Collapsible pipeline inspection tool

An in-line inspection (ILI) tool 20 for use inspecting pipelines includes a plurality of collapsible guide centralizers 100 configured and sized to correspond to the inside diameter of the pipeline being inspected. The guide centralizes 100 include wheels 102 roll along the inside wall of the pipeline being inspected to maintain the guide centralizers “centered” within the pipeline. A collapsible exciter unit centralizer 200 is positioned between collapsible guide centralizers 100 to “center” the exciter unit centralizer relative to the interior of the pipeline. The exciter unit centralizer 200 generates signals in the form of an alternating magnetic field that travel along the wall of the pipeline which in turn generates eddy current signals. The eddy current signals undergo a change if a discontinuity in the pipeline is encountered by the inspection tool 20, which signal change or deviation is detected by a collapsible detector unit centralizer 300 positioned between the collapsible guide centralizers 100.

BACKGROUND

Corrosion and leaks in pipelines, especially in the water and the wastewater industry, are particularly serious problems. It has been estimated that on average in North America, only 70% of the water that is treated for drinking actually makes it to the taps of consumers. The 30% that is “lost” leaks out of joints that are not well sealed, or out of corroded-through holes in the pipes into the ground, causing contamination from the chlorine used to treat the water. Leaks from wastewater pipes are even more polluting due to the phosphates (from washing machines) and other chemicals that are flushed down our drains and mix with water from industrial users before reaching the treatment plant.

In order to detect the location of corroded areas and leaks, pipeline owners employ “in-line inspection (ILI) Tools” which use a variety of non-destructive testing (NDT) methods to interrogate the pipe. These ILI Tools use techniques such as Magnetic Flux Leakage (MFL), Ultra-sonic Technology (UT), or Remote Field Technology (RFT).

To access the pipelines, especially in the oil and gas marketplace, the pipelines are equipped with “pig launchers” and pig receivers” which are connected to the pipeline through “riser pipes.” The water and wastewater industry are not as advanced as the oil and gas industry, where ILI Tools have been in use for almost a century. Because of this, water and wastewater pipelines were not designed to have “pig launchers” and “pig receivers” fabricated and installed when the pipeline is first built, and it is very costly to install them after the pipe has been in service for many years.

For metallic pipelines (made of steel, cast-iron, ductile-iron, and concrete pressure pipe), the ravages of corrosion are the same as for oil and gas pipelines. While pipe wall thicknesses are generally thicker than pipe used in oil and gas applications, and the pressures are typically lower, the protection that is provided to the pipes to protect from soil side ground-water corrosion is usually quite limited, and therefore soil-side corrosion is common and causes many failures of these pipelines. In water pipelines in North America, the leakage rate due to corroded through holes can be as high as 30%, and thus never make it to the faucets of customers. This has environmental consequences through chlorinated water being introduced into the water table and extra costs for pumping and water treatment. In water-starved states such as Nevada and Arizona, this loss of water is a serious threat to sustaining sources of water for domestic use. Hence, the water industry is driven to inspect their pipes for corroded and weakened areas, and ILI tools are very good technology for that purpose, especially for large transmission mains.

Large water and wastewater transmission mains can vary in size from 16 inches to over 120 inches in diameter, and the larger mains are often equipped with manways, enabling inspection and internal repairs of the pipes periodically. Manways offer a low-cost means of accessing the pipelines; however, many ILI Tools cannot fit through the manway unless they are completely dis-assembled, passed through the manway in pieces, and re-assembled inside the pipe. This is a time-consuming exercise, which can take a full day for assembly and then another day for dis-assembly after the pipe is inspected.

The present disclosure seeks to address the forgoing short comings in current systems and methods for inspecting water and wastewater lines.

SUMMARY

In accordance with one embodiment of the present disclosure, a collapsible centralizer is provided for positioning measuring/testing equipment within the interior of the pipeline while traveling through the pipeline. The collapsible centralizer includes a hub portion defining a longitudinal axis extending through the hub portion, and a collapsible superstructure encircling the hub portion, and a plurality of tethering lines radiating from the hub portion to the collapsible superstructure to inter-connect the superstructure relative to the hub portion.

