Cross-Reference to Related Application

This application claims the benefit of and priority to United States Provisional Patent Application No. 61/494,602 filed 08 June 2011 under the title ROBOTIC APPARATUS FOR AUTOMATED INTERNAL PIPELINE GIRTH WELD ULTRASONIC INSPECTION.

The content of the above patent application is hereby expressly incorporated by reference into the detailed description hereof.

Background to the Invention [0001] Pipeline, such as long distance oil pipeline, is often installed as a series of tubes of pipe, which have their ends welded together at the installation site. These girth welds are often of variable quality, since they are often welded in extreme conditions, such as on a pipe lay barge, or in the middle of a desert. Accordingly, there is a need to inspect pipeline girth welds, either after installation, or on a regular basis. One conventional method and apparatus for inspecting pipeline girth welds involves ultrasonic inspection by deploying an array of ultrasonic probes onto an externally mounted orbiting mechanism, which is clamped around the pipeline circumference. This deployment method usually comprises of a semi-rigid 'band' clamped around the pipe circumference and a removable drive mechanism, commonly called a 'buggy', which carries the ultrasonic array, water for probe coupling to the pipe, and a position transducer. An umbilical cable from the u ltrasonic array carries the transmit pulses from the probe, and the received echoes and other signals, to an ultrasonic acquisition system. The acquisition system then sends the raw ultrasonic signals to a computer workstation. Analysis of these ultrasonic signals is common in the industry; from the signals provided by the ultrasonic probe bouncing off the girth weld, one can determine the quality of the girth weld.

[0002] In the case of an offshore pipe laying vessel, this method of inspection requires a separate, fixed inspection station, downstream of the welding of the pipe lengths, which houses the band and buggy. This inspection station is undesirable since it takes up valuable space in the vessel.

[0003] In the case of an existing pipeline, buried in the ground, the external ultrasonic inspection methodology of inspection is not possible without excavation of the pipeline to expose the welds.

[0004] To add to the difficulty in inspecting an existing pipeline, in many cases, buried and surface mounted pipelines are often protected by external protective coatings and lagging . These outer coatings need to be removed for the inspection, then replaced post-inspection, which is time consuming and expensive.

[0005] There is therefore a need for a pipe girth weld inspection apparatus and method, which allows for internal inspection of the pipe girth weld.

Summary of the Invention

[0006] According to one aspect of the invention is provided a cart for ultrasonic inspection of pipeline girth welds from inside a pipeline having an inside wall, comprising : a frame on wheels;a multi axis robotic arm, affixed to said frame and extending therefrom, said robotic arm having a frame end and a distal end, and capable of displacement from a first, retracted position wherein, when the cart is inside the pipeline, the cart is capable of longitudinal displacement along the pipeline without said distal end contacting the inside wall; and a second, extended position wherein the d istal end is located proximal to the inside wall; said robotic arm capable, when in said second, extended position, of 360 rotation of its distal end around a circumference of the inside wall; said robotic arm also capable, when in the second, extended position, of fine adjustment and positioning relative to said inside wall; an ultrasonic array assembly, located proximal to or on the distal end of the robotic arm, said ultrasonic array assembly comprising at least one camera and an ultrasonic array having at least one ultrasonic probe; a robotic controller module affixed to said frame and able to control positioning of the robotic arm; and an on-board computer connected to said robotic controller module and capable of sending and receiving a signal from an operator located remotely. [0007] In certain embodiments, the cart also comprises a water dispersal system proximal to or within the ultrasonic array assembly, and, when the robotic arm is in the second, extended position, of dispensing water between the at least one ultrasonic probe and the inside wall; said water dispersal system being connected to a source of pressurized water. For example, the source of pressurized water is a water storage tank affixed to said frame, and/or an umbilical cord with one end connected to the water dispersal system and another end connected to a water storage tank located outside of the pipeline.

[0008] According to certain embodiments, the cart also comprises a position transducer located proximal to or on the distal end of the robotic arm and, when the robotic arm is in the second, extended position, is in contact with the inside wall and is capable of measuring the integral force exerted by the ultrasonic array assembly onto the inside wall.

