CA1153604A - Pipeline inspection apparatus - Google Patents
Pipeline inspection apparatusInfo
- Publication number
- CA1153604A CA1153604A CA000370419A CA370419A CA1153604A CA 1153604 A CA1153604 A CA 1153604A CA 000370419 A CA000370419 A CA 000370419A CA 370419 A CA370419 A CA 370419A CA 1153604 A CA1153604 A CA 1153604A
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- Canada
- Prior art keywords
- pipe
- internal surface
- camera
- film
- movement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
PIPELINE INSPECTION APPARATUS
.
ABSTRACT OF THE DISCLOSURE
Pipeline inspection apparatus as provided including a camera unit and associated illumination means, preferably a strobe flash unit, for recording on photographic film the rectangular images corresponding to generally rectangular internal surface portions of a pipe for detection of defects, a viewing axis of the camera being normal to the axis of the pipe. Weight means are provided for operating in a manner such as to establish a viewing axis in predetermined angular relation to a vertical plane through the axis of a horizontal pipe. In one embodiment, the device is supported by resilient cups for movement through the pipe and the entire device is rotatable under the influence of the weight means. In another embodiment, at least the optical portion of the camera unit is rotatably supported and connected to the weight means. Magnetic flaw detection means are provided for triggering the camera unit.
.
ABSTRACT OF THE DISCLOSURE
Pipeline inspection apparatus as provided including a camera unit and associated illumination means, preferably a strobe flash unit, for recording on photographic film the rectangular images corresponding to generally rectangular internal surface portions of a pipe for detection of defects, a viewing axis of the camera being normal to the axis of the pipe. Weight means are provided for operating in a manner such as to establish a viewing axis in predetermined angular relation to a vertical plane through the axis of a horizontal pipe. In one embodiment, the device is supported by resilient cups for movement through the pipe and the entire device is rotatable under the influence of the weight means. In another embodiment, at least the optical portion of the camera unit is rotatably supported and connected to the weight means. Magnetic flaw detection means are provided for triggering the camera unit.
Description
PIPELINE INSPECTION APPARATUS
This invention relates to pipeline inspection apparatus and more particularly to apparatus movable within a pipe for detecting potentially damaging and dangerous flaws in the pipe with a high degree of effectiveness and reliability. The apparatus produces a photographic record which can be accurately interpreted and which facilitates repair of the pipe and, at the same time, the apparatus is relatively simple and easy to operate.
Background of the Prior Art Various techniques have heretofore been proposed for pipe inspection, including magnetic inspection by leakage field and/or eddy current techniques, gamma or X-ray tech-niques, ultrasonic techniques, television techniques and photographic techniques. Each of such techniques may be used to advantage in certain applications. However, each technique, as heretofore employed, has serious limitations in other applications, such as, for example, in the inspec-tion of pipeline used for transport of natural gas from o~fshore stations. Natural gas cannot be safely treated offshore and in a raw state it may include the combination of carbon dioxide and free water which produces carbonic acid and causes corrosion of steel, especially when the temperature is relatively high as is often the case. The corrosion is augmented by an erosion effect where the rate of flow is high and at bends and over weld beadis or the like where the flow is turbulent.
.
, , , :, , If locali~ed damage to the pipe could be detected before it presents a serious problem, it would be possible to effect repair or to otherwise take corrective measures.
For example, it is possible to move devices known as ~Ipigs~
through a pipe and by moving a series of such pigs through a pipe, it can be cleaned, etched, washed, dehydrated and then coated with a protective coating such as an epoxy. Such a procedure is, of course, relatively expensive especially in that the pipeline cannot be used for an extended period of time, and it is not desirable to utilize the procedure unless and until the necessity therefor can be established by a suitable inspection. Also, even after a protective coating is applied, there is the possibility of breaks in the coating and further periodic inspection is desirable to make certain that the coating is properly protecting the pipe. Accordingly, a reliable and accurate way of inspecting such pipeline for defects would be highly desirable.
As above indicated, prior art techniques are not satisfactory. Magnetic inspection, if properly performed, has many advantages including a high degree of sensitivity to flaws of types which may cause problems and the ability to cover large distances with suitable magnetic recording or other information storage equipment. ~owever, there are disadvantages including the necessity of having operators with a high degree of skill in order to obtain an accurate interpretation of the information obtained.