In any of the embodiments described herein, wherein, when in collapsed configuration, the superstructure occupies a reduced configuration relative to when in erected configuration, and when in erected configuration, the superstructure encircles the hub portion with the tethering lines in taut condition.

In any of the embodiments described herein, wherein the collapsible superstructure is inflatable into erected configuration and deflatable into collapsed configuration.

In any of the embodiments described herein, wherein the inflatable superstructure comprises an inflatable toroid that encircles the hub portion.

In any of the embodiments described herein, wherein the tethering lines are loaded under tension when the collapsible superstructure is in erected configuration.

In any of the embodiments described herein, further comprising tensioners for adjusting the tension load on the tethering lines when the superstructure is in erected configuration.

In any of the embodiments described herein, wherein the superstructure when erected is configured to carry a component selected from the group consisting of guide wheels, signal generators, and signal detectors through the pipeline.

In any of the embodiments described herein, wherein the selected component is mounted on the superstructure when the superstructure is in collapsed configuration so that when the superstructure is erected, the component is in position to perform its function.

In any of the embodiments described herein, wherein the guide wheels are mounted on trucks disposed about the circumference of the superstructure to axle the guide wheels about axes transvers to the longitudinal axis of the hub section.

In any of the embodiments described herein, wherein the signal detectors comprise sensors disposed within pods spaced along the circumference of the superstructure.

In any of the embodiments described herein, wherein the pods are mounted on the superstructure by resilient mounting structures to enable the pods to retract toward the superstructure when subjected to a load.

In any of the embodiments described herein, further comprising a signal receiver module which is paired with the signal detectors, said signal receiver module disposed within the hub structure.

In any of the embodiments described herein, comprising signal exciter units positioned around the circumference of the superstructure.

In any of the embodiments described herein, further comprising a signal exciter module which is paired with the signal exciter units, said signal exciter module disposed within the hub structure.

In any of the embodiments described herein, wherein the hub structure is configured to receive and carry a component selected from the group consisting of a battery, a signal exciter module, a signal receiver, a signal processor, a signal transmitter, a signal recorder.

In any of the embodiments described herein, wherein a signal exciter module is carried by the hub structure and is paired with signal exciter units carried by the superstructure.

In any of the embodiments described herein, wherein a signal receiver is carried by the hub structure and is paired with signal detectors carried by the superstructure.

In any of the embodiments described herein, wherein the hub portions of the collapsible centralizers are interconnected together.

In accordance with one embodiment of the present disclosure, an in-line inspection tool for a pipeline includes a plurality of centralizers, each comprising a hub portion defining a longitudinal axis extending through the hub portion; an inflatable superstructure encircling the hub portion; and a plurality of tethering lines radiating from the hub portion to the superstructure to position the superstructure relative to the hub portion; Further the superstructure when inflated is configured to carry a component selected from the group consisting of guide wheels, signal generators, and signal detectors through the pipeline.

In any of the embodiments described herein, further comprising an exciter module which is paired with the signal generators, and a signal receiver module which is paired with the signal detectors; and wherein the signal exciter module and signal receiver module are disposed within a respective hub structure.

In accordance with one embodiment of the present disclosure, a method is provided for deploying a collapsible in-line inspection tool into a pipeline having an access location. The method includes: placing at least one collapsed guiding centralizer into the pipeline through the access location; placing an exciter unit mounted on a collapsed centralizer into the pipeline through the access location; placing a detector unit mounted on a collapsed centralizer into the pipeline through the access location; linking together the guiding centralizers with the exciter unit centralizer and the detector unit centralizer; and transforming the guiding centralizers, the exciter unit centralizer and the detector unit centralizer into erected configuration.

In any of the embodiments described herein, the centralizers comprise inflatable superstructures that encircle the hub sections and transform the at least one guiding centralizer, the exciter unit centralizer, and the detector unit centralizer into erected configuration by inflating the respective superstructures.

