparatus showing the pivot arm in an inward position and the test cable engaged against the drive pulley during testing of a heat exchanger tube under test.

[0027] [Figure 12] FIG. 1 is a perspective view of the tube clamp assembly of the test device in isolation.

[0028] [Figure 13] FIG. 1 is a first exploded perspective view of a tube clamp assembly.

[0029] [Figure 14] FIG. 10 is a second exploded perspective view of the tube clamp assembly.

[0030] [Figure 15] The actuation lever of the tube clamp assembly is shown in the locked position.

[0031] [Figure 16] The tube clamp assembly actuation lever is shown in the unlocked position.

[0032] [Figure 17] 1 is a schematic diagram including a side cross-sectional view through a typical shell-and-tube heat exchanger that can be used with the present test apparatus, showing the tubesheet and penetrating heat exchanger tubes.

[0033] [Figure 18] FIG. 1 is a front perspective view of a tubesheet showing multiple eddy current testing devices removably mounted and operating in parallel to simultaneously perform eddy current testing of heat exchanger tubes.

[0034] All drawings are schematic and not necessarily drawn to scale, and numbered elements in one drawing that are not numbered in another drawing refer to the same element unless otherwise stated. DETAILED DESCRIPTION OF THE INVENTION

[0035] Features and advantages of the present invention are described below with reference to non-limiting exemplary embodiments (examples), which should be read in conjunction with the accompanying drawings as part of the entire description of the present specification. Therefore, the disclosure herein should not be limited to these exemplary embodiments, but is expressly intended to encompass all other possible embodiments, including any single implementation or any combination of the features shown in the examples.

[0036] In describing the embodiments described herein, references to directions and positions are for convenience only and are not intended to limit the scope of the present invention in any way. For example, relative terms such as "lower," "upper," "horizontal," "vertical," "top," "lower," "top surface," and "bottom," and similar terms (e.g., "horizontally," "downward," "upward," etc.), refer to directions relative to the orientation of the device in the description or relevant drawings. These terms are used solely for convenience of description and do not imply that the device must be manufactured or operated in a particular orientation. Furthermore, terms such as "mounted," "fixed," "connected," "coupled," and "connected" are intended to encompass both fixed, coupled, and connected relationships between components directly or via other configurations, as well as movable and rigid relationships, unless otherwise specified.

[0037] Numerical ranges used herein are used as shorthand notations that include all values ​​within the range. Any value within the range can be selected as the endpoint of the range. In addition, all references cited herein are incorporated by reference in their entirety. In the event of a discrepancy between the definitions in the references and the present specification, the definitions in the present specification shall prevail.

[0038] As used herein, the term "seal weld" or "seal welding" is to be interpreted in accordance with its conventional meaning in the art, which means a continuous weld that forms a gas-tight joint between the joined members.

[0039] 17 and 18 illustrate a typical shell-and-tube heat exchanger 200, the heat exchanger tubes 206 of which can be tested using the eddy current testing system 100 disclosed herein. The heat exchanger includes an elongated cylindrical shell 202 defining an interior cavity 203 containing a tube bundle 208 of heat exchanger tubes 206. The tube bundle may be either straight or U-shaped. The tubes are connected at least at one end to a thick-walled metal tube sheet 204, which has an inner surface 204a and an outer surface 204b facing the cavity 203. The tube sheet 204 is oriented perpendicular to the longitudinal axis of the elongated shell. The tube sheet shown in the figures is oriented vertically because the shells of this type of heat exchanger (i.e., shell-and-tube type) are typically oriented horizontally and rest on a horizontal support surface. However, the heat exchanger and tubesheet may be oriented in other ways (e.g., vertical shell and tubes with horizontal tubesheet), and the eddy current testing equipment disclosed herein can accommodate all of these orientations.

[0040] The open end 206a of each heat exchanger tube 206 in the tube bundle extends through a perforation in the tubesheet 204 from the inner surface 204a to the outer surface 204b of the tubesheet, where it terminates. The tube end may be rigidly secured to the tubesheet penetration by any suitable method known to those skilled in the art, such as explosion expansion, mechanical expansion, hydraulic expansion, welding, or other methods, or a combination thereof. In this manner, the open end 206a of the tube 206 is accessible for eddy current testing by a test equipment operator from the outer surface 204b of the tubesheet 204. The tubesheet is typically accessible through a heat exchanger head or channel 210, which includes a removable bolted or welded closure plate 209 (depending on the operating pressure of the heat exchanger). The channels 210 define an internal flow path plenum 211 for the tube-side fluid, while the internal cavity 203 of the shell defines the shell-side flow path. Tube-side fluid connections 212 are connected to the channels and are fluidly connected to the plenum 211 for introducing or discharging the tube-side fluid into the heat exchanger, depending on the flow direction and configuration of the installed heat exchanger (several designs of shell-and-tube heat exchangers are known). Also shown is a shell-side fluid inlet connection 207 connected to the shell 202 for introducing the shell-side fluid into the heat exchanger. An opposite shell-side fluid outlet connection (not shown) is also provided for discharging the shell-side fluid. Shell-and-tube heat exchanger configurations and variations thereof are known to those skilled in the art and need not be described in further detail here.

[0041] The eddy current testing system 100 of the present invention can be used with either straight or U-shaped tubes 206, as long as the open ends 206a of the tubes are accessible through the tubesheet 204. The eddy current testing system can also be used to test tubes 206 arranged in any pitch pattern on the tubesheet 204. A staggered (offset) pitch, as shown in FIG. 18, is commonly used to pack as many tubes as possible into the tube bundle. This saves installation space and reduces the shell diameter, resulting in a smaller tubesheet size for a given heat load (this is also affected by the thermal conductivity of the metal tubes used in the heat exchanger).

[0042] 1-16 illustrate a non-limiting embodiment of an eddy current testing apparatus 100 and its components disclosed herein. The figures show the apparatus in an upright (vertical) position, typically used for testing heat exchangers, which often have vertically oriented tubesheets. However, the apparatus may be oriented differently depending on the orientation of the tubesheet. For ease of description, in the illustrated orientation, the testing apparatus is defined as having a top 140, a bottom 141, a front face 142 facing the heat exchanger tubesheet, a rear face 143 facing away from the tubesheet, and left and right side faces 144, 145.

