Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/38—Investigating fluid-tightness of structures by using light
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/22—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
  • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
  • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
  • G01N23/043—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using fluoroscopic examination, with visual observation or video transmission of fluoroscopic images

Definitions

• the present invention relates to the examination of pipes, and in particular to the X-ray fluoroscopic inspection of the circumferential weld between two sections of a double-jointed steel pipe, as well as other pipe characteristics.
• Steel pipes that are intended for use in installations such as oil pipelines and the like are typically manufactured in forty foot (12.192 meter) lengt for ease of transportation.
• t forty foot (12.192 meter) lengths of pipe are typically welded together at the manufacturing site to form an eighty foot (24.384 meter) length of pipe that is commonl referred to as a "double-jointed" steel pipe.
• radiographic which utilizes a form of ionizing radiation that penetrates the material on the pipe and produces a reaction on an image receiving device.
• a radiographic film was typically used as the image receiving device. The radiation source was placed inside the pipe and a strip of radiographic film surrounded the outside of the pipe on the girth weld. The film was irradiated by X-rays passing through the pipe, and then removed from the outside of the pipe and developed in a processing laboratory. Once the film was developed, the quality of the weld could be determined from the quantity of X-rays that impinged on the film.
• the apparatus disclosed in the patent includes a movable source of gamma radiation that is disposed within the pipe, and an elastomeric belt that forms a track and that is attached around the pipe adjacent a weld to be inspected.
• a cart carrying a photomultipiier tube and a crystal detector is placed on the track formed by the belt and moved around the entire circumference of the pipe to detect the gamma radiation passing through the pipe at the location of the weld.
• the above noted patent provides an alternative to the use of radiographic film, it is primarily directed to the inspection of pipe at remote locations, and it posesses a number of features which render it less than ideal for use in a production line type of environment.
• the use of the elastomeric belt that must be placed around the pipe for each inspection still requires a significant amount of manpower and time.
• the results detected by the radiation detector are fed to a chart recorder that produces a record medium of the results, hile these results are pro ⁇ vided to an operator much faster than those obtained
• OMPI with radiographic film they are not instantaneous, in that the operator is not apprised of a fault in the weld seam and able to note it as soon as it is detected by the radiation detection apparatus. Rather, in the operation of the system, the entire circumference of the pipe weld " is first recorded on the chart, and thereafter the operator must determine the location of any detected faults by correlating a fault noted on the printed chart with a distance from a starting point at which the "detection apparatus began the inspection of the weld. In a production environment, it is prefer ⁇ able to have the operator note the location of any - detected flaws directly on the pipe as the flaw is being scanned by the radiation detector, to thereby . avoid the extra step of having ' to correlate the printed results with a distance around the circumference of the pipe, and thereby eliminate the time consumed in such a step.
• OMPI inspection method and apparatus that substantially reduces the time required for inspection over prior art methods, and thereby renders the inspection method suitable for use in a production line situation.
• a system for accomplishing these objectives in accordance with the present invention includes a source of radiation mounted on an adjustable canti- levered boom.
• a pipe whose girth weld is to be examined is placed on a cart that is movable longi ⁇ tudinally of the boom.
• the cart is moved to cause the boom to be located within the pipe, with the girth weld in registry with the radiation source.
• a fluoroscope located outside of the pipe in alignment with the radiation source produces a visible image of radiation penetrating through the pipe.
• the cart has rollers- for rotating the pipe about its longitudinal axis, so as to produce an image of the entire weld.
• the image of the weld can be observed on a video monitor and recorded on a video cassette recorder and a facsimile unit. Appropriate instructions relat ⁇ ing to repairs to be performed on the pipe can be included in the recordings.
• a spray marker located adjacent the fluoroscope enables an operator to mark detected flaws on the pipe, for subsequent repairs.
• Fig. 1 is a side elevation, partly in section, showing a double-jointed pipe section mounted on a conveying cart wherein the radiation source at the end of the cantilevered boom extending within the pipe section is in registry with a camera for recording the character of the weld seam and adjacent wall area, and wherein the region adjacent the weld seam is broken away and shown in section; and
• Fig 2 is an end view of the pipe when mounted on the cart shown partly in section and taken along the line II-II of Fig. 1.
• the principal elements of the embodiment of the invention illustrated therein comprise a conveyor cart W, a cantilevered boom B, and a camera unit C that are used to inspect the weld between the two sections of a steel pipe D.
• the pipe D is a so-called "double-jointed" steel pipe that consists of two separate sections of pipe that are welded together at their abutting ends to form a longer, single piece of pipe.
• the weld which joins the two sections extends around the entire periphery of their abutting surfaces and is called a girth weld.
• the term "double-jointed" steel pipe as used in the context of the present invention is intended to refer to pipe of this type; i.e. any type of pipe which for various reasons is formed from two or more individual sections of pipe that are welded together.
• the cantilevered boom B includes a base 11 upo " n which is mounted a vertically adjustable support platform 12 to which a boom element 13 is affixed and extends in the horizontal direction a distance equal to at least the length of one of the pipe sections of the double-jointed pipe unit D.