In any of the embodiments described herein, wherein the superstructures comprise inflatable toroids that encircle the hub sections.

DETAILED DESCRIPTION

The description set forth below in connection with the appended drawings, where like numerals reference like elements, is intended as a description of various embodiments of the disclosed subject matter, and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result.

The present application may include references to “directions,” such as “forward,” “rearward,” “front,” “back,” “ahead,” “behind,” “upward,” “downward,” “above,” “below,” “horizontal,” “vertical,” “top,” “bottom,” “right hand,” “left hand,” “in,” “out,” “extended,” “advanced,” “retracted,” “proximal,” and “distal.” These references and other similar references in the present application are only to assist in helping describe and understand the present disclosure and are not intended to limit the present invention to these directions.

The present application may include modifiers such as the words “generally,” “approximately,” “about,” or “substantially.” These terms are meant to serve as modifiers to indicate that the “dimension,” “shape,” “temperature,” “time,” or other physical parameter in question need not be exact but may vary as long as the function that is required to be performed can be carried out. For example, in the phrase “generally circular in shape,” the shape need not be exactly circular as long as the required function of the structure in question can be carried out.

In the following description and in the accompanying drawings, corresponding systems, assemblies, apparatus, and units may be identified by the same part number, but with an alpha suffix. The descriptions of the parts/components of such systems assemblies, apparatus, and units that are the same or similar are not repeated so as to avoid redundancy in the present application.

One embodiment of an in-line inspection (ILI) tool20for use inspecting pipelines in accordance with the present disclosure is shown inFIGS.1,2, and3. As depicted the ILI tool20includes a plurality of collapsible guide centralizers100A,100B,100C,100D,100E, and100F (generically “100”). The guide centralizers100are configured and sized to correspond to the inside diameter of the pipeline being inspected. To this end, the wheels102of the guide centralizers100roll along the inside wall of the pipeline being inspected

A collapsible exciter unit centralizer200is positioned between collapsible guide centralizers100A and100B so as to “center” the exciter unit centralizer relative to the interior of the pipeline being inspected. As explained below, the exciter unit centralizer200generates signals in the form of an alternating magnetic field that travels along the wall of the pipeline, which in turn generates eddy current signals. The eddy current signals undergo a change if a discontinuity in the pipeline is encountered by the inspection tool20, which signal change or deviation is detected by a collapsible detector unit centralizer300positioned between the collapsible guide centralizers100E and100F.

Linkage units22interconnect the collapsible guide centralizes100B and100C as well as collapsible guide centralizers100D and100E. Swivel connectors24are interposed between the ends of the linkage units22and the guide centralizes100so that the guide centralizes can navigate around corners and turns and other nonlinear features of the pipeline. Also, a battery unit26is disposed between collapsible guide centralizers100C and100D to provide power for the ILI tool20, including the collapsible exciter unit centralizer200and the collapsible detector unit centralizer300.

As shown inFIGS.1and2, eye bolts28are located at the ends of the ILI tool20for towing the tool through the pipeline and for applying a resisting or restraining force on the trailing end of the tool so that the tool remains in taught configuration during use. As a consequence, the collapsible exciter centralizer200and the collapsible detector centralizer300remain properly centered relative to the pipeline being inspected.

Next, describing the collapsible guide centralizers100on more detail, as shown inFIGS.4,5,6,10A,10B,14, and15, in basic construction, the guide centralizers100include a hub portion104that defines a longitudinal axis30. A collapsible superstructure118surrounds the hub portion and is tied to the hub portion by a series of restraining or tethering straps or lines120that radiate out from the hub portion. In one form of the present disclosure, the collapsible superstructure can be in the form of a toroid, and moreover the toroid can be inflatable and deflatable. When inflated, the toroid superstructure118carries and supports a series of wheels102extending around the circumference of the guide centralizer100to roll along the inside wall of the pipeline being inspected. When deflated, the toroid is collapsed into a smaller configuration so as to be insertable into a pipeline and removed from the pipeline through an opening that is smaller than the size of the centralizer100when the superstructure is erected/the toroid is inflated. Nonetheless, the wheels are mounted on the superstructure118so that before or after the toroid superstructure is inflated, it is not necessary to mount the wheels to the superstructure; rather it is only necessary to erect (inflate) the superstructure wherein the wheels are in proper position on the superstructure for use of the guide centralizer to be used for inspecting the pipeline.