[0043] The eddy current testing apparatus 100 generally comprises components including a support bracket 102, a drive motor 104, a drive pulley 106 operatively connected to the drive motor, a pivot arm 110 including at least one idler pulley 108, and a tube clamp 120 attached to the bracket for removably connecting the apparatus to a tubesheet containing the heat exchanger tubes to be eddy current tested. For convenience of explanation and without limitation, reference axes may be defined as a horizontal axis (HA) and a vertical axis (VA), which intersect through the geometric center of the drive pulley 106 (see, e.g., FIG. 7).

[0044] In one embodiment, the bracket 102 includes a faceplate 102 and a motor support plate 103 fixedly attached to the faceplate. The motor 104 can be removably attached to the motor support plate 103 using suitable means, such as screws. The faceplate 102, in one embodiment, is flat and configured to be oriented parallel to the plane or surface 204 of the tube sheet 204 accessible for eddy current testing, through which the open ends 206a of the tubes 206 of the tube bundle 208 extend, as previously described. The faceplate 102 may also be oriented perpendicular to the motor support plate 103, which may also be generally flat. This allows the bracket 102 to form an overall T-shaped structure. Other bracket shapes may be employed as desired. The bracket may preferably be formed of a metal, such as steel or aluminum, or a material, such as a fiber-reinforced plastic, having suitable strength. The selection of the bracket material is not intended to limit the present invention.

[0045] The eddy current testing system 100 further includes an eddy current test probe 150, which is an assembly consisting of a test head 151 and a test cable 152. The test head 151 is connected to one end of the test cable 152, forming an electrical connection between the conductive traces within the cable and the test head to transmit electrical current and control signals for eddy current testing of the heat exchanger tube. The test head 151 may be an elongated, generally cylindrical "bobbin-type" head commonly used for eddy current testing of heat exchanger tubes. The test head and connected cable are advanced lengthwise through the tube to detect defects such as cracks on the interior surface of the tube or reduced wall thickness due to erosion from either the shell or tube side. Many commercially available test head and cable assemblies are compatible with the eddy current testing system of the present invention and can be used for internal eddy current testing of tubes.

[0046] The basic operating principle of an eddy current testing system is as follows: When the test coil built into the test head 151 is energized with an alternating current and positioned at the center of the heat exchanger tube under test, the alternating magnetic field generated by the coil generates eddy currents within the tube. The magnitude, phase, and flow pattern of these eddy currents are affected by the material properties (conductivity, permeability, shape, and size) of the workpiece and the presence or absence of defects. The coil's voltage and impedance change in response to this magnetic field. Therefore, the change in the test coil's voltage or impedance can be measured by a test unit (e.g., controller 250) to determine the nature, condition, and presence or absence of defects in the workpiece.

[0047] The motor 104 may be any commercially available motor capable of rotating the drive pulley 106 in both forward and reverse directions, thereby making the motor 104 a reversible motor capable of rotating the motor drive shaft 105 coupled to the drive pulley 106 in one direction to advance the test cable 152 out of the testing fixture 100 and advance the test head 151 into the heat exchanger tube 206, and rotating the motor drive shaft in the other direction to unwind the test cable and retract the test head 151.

[0048] In one embodiment, motor 104 may be a servo stepper motor that allows for precise, intermittent (indexing) control of the advancement and retraction of test cable 152 and test head 151 through the interior of the heat exchanger tube. As known to those skilled in the art, a stepper motor is an electromagnetic device that converts digital electrical pulses generated by a microprocessor in programmable controller 250 into incremental or "step" rotations (i.e., small angular steps) rather than continuous rotations like conventional motors. A dual-shaft stepper motor may be used with an on-board encoder 107 that measures the rotation and angular position of motor shaft 105 and transmits this information to controller 250. Based on this information from the encoder, the controller can be programmed to calculate the axial position of eddy current test head 151 relative to the length of the heat exchanger tube, thereby pinpointing tube-wall anomalies at specific locations along the tube. A dual shaft stepper motor has a single shaft 105 with opposite ends protruding from opposite sides of the motor housing (see, for example, FIG. 9), one end connected to a drive pulley 106 and the other end connected to an encoder 107.

[0049] The controller 250 may be configured to automatically control the entire eddy current testing process of the tube 206 under test, including operating the motor 104 to advance the probe's test head 151 and cable 152 stepwise into the tube under test and retract the head and cable from the tube when the test is complete. Conductive wiring in the cable provides a functional and communicative connection between the controller 250 and the test head, allowing the controller to receive test data signals from the test head, record defects in the tube in memory, and pinpoint their exact location. Based on this information, if the tube bundle is physically accessible, repairs can be made, such as welding or sealing cracks to prevent tube-side fluid leakage. Alternatively, in an operating heat exchanger where access to the tube is difficult without pulling the tube bundle 208 out of the heat exchanger shell, or if repairs are impractical, a plug can be installed in the tubesheet 204 of the defective tube 206, disabling the entire tube.

[0050] Controller 250 may be any suitable commercially available controller having a programmable processor with conventional electronics and peripherals and other necessary components to provide a fully functional, user-configurable controller. As a non-limiting example, the controller may be a computer (e.g., a laptop or other programmable device) running software that controls the eddy current testing.

[0051] Pivot arm 110 is pivotally connected to support bracket 102 via pivot pin 110a, which defines a pivot axis PA for the arm. In one embodiment, pivot arm 110 may have an L-shaped body. Pivot pin 110a passes through an upper end 111a of the arm and is attached to bracket 102. The opposite lower end 111b of the arm may be biased toward the bracket by a return spring 112 that connects the arm to the bracket (see, e.g., FIGS. 11A and 11B). In one embodiment, spring 112 may be a helical tension spring, although other suitable types of springs, such as a torsion spring, may be used as long as they are capable of biasing the pivot arm toward the drive pulley of the eddy current testing equipment.