• the support platform to which the boom element 13 is affixed is adjustable in height to raise and lower the boom an appropriate distance to enable it to be inserted into various dia- meters of pipe section approximately along the central axis thereof.
• An X-ray tube 14 is mounted on the end of the boom element 13 that is remote from the platform unit 12.
• the tube 14 is disposed so as to emit X-rays in a substantially vertically upward direction from its output port when it is energized.
• a shutter mechanism 15 is affixed on the boom element 13 adjacent the output port of the X-ray tube 14, and includes a shutter element 16 that is adapted for reciprocal ove- ment to selectively interrupt or pass the X-rays eminating from the source 14 by advancing or retracting the element as desired.
• the pipe D is moved longitudinally by means of the cart W to the position illustrated in Fig. 1, wherein it surrounds the X-ray source 14.
• the cart is mounted on a set of tracks 17 that guide it in its movement between the location illustrated in Fig. 1 and a remote location where it is in position to receive assembled double-jointed pipes at an appropriate point in a production line.
• a pair of oscillatable transfer rails 18 are disposed on the cart W and engage the pipe to move it onto, and from the cart at the remote loca ⁇ tion.
• the cart is also equipped with two sets of rollers 19 that rotate about axes extending in the longitudinal direction of the cart. These rollers are ' mounted on hydraulic cylinders 20 that enable them to be raised and lowered into and out of contact with a pipe supported on the cart.
• the movement of the cart along the rails 17, the actuation of the transfer rails 18, and the raising and lowering of the rollers 19 are provided by a suitable power unit 21 mounted on the cart W and controlled from a remote operator's station.
• the camera unit C is disposed " on the exterior of the pipe D to be inspected in alignment with the output port of the X-ray tube 14.
• the unit includes an imaging fluorescent screen 22, an image amplifier 23, a set of focusing lenses 24 and a video camera 25 for viewing a fluorescent image on the screen 22. All of these components are mounted on a platform 26 that can be raised and lowered by suitable means (not shown) to accommodate pipes of different diameters while main ⁇ taining the alignment of the unit C and the source 14. Two remotely operated.
• spray markers 27 and 28 are mounted on the camera platform 26 in a position to be adjacent a pipe when it is moved into the location illustrated in Fig. 1 by the cart W. These two spray markers are preferably filled with different colors of ink or paint, such as yellow and white, for example.
• An incremental position detector 30 is mounted on the platform unit 26 and adapted to
• OM engage the pipe being inspected and provide an indica ⁇ tion of the rotational position of the pipe.
• the video camera 25 is connected to a conventional camera control circuit 31 that provides suitable control signals in response to the output signal of the camera to produce a video image on a viewing monitor 32.
• the camera control circuit 31 is also connected to a video cassette recorder 33 that records the video image, which is simultaneously displayed on a recording monitor 34.
• the recording monitor 34 In addition to receiving the video signal from the camera control circuit 31, the recording monitor 34 also receives input information from an alpha-numeric video character generator 35 and an incremental position indicator 36 that is responsive to the position detector 30. The information from these two input sources is also recorded by the video cassette recorder 33.
• a video image facsimile unit 37 is connected to the recording monitor 34 to enable a hard copy record of the video image to be obtained by an operator.
• the support platform 12 and the camera platform 26 are appropriately positioned in height to accommodate the particular diameter of pipe that is to be inspected.
• the boom 13 is preferably positioned so that it lies approximately along the central axis of the pipe, and the camera assembly platform is posi ⁇ tioned just slightly above the top surface of the pipe. After a double-jointed pipe has been welded, it procedes on the production line to the location of the inspection device.
• the cart W is moved to a position in the production line just ahead of the pipe. As the pipe arrives at the cart, the operator
• OMP actuates the transfer rails 18 so that the pipe is moved onto the cart.
• the hydraulic cylinders 20 are then actuated to raise the pipe rotating rollers 19 and thereby elevate the pipe a few inches above the trans- 5 fer rails 18, to the position illustrated in Fig. 2, so that the pipe becomes cradled on the rollers.
• the cart is then driven from the production line towards the location of the inspecting apparatus.
• the photo ⁇ cells 29 provide a signal that energizes the shutter mechanism 15 to open the X-ray tube output port.
• the image that is produced on the fluorescent screen 22 is received by the video camera 25 and dis-
• the spray markers for example the white marker 28
• the cart can then continue ' on towards the production line, where the operator can lower the rollers 19 and actuate the transfer rails 18 to move the pipe towards the next facility in the line.
• the shutter mechanism 15 is actuated to close the output port of the X-ray tube 14, to thereby prevent X-rays from being emitted while there is no protective covering, such as a pipe, around the source. If, during the visual inspection of the pipe, the operator observes a discontinuity or other such flaw that is sufficient to impair the quality of the weld, he can stop the rotation ⁇ of the pipe at the point where the observed discontinuity appears on the recording monitor, by means of the control panel 38.
• the video image facsimile unit 37 can also be actuated to provide a hard copy duplicate of the video image on a piece of paper, for use by the individuals who will be repairing the observed weld.