[0009] According to a further embodiment, one or more of the wheels can be a drive wheel; the cart may comprise a battery affixed to said frame and powering said drive wheel(s).

[0010] According to a further aspect of the invention, the cart can comprise wheels are user-replaceable or adjustable for use in pipe of different diameter. [0011] In certain embodiments, the cart may further comprise an inclinometer affixed to said frame and capable of measuring the incline of said cart relative to the ground .

[0012] According to a further aspect of the invention, the camera is pointed towards the inside wall when the robotic arm is in the second, extended position.

[0013] The cart of any one of claims 1- 10 further comprising a forward facing camera . [0014] According to a further aspect of the present invention is described an inspection apparatus for internal inspection of pipeline girth welds in a pipe on a pipe laying vessel, comprising : A cart as herein described; an umbilical cable, extending from the frame to a control room and providing bi-directional data transmission from the on-board computer to an interpretation workstation in the control room ; a line-up clamp capable of clamping a new pipe length to the pipe, and through which the umbilical cable can pass; an umbilical cable spooling device on which a slack portion of the umbilical cable is wound ; and a user interface on the interpretation workstation which allows a user to operate the cart and obtain data from the cart while in the control room .

[0015] The inspection apparatus of claim 12 further comprising a water replenishment system outside of the pipeline and connected via the umbilical cable, and capable of transporting pressurized water therethrough, to the water dispersal system. [0016] According to a further aspect of the present invention is described an inspection apparatus for internal inspection of pipeline girth welds on a buried pipe or a pipe with weld coatings or lagging applied thereto, said inspection apparatus comprising : A cart as herein described; a wireless transmitter, having an antenna, and affixed to said cart, connected to the on-board computer, and capable of transmitting a data signal from said on-board computer; a wireless receiver, having an antenna, and affixed to said cart, connected to the on-board computer, and capable of receiving a controller data signal and imparting said controller data signal to said on-board computer; an interpretation workstation located remotely from said pipeline, having a second wireless receiver and a second wireless transmitter, both connected to one or more antenna, and capable of receiving said data signal from said wireless transmitter and sending said controller data signal to said wireless receiver; said interpretation workstation capable of generating controller data signal based on user input.

[0017] According to a further aspect of the present invention is described a method of inspecting a girth weld on a pipe, comprising : Placing into an open end of the pipe, a cart having : a frame; a multi axis robotic arm, affixed to said frame and extending therefrom, said robotic arm having a frame end and a distal end, and capable of displacement from a first, retracted position wherein, when the cart is inside the pipe, the cart is capable of longitudinal displacement along the pipeline without said distal end contacting the inside wall; and a second, extended position wherein the distal end is located proximal to the inside wall; said robotic arm capable, when in said second, extended position, of 360 rotation of its distal end around a circumference of the inside wall; said robotic arm also capable, when in the second, extended position, of fine adjustment and positioning relative to said inside wall; an ultrasonic array assembly, located proximal to or on the distal end of the robotic arm, said ultrasonic array assembly comprising at least one camera and an ultrasonic array having at least one ultrasonic probe; a robotic controller module affixed to said frame and able to control positioning of the robotic arm; an on-board computer connected to said robotic controller module and capable of sending and receiving a signal from an operator located remotely; and a forward facing camera; wherein the cart is in the first, retracted position; sending a signal to said cart which results in displacement of the cart along the pipe; reviewing images from the forward facing camera to determine placement of the cart along the pipe as it is displaced; remotely stopping displacement of the cart along the pipe, when the cart is located proximal to the girth weld; sending a signal to said cart which results in extension of the robotic arm to the second, extended position; finely adjusting the position of the robotic arm by reviewing images received from the at least one camera and controlling the arm by remote;

activating the ultrasonic array; capturing data from said ultrasonic array;

sending a signal to said cart which results in the rotation of the robotic arm at least 360 degrees, around the length of the girth weld and around the

circumference of the pipe; deactivating the ultrasonic array; and storing the data captured from the ultrasonic array. The operation of the cart may be done either within, or from outside of the pipe, for example, from a control room or a vehicle or trailer. [0018] According to certain embodiments, the data captured from the ultrasonic array is sent to the control room or the vehicle or trailer for further analysis. [0019] According to certain embodiments, the rotation of the robotic arm can be finely adjusted in near real time by an operator, remotely, in response to information received by said operator from the at least one camera .