[0052] The pivot arm includes at least one idler pulley 108 for pressing the test cable 152 against the drive pulley 106 to maintain precise contact therebetween. In a preferred, non-limiting embodiment, two idler pulleys 108a and 108b are provided, creating two spaced apart points of contact with the cable to maintain a contact angle of approximately 90 degrees (±5 degrees) between the test cable 152 and the drive pulley 106. The upper idler pulley 108b is positioned above the drive pulley 106 on the pivot arm 110 and presses the cable 152 against the top of the drive pulley, while the other idler pulley 108a is positioned to one side of the drive pulley (90 degrees away from the upper idler pulley) and presses the cable against the side of the drive pulley. This dual-idler pulley arrangement provides 90-degree contact between the test cable 152 and the drive pulley 106, advantageously allowing for smooth and accurate cable feeding and unwinding during motor operation. The L-shaped pivot arm body allows one idler pulley 108b to be mounted on top of the drive pulley 106 and the other idler pulley 108a to be mounted to its side, achieving 90-degree contact between the cable and the drive pulley. Each idler pulley is rotatably mounted to the pivot arm 110 via a cross pin 109, allowing for free 360-degree rotation during cable feeding or retraction. In one embodiment, the center of the upper idler pulley 108b intersects the vertical axis VA, and the center of the side idler pulley 108a intersects the horizontal axis HA. This means that both of these axes intersect the drive pulley 106. However, in other configurations, one or both of the idler pulleys may not be positioned on these axes.

[0053] The pivot arm 110 is pivotable about a pivot axis PA to facilitate manual routing of the eddy current test head 151 and associated test cable 152 between the idler pulleys 108 a, 108 b and the drive pulley 106 during initial setup of the eddy current testing apparatus 100. The pivot arm is movable between an inner, engaged position (see, e.g., FIG. 11B ) in which the idler pulleys 108 a, 108 b (or one of them, if there is only one) press the test cable 152 of the test probe 150 against the drive pulley 106, and an outer, released position (see, e.g., FIG. 11A ) in which the cable is released from the drive pulley. As shown in FIG. 11A , when the pivot arm is in the outer, released position, both idler pulleys are clear of the test cable 152. A convenient handle 113 is provided on the lower portion of pivot arm 110 near its lower end 111b for easy gripping by a test operator to manually move the arm between the two positions. To provide maximum leverage to open the pivot arm against the biasing force of return spring 112 and to ensure maximum displacement, the upper end 111a of the arm is attached to support bracket 102 via pivot pin 110a. This has the advantage of providing the longest possible lever arm and maximum arm displacement.

[0054] The faceplate 101 of the support bracket 102 includes a test probe feed opening 131 configured (e.g., sized and shaped) to allow the test head 151 and connected test cable 152 to slide through the opening from the drive pulley 106 and into the heat exchanger tubes 206 in the tubesheet 204. In one embodiment, a replaceable alignment ferrule 130 is provided and removably attached to the faceplate through the test probe feed opening. The alignment ferrule 130 includes a central through-hole 132 concentric with the test probe feed opening 131. The through-hole 132 is sized to be larger than the maximum outer diameter of the eddy current test head 151 and test cable 152 so that they can be fully inserted through the alignment ferrule through-hole and into the heat exchanger tubes to be tested in the tubesheet 204 of the heat exchanger 200, as described in more detail below.

[0055] In one embodiment, the alignment ferrule 130 has an annular body with a forward frusto-conical portion 130a disposed on the front major surface 101a of the faceplate 101, which faces the heat exchanger tubesheet when the test fixture 100 is in use, and a cylindrical rear portion 130b disposed on the rear major surface 101b of the faceplate 101. The ferrule 130 may have a monolithic body made of a single piece, as shown (see, for example, FIGS. 1 and 10, among others). The rear portion 130b is inserted into and secured in a test probe feed opening 131 formed in the faceplate 101 of the support bracket 102. The front portion 130a forms an annular lip 133 having a diameter larger than the test probe feed opening 131 in the faceplate 101 of the support bracket 102, and seats against the front surface of the faceplate. The frustoconical walls of the alignment ferrule 130 converge forward from the faceplate 101 and are partially inserted into the open end 206a of the tube under test 206 and engageable with the tubesheet 204. The ferrule 130, and in particular its frustoconical walls, facilitate the operator's guidance and centering of the ferrule in the tube under test opening in the tubesheet, thereby properly centering the eddy current test head 151 and cable 152 on the tube under test. Because the faceplate 101 of the instrument support bracket 102 may at least partially obstruct the view of the tube opening in the tubesheet 204 under test, the operator's longitudinal extension of the faceplate 101 significantly aids the operator in aligning the instrument and test probes with the tube being tested. The alignment ferrule can be fabricated from any suitable metallic or non-metallic material (e.g., plastic).

[0056] The alignment ferrule 130 is interchangeable, allowing for different diameters of eddy current test head 151 and cable 152 to be accommodated by replacing it with another ferrule having a different diameter through-hole 132. The cylindrical test head can have different outer diameters depending on the inner diameter of the heat exchanger tube. This advantageously allows the same support bracket 102 and associated components described above to be reused for testing different heat exchanger tubes having different tube diameters. Therefore, multiple alignment ferrules with the same structure and features, such as a frusto-conical shape, but with different diameters of through-hole 132 may be provided. Additionally, test equipment operators can carry multiple sizes of alignment ferrules with the eddy current test equipment and interchange ferrules as needed for different heat exchangers with different sized tubes at the test site.

[0057] The eddy current testing apparatus 100 includes a plurality of tube clamps 120 for removably connecting the apparatus to a tubesheet. The tube clamps 120 are configured and operable to secure to tubes of a heat exchanger that is not currently being tested for defects. In one embodiment, the tube clamps 120 can be removably coupled to the faceplate 101 of the support bracket 102, as described below.

[0058] A plurality of radially expandable tube clamps 120 may be attached to removably couple the eddy current testing apparatus 100 to a heat exchanger tubesheet for testing the heat exchanger tubes coupled thereto. In one embodiment, each tube clamp 120 is removably coupled to the faceplate 101 of the support bracket 102 via an adjustment slot 121 formed in the faceplate 101. This configuration allows the position of the tube clamp to be adjusted to insert and engage the clamp's locking portion to match the pitch of the available heat exchanger tubes 206 in the tubesheet 204. In one embodiment, the adjustment slots 121 are diagonally oriented relative to the horizontal axis HA and vertical axis VA of the apparatus 100. This allows the position of the tube clamp to be adjusted both horizontally and vertically relative to the heat exchanger tubes 206.

