Abstract: Tools and methods are described to measure dimensions of wellbores. Downhole caliper tools include: a downhole collar; an uphole collar; and a caliper sensor assembly disposed between the downhole collar and the uphole collar. The caliper sensor assembly include: an annular sensor module defining a plurality of radially extending tracks; and a caliper including: a plurality of linear slide arms, each linear slide arm at least partially disposed in the annular sensor module in one of the plurality of radially extending tracks and radially moveable relative to the annular sensor module, each linear slide arm extending from a first end within the annular sensor module to a second end outside the annular sensor module, and a cover extending from the downhole collar to the uphole collar. The annular sensor module can measure the radial position of the plurality of linear slide arms relative to the annular sensor module.

Abstract: Tools and methods are described to measure dimensions of wellbores. Downhole caliper tools include a downhole collar and an uphole collar having a running position and a sensing position. The uphole collar is farther from the downhole collar in the running position than in the sensing position. A caliper sensor assembly includes: a sensor module defining tracks extending parallel to an axis of the caliper tool, the sensor module positioned towards an uphole end of the caliper tool relative to the uphole collar; and a caliper disposed between the downhole collar and the uphole collar including: a flexible mesh extending from the downhole collar to the uphole collar. Movement of the uphole collar from the running position to the sensing position axially compresses and radially expands the flexible mesh. The annular sensor module can measure dimensions of the flexible mesh relative to the axis of the caliper tool.

Abstract: A variable crimp machine includes an actuator adjustment assembly including a dial that rotates about an actuation axis and a barrel positioned along the actuation axis within the dial. The barrel includes a first set of axially spaced markings corresponding to a first hose and a second set of axially spaced markings correspond to a second hose. The dial includes a first set of circumferentially spaced markings corresponding to the first hose and a second set of circumferentially spaced markings corresponding to the second hose. The first set of circumferentially spaced markings are used in concert with the first set of axially spaced markings to adjust an actuator for use with the first hose, and the second set of circumferentially spaced markings are used in concert with the second set of axially spaced markings to adjust the actuator for use with the second hose.

Abstract: A measuring device for inspecting a hole, which can favorably be mounted on a riveting robot adapted to insert a rivet into the hole after inspection. The measuring device includes a test mandrel having a hollow housing and interacting means, whereby the relative position of the interacting means can be detected to determine characteristics of the inspected hole. The measuring device further includes a bushing which is arranged movable relative to the test mandrel.

Abstract: A method and apparatus for flatness measuring and measuring of residual stresses in a metallic flat product (1): The method includes bending the flat product (1) in a bending device (3) such that a planar flat product (1) forms an arc (5) with a target bending radius r0 after bending; measuring the contour and the actual bending radii r(y), in the region of the arc (5) of the bent flat product (1) at a plurality of positions along the width direction of the flat product (1); and determining the flatness of the flat product (1) taking into account the measured contour of the bent flat product (1).

Abstract: A tool for evaluating the internal surfaces of tubular is provided, wherein one or more arms extend outwardly from the tool into contact with an inner wall of the tubular, and changes in the dimensions or condition of the inner wall result in changes in the position of the ends of the arms relative to the tool. This motion is converted, through an electromagnetic transducer, into an electrical signal, the accuracy of which deteriorates as the temperature of the tool changes. Calibration transducers are provided on the tool to provide correction factors to convert the electromagnetic transducer output into an accurate reading of the distance of the end of the arms from the tool thereby increasing the accuracy of the assessment of the inner wall of the tubular.

Abstract: An instrument for assembling a polyaxial bone anchor is provided, the polyaxial bone anchor including a bone anchoring element and a receiving part that is configured to pivotably receive the bone anchoring element wherein the instrument includes a first member that is configured to engage the receiving part, a second member that is configured to contact the anchoring element when it is received in the receiving part, and a position indicator that is configured to indicate the position of the anchoring element relative to the receiving part based on the position of the second member relative to the first member.

Abstract: A method for determining the location and orientation of a transmitter object by measuring a set of complex electromagnetic field magnitude and phase strengths within a space using one or more receivers is provided. The method includes modeling a set of expected complex electromagnetic strengths to estimated position and orientation of the transmitter object. And estimating parameters related to the transmitter object position based on the residual error between the measured set of complex electromagnetic field values and a set of expected electromagnetic field values. Further embodiments include a method as above including a plurality of receivers with known positions within a limited space including the transmitter object. A sensor network including a plurality of receivers to perform the above method is also provided. The receivers may communicate using a wireless channel.