[0020] According to yet a further aspect of the present invention is disclosed a dynamic force feedback system which keeps the ultrasonic array at a constant force on the pipe to compensate for cart centralization positional errors and pipe out of round, as the robotic arm rotates.

[0021] According to a further aspect of the invention, the in-pipe orientation of the robotic arm is determined and/or recorded by means of an inclinometer mounted on said cart.

[0022] According to a further embodiment of the present invention is provided a quick release umbilical docking device, deployed by a line-up clamp for releasing/connecting the umbilical cord that passes through existing line-up clamp equipment to the inspection control station. [0023] According to yet a further embodiment of the present invention is provided an umbilical docking device that can be moved from pipe end to pipe end by the line-up clamp and released from the line-up clamp whilst new pipes are positioned at the pipeline open end for girth welding.

Brief Description of the Drawings

[0024] Figure 1 shows a schematic representation of an apparatus according to one embodiment of the present invention, depicted within a cross- section of a pipe.

[0025] Figure 1A is a schematic representation of an apparatus according to one embodiment of the present invention, depicted in two alternative wheel configurations.

[0026] Figure 2 shows a schematic representation of an apparatus according to one embodiment of the present invention, depicted within a cross- section of a pipe, and connected, by umbilical cord, to a controller outside of the pipe.

[0027] Figure 3 shows a schematic representation of an apparatus according to one embodiment of the present invention, depicted within a cross- section of a pipe, and connected, by two-way wireless link, to a controller outside of the pipe.

[0028] Figure 4 shows a flowchart of signal transmission between various components of an apparatus according to one embodiment of the present invention. Detailed Description

[0029] One embodiment of the apparatus of the present invention is depicted in figures 1-3. A remote controlled robotic cart 10 comprises a frame 12 having rear wheels 14 and front wheels 16 on axes 18. As shown, both rear wheels 14 and front wheels 16 are each powered by a motor (18, 20) controlled by an on-board computer 22 through robotic controller module 24. As would be evident to a person of skill in the art, in alternative embodiments (not shown), only one set of wheels is powered, with the other set of wheels free spinn ing. Not shown, but in a typical configuration, each wheel is individually powered . Thus, motor 18 as shown is actually powering the right, rear wheel, where there is a second rear motor (not shown) powering the left rear wheel. Having separate motors for left and right wheels allow a user to control the speed and/or torque of the left wheel in relation to the right wheel, which in turn allows for steering of the cart 10.

[0030] As shown in Figure la, the wheels 14, 16 are shaped to conform to the inside wall 26 of a pipe 28 of a standard diameter, for example, a 4 foot pipe. Wheels 14, 16, along with their axle 30, can easily be removed from the cart 10 and replaced with wheels 14a of a different shape, on axle 30a of a different length, to allow cart 10 to be used on a pipe of a different diameter. The apparatus may thus be equipped with wheels 14, 14a on axles 30, 30a of a multitude of varying shapes, sizes, and lengths, each optimized for a different pipe diameter or alternatively a different pipe material. [0031 ] Cart 10 is self powered by means of a battery pack 32. The battery pack may be a rechargeable battery pack, for example with a rapid connector (not shown) for easy recharging, or it may be a disposable battery pack. In the shown embodiment, battery pack 32 is connected both to the drive motors 18, 20, and to the electronics (robotic controller module 24 and on-board computer 22, for example), and provides power to both. As would be understood to a person skilled in the art, the battery pack 32 and motors 18, 20 are optional; in certain embodiments (not shown), the cart 10 is not self-propelled, instead having a coupling capable of attaching the cart 10 to a standard pipeline drive cart, which would comprise drive means and could be similarly remote controlled .

[0032] Extending from the front end 34 of cart 10 is a robotic arm 36. The robotic arm 36 is multi-axis, and controlled by on-board computer 22 through robotic controller module 24. As shown, the robotic arm 36 is configured such that its base is at about the center of the diameter of the pipe, though, depending on the robotic arm used, this may not be essential. An ultrasonic array assembly 38 is mounted to a distal portion 40 of the robotic arm 36.