• the operator can also energize the other spray marker 27 to place a spot of ink or paint directly onto, or adjacent, the weld at the location of the observed discontinuity.
• the repair instructions that are generated by the video character generator 35 can then be erased and the rollers 19 reactuated to again rotate the pipe about its axis and enable the remainder of the weld to be inspected. If additional discontinuities are observed, the foregoing steps ean be repeated until the entire weld has been examined.
• the operator can control the cart to move it to a desig ⁇ nated repair area and unload the pipe from the cart, where it will be repaired in accordance with the instructions printed out on the hard copies produced by the video image facsimile unit 37.
• the present invention provides a novel system for inspecting girth welds on double-jointed steel pipe that is particularly well suited for production line use.
• the fixed alignment of the X-ray source and detector, and the remotely controlled delivery of a pipe into registry with them protects the operator from any harmful exposure to X-rays and eliminates errors that are caused by manual affixation of the source or detector to the pipe.
• the rotation of the pipe about its longitudinal axis relative to the source and detector eliminates the need for a detector that circumscribes the entire periphery of the weld, and any associated manpower required to fit the detector in
• the video -Image of the inspected area of the girth ' weld provides an operator with the ability to instantaneously interrupt the rotation of the pipe, mark the location of a detected flaw, and record appropriate information relating to repairs.
• the apparatus provides a measure of flexibility that enables it to be successfully employed in measurement or inspection operations in addition to girth weld examination.
• the individual sections of a double-jointed steel pipe are commonly formed by rolling a flat sheet of steel into a tube shape and welding the abutting edges of the sheet along the length of the pipe. It is often desirable to inspect' the quality of the weld along the longitudinal seam of the pipe sections. Such examination can be easily accomplished with the apparatus of the present invention.
• the cantilevered boom having a length equal to or greater than that of one pipe section, permits the entire longitudinal seam of a section to be viewed by the operator as the cart brings the girth weld into registry with the source and detector. The only extra step that is required is to rotate the pipe immediately after the shutter 15 is opened to bring the longitudinal seam into registry with the source and detector, to thereby enable it to be viewed as the cart moves toward the final position of inspection illustrated in Figure 1.
• OMPI to provide a long enough boom 13 that enables the cart to be moved an additional 6-10 inches (15.24-25.40 cm) to the right, as viewed in Figure 1.
• Such a feature will permit the portion of the longitudinal weld adjacent the girth weld to be examined without the need to reposition the pipe or turn the cart.
• Another characteristic of double-jointed pipes that must be measured relates to the circumferential spacing between the respective longitudinal seams of • the two pipe sections.
• the specifications relating to such pipes require that a minimum spacing be present between the two seams around the periphery of the pipe, primarily for stress control purposes.
• Such spacing can be easily measured with the apparatus of the present invention, preferably at the beginning of the girth weld examination. The examination can be initiated at a point where one of the longitudinal seams intersects the girth weld, which is easily provided for when the apparatus is used to examine the longitudinal seam, as described above. As the pipe is rotating during the girth weld examination, the image of the other longitudinal seam will appear on the video monitors 32 and 34.
• the operator can observe the reading of the incremental position indicator 36 and determine whether the spacing between the two seams meets the specifications for the pipe. If it does, the girth weld examination can continue in the normal manner. If the spacing is less than the required minimum, the operator can halt the examination operation as soon as the spacing is determined, since there is no need to continue when the pipe does not meet all specifications.
• the use of the apparatus in this manner can save time by reducing the time required to examine the girth welds of pipes that are defective in terms of longitudinal seam spacing.
• OMP Body defects such as gouges or scratches
• OMP Body defects can also be radiographically examined with the appara ⁇ tus of the present invention.
• the ability to both rotate a pipe and move it longitudinally with the cart enables the operator to position any portion of the pipe section between the source and the detector for radiographic examination.
• Gouges are typically removed by grinding the surrounding surface area of the pipe so that a smooth contour is presented.
• the inspection apparatus of the present invention facilitates inspection of the ground area to ascertain whether the thickness of the pipe wall has been reduced to a value that is less than that required by the specifications.
• the present invention may be embodied in
• the detector could be located on the side of the pipe, rather than above it, and the X-rays could be directed in a horizontal direction from the source. It is also possible to have the cantilevered boom longitudinally movable, as well as vertically adjustable. However, in such a case, provision should be made for adjusting the camera unit laterally as well, since it is important that the camera and X-ray source be in alignment with one another during the examination of a pipe.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Radiology & Medical Imaging (AREA)
• Life Sciences & Earth Sciences (AREA)
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• Analytical Chemistry (AREA)
• Biochemistry (AREA)
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• Analysing Materials By The Use Of Radiation (AREA)
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• 1982
  • 1982-08-25 CA CA000410120A patent/CA1206278A/en not_active Expired
  • 1982-09-30 EP EP82903383A patent/EP0094400A1/en not_active Withdrawn
  • 1982-09-30 WO PCT/US1982/001382 patent/WO1983001509A1/en unknown
  • 1982-10-15 KR KR8204642A patent/KR910001250B1/ko active
  • 1982-10-15 IT IT23756/82A patent/IT1152908B/it active

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