Abstract: A method of surveying the condition of an underground conduit by positioning a propelled carriage assembly within the underground conduit. The carriage assembly includes (i) at least one transmitter/receiver unit capable of transmitting a pulsed signal toward at least a portion of an inner wall of the conduit, and (ii) a secondary sensor positioned on the carriage assembly. The data derived from the pulsed signal at a given lateral location within an underground conduit is read as is a secondary sensor condition derived from secondary sensor data taken at the given lateral location. Then it is determined whether the secondary sensor condition indicates a basis for a false void detection by the data derived from the pulsed signal and if the basis for false void detection exists, providing an indication of such basis.

Abstract: An apparatus for the industrial measurement of bores in a measurement object is provided. The apparatus includes a measurement probe which can be introduced into the bore and at which at least one distance sensor is provided with which the instantaneous distance of a reference point of the measurement probe from a wall of the bore can be determined. The measurement probe is rotatably supported at a holder which is fixed with respect to the measurement object and/or whose position relative to the measurement object is known. An evaluation device receives a number of sequentially determined distances in the course of a rotation of the measurement probe.

Abstract: A system for determining the grip length of a hole extending through a stack of panels so that a fastener of appropriate length can be selected for insertion into the hole. A shaft carrying an array of probes is inserted into the hole and the array generates signals indicating which probes of the array are contacting an inner wall of the hole.

Abstract: An apparatus for measuring an inside diameter of hole of a workpeice comprises a main body, two probing legs, two pressure sensors, a controller unit, a display unit, and a step-motor. The two probing legs have a first end and a two second end. Two pressure sensors are respectively mounted on the second end and configured from generating a pressure signal in response to a reacting force applied thereon by an inner wall in the hole. The step-motor is configured for driving the two probing legs to rotate so as to enable the pressure sensors to about against the inner wall. The controller unit is configured for controlling the step driving the probing legs to rotate in response to the pressure signal and computing a rotation angle of each probing leg. The display unit is configured for display the inside diameter of a the hole.

Abstract: An excavation device (1) and profile analysis of the excavation includes a device (1) realizing excavations of prismatic shape and having a frame (3) and a plurality of excavation wheels (2). The frame (3) includes a first upper section (3c), a second intermediate section (3b) and a third lower section (3a. The excavation wheels (2) are positioned at least within said third section (3a). Sensors (4) carry out the measurement of the section and/or the shape of said excavation; the sensors of measure (4) are directed towards the walls of said excavation and measure the profile of said excavation on at least two opposite walls. A method of analysis of a shape and/or a section of an excavation of prismatic shape in the soil includes excavation of the soil through a device (1) having a frame (3) and a plurality of excavation wheels (2).

Abstract: A downhole tool for measuring a diameter of a borehole that includes a mandrel and a collet is disclosed. The collet is disposed about the mandrel that includes a tapered surface formed on an outside surface of the mandrel that increases in diameter across a portion of the mandrel. The collet includes deflectable arm portions with a borehole engagement portion that are adapted to engage the borehole. The borehole engagement portions in-turn may then engage the tapered surface or the steps of the mandrel, such that the collet can move with respect to the mandrel. With this movement of the collet, the outer diameter of the collet may progressively decrease, thereby also decreasing the outer diameter of the downhole tool.

Abstract: An electronically activated tool (50) comprising a tool body, cutter blocks and sensors with means for attachment to a drilling support and rotation so as to permit the simultaneous underreaming and measurement of the diameter of a wellbore (especially in oil and gas drilling) characterized by a means of activation using an electronic signal sent by mud-pulse, fibre-optics, wireless transmission or other means which may also communicate commands and receive data from the underreamer during drilling, at least one radially extendable cutter block (62) incorporating positional sensors adapted to measure the relative position of the cutter block to the tool, at least one calliper means (76) to measure wellbore diameter, all of which are inter-linked by a means of communication using receivers, sensors and microprocessors and a system that optimizes underreaming or expansion (22) by simultaneously comparing and correlating wellbore diameter data (22) and underreaming parameters in real-time or in memory.

Abstract: Example methods and apparatus to determine and use wellbore diameters are disclosed. A disclosed example method comprises positioning a downhole tool in a wellbore, counting a number of rotations of a motor used to cause the downhole tool to contact a surface of the wellbore, and determining a diameter of the wellbore based on the number of rotations of the motor.