[0033] An ultrasonic array assembly 38 comprises an ultrasonic wedge 39, resistant to temperature, and phased array transducers 42, typically with 48 to 64 small individual elements that can be pulsed separately. The phased array transducers deployed are customized to girth weld inspection typically in the vicinity of 5MHz depending on the detection requirement. The phased array transducer is configured so that it can be placed on both sides of the girth weld to enable upstream and downstream inspection simultaneously. In addition, a Time of Flight Differaction (ToFD) ultrasonic array (not shown) can be attached to the side of, in addition to, or in lieu of, the phased array transducers 42. The ToFD ultrasonic array typically comprises a pair of wedges that can introduce desired longitudinal wave into an inspection piece, a pair of ToFD transducers with a frequency typically from 5 MHz to 15 MHz depending on wall thickness and resolution requirements. Use of a combination of the ToFD ultrasonic array and the phased array transducers can improve the resolution and/or detection of weld defects. [0034] The robotic arm 36 can be positioned in a retracted, "park" position (not shown) whilst the robotic cart 10 is displaced along the inside wall 26 of the pipe. Once the robotic cart 10 has moved to a position proximal to a girth weld 38 (as shown), the robotic arm 36 can be positioned in an extended position (as shown), which provides for placement of the ultrasonic array assembly 38 proximal to the girth weld 48. The robotic arm 36 is moved until the u ltrasonic array assembly 38 is at a proper position for inspection of the girth weld 48. The distal portion 41 of the robotic arm 36 is capable of 360 degree rotation relative to the cart 10, to allow the ultrasonic array 42 to travel the entire length of the girth weld 48, i.e. the entire perimeter of the pipe inside wall 26.

[0035] The robotic arm 36 is specifically designed for accurate placement on either side of the weld (+/- approx. 1mm), and rotation 360 degrees around the weld, whilst maintaining both positional accuracy and constant rotational speed. This positional accuracy is achieved by a combination of typically five articulations within the arm and a 360 degree rotational base unit, mounted to the front of the cart 10.

[0036] Location of the ultrasonic array assembly 38 at the correct inspection position is assisted by two camera assemblies 50, 52 mounted onto the ultrasonic array frame 40, and a forward facing camera assembly 54 mounted onto the robotic cart 10. The camera assemblies 50, 52, 54 can be any form of camera that will provide an image to the operator. As shown, camera assemblies 50, 52, 54 are CCTV video cameras with built-in LED light arrays. These camera assemblies 50, 52, 54 are activated by, and relay signal through, robotic controller module 24 to on-board computer 22. The camera assemblies 50, 52, 54 also allow the operator to view the inspection taking place and assist the operator in locating the next girth weld as the robotic cart 10 is displaced . The two camera assemblies 50, 52, pointing at the girth weld 48 are used with automated optical weld tracking vision software, to ensure accurate ultrasonic probe alignment by adjusting the robotic arm 36 position as required.

Generally, the camera assemblies 50, 52 allow for the accurate initial placement of the ultrasonic array 42 proximal to the girth weld 48. The camera assemblies 50, 52 also help the placement of the ultrasonic array 42 throughout the movement of the ultrasonic array 42 around the girth weld 48, insuring that the ultrasonic array 42 does not deviate from the girth weld 48 during inspection. This position optimization can be carried out by either the operator or

automatically using a vision recognition software.

[0037] Also located on the ultrasonic array assembly 38 is a position sensor 44, typically an encoder, having an integral force sensing transducer 46. When the robotic arm 36 is positioned proximal to the girth weld 48, the position sensor 44 is oriented such that it presses onto the pipe inside wall 26, which allows recording of the ultrasonic array 42 position on the pipe during rotation, and to monitor the force applied to the pipe inside wall 26 by the robotic arm 36. The robotic controller module 24 utilizes the information received from the position sensor 44 to adjust the robotic arm 36 to achieve a relatively constant force at the ultrasonic array 42. This closed loop control compensates for both centralisation errors of the robotic cart 10 and for out of roundness of the pipe.