Ultrasonic techniques have a serious disadvantage in that it is difficult to couple the ultrasonic energy into the wall of a pipe and television techniques have a serious disadvantage, at least in the present state of development, in that a high sensitivity and high resolution is difficult to obtain especially if a substantial length of pipe is to ' -'' :
~ ~3~
be inspected and the information is to be recorded. If the information is to be transmitted through a cable, there is a problem as to loss of sensitivity at great distances and the difficulty in moving a cable having a large mass through a pipeline. Photographic techniques as heretofore proposed have had limitations not recognized in the prior art parti-cularly with respect to obtaining records which can be easily and accurately interpreted and also with respect to reliability.
With regard to specific prior art disclosures, the Nettles et al. United States Patent No. 2,892,150 discloses a device movable through a pipe and including seal or cup members for sealing engagement with the inside of the pipe to permit drive of the device by fluid pressure. A
magnetic testing device is provided for detecting variations in the thickness of the wall of the pipe and indications obtained are recorded on a recording tapeO To correlate the recorded indications with the position of the device while permitting variations in speed, the recording tape is driven from a wheel engaged with the inside surface of the pipe.
The Green et al. United States Patent No. 3,064,127 discloses a pipeline survey instrument in which a survey capsule or "pig" carries cups or sealing flanges engageable with the inside of a pipe so that the capsule may be moved through the pipe by fluid pressure. The capsule carries various instruments for making tests including a radiation analysis assembly for detecting cavities in the pipe wall, a caliper assembly for measuring the inside diameter of the pipe, a water detector and an electric current sensing assembly. In addition, a recording assembly is provided for recording the results of the various measurements. Since , .
the pig may move at various speeds, the recording assembly is driven from a wheel engaged with the inside of the pipe and the measurements are thereby correlated with the distance along the pipe regardless of the speed of movement of the pig.
No camera is carried by the pig of the Green et al.
patent. However, the use of a camera for the internal inspection o~ pipe has been proposed in other prior art references. For example, the Pulfer United States Patent No. 3,244,085 discloses a capsule movable along the inside of a pipe or tube and including a camera and illumination means. Film exposures are taken at spaced locations along the length of the pipe or tube, the direction of each exposure being controlled by a shutter or by control of the duration of the operation of the illumination means.
Another similar disclosure is contained in the Watts et al.
United States Patent No. 3,667,359 in which the camera and illumination means are supported by a pig which carries cups or sealing flanges engageable with the inside of the pipe so as to be movable by fluid pressure, as in the Green et al.
patent. The Watts et al. assembly also includes a wheel engageable with the inside of the pipe and connected to the camera so as to correlate the pictures with the distance along the pipe.
In both the Pulfer and the Watts et al. devices, the pictures are taken from one end of the capsule or pig, the viewing axis of the camera being coincident with the axis of the pipe and the illumination means being posi-tioned radially outside the axis of the camera.
.:
The Watts et al. Patent No. 3,667,359 also dis-closes an arrangement for directing a gas spray across the surface of a lens assembly for preventing fogging thereof.
Summarv of the Invention This invention was evolved with the general object of overcoming the disadvantages of prior art pipeline inspec-tion systems and of providing apparatus which can move within a pipeline and which will detect potentially dangerous flaws with a high degree of reliability and effectiveness and which produces records which ~an be easily and accurately interpreted.
Important facets of the invention relate to the recognition of problems with arrangements such as proposed in the prior art~ One problem relates to the production of photographic records which can be accurately interpreted in a manner such that standards can be established for determining whether a pipe is satisfactory or whether steps should be taken to repair the pipe or otherwise take a cor-rective measure.
In accordance with this invention, an orientation of the viewing axis is used which has been found to produce highly advantageous results. In particular, a viewing axis is provided which is transverse to the axis of the pipe and a generally rectangular image is produced which corresponds to a generally rectangular surface area of the pipe with length and width dimensions, respectively, corresponding to the axial length and arcuate width dimensions of the internal surface area of the pipe.