Abstract: An orientation sensing apparatus includes a rotatable first member, an orientation sensor device fixed with the first member for generating orientation data relating to an orientation sensor device orientation, and a rotation sensor device for generating rotation data relating to rotation of the first member. A method for determining an orientation includes assembling a set of sensor data including the orientation data and rotation data and processing the set of sensor data to generate a set of corrected orientation data. The set of corrected orientation data includes the orientation data which has been corrected using the rotation data to reduce the effects of rotation of the first member and misalignment of the gravity sensor device. One or more sets of corrected orientation data may be processed to determine an inclination orientation of the first member or a toolface orientation of a second member which is connected with the first member.

Abstract: A method and apparatus for measuring the bore diameter of a hole as a function of hole depth is disclosed. In one embodiment, the apparatus comprises a diametric probe, for generating first measured bore diameter data along a diametric probe sensitive axis; a foot, for positioning the diametric probe sensitive axis in a plane parallel to the hole; a linear distance probe, coupled to the diametric probe, for generating first measured depth data describing the depth of the diametric probe sensitive axis within the hole; and a data acquisition system, for recording first measured bore diameter data from the diametric probe and first measured depth data from the linear distance probe of an insertion of the diametric probe into the hole.

Abstract: The present invention relates to a method of measuring the difference in alignment between a first plan position of an element (1) and a second plan position of an element, the method comprising the use of: i) at least one rigid or taut connection (4) extending between a first point (2) at the level of the first plan position and a second point (3) at the level of the second plan position, the first and second points being at an identical displacement from the element; and ii) one or more electrolevel gauges (5) provided on the or each rigid or taut connection, so as to measure the inclination of the rigid or taut connection.

Abstract: The present application relates to an apparatus and method for placing an element (14), such as a steel column or concrete section, into a pile shaft (1) during top-down construction techniques. The apparatus is provided with an upper and lower positioning means (2, 3) which allow the plan position of the element at upper and lower levels respectively to be adjusted.

Abstract: A system for measuring an internal dimension, such as the radius, of a cylindrical cavity over a determined length, particularly in a hollow shaft belonging to a turbomachine. The system includes a measurement module mounted removably on a support that has translational mobility inside and along the axis of the cavity, the module including a measurement component for measuring the dimension and delivering signals corresponding to the measured values and incorporating a recording and storage for recording and storing the values. More particularly, the module includes a mechanical sensor component able to move between a retracted position and an extended position for sensing the internal surface of the cavity.

Abstract: The drilling device, according to the invention, comprises: a) a drilling device (29) arranged to make a drilling hole parallel to a drilling axis (AF); b) a pressure device (25), mechanically connected to the drilling device (29) and comprising in turn b1) a piston head (39), wherein the pressure device (25) is arranged to apply pressure to the work piece during the drilling by leaning on it the piston head (39); b2) a compensating articulated joint (63) connecting the piston head (39) to the rest of the pressure device (25) and allowing it to tilt with respect to the rest of the pressure device (25), adapting to different possible inclinations of the part to manufacture with respect to the drilling axis (AF). This device can be used to achieve with a greater accuracy holes with a opening flared to accept a stud or a rivet having a conic head.

Abstract: A borehole tool, comprises: a tool body; a series of arms connected to the tool body and moveable radially relative thereto; and a series of pads mounted on the arms so as to be pivotable about a radial axis relative to the tool body. By allowing pivoting of the pads about a radial axis, elongate pads can be arranged to provide different circumferential coverage according to the orientation with respect to the longitudinal axis of the borehole.

Abstract: A tool system is provided for aligning and plumbing a poured concrete form (e.g., a lower vertical form portion) for forming a structural column assembly of the type used for erecting building structures and the like, such as a concrete column or footing formed in situ in an earthen hole. The system includes a center line running vertical to the length of the tool and a two-way level system incorporated therein. The tool can be used to line up the lower vertical form portion with a layout string and plumb the lower vertical form portion square. A metering pole that can be locked in place is used to lower and raise the tool into and out of the lower vertical form portion, wherein the tool is completely rotatable about the metering pole. Once the lower vertical form portion is aligned with the tool, the earthen hole is back filled, thus holding the lower vertical form portion in place in the correct position.

Abstract: A device to measure minute displacement in rocks, including anchor deployment means, anchor registration means, and frame release means. Further including anchor units comprising a fixed anchor point, a reversible anchor actuator and a deployable anchor face capable of being deployed with a force of up to 2000 lbs.