The hub portion104, includes a longitudinal axle106extending centrally through the hub portion along axis30. A pair of flexible discs108are mounted stationary in spaced apart relationship relative to the axle106by inner and outer clamping discs110and112disposed on opposite sides of each of the flexible discs108. The inner and outer clamping discs110and112are significantly smaller in diameter than the flexible discs108so that outer diameter of the flexible discs extend radially a distance beyond the outer circumference of the clamping discs110and112. The inner and outer clamping discs110and112have hub portions114and116, respectively, to retain the inner and outer discs110and112stationary relative to the axle106.

The restraining/tethering straps120radiate outwardly from the flexible discs108to engage the erectable superstructure/inflatable toroid118. In this regard, the straps112extend radially outwardly from a first flexible disc to pass through a first slot122formed in a side margin of an outer ring124that closely surrounds the outer circumference of the toroid118. The strap extends around a restraining rod126, then back down through the slot122to wrap around the inward portion of the toroid facing radially inwardly toward the axis30, to then extend outwardly through a second slot128formed in the opposite side margin of the outer ring114. Thence, the strap extends around a second restraining rod130and then back down through the second slot128to the second flexible disc108. The ends of the straps120can be securely attached to the flexible discs by any convenient means, for example, by thermal welding, by an adhesive, by a mechanical fastener, or a combination of these or other fastening means.

The inflatable configuration of the toroid118can be composed of any suitable flexible material capable of containing pressurized air, for example, a polyurethane material that may be composed of reinforcing fabric, or a Mylar material or other tough, durable, but flexible material. Moreover, the toroid can be composed of a layered construction to optimize the composition of the toroid.

The cross-sectional diameter of the toroid118can be sized based on the size of the pipeline being inspected. In this regard, the cross-sectional diameter of the toroid118may be from about 30 inches to about 120 inches. One or more valves are provided through which the toroid may be inflated. By employing multiple valves, the likelihood of the valve being in convenient position for inflation is increased.

The restraining/tethering straps120may also be composed of flexible material, but that is capable of carrying the tension load. In this regard, the flexible material can be composed of, for example, a polyurethane fabric material. Similarly, the flexible discs108may be composed of a strong tough flexible material such as the type of polyurethane. Of course, other types of materials may be employed to form the restraining straps120and the flexible discs108. Further, the flexible discs108and restraining straps120could be replaced with other structures that function to position the erected superstructure/inflated toroid118relative to axle106.

Continuing to refer toFIGS.4,5,6,10A,10B,14, and15, wheels102are mounted on trucks132that extend transversely to the outer surface of the toroid in a direction aligned with axis30. The trucks132are in the form of an elongate beam structures134which are mounted to the outer surface of the outer ring124by hardware members136that extend through being structures134to engage the outer ring. At one end, the trucks132are defined by spaced apart arms138for receiving wheel102therebetween. The wheel102is rotationally mounted on an axle140that spans between the arms138. At the other end, the trucks are defined by a longitudinally projecting central arm142for supporting wheels102on each side thereof through the use of an axle144extending through an axle housing formed at the distal end of the central arm.

As shown, the positions of the trucks132are alternated or reversed about the circumference of the outer ring124. It will be appreciated by the foregoing construction and positioning of the trucks132that the wheels102can be positioned in close relationship to each other, thereby to provide adequate support for the guiding centralizer100when traveling through a pipeline, and in particular when rounding the corner or a bend in the pipeline, wherein the wheels102ride against the adjacent surface of the pipeline inside wall without having to use relatively large diameter wheels.