[0038] In an alternative embodiment (not shown), the robotic arm can be a pantograph type robotic arm with near constant pressure compliance. For this type of system, extend/ retract actuators are used to deploy the ultrasonic array.

[0039] Information with regards to the orientation of the robotic cart 10, and thus the robotic arm 36, with respect to the pipe 28 axial position is provided by means of an inclinometer 56, mounted onto the robotic cart frame 12. In use, the inclinometer 56 is useful to determine the exact and constant start of scan position on the girth weld 48 circumference. For example, the inclinometer 56 can be used to position the ultrasonic array so that the start of the inspection is always at the "top" of the inside wall 26 of the pipe. The inclinometer can also be useful in adjusting the torque on the left and right side drive motors 18, 20 while cart 10 is travelling to the next weld to prevent the cart wheels from climbing up the pipe walls and potentially toppling.

[0040] Also positioned on the cart 10 is a water storage tank 58. The water storage tank 58 has an integrated pressure regulator, and is connected to the ultrasonic array assembly 38, to supply water at required pressure to an integral water dispersal system 60 thereon . The water is used as a medium for transmitting and receiving the u ltrasonic signals emitted by the ultrasonic array 42. In the case of newly welded, hot pipes the water used to cool the ultrasonic array assembly 38, specifically, the phased array transducers 42, when in use. The water is carried by means of flexible pipe, located in an umbilical cable (not shown), between the water storage tank 58 and the water dispersal system 60. [0041 ] Umbilical cables (not shown) also connect the ultrasonic array assembly 38 (either phased array and/or ToFT probes, as described above) to an ultrasonic data acquisition system 62, which in turn sends the ultrasonic signals to the on-board computer 22 for analysis or transmittal. The ultrasonic data acquisition system 62 comprises an ultrasonic electronics module and a system computer. The ultrasonic electronics module provides up to 128 transmit and receive phase array channels plus 16 single-element / TOFD channels, including processing of signals to and from the probes and transmission of data to the onboard computer 22. The on-board computer sends the acquired ultrasonic data to the system computer 94 via fast Ethernet connection . The system computer 94 has all the data acquisition and presentation software to collect and display the inspection data .

[0042] Figure 2 shows one embodiment of the robotic cart 10, as one part of an inspection system 104 intended for use in offshore, new pipeline laying vessel applications. In th is embodiment, the robotic cart 10 is umbilical cord controlled . For offshore pipe lay vessel applications, use and analysis and interpretation of the inspection data provided by the robotic cart 10 is required very quickly (near real-time) in order to maximise productivity. In use, the robotic cart 10 remains in the pipe throughout the pipe welding/joining process. An umbilical cable 70 carries bi-directional high speed data transmission of the inspection data, robotic cart controls, CCTV camera images, water replenishment and battery re-charge power through a modified version of a lay barge pipe to pipe centring device, commonly known as a 'line-up clamp' 72. The line-up clamp 72 is similar to those already known in the art, with many different designs in operation, depending on the manufacturer or pipe lay vessel, but each line-up clamp design is modified to allow the umbilical cable 70 to pass through it. It is used in a manner similar to that known in the art, with the following modifications. The line-up clamp 72 is used to deploy an umbilical fast connect/disconnect docking device 74 that remains in the pipe when the line-up clamp 72 is removed to allow a new pipe length to be introduced for welding . The docking device has a central docking cone to assist in line-up. At the tip of the cone four self sealing fast connect/disconnect plug and sockets are provided . Each connector carries the following services/signals: Water, Air, Power & Data Signals. When the line-up clamp 72 is re-introduced into the new pipe length prior to welding, the line-up clamp 72 first 'docks' with the docking device 74, engages and locks to the plug and socket arrangement, releases docking clamps 76, and positions itself and the docking device 74 at the correct position for accurate welding to take place external to the pipe. [0043] On completion of welding of a new pipe length 78 onto the pipeline 80, the line-up clamp 72 and docking device 74 are retracted (i.e. displaced) to the open end 82 of the new pipe length 78. The docking device 74 is clamped at the open end 82 and un-docked from the line-up clamp 72, breaking the umbilical connection. An umbilical cable spooling device 84 is used wind out and wind in the umbilical cable 70 inside the pipe as the cart 10 is displaced in the inside of pipeline 80. The umbilical cable 70 exits the line-up clamp 72 at a gland 86 and is connected to a second umbilical cable spooling device 88 that controls the length of the umbilical cable 70 required by the line-up clamp 72.