[0059] In one embodiment, at least two tube clamps 120 are provided, preferably one on each side of the probe test head and cable feed opening 131 in the faceplate 101 (and alignment ferrule 130). This provides a stable cantilever connection between the test fixture support bracket 102 and the heat exchanger tubesheet 204. In some embodiments, the bracket faceplate 101 has three or more alignment slots, allowing at least two heat exchanger tubes 206 to be aligned with the tube clamp locations on the faceplate. In some cases, more than two tube clamps may be used to provide a more stable support for the test fixture.

[0060] In one embodiment, each tube clamp 120 includes a cylindrical locking sleeve 122 having an enlarged end 127 with circumferentially spaced axial slots 123. These slots are configured to allow the sleeve material to expand radially outward when deformed by a radially expanding force acting from the inside outward. The slots 123 extend along the length of the sleeve and partially along the length of the sleeve to securely grip against the inner surface of the anchor tube of the heat exchanger tube to which the tube clamp is engaged. The slots 123 are arranged parallel to one another and define resiliently deformable fingers therebetween that can be expanded outward to frictionally grip the heat exchanger tube, as achieved by being widened by an expander plug 125, described in more detail below. To this end, the locking sleeve 122 may be formed of a suitable metallic material with a wall thickness that allows the enlarged end 127 of the sleeve to be resiliently deformable. In other embodiments, the sleeve may be made of plastic.

[0061] In one embodiment, the retaining sleeve 122 may be located on the front major surface 101a of the faceplate 101 that faces the heat exchanger tubesheet 204 when the testing apparatus 100 is in use. The sleeve has a length sufficient to securely engage the inner surface of the heat exchanger tube 206 to temporarily connect and secure the tube clamp. The retaining sleeve 122 may have an attachment end 138 (opposite the enlarged end 127) that may terminate near the front major surface of the faceplate 101. The retaining sleeve projects perpendicularly outward from the faceplate front major surface 101a and is configured to be inserted into an anchor tube in the tubesheet 204. Additionally, an annular base collar 139 may be provided that abuts the faceplate 101 and surrounds the attachment end 138 of the retaining sleeve on the front major surface 101a of the faceplate. The base collar has a circular receiving portion 139b that receives the mounting end 138 of the retaining sleeve 122, providing lateral support for the sleeve and preventing twisting of the sleeve when the actuating lever 126 is pivoted to the locked position, thereby maintaining perpendicularity to the faceplate. The base collar 139 also has a through-hole 139a through which the operating rod 122 passes to connect to the expander plug. The collar 139 may be removably and loosely positioned on the faceplate 101 of the equipment support bracket 102, with the collar 139 being held in compression by a tube clamp assembly consisting of the retaining sleeve 122, operating rod 124, and expander plug 125. In other embodiments, if the collar is made of metal, it may be fixedly attached to the faceplate and, if a more rigid, permanent attachment is desired, optionally coupled to the retaining sleeve by welding or the like.

[0062] As described above, tube clamp 120 includes a linearly movable operating rod 124 that passes through a fixed sleeve and an expander plug 125 attached near one end of the operating rod. Operating rod 124 passes completely through faceplate 101 and has a front portion 124a of the rod that projects outward from fixed sleeve 122 on the front side of the faceplate, and a rear portion 124b that projects outward from the fixed sleeve on the rear side of the faceplate.

[0063] The expander plug 125 has a threaded throughbore 125c for receiving and threadedly engaging the threaded forward portion 124a of the operating rod 124. The expander plug is positioned adjacent to and engageable with the slotted expander end 124 of the locking sleeve 122.

[0064] The expander plug 125 has a tapered configuration that engages and radially expands the slotted expanded end of each retaining sleeve 122 to frictionally engage and grip the inner surface of the heat exchanger anchor tube 206 to which the tube clamp 120 is removably engaged to support the eddy current testing apparatus 100. The expander plug has a substantially frustoconical shape over the majority of its length and is at least partially insertable into the expanded end 127 of the retaining sleeve 122 (see, e.g., FIGS. 13-16 ). The expander plug 125 includes an inner portion 125a having a diameter smaller than the inner diameter of the expanded end 127 of the retaining sleeve 122 and an outer portion 125b having a diameter larger than the inner diameter of the expanded end. The tapered walls of the expander plug gradually diverge outward from the inner portion toward the outer portion, in a direction away from the operating rod 122. When the operating rod 124 is retracted back into the locking sleeve 122 by pivoting the actuating lever 126, the outer portion 125b acts on the slotted enlarged end 127, spreading it radially outward and frictionally engaging the inner surface of the heat exchanger tube 206 to secure the tube clamp. The enlarged end 127 assumes an outwardly flared or flared shape as it expands radially.

[0065] To actuate and linearly move the operating rod 124, each tube clamp 120 includes a manually operated actuating lever 126 pivotally coupled to the rear end 124b of the operating rod. The lever 126 can linearly move the operating rod 124 in either a forward or rearward direction within the fixed sleeve 122. The actuating lever 126 has an elongated structure so that it can be easily grasped and manipulated by an operator of the testing equipment. The lever 126 includes a gripping end 126a and a cam actuating end 126b located adjacent to the rear end 124b of the operating rod 124, and operation of the lever actuates and linearly moves the rod.

[0066] To convert pivotal motion of the actuating lever 126 into linear motion of the operating rod 124 within the retaining sleeve 122 and radially expand the slotted, enlarged end 127 of the sleeve to grip an anchor tube of the heat exchanger, the camming end 126b of the lever is formed with a selectively engageable, arcuately curved cam surface 128a which functions in contact with a flat abutment surface 128b located on the rear end 124b of the operating rod. In one embodiment, the abutment surface 128b may be formed by a cam washer 129 having an opening 129a for allowing the rear end of the operating rod 124 to pass through the rear major surface 101b of the faceplate 101. The abutment surface 128b may have a curved configuration complementary to the arcuate cam surface 128a of the actuating lever 126.