Abstract: The invention provides a measuring sonde (1) for a hydrocarbon well, the sonde comprising a main body (2), a downstream arm (3), and an upstream arm (5), at least one of said arms being fitted with measurement means (6) for determining the characteristics of the fluid flowing in the well; said downstream and upstream arms being connected to the main body respectively via first and second sliding pivot links (A and E).

Abstract: The present invention relates to a system for measuring an internal dimension, such as the radius, of a cylindrical cavity over a determined length, particularly in a hollow shaft (1) belonging to a turbomachine. The system is one which comprises a measurement module (40) mounted removably on a support that has translational mobility inside and along the axis of the cavity, the module (40) comprising a measurement component (43) for measuring the dimension and delivering signals corresponding to the measured values and incorporating a recording and storage means (461) for recording and storing said values. More particularly, the module (40) comprises a mechanical sensor component (43) able to move between a retracted position and an extended position for sensing the internal surface of the cavity. The system applies in particular to checks on the boring-out of the internal cavity of a turbomachine shaft.

Abstract: A borehole caliper tool includes a tool body and an arm coupled to the tool body. The arm is deflectable relative to the tool body. The caliper tool further includes a cam coupled to the arm such that a position of the cam changes as the arm deflects. The caliper tool further includes a proximity sensor for sensing the position of the cam, wherein the position of the cam provides an indication of the deflection of the arm relative to the tool body.

Abstract: A surveyor's tool to facilitate the measurement of the elevation of an invert within a manhole includes a rod with a dimensioning along its length. The tool further includes a slide moveable with respect to said rod. The slide includes a pair of opposing arms, the arms extending from opposite sides of the slide and extending perpendicular to the length of the rode. The slide further includes an inclinometer for measuring the angle of incline of the rod. Using the length of the rod extending into the manhole and the angle of the rod as determined by the inclinometer the depth of the invert can be calculated.

Abstract: A system for measuring inner diameter of a tubular, e.g., but not limited to, a riser or a pipe, the system including at least one linear distance measuring device movable through a hollow tubular, a main body also movable through said tubular, the at least one linear distance measuring device mounted on the main body, and the at least one linear distance measuring device for producing a measurement signal indicative of a measurement of inner diameter of the tubular.

Abstract: An apparatus for measuring an inner diameter of a pipeline is incorporated into a passage pig for checking passableness through the pipeline or a cleaning pig for cleaning within the pipeline, the passage pig and the cleaning pig including at least one seal cup sealably sliding along an interior surface of the pipeline. The apparatus includes a travel distance measuring unit for measuring a travel distance of the passage pig or the cleaning pig within the pipeline, a swing angle detector for detecting a swing angle of a pig body during the travel distance measurement, a displacement detector for individually detecting a radial displacement of the peripheral portion of the seal cup at a number of points along an entire circumference during the travel distance measurement, a computing unit for computing an output from each of said means, and a recording means for recording an output from the computing unit.

Abstract: The present invention provides methods of measuring downhole the curvature of a borehole and, in a particular application of the invention, using the curvature information as an input component of a bias signal for controlling operation of a downhole bias unit in a directional drilling assembly.

Abstract: A distance measurement device and method for measuring a distance between two reference points comprising a housing, a base, and a flexible member curving therebetween. The flexible member housing end is allowed to slide in a slide track in the housing. The housing also comprises sensors that detect the position of the flexible member housing end relative to the housing. The distance measurement device measures the distance between the two reference points by engaging the first reference point with the housing and engaging the second reference point with the flexible member apex. As the distance from the housing to the flexible member apex changes, the flexible member housing end slides in the housing slide track. There is a unique correlation between the location of the flexible member housing end and the distance to flexible member apex, and thus the second reference point.

Abstract: A distance measurement device and method for measuring a distance between two reference points comprising a housing, a base, and a flexible member curving therebetween. The flexible member housing end is allowed to slide in a slide track in the housing. The housing also comprises sensors that detect the position of the flexible member housing end relative to the housing. The distance measurement device measures the distance between the two reference points by engaging the first reference point with the housing and engaging the second reference point with the flexible member apex. As the distance from the housing to the flexible member apex changes, the flexible member housing end slides in the housing slide track. There is a unique correlation between the location of the flexible member housing end and the distance to flexible member apex, and thus the second reference point.