[0044] The umbilical cable 70 is routed from gland 86 to a control room 90 and terminated in plant control box 92. The plant control box 92 distributes the signals received from umbilical cable 70 to an interpretation workstation 94, which includes an operator display 96 and a video monitoring station 98. Water 100 is fed to water storage tank 58 by a water replenishment system 102. A human operator in the control room 90 controls the complete inspection cycle by operating interpretation workstation 94. From the control room, the operator can view the output from the cameras 50, 52, 54 to understand the position of the cart 10 relative to girth weld 48, control motors 18, 20 and thereby the movement of the cart 10 within the pipe 28 to a girth weld 48, control the alignment of the ultrasonic array assembly 38 onto the girth weld 48, and the rotation of the robotic arm to displace the ultrasonic array assembly 38 around the circumference of the girth weld 48. The operator also controls the water flow to the ultrasonic array assembly 38 and monitors the coupling of the ultrasound signals into and out of the pipe inside wall 26. In the event of loss of data due to a loss of coupling the operator can stop the rotation of the ultrasonic array assembly 38, reverse the axial rotation of the distal portion of the robotic arm 41 and repeat the scan, thus capturing the lost ultrasound data.

[0045] Data from the ultrasonic probe can be reviewed in near real-time to determine whether there are any imperfections or holidays in the girth weld 48, and if those imperfections or holidays are substantial enough to require re- welding or repair. This data is also stored in interpretation workstation 94 for future use, and to document the inspection process and the quality of the girth weld 48 welding processing. [0046] As would be evident to a person of skill in the art, the use of the inspection system 104 can eliminate the need for a dedicated ultrasonic inspection station that conventional external pipe inspection methods require, thus increasing the available floor space on the vessel. This potentially allows the vacated inspection area to be utilised for an additional welding station, with the resultant increase in productivity.

[0047] Figure 3 shows a further embodiment of the robotic cart 10, as one part of an inspection system 106 intended for use in land-line inspection of existing, in service pipelines, that may be buried or have weld coatings and/or lagging applied. The embodiment shown in figure 3 is of a bi-directional radio link robotic cart.

[0048] In this embodiment the robotic cart 10 is fitted with a bi-direction wireless transmitter/receiver 108, with an antenna 110, fixed to the cart rear. Optionally (not shown), the robotic cart 10 can be fitted with separate, discrete, unidirectional transmitter and receiver. [0049] At the open end 82 of the pipe 28 a second antenna 112, is located, and is connected via a suitable radio frequency cable 114 to a master wireless transmitter/receiver 116.

[0050] Bi-direction wireless transmitter/ receiver 108 is connected to board computer 22 through which it sends and receives signals to robotic controller module 24, motors 18, 20, and other components of the cart 10, for example, the position transducers 44 and the robotic arm 36. The bi-direction wireless transmitter/receiver is also capable of transmitting image data from the cameras 50, 52, 54 to the master wireless transmitter/receiver 116. [0051 ] The wireless transmitter/receivers 108, 116 operate using existing, known, and preferably approved, wireless protocol standards.

[0052] An operator can thus operate all required controls of the cart 10, and receive all of the pertinent signals and information from cart 10, by remote control. Typically, master wireless transmitter/ receiver 116 is housed in a suitable control environment, for example an all-terrain vehicle or trailer 118. Also housed within the vehicle or trailer 118 is interpretation workstation 94, operator display 96, and video monitoring station 98, generally identical to those described above in the inspection system 104. The operator sits in the vehicle or trailer 118, and controls the complete inspection cycle. [0053] As the girth weld 48 is scanned the ultrasonic data is recorded onto the on board computer 22. Basic data on the inspection and images from the cameras 50, 52, 54 are sent via the wireless link 120 as the inspection progresses; also sent is information regarding data integrity and other housekeeping activities. On completion of the ultrasonic inspection the acquired ultrasonic data can either be sent to the interpretation workstation 94 via the wireless link 120, or kept in the on-board computer 22 for later analysis.