[0067] In one embodiment, the operating rod 124 may be a partially or fully threaded rod connected to the cam actuation end 126b of the actuation lever 126. If partially threaded, at least the front and rear ends 124a and 124b of the rod are threaded for engaging the expander plug 125 and cam washer 129, respectively (the central portion may be unthreaded).

[0068] The camming end 126b of the actuating lever 126 forms an enlarged cam head 126e at one end of the lever. While generally circular, the cam head 126e has a non-uniform elliptical or lobular shape, with a curved outer surface extending along its periphery that defines a cam surface 128a and a release surface 128c. Thus, both the cam surface and the release surface may be arcuately curved. The cam surface 128a is adjacent to and continuous with the release surface 128c, adjacent one end of the release surface. The cam surface has a shorter arc length than the release surface 128c, which occupies a larger area around the cam head 126e. For purposes described below, the cam surface 128a is located furthest from the pivot pin 124c and is further from the release surface 128c. The length from the cam pin 124c to the outer surface of the cam head 126 may be gradually reduced, with the cam surface furthest from the pin and the release surface closest.

[0069] The cam head 126e of the actuating lever 126 may have a branched structure consisting of two spaced apart portions 126g, with a slot 126d formed between them and a hole 126c formed in each of the two portions. Each of the two portions 126g constitutes a cam surface 128a and a release surface 128c. The slot 126d is for receiving a pivot pin 124c, which is connected to the actuating rod 124 via a threaded through-hole 129b that threadably engages with the rear portion 124b of the actuating rod 124. The holes 126c in each of the two portions 126g are coaxial and receive the pivot pin 124c to pivotally connect the actuating rod and the actuating lever.

[0070] The actuating lever 126 of each tube clamp 120 is pivotable to move between (i) a locked position in which the operating rod 124 and expansion plug 125 are retracted toward the actuating lever and into the forward expanded end 127 of the fixed sleeve 122, causing the expanded end to spread radially outward (i.e., expand radially) and frictionally engage with the inner surface of the heat exchanger tube 206 to which the tube clamp is to be engaged, and (ii) an unlocked position in which the operating rod and the expansion plug attached to its end are pushed away from the actuating lever and out of the expanded end of the fixed sleeve, causing the expanded end to contract inward, releasing the tube clamp from the heat exchanger tube so that the tube clamp can be pulled out.

[0071] When the actuating lever 126 is in the locked position, the tapered expander plug 125 slides fully into the expanded end 127, forcing the expanded end radially outward, whereas in the unlocked position, the expander plug 125 retracts slightly from the retaining sleeve, sufficiently releasing the expanded end of the sleeve so that when the test rig operator manually pulls the tube clamp 120 off the heat exchanger tube 206 to which it is secured, the expanded end is no longer being pushed outward to allow the tube clamp 120 to be withdrawn.

[0072] When the actuating lever 126 is pivoted from the unlocked position to the locked position, the cam surface 128a slides into full engagement with the curved abutment surface 128b of the cam washer 129 (see, for example, the locked position shown in FIG. 15). As previously mentioned, because the cam surface is located farther from the pivot pin 124c than the release surface, contact between the cam surface and the abutment surface creates a linear force on the actuating rod 124, pulling the rod rearward due to the camming action of the actuating lever. This tightens the actuating lever, causing linear movement of the actuating rod. The actuating lever 126 can be approximately vertical (when in its normal upright vertical position as shown in the test fixture 100 diagram). As shown, the gripping end 126a of the lever is located near the faceplate 101 of the fixture bracket 102.

[0073] Returning the actuating lever 126 to the unlocked position releases the actuating lever, disengaging the cam surface 128a of the lever 126 from the abutment surface 128b of the cam washer 129. As previously mentioned, because the release surface 128c is located close to the pivot pin 124c, the actuating lever is in a relaxed state because the engagement between the release surface and the abutment surface 128b does not create a linear pulling force that would pull the expander plug into the locking sleeve. The release of the cam surface 128a from the abutment surface 128b immediately releases the tube clamp 120 to some degree. This may be sufficient to disengage the expanded end 127 of the locking sleeve 122 from the previously engaged anchor tube and allow the tube clamp to be withdrawn. Further pivoting of the actuating lever further loosens the engagement as the abutment surface 128b continues to slide along the release surface 128c of the lever's cam head 126e. When actuating lever 126 is in a substantially horizontal position to fully open and loosen the lever, slotted enlarged end 127 of locking sleeve 122 is allowed to contract radially to its maximum extent (see, for example, FIG. 16). However, as noted above, once cam surface 128a and abutment surface 128b are disengaged, the lever begins to loosen until the cam surfaces are disengaged and loosened, and the degree of loosening gradually increases as the lever is further rotated horizontally.

[0074] The following briefly describes a method or process for installing and using the eddy current testing apparatus 100 to inspect heat exchanger tubes for defects. Each tube clamp 120 of the apparatus can be initially configured by inserting an actuating rod 124, previously pinned to an actuating lever 126, through a predetermined alignment slot 121 from the rear to the front of the apparatus faceplate 101. At the front of the faceplate, the actuating rod passes through a base collar 139 and a retaining sleeve 122, with the threaded front portion 124a of the actuating rod projecting outward from an enlarged end 127 of the retaining sleeve. An expander plug 125 is then threaded onto the protruding tip of the actuating rod 124, with the tapered inner portion 125a of the expander plug partially inserted into the enlarged end 127 of the retaining sleeve 122 (see, for example, FIG. 16). During this setup process, the actuating lever 126 is in the unlocked position (i.e., the lever's release surface 128c is engaged with the curved abutment surface 128b of the cam washer 129). The test fixture is now removably secured to the heat exchanger tubesheet and is ready to conduct electrical current testing for defects in the tubes. The actuating lever can be left in the unlocked position at the beginning of the following procedure to facilitate adjustments for mounting the fixture to the tubesheet, as described below.

[0075] At least two tube clamps 120 are preferably provided to securely cantilever the device to the tube. This configuration provides a stable hold under almost all circumstances, resisting twisting caused by the device's own weight and the motor operating during insertion of the test probe into the heat exchanger tube 206 in the tubesheet 204. When possible, it is preferable to provide one tube clamp on each side of the alignment ferrule 130. Additional tube clamps 120 may be used for stable mounting if desired.