Abstract: Techniques for measuring a displacement include generating a magnetic field using a magnetic field source; measuring a first magnitude of a component of the magnetic field using a sensor disposed within the magnetic field; displacing the magnetic field source; measuring a second magnitude of the component of the magnetic field using the sensor; determining a distance that the magnetic field source is displaced using the first magnitude and the second magnitude. An apparatus for measuring a radius of a hole includes a support member having at least one arm, each having a first end and a second end, the first end attached to the support member; a magnet moveably attached to the support member via the second end of the each of the at least one arm; and a first magnetic sensor fixed to the support member. An apparatus of the invention may further include a second and third sensors.

Abstract: An apparatus for measuring an inner diameter of a pipeline according to the present invention is incorporated into a passage pig for checking passableness through the pipeline or a cleaning pig (60) for cleaning within the pipeline while running through the pipeline, the passage pig and the cleaning pig including at least one seal cup (60B to 60D) sealably sliding along an interior surface of the pipeline.

Abstract: A system for measuring inner diameter of a tubular, e.g., but not limited to, a riser or a pipe, the system including at least one linear distance measuring device movable through a hollow tubular, a main body also movable through said tubular, the at least one linear distance measuring device mounted on the main body, and the at least one linear distance measuring device for producing a measurement signal indicative of a measurement of inner diameter of the tubular.

Abstract: A downhole caliper instrument utilizing a linear or arcuate magneto resistive sensor to determine the position of one or more caliper arms which extend from a carrier tool to touch the surface of a borehole wall. A processor and firmware are included to calculate and plot the borehole radius. A plurality of magneto resistive sensors are provided to calculate the sine, cosine and tangent for accurate motion of each independent arm. The magneto resistive sensors sense the position a precise magnetic ruler linked to the caliper arm. The position of the caliper arm determines the radius of the borehole. Calculation of Radius/Diameter is preferably performed in the computer on surface. The downhole controller's firmware controls the multiplexer switching, A/D conversion and other functions.

Abstract: A downhole caliper instrument utilizing a magneto resistive sensor to determine the position of a caliper arm which extends to touch the surface of the borehole wall.

Abstract: A downhole caliper instrument utilizing a linear or arcuate magneto resistive sensor to determine the position of one or more caliper arms which extend from a carrier tool to touch the surface of a borehole wall. A processor and firmware are included to calculate and plot the borehole radius. A plurality of magneto resistive sensors are provided to calculate the sine, cosine and tangent for accurate motion of each independent arm. The magneto resistive sensors sense the position a precise magnetic ruler linked to the caliper arm. The position of the caliper arm determines the radius of the borehole. Calculation of Radius/Diameter is preferably performed in the computer on surface. The downhole controller's firmware controls the multiplexer switching, A/D conversion and other functions.

Abstract: Method for measuring the gap separating a vault of at least one end fitting and a given element of one end of a thermal part of a pipe, comprising; moving an autonomous measuring detector inside the said pipe, carrying out at least one series of measurements during the movement of the detector in the end fitting, the measuring comprising detecting in real time, the passage of the consecutive transitions between the vault of the end of the terminal part of the pipe, triggering the measurements for a predetermined time between the detections of the transitions, storing the said measurements in the form of signals in at least one memory and processing the stored signals in order to determine the gap (D) and separating two consecutive transitions. The device for measuring includes two eddy current detectors on a support wound through the pipe and a memory for the detected signals and a processing circuit for processing the signals in memory.

Abstract: A measurement tool used with an indicator for simplfying the task of measuring a hard-to-reach surface of an object. The measurement tool used with an indicator includes a cylindrical member having a first and a second end and a bore extending therethrough and a first longitudinal slot and a second longitudinal slot; and also includes a shaft moveably disposed in the bore and having a collar securely attached thereabout to limit the movement of the shaft in the bore; and further includes a linkage member pivotally attached to the shaft and moveably disposed in the first longitudinal slot and being pivotally attached to an arm member; and further includes a fastening member securely mounted to the cylindrical member for tightly securing the indicator in the cylindrical member with the shaft being in contactable relationship with the indicator.