, ~;3~4 It is found that the orientation in which the viewing axis is normal to the axis of the pipe is highly advantageous in that the relationship between the size of defects and the size of the corresponding portions of the images produced on the developed film is substantially uniform. This is particularly true when the illumination means projects a beam toward the internal surface area of the pipe at a generally uniform acute angle to the axis of the pipe. Thus, the dimensions of shadows produced are generally uniformly proportional to the size of recesses in the internal surface area of the pipeO It is found that such relationships cannot be readily obtained with the second orientation in which the viewing axis is substan-tially coincident with the pipe axis. It is also difficult to obtain uniform illumination such that the size of recorded indications bear a readily determinable relationship to the sizes of the actual recesses in the surface of the pipe.
For these reasons, the first orientation is highly advanta-geous and is much to be preferred over the second orientation.
Further problems which have not been recognized and dealt with relate to those wh~ch arise when extremely long lengths of pipe must be inspected. When many miles of pipe are to be inspected, it is not possible to carry enough film and to otherwise make it possible to photograph all portions of the pipe. In order to make the most effec-tive use of time, equipment, and materials, it i5 found to be highly desirable to restrict the pictures to only those portions of the pipe in which defects are most likely to occur. One portion of the pipe of primary interest is the lower part of the pipe in which water may collect to combine with carbon dioxide and cause corrosion. To restrict the taking of the pictures to the lower portion of the pipe, the camera support is rotatable relative to the axis of the , -pipe, so that it may be weighted to be positioned at a predetermined angular position and thus the camera may be positioned so that the viewing axis is directed straight downwardly or at any desired angular position relative to the pipe. In one type of construction, a support is pro-vided including wheels engaged with the inside of the pipe, and the camera support is journalled through suitable bearings. In another arrangement, an entire pig is so weighted as to assume a predetermined angular position, the camera support being adjustably positionable at a certain angular position relative to the weighted pig.
It is also desirable to record images where there are magnetic discontinuities and magnetic leakage field detector units are provided for use in detecting magnetic discontinuities, such being usable to trigger the operation of the camera.
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In accordance with a specific feature of the invention, circuitry including a delay circuit is provided for responding to signals produced from the magnetic leakage field detector units to activate the camera and illumination means in a manner such that a picture is produced of the area producing such signals.
; In addition to producing pictures where there are magnetic discontinuities including pipe welds, pictures may be taken at predetermined positions along the pipe suffi-cient in number to insure a high degree likelihood of detecting any problems which might exist while conserving on the amount of film used.
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~03 Additional features of the invention relate to 04 construction of the apparatus in a manner such that it is very 05 rugged and relia~le and capable of being moved through long 06 lengths of pipeline without damage to the camera and other 07 instrumentation carried by the apparatus and while also avoiding 08 any damage to the pipeline.
09 In one type of construction, the camera may be moved by means of wheels engaged with the inside surface of the pipe and 11 driven by drive means including an electric motor or other power 12 source. In another type of construction, the camera may be ~13 supported on a pig which is moved through the pipe by a fluid 14 pressure differential on opposite sides thereof. In the ~`15 construction in which wheels are used, the assembly may be 16 connected to a cable and reversing means are provided for 17 automatically reversing the drive when the device is moved a 18 certain distance in the pipe. The drive means may preferably be ~19 operated to a release condition to permit withdrawal of the device through a tether.
21 According to one embodiment of the invention, in pipe 22 inspection apparatus, a device is arranged to be inserted into a 23 pipe for longitudinal movement therewithin. Photographic camera 24 apparatus is carried by the device including film storage and transport apparatus arranged for feeding film through an image ` 26 area and optical apparatus for projecting to the image area an , 27 image from an internal surface area of the pipe. Illumination 28 apparatus illuminates the internal surface area of the pipe, and ~29 operating apparatus operates the film storage and transport ~30 apparatus and the illumination apparatus during movement of the 31 device along the pipe for recording on the film a sequence of 32 images of the internal surface of the pipe. Drive apparatus 33 including drive wheel apparatus engages the inside surface of the 34 pipe and motive power apparatus rotates the drive wheel apparatus to move the device along the pipe. Connection apparatus is 36 adapted for connecting a tether to the device for withdrawal of 37 the device from the pipe independently of the drive apparatus.