The wheels102are constructed with solid tires having a smooth circumferential rolling surface composed of rubber, a rubber like composition, plastic, or a plastic-like composition so as to not damage the interior of the pipeline, even if the pipeline has been lined with cement mortar, polyurethane, high-density polyurethane epoxy, or other material.

It will be appreciated that by mounting the trucks132on the outer ring124, when the superstructure118is erected (e.g., the toroid118is inflated), the trucks132and the corresponding wheels102are in position to perform their guiding function during the inspection of the pipeline, without requiring assembly of the trucks to the superstructure after the guide centralizer has been positioned within the interior of the pipeline to be inspected.

Next referring primarily toFIGS.4,7,13, and14, the collapsible exciter unit centralizer200is illustrated as including a hub portion202connected to adjacent inflatable centering/guiding centralizer's100using swivel joints between. A collapsible/erectable superstructure in the form of an inflatable toroid204surrounds the hub portion and is tied to the hub portion by a series of restraining straps or lines206that radiate out from the hub portion. When inflated, the toroid204carries and supports a plurality of exciter coils208extending around the circumference of the toroid.

The hub portion202includes an outer shell210for receiving one or more exciter coils212therein. Flexible discs214, similar to flexible discs108, are positioned between the outer shell210and exterior clamping rings216located at each end of the hub portion202. The clamping rings216may be clamped together and against the ends of the outer shell210by tie rods218. Hardware members214-220extend through holes formed in the clamping rings216to engage with blind holes formed in the ends of the tie rods218.

Restraining straps206extend radially outwardly from the perimeter portion of the flexible discs214to pass through a first slot224formed in a side margin of an outer ring226that surrounds the outer circumference of the toroid204. The strap extends through a slot228formed in the side wall244of a cover structure that surrounds exciter coil212. An enlarged end portion230is affixed to the end of the restraining strap206to prevent the restraining strap from disengaging from the slot228. Buckles232are provided in the straps206to adjust the lengths of the straps to place the desired tension on the straps. The inward ends of the restraining straps206can be securely attached to the flexible discs214by any convenient means, for example, by thermal welding, by an adhesive, by a mechanical fastener, or a combination of these or other fastening means.

As discussed above, a plurality exciter coils212extend circumferentially around the exterior of the outer ring226. Two rows of coils to follow are illustrated inFIGS.4and13; however, the number of coils and rows of coils from that shown in theFIGS.4and13can be varied so as to generate the desired level of alternating magnetic field, which couples with the ferrous metal over pipeline to induce eddy currents, which in turn generate their own magnetic fields to be sensed by the collapsible/erectable detector centralizer300.

The exciter coils208are disposed within the cover structure240for holding the exciter coils in place. The cover structure240includes an outer surface242surrounding the coils208and side walls244extending radially inwardly from the side margins on the outer surface242to be held in place by the restraining straps, described above. It will be appreciated that by the foregoing construction, it is not necessary to assemble the exciter coils onto the exciter unit centralizer200once the centralizer200, in collapsed form, has been placed into the interior of the pipeline to be inspected. Rather it is only necessary to attach the exciter unit centralizer with the other components of100and300of the inspection tool20. Once the exciter centralizer unit200has been position within the pipeline to be inspected, the unit can be erected by, for example, inflating the toroid204, whereupon the centralizer unit200is substantially ready for use in the sense that assembly of the unit200is not required.

Next referring primarily toFIGS.5,8,11,12, and15, the collapsible detector unit centralizer300is illustrated as including a hub portion302connected to adjacent collapsible centering/guiding centralizer's100using swivel joints between. A collapsible/erectable superstructure in the form of an inflatable toroid304surrounds the hub portion and is tied to the hub portion by a series of restraining straps or lines306that radiate out from the hub portion. When inflated, the toroid304carries and supports a plurality of eddy current detectors308disposed around the circumference of the toroid.