[0076] To attach the eddy current testing apparatus 100 to the heat exchanger tubesheet 204, the support bracket 101 of the testing apparatus 100 is moved toward the tubesheet 204 and positioned adjacent to the tubesheet. Each tube clamp 120 is then aligned for clamping to a tube 206 not currently being tested and inserted onto that tube, with the actuation lever in the unlocked position to leave the tube clamp loose. This allows the tube clamp's position on the faceplate 101 to be easily adjusted via the adjustment slots 121, as described above, to guide the clamp onto the heat exchanger tube selected for clamping. Such tubes are sometimes referred to as "anchor tubes" for convenience, but are distinct from the test tubes inspected by the eddy current testing apparatus 100.

[0077] During the process of inserting the tube clamp 120 onto the heat exchanger tube to be anchored, the tapered alignment ferrule 130 on the faceplate 101 of the device simultaneously partially engages the heat exchanger tube selected for testing. The tapered-walled frusto-conical portion of the alignment ferrule engages the heat exchanger tube. Once the test device operator or technician is satisfied that the test device is properly aligned and in place, they can manually rotate the actuating levers 126 to the locked position (see, for example, FIG. 15). This causes the cam surface 128a on the cam head 126e of each actuating lever to engage the abutment surface 128b of the corresponding cam washer 129, clamping the tube clamp. Engagement of the cam surface and the abutment surface (as described above) simultaneously draws the operating rod 124 rearward, further into the retaining sleeve 122, and simultaneously draws the larger diameter outer portion 125b of the expansion plug 125 into engagement with the slotted expanded end 127 of the retaining sleeve 122. This causes the expanded end to radially expand and frictionally engage the inner surface of the selected anchor tube, locking the tube clamp 120 to the tube. The test fixture is then removably cantilevered from the heat exchanger tubesheet 204.

[0078] The test probe 150, consisting of the test head 151 and attached test cable 152, is then manually loaded into the eddy current testing apparatus 100 and inserted into the tube under test. The use of the spring-loaded pivot arm 110 makes this process convenient and easy for the test apparatus operator. With the apparatus secured and supported on the heat exchanger tubesheet 204, the pivot arm is opened and manually rotated (against the biasing force of the return spring 112) to its outward, spaced-apart position, positioning the idler pulleys 108a, 108b away from the drive pulley 106 (see, for example, FIG. 11A). In FIG. 11A, this is done by moving the pivot arm upward. This provides sufficient clearance between the drive pulley 106 and the idler pulley 108, allowing the test head and cable to be easily threaded between the drive pulley 106 and the idler pulley 108, and then inserted through the through passage 132 of the alignment ferrule 130 from the rear side of the faceplate 101 and into the heat exchanger tube under test that is already engaged by the ferrule as described above. The cable can be engaged by hooking it onto the drive pulley 106 as shown.

[0079] When the operator releases the pivot arm 110, the pivot arm 110 automatically returns to its original inward, engaged position due to the action of the return spring 112 (which in FIG. 11B is a downward movement). This closing movement of the pivot arm causes the idler pulleys 108a, 108b to press the cable 152 of the test probe 150 against the drive pulley 106 (see, for example, FIG. 11B). This clamps the cable between the drive and idler pulleys, but allows it to rotate by rotating the drive pulley 106 via operation of the motor 104, as described above. The test apparatus 100 is now ready to perform an eddy current test on the tubing under test.

[0080] The controller 250 can automatically perform the inspection process of the heat exchanger tube by gradually feeding and advancing the test probe head 151 and cable 152 into the tube under test, and also receives test data signals sent from the test head to detect defects in the tube.

[0081] Once testing is complete, the above steps are reversed: first, the pivot arm 110 is moved back to its outward position to release the cable, and the test head 151 and cable 152 of the test probe 150 are withdrawn from the tube under test. The previously described process of attaching the tube clamp 120 to the anchor tube is then reversed to remove the test fixture 100 from the tube sheet. Specifically, the actuating levers 126 are returned to their unlocked positions, loosening the tube clamp assembly and radially contracting the slotted, enlarged end 127 of the retaining sleeve 122, allowing the test fixture operator to simply pull back on the fixture's support bracket 102 to remove the tube clamp from the anchor tube. The test fixture can then be reinstalled at the location of the next tube to be tested. Note that multiple eddy current testing fixtures can be simultaneously attached to a tube sheet, allowing multiple heat exchanger tubes to be tested in parallel.

[0082] As described above, once one or more test fixtures 100 are set up for testing and attached to the heat exchanger tubesheet 204, the eddy current testing of all tubes can be automatically controlled by the programmable controller 250.

[0083] Multiple Test Unit System

[0084] Time is of the essence when heat exchanger inspections are performed during power plant outages. The number of days a power generating unit cannot be returned to operation can cost tens of thousands of dollars in lost power generation and revenue, so the time frame allotted for equipment maintenance and inspection is short. The eddy current testing system configuration disclosed herein, which uses multiple eddy current testing devices 100 simultaneously, has the advantage of being able to test multiple tubes at once in conjunction with a controller 250, thereby making efficient use of inspector time. Each eddy current testing device is functionally and communicatively connected to the controller 250 via a wireless or wired communication link, allowing for simultaneous control and coordination of the testing of multiple tubes. Test data is transmitted from each device to the controller, where it is recorded and used for analysis.

[0085] Each eddy current testing device 100 can be quickly and manually attached to the heat exchanger tubesheet 204 by expanding and securing the tube clamp 120 inside the anchor tube adjacent to the tube being tested, as described above. Once installed, each device's eddy current probe cable is driven at a controlled speed, and the probe's position within the tube is measured by an integrated drive motor / encoder assembly. The position information and tube status of each device are recorded as data in the controller 250. A testing device operator or technician can operate one, two, three, four, or more devices simultaneously, provided there is sufficient workspace. Time savings can be achieved depending on the number of devices. A skilled inspection team can inspect 3,000 tubes in a single eight-hour shift.