Abstract: A tool for initiating a downhole function in a subsurface well, such as a cased well. The tool has memory adapted to store a well-specific reference pattern of one or more downhole well characteristics as a function of position along the well, one or more sensors responsive to the downhole well characteristics, and a clocked processor. The processor is adapted to receive well characteristic signals from the sensors, determine, from the signals and the reference pattern in memory, the position of the tool along the well, and automatically initiate a downhole function at a preprogrammed position along the well while the tool is moved at a substantially constant rate along the well. The tool may be configured in a string of tools for performing multiple downhole functions. In some embodiments the reference pattern is the known spacing of discrete downhole features, such as casing collars. In some other embodiments the reference pattern is a log of a geophysical parameter, such as a natural gamma log.

Abstract: The invention relates to a logging method and apparatus adapted for use in non-circular boreholes which, in one embodiment, comprises the use of a first and a second sonde, each sonde having: a pad adapted for contact with the borehole wall, at least a sensor on each pad, and an extendable arm for keeping the pad against the wall of the borehole. The first and second sonde produce measurements related to the same property of the formations, and the first and the second sonde are connected so as to keep the pads aligned with a 90.degree. azimuthal spacing therebetween.

Abstract: A method and apparatus are provided for estimating the cross-sectional shape and orientation of an earth borehole and the motion of a tool therein. The method and apparatus involve measuring the distance from the tool to the borehole wall at a plurality of locations around the periphery of the tool and fitting those measured distances to a predetermined shape function using a nonlinear parameter estimation technique to minimize the error between the estimated shape of the borehole and the measured distances. The method and apparatus may be used to estimate elliptical and higher order borehole shapes. Additionally, the method and apparatus may be used while drilling the borehole.

Abstract: The essence of the proposed method resides in that assumed as the datum point of measurement of the well azimuth is an azimuthally stabilized housing of a down-the-hole inclinometer and the magnitude of the azimuth is determined by measuring the angle of rotation of the housing of the down-the-hole instrument (1) round its longitudinal axis, which rotation occurs in response to an azimuthal deviation of the longitudinal axis of a well (5). According to a first embodiment of the proposed device, it comprises a plurality of spring-loaded arcuate elements (3) secured on an external surface (2) of the housing of the down-the-hole instrument (1) so as to form at least three rows, each row consisting of at least three elements (3), each of the latter establishing, together with an internal surface (4) of the well (5), a contact spot (6) whose portion having a greater size (h) is arranged lengthwise the longitudinal axis of the well (5).

Abstract: A measuring device includes a generally tubular, flexible body with opposite ends and a longitudinally-extending bore. The body includes a plurality of measuring indicia at regularly-spaced intervals therealong. It can be selectively mounted on the body ends and have a predetermined length which corresponds to the measuring indicia spacing. An extension connector is also provided for connecting two measuring device bodies together. A centering assembly has a sleeve which receives the body and wings projecting radially outwardly therefrom for generally centering the measuring device within a pipe bore.

Abstract: An automated hole inspection system for measuring, on a plurality of planes, the diameter of a hole in a workpiece includes a hole gauge for measurement of a hole diameter in one plane, and a remote centering compliance device connected to the proximal end of the probe for allowing the probe to move laterally, perpendicularly to the probe axis, to self-center in the hole. A center locking device locks the remote centering compliance device on the axis of the probe after the probe has self-centered in the hole. A rotary actuator rotates the remote centering compliance device to rotate the probe to a new desired plane for making an additional diameter measurement in the hole.

Abstract: A centering apparatus and method is provided which automatically measuring the radius or radius deviation of a large cylindrical bore, and shorten the time required for centering. The inspection apparatus is supported on a rise and fall base which is horizontally supported on a top portion of the large cylindrical bore in such a manner that it is allowed to vertically move in parallel with a fine wire which is hung perpendicularly from the center of the top portion. The inspection apparatus having a non-contact type two-dimensional position sensor for detecting the relative position of the fine wire to the cent-er of the inspection apparatus. The inspection apparatus is positioned at an arbitrary height.

Abstract: The present invention relates to a moving device for intervening inside small-diameter pipework. The technical field of the invention lies in constructing measurement apparatus for monitoring pipework and capable of moving along the inside of the pipework in substantially independent manner driven by thrust from the substance conveyed by the pipework acting on the device. According to the present invention, the device comprises a drive piston itself made up of at least two flexible and strong annular tractor cups and defining a sealed section of inside surface, and at least one third centering cup disposed between said two tractor cups. The supports for said cups are interconnected axially in pairs by respective traction cables associated with respective springs surrounding said cables, each spring bearing at each end against said supports of two consecutive cups, and serving to keep said cable under tension.