The hub portion302includes an outer shell310for housing signal receiving units312therein. Flexible discs314, similar to flexible discs214, are position between the outer shell310and exterior clamping rings316located at each end of the hub portion302. The clamping rings316are clamped together and against the ends of the outer shell310by tie rods318. Hardware members320extend through holes formed in the clamping rings316to engage with blind holes formed in the ends of the tie rods318.

Connectors322project outwardly from the clamping rings316to engage connection wires324leading to signal sensing units308. In a manner typical of an eddy current ILI tool, the sensing units308are able to detect changes in the eddy currents generated by the exciter unit200due to defects or other discontinuities in the pipeline being detected. The eddy current based signals detected by the sensing units308are transmitted to the signal receiving unit312housed in hub portion302.

Restraining straps306extend radially outwardly from the perimeter portion of the flexible discs314to pass through a slot330formed in a side margin of an outer ring332that surrounds the outer circumference of the inflatable toroid304. Enlarged end structures334are attached to the ends of the straps306to prevent the straps from disengaging from the outer ring332. The inner ends of the restraining straps306can be securely attached to the flexible discs314by any convenient means, for example, by thermal welding, by an adhesive, by a mechanical fastener, or a combination of these fastening or other means.

As perhaps most clearly shown inFIGS.5and11, take up buckles340are engaged with the restraining straps306. The buckles340are used to adjust the tension on restraining straps306to help ensure that the exterior of the detector centralizer300is circular in configuration so as to properly position the detector centralizer300relative to the interior of the pipeline being inspected.

As discussed above, a plurality of eddy current signal sensing or detecting units308are mounted on the exterior of the outer ring332. The detecting units308include detectors350positioned within generally tubular shaped, elongate pods352extending parallel to axis30. As shown in the FIGURES, the pods352have tapered end portions354that terminate at blunt ends which are curved radially inwardly toward the axis30. This configuration helps to reduce the likelihood that one or more of the pods352will catch against the inside surface of the pipeline, especially since the pods are mounted on the outer ring332using resilient mounting structures360.

The mounting structures360are in the form of an “hourglass” spring structure. In this regard, the mounting structure360includes upper and lower brackets361, each composed of a longitudinal base362and diagonal arms364extending away from the base in an inwardly direction. The base362of the upper bracket361is attached to the adjacent surface of the pond352, whereas the base362of the opposite bracket361is attached to the outer ring332. Hardware assemblies366are provided for such attachment.

The upper and lower brackets361are attached at their arms364by shaped flat springs368, each having a mounting flange portion370to overlie the surface of arms364of the mounting brackets361and the central arcuate portion372, which is capable of coiling and uncoiling as the upper and lower brackets361move towards and away from each other. It can be appreciated that this function of the springs368is made possible by constructing the springs from spring steel or similar material that is capable of flexing. The mounting flange portions370are attached to bracket arms364by hardware assemblies374. As can be appreciated, there is little resistance to the ability of the bracket arms364to pivot relative to bracket base362. As such, the position of the bracket arms364relative to the corresponding base362is dictated by the position/configuration of springs368.

As shown inFIG.12, a cord376extends between the base structures of the mounting structures361to limit the unwinding of the springs368, and thus limit the distance separating the pods352from the outer ring332. It is to be appreciated that the FIGURES of the present application illustrate only one manner in which the pods352may be mounted on the outer ring332. The pods352can be mounted on the outer ring332by innumerable other means, while enabling the pods to shift radially inwardly toward axis30during use ILI tool20, for example, when rounding a corner or a bend in the pipeline or when encountering discontinuity, such as the indentation in the pipeline.

It will be appreciated that by mounting the eddy current signal sensing or detecting units308on the exterior of the outer ring332, it is not necessary to assemble the sensing/detecting units onto the exciter unit centralizer200. After the centralizer200, in collapsed form, has been placed into the interior of the pipeline to be inspected. it is only necessary to attach the detector unit centralizer with the other components of100and200of the inspection tool20. Once the detector centralizer unit300has been position within the pipeline to be inspected, the unit can be erected by, for example, inflating the toroid304, whereupon the detector unit300is substantially ready for use in the sense that assembly of the unit300is not required.