[0086] The eddy current testing apparatus 100 disclosed herein offers numerous advantages, including the ability to easily insert the test probe head and cable through the support bracket 102 and into the tube under test by rotating the pivot arm 110 to its outward, released position after the test apparatus is attached to the tubesheet. The additional clearance provided by the pivot arm makes it easier for the test apparatus operator to thread the test head 151 and cable 152 of the test probe 150 through the apparatus' pulley arrangement (106, 108a, 108b) and into the heat exchanger tube under test. When the pivot arm is released, the arm automatically rotates inward under the action of the return spring 112, causing the idler pulleys 108a, 108b to press the test cable firmly against the drive pulley 106, ensuring reliable delivery of the test cable, allowing the eddy current test to be performed. It is worth noting that the spring 112 has the advantage of biasing the pivot arm 110 inward, thereby applying constant pressure to the cable at all times.

[0087] The manually operated actuation lever 126 of the tube clamp 120 allows the test device to be easily and securely attached and detached from the tubesheet, simplifying setup and teardown. Because the entire tube clamp remains attached to the device's support bracket, the test device operator can move the device from one tube under test to another without worrying about losing parts. The device is also compact and portable, allowing it to be easily transported, even with the drive motor attached. The device's small size allows multiple eddy current test devices to be operated simultaneously on the heat exchanger tubesheet 204, testing multiple tubes in parallel and reducing the time required to test the entire heat exchanger. Other advantages are discussed elsewhere in this specification.

[0088] While the foregoing description and drawings illustrate several example systems, it will be understood that various additions, modifications, and substitutions can be made thereto without departing from the spirit, scope, and equivalents of the appended claims. In particular, it will be apparent to those skilled in the art that the present invention can be embodied in other forms, structures, arrangements, proportions, sizes, and other elements, materials, and components without departing from the spirit or essential characteristics of the present invention. Various modifications are also possible in the methods and processes described herein. Those skilled in the art will further appreciate that the present invention can be implemented with various modifications in structure, arrangement, proportions, sizes, materials, components, and other aspects specifically adapted to particular environments of use and operational requirements, without departing from the principles of the present invention. Accordingly, the embodiments disclosed herein are intended to be illustrative in all respects and not restrictive. The scope of the present invention is to be defined by the appended claims and their equivalents, and should not be limited to the foregoing description or embodiments. Rather, the appended claims should be interpreted broadly to encompass other modifications and embodiments that may occur to those skilled in the art without departing from the scope of the present invention and their equivalents.

Claims

1. An eddy current flaw detection testing device, a bracket configured to be removably coupled to a tubesheet of a heat exchanger; a rotatable drive pulley supported by the bracket and operatively coupled to a motor; a pivot arm coupled to the bracket and configured to be pivotable about a pivot axis; an idler pulley including a first idler pulley; an eddy current test probe including a test head and a cable, the cable being positioned between and engaging the first idler pulley and the drive pulley; Equipped with the first idler pulley functions to press the test cable against the drive pulley to maintain engagement therebetween; 1. An eddy current flaw detection testing apparatus, comprising: a drive pulley configured to rotate in a first rotational direction to feed a cable out of the apparatus; and a drive pulley configured to rotate in a second rotational direction to retract the cable into the apparatus.

2. 2. The apparatus of claim 1, wherein the bracket includes a faceplate having a test probe feed opening for slidably passing the test head and cable from the drive pulley and into a first tube to be tested in the tubesheet.

3. 3. The apparatus of claim 2, further comprising a replaceable alignment ferrule removably coupled to the faceplate through the test probe feed opening, the alignment ferrule engageable with a first tube when the faceplate is positioned adjacent to the tubesheet.

4. 4. The apparatus of claim 3, wherein the alignment ferrule has an annular body with a central passage defining the test probe feed opening, the passage being sized to allow the test head and the cable to pass therethrough.

5. 5. The apparatus of claim 4, wherein the alignment ferrule has a two-piece structure including a rear member coupled to a front member through the test probe feed opening in the faceplate.

6. 6. The apparatus of claim 3, wherein the alignment ferrule includes a tapered frustoconical portion that partially inserts into and engages the open end of the first tube of a tubesheet to center the test head within the first tube.

7. 7. The apparatus of claim 2, further comprising a pair of tube clamps detachably coupled to the face plate, the tube clamps including tubular fastening sleeves having radially expandable portions insertable into second and third heat exchanger tubes, respectively, in the tube sheet, thereby securing the bracket to the tube sheet.

8. 8. The apparatus of claim 7, wherein each securing sleeve includes a radially expandable end portion that functions to frictionally engage an inner surface of the second or third heat exchanger tube to secure the bracket.

9. 9. The device of claim 8, wherein the expandable end of each fixation sleeve includes a plurality of circumferentially spaced slots disposed along the length of the fixation sleeve.

10. 10. The apparatus of claim 8 or 9, wherein each tube clamp includes an operating rod extending through the fixing sleeve and an expander plug coupled near a first end of the operating rod and engageable with the expandable end of the fixing sleeve, the expander plug configured to expand the expandable end of each fixing sleeve radially outward to frictionally engage the inner surface of the second or third heat exchanger tube.

11. 11. The device of claim 10, wherein the expander plug includes an inner portion that is inserted into the expandable end of the fixation sleeve and an outer portion that is positioned outside the expandable end and has an enlarged diameter that is larger than the inner diameter of the expandable end.

12. 12. The apparatus of claim 11, wherein each of the tube clamps includes a manually operated actuation lever pivotally connected to the second end of the operating rod.

13. 13. The device of claim 12, wherein the actuating lever (126) of each tube clamp (120) comprises: (i) a locked position in which the operating rod and the expander plug are directed toward the actuating lever and retracted into the locking sleeve, thereby expanding the expandable end of the locking sleeve radially outward to frictionally lock the tube clamp to the second or third heat exchanger tube; (ii) an unlocked position in which the operating rod and the expander plug are projected away from the expandable end of the actuation lever and the fixing sleeve, thereby contracting the expandable end radially inward to release the tube clamp from its engagement with the second or third heat exchanger tube; 10. A device characterized in that it is pivotable to move between.

14. 14. The apparatus of claim 7, wherein the tube clamp supports the bracket in a cantilevered manner from the tube sheet when the actuating lever is in the locked position.