[0054] The wireless link 120 can alternatively transmit a sub set of the ultrasonic data, related to scan success and data validity, prior to the cart moving to the next weld. During transit to the next weld the full ultrasonic data set can transmitted to the interpretation workstation 94 for analysis, or alternatively stored on the on board computer 22 for later analysis. This configuration allows in-service pipeline girth welds, buried, coated or lagged, to be inspected from the inside.

[0055] Inspection systems 104 and 106 generally work in the same manner. In use, an operator utilizes interpretation station 94 to control the cart 10. First, an operator, or a team of personnel, place the cart 10 within a pipeline, through the open end 82 of the pipe 28. In the case of inspection system 104, the operator or team of personnel will then connect line-up clamp through the open end 82 of the pipe 28, as would be done in a conventional system found within a typical pipe laying vessel. Then the operator, using controls (not shown) found on interpretation station 94, displaces the cart 10, to a desired location, proximal to a girth weld 48 to be inspected. To do this, the operator looks for the girth weld 48 using images captured by forward facing camera 54, transmitted to interpretation workstation 94, and displayed on video monitoring station 98. Optionally (and not shown), in the case of inspection system 106, a GPS positioning system or a odometer located on cart 10 may also be used. Once the cart 10 is in the correct position, adjacent to a girth weld 48, the operator then extends robotic arm 36 such that the ultrasonic array 42 is at a desired location immediately adjacent to girth weld 48. To do this, the operator uses information provided by camera assemblies 50, 52, again transmitted to interpretation workstation 94 and displayed on video monitoring station 98. The operator also uses information provided by position transducer 44. The operator then activates water dispersal system 60, and ultrasonic array 42. The operator then rotates the robotic arm 36, such that ultrasonic array 42 travels along the entire length of girth weld 48. Again, information from position transducer 44 and cameras 50, 52 are used to fine tune this movement so that the ultrasonic array 42 accurately measures the length of the girth weld 48. While the operator is rotating the robotic arm 36, ultrasonic array 42 is measuring data regarding the girth weld 48. Once the entire girth weld 48 has thus been inspected (through an approx. 360 degree rotation of the robotic arm 36), the operator then deactivates ultrasonic array 42, deactivates water dispersal system 60, and retracts the robotic arm 36 away from the pipe inside wall 26. As discussed above, data from the ultrasonic inspection is optionally transmitted back to the operator at interpretation workstation 94, or is stored on the on-board computer 22. The operator receives confirmation that the inspection is complete, and then repeats the process for the next girth weld.

[0056] Figure 4 is a flowchart depicting the flow of information to and from the various components of the apparatus, as described above. [0057] Although the invention has been described in connection with certain embodiments thereof, it is not limited thereto. Rather, the invention includes all embodiments which may fall within the scope of the following claims.

Parts List

Cart 10

Frame 12

Rear wheels 14, 14a

Front wheels 16, 16a

Rear motor 18

Front motor 20

On-board computer 22

Robotic controller module 24

Inside wall 26

Pipe 28

Axle 30

Axle 30a

Battery pack 32

Front end 34

Robotic arm 36

Ultrasonic array assembly 38

Ultrasonic wedge 39

Ultrasonic array frame 40

Distal portion of robotic arm 41

Phased array transducers 42

Position sensor 44

Integral force sensing transducer 46 Girth weld 48

Camera assembly 50, 52

Forward facing camera assembly 54

Inclinometer 56

Water storage tank 58

Water dispersal system 60

Ultrasonic acquisition system 62

Umbilical cable 70

Line-up clamp 72

Docking device 74

Docking clamps 76 New pipe length 78

Pipeline 80

Open end 82

Umbilical cable spooling device 84 Gland 86

Second umbilical cable spooling device 88 Control room 90

Plant control box 92

Interpretation workstation 94

Operator display 96

Video monitoring station 98

Water 100

Water replenishment system 102