FIGS.1,2, and3illustrate the ILI tool20in assembled configuration and ready for use to inspect a pipeline. In this regard, the guiding centralizer is100, the exciter centralizer200and the detector centralizer300are erected/inflated and interconnected together. However, prior to achieving an assembled configuration, the individual guiding centralizers100, the exciter centralizer200, and the detector centralizer300were first inserted into the pipeline through a manway or other opening publicize smaller than the erected/inflated circumference of the centralizers100,200, and300. As such, the centralizers were placed into the pipeline in deflated configuration, thereby enabling the diameter of the centralizers to be substantially reduced. For example, guiding centralizer100, which is 36 inches in diameter when inflated, can be reduced to a width of about 12 inches when deflated so that it can easily fit through a standard 20-inch-wide manway.

Once placed within the pipeline to be inspected, the centralizers100,200, and300can be attached together in desired configurations and the superstructures of the centralizers inflated either manually or by a powered source of pressurized air.FIGS.14and15show the leading centralizer100erected/inflated and show the centralizers200and300and the trailing centralizers100in collapsed/deflated configuration. As noted above, to facilitate inflation, the toroid superstructures may each include a number of insulation valves, so that likely a valve is near the location of work person tasked with inflating the toroids. Once the centralizers100,200, and300have been assembled and the respective superstructures inflated, the tool is ready for use without assembly of the components of the centralizers. As mentioned above, the tool20is towed through the pipeline using a towing line attached to the forward end of the tool, and the restraining line attached to the trailing end of the tool.

It will be appreciated that the inflatable tool20can save significant time in readying the tool for use since the various centralizers100,200,300did not themselves be disassembled for delivery to the interior of the pipeline and then reassembled for use. Similarly, after the completion of the inspection of the pipeline, it is not necessary to disassemble the various centralizers in order to remove the centralizers from the pipeline. Rather, it is only necessary to decouple the centralizers from each other and deflate the centralizers so they occupy a reduced size that is small enough to be removed from the pipeline as a complete unit.

While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention. For example, rather than using a superstructure in the form of a singular inflatable toroid, such as toroids118,204, or304, a plurality of smaller cross-sectional diameter inflatable tubular structures can be utilized. As an example, six such smaller diameter inflatable tubular structures can be arranged to cooperatively define superstructure of an overall cross-sectional shape and size similar to toroids118,204, or304. Rings can extend around such tubular structures so as to define the overall cross-sectional shape of the resulting superstructure. Also, the inflatable tubular structures can be interconnected with compressed air flow communication so that they are all inflated simultaneously, rather than having to inflate each tubular structure individually.

A further alternative to a superstructure can be constructed from solid arcuate segments that cooperatively define a toroid shape corresponding to toroids118,204, or304. For example, the superstructure could be composed of 8, 10, 12, etc. segments that are hinged together, but are allowed to collapse into, for example, and oval-shaped, so as to reduce the overall envelope of the centralizer to a small enough size to enable the centralizer to be inserted into pipeline being inspected through a smaller entrance opening. The collapsed superstructure can be directed by tightening a cable that extends either through or around the segments of the superstructure, thereby to cause the segments to assume a circular shape.

As another alternative the superstructure can be composed of solid arcuate segments that are telescopic really engageable with each other, to be able to telescope between and erected circular size and smaller circular size. Telescoping spokes or other supports may extend between the segments of the superstructure and the hub structure to change in length as the superstructure is collapsed or erected. Once the superstructure is fully erected, the spokes can be locked to maintain their extended length thereby supporting the superstructure relative to the hub structure.

Further, these alternatives superstructures may employ outer rings similar to outer rings124,226, and332so that assembly of the wheels, exciter coils, or sensing/detecting units on respective centralizers, such as centralizers100,200, or300, is not required.