15. 15. The apparatus of claim 10, wherein each operating rod extends through an elongated adjustment slot formed in the faceplate, the adjustment slots allowing adjustment of the position of the tube clamp relative to the faceplate.

16. 16. The apparatus of claim 1, wherein the pivot arm is movable between an inner engaged position in which the first idler pulley presses the test cable of the test probe against the drive pulley, and an outer released position in which the first idler pulley releases the test cable from the drive pulley.

17. 17. The apparatus of claim 16, further comprising a return spring biasing the pivot arm toward the inner engaged position.

18. 18. The apparatus of claim 1, further comprising a second idler pulley rotatably coupled to the pivot arm, the second idler pulley positioned to press the test cable of the test probe against the drive pulley at a different location than the first idler pulley.

19. 20. The apparatus of claim 18, wherein the first and second idler pulleys operate to maintain a contact angle of approximately 90 degrees between the drive pulley and the cable.

20. 20. The apparatus of claim 19, wherein the second idler pulley is positioned above the drive pulley and the first idler pulley is positioned to the side of the drive pulley.

21. 21. The apparatus of claim 18, wherein the drive pulley and the first and second idler pulleys are (a) aligned collinearly and parallel to one another, and (b) aligned perpendicular to the face plate, which is aligned parallel to the tube sheet when the bracket is coupled to the tube sheet.

22. 22. Apparatus according to any one of the preceding claims, characterized in that the pivot arm is L-shaped.

23. 23. The device of any one of claims 1 to 22, wherein a first end of the pivot arm is connected to the bracket via a pivot pin defining a pivot axis, and a second end of the pivot arm is not connected to the bracket to provide a handle for manually rotating the pivot arm about the pivot axis between the inner engagement position and the outer release position.

24. 24. The apparatus of any one of claims 1 to 23, further comprising a programmable controller operatively connected to the motor and the test probe, the controller being capable of rotating the drive pulley via the motor in the first and second rotational directions.

25. 1. A method for performing eddy current testing of a heat exchanger tube, the method comprising: providing an eddy current testing apparatus having a bracket with a pair of tube clamps, each tube clamp including a radially expandable portion operatively connected to a pivotable actuation lever configured to actuate the expandable portion, the actuation lever of each tube clamp being in an unlocked position; positioning the bracket adjacent to a tubesheet of a heat exchanger, the heat exchanger including a plurality of heat exchanger tubes coupled to the tubesheet; inserting the expandable portion of each tube clamp into a corresponding anchor tube of the heat exchanger accessible through the tubesheet; rotating the actuation lever of each tube clamp to a locked position; radially expanding the expandable portion of each corresponding tube clamp to frictionally engage an anchor tube of the heat exchanger; Including, The method of claim 1, wherein the test device is cantilevered from the tubesheet.

26. 26. The method of claim 25, wherein the rotating step includes manually rotating the actuating lever between an unlocked position and a locked position.

27. 27. The method of claim 26, wherein the radially expanding step includes, in each tube clamp, slidingly engaging an expander plug operably coupled to an actuation lever with the expandable portion, wherein engagement of the expander plug with the expandable portion causes the expandable portion to radially expand and frictionally engage a corresponding anchor tube when the actuation lever is rotated to a locked position.

28. 28. The method of claim 27, wherein the tube clamps include a tubular fixation sleeve having an expandable end with a slot therein that is acted upon by the expander plug, the expandable end forming the expandable portion of each tube clamp.

29. 29. The method of claim 28, wherein the expander plug includes a frusto-conical portion that tapers to a diameter greater than the inner diameter of the expandable end of the fixation sleeve of each tube clamp.

30. 30. The method of claim 29, wherein the expander plug is coupled to a linearly movable operating rod that extends through a locking sleeve of each tube clamp.

31. 31. The method of claim 30, wherein the operating rod is operatively connected to the actuating lever such that (1) rotating the actuating lever from the locked position to the unlocked position moves the frusto-conical portion of the expander plug out of the expandable end of the fixation sleeve, and (2) rotating the actuating lever from the unlocked position to the locked position retracts the frusto-conical portion into the expandable end of the fixation sleeve, causing the expandable end to radially expand and frictionally engage the anchor tube.

32. 32. The method of claim 31, wherein rotating the actuating lever of each tube clamp to a locked position includes engaging an arcuately curved cam surface on the actuating lever with an arcuately curved abutment surface, the cam surface of each actuating lever serving to retract the operating rod and the frusto-conical portion of the expander plug toward engagement with the expandable end of the locking sleeve, thereby expanding the expandable end radially outward.

33. 33. The method of any one of claims 25 to 32, further comprising the step of simultaneously inserting the expandable portion of each tube clamp into an anchor tube of the heat exchanger and engaging an alignment ferrule attached to the bracket with a heat exchanger tube under test.

34. 34. The method of claim 33, wherein the alignment ferrule includes a frusto-conical portion that engages a heat exchanger tube under test.

35. 35. The method of claim 33 or 34, wherein the alignment ferrule includes a through hole configured to pass a test head and cable of an eddy current test probe into a heat exchanger tube under test.

36. 36. The method of any one of claims 25 to 35, further comprising a rotatable drive pulley mounted on the bracket and a pair of idler pulleys rotatably mounted on pivotable pivot arms connected to the bracket.

37. 37. The method of claim 36, moving the pivot arm about a pivot axis to an outer position where the idler pulley is spaced from the drive pulley; inserting a test head and test cable of an eddy current test probe through the test probe feed opening in the bracket and into the heat exchanger tube under test; moving the pivot arm about the pivot axis to an inner position where the idler pulley presses the test cable into engagement with the drive pulley; The method further comprising:

38. 38. The method of claim 37, wherein the test cable contacts the drive pulley at approximately 90 degrees.

39. 39. The method of claim 37 or 38, further comprising a return spring biasing the pivot arm toward the inward position.

40. 40. The method of any one of claims 36 to 39, further comprising: operating a motor coupled to the drive pulley in a first operating mode to feed the test head and test cable into a heat exchanger tube under test; and operating the motor in a second operating mode to retract the test head and test cable from the heat exchanger tube under test.

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