38 The drive apparatus is operable between a drive condition wherein 01 - 8a ~
~02 -~03 the drive wheel apparatus are in pressure engagement with the ~04 inside surface and are coupled to the motive power apparatus to 05 develop a relatively high frictional force opposing movement of 06 the device by the tether and a release condition in which the ~07 frictional force is reduced to a relatively low value, and 08 apparatus interconnecting the connection apparatus with the drive 09 apparatus for operating the drive apparatus to the release condition in response to application of a predetermined force by ~11 the tether.
12 According to a further embodiment, reversing apparatus 13 is operable upon movement of the device through substantially a 14 predetermined distance along the pipe for reversing the drive apparatus to effect movement of the pipe in a reverse direction.
16 The reversing apparatus is comprised of apparatus for developing ~17 an electrical pulse in response to movement of the device through ~18 a certain distance. Counter apparatus counts a predetermined `;~19 number of the pulses to develop a reversing signal, and apparatus responsive to the reversing signal reverses the drive apparatus.
21 According to a further embodiment, in pipe inspection 22 apparatus, a device is arranged to be moved downward through a 23 vertically extending pipe section and thence into a horizontal -24 pipe section for longitudinal horizontal movement therein. The ~25 device is comprised of photographic camera apparatus including ~26 apparatus defining a rectangular image area, film storage and 27 transport apparatus arranged for feeding film through the image 28 area and optical apparatus for projecting an image to the image 29 area. The optical apparatus is arranged to project the image ~30 along a viewing axis from an internal surface area of the pipe 31 with the viewing axis being normal to the axis of the pipe and 32 with the generally rectangular image being produced in the image - 33 area which corresponds to a generally rectangular internal ` 34 surface area of the pipe and which has length and width dimensions respectively corresponding to the axial length and 36 arcuate width dimensions of the internal surface area.
37 Illumination apparatus illuminates the internal surface area of 38 the pipe. Operating apparatus operates the film storage and . ~
, ' ', ~ , .
1~3~
01 ~ 8b -03 transport apparatus and illumination apparatus during movement of 04 the device along the pipe for recording on the film a plurality 05 of images corresponding to axially spaced generally rectangularly " 06 surface areas of the pipe. The illumination apparatus is spaced `~ 07 axially from the viewing axis and is arranged to project light ; 08 toward the internal surface area of the pipe in a direction at a 09 substantially uniform acute angle to the axis of the pipe and with substantially uniform intensity, the relationship between 11 the direction of the light and the surface of the pipe being 12 substantially uniform throughout all of the internal surface of 13 the pipe such that shadows are produced across recesses in the 14 internal surface area of the pipe and such that there is a substantially uniform relationship between the size of the images ~- 16 of the shadows and the size of corresponding recesses in the ~17 internal surface area. Engagement apparatus including at least 18 two axially spaced cup members defining resilient annular flanges 19 are in engagment with axially spaced portions of the inside surface of the pipe. A central housing section supports the ~21 camera and illumination apparatus therewithin. A pair of cup ~22 member support structures is secured to opposite ends of the 23 central housing section for support of the central housing ; 24 section from the cup members. The viewing axis is approximately mid-way between the cup member support structures. Weight 26 apparatus operative under the force of gravity urges the device 27 toward a certain angular position when moving longitudinally 28 through a horizontal pipe section and places the viewing axis at
This invention relates to pipeline inspection apparatus and more particularly to apparatus movable within a pipe for detecting potentially damaging and dangerous flaws in the pipe with a high degree of effectiveness and reliability. The apparatus produces a photographic record which can be accurately interpreted and which facilitates repair of the pipe and, at the same time, the apparatus is relatively simple and easy to operate.
Background of the Prior Art Various techniques have heretofore been proposed for pipe inspection, including magnetic inspection by leakage field and/or eddy current techniques, gamma or X-ray tech-niques, ultrasonic techniques, television techniques and photographic techniques. Each of such techniques may be used to advantage in certain applications. However, each technique, as heretofore employed, has serious limitations in other applications, such as, for example, in the inspec-tion of pipeline used for transport of natural gas from o~fshore stations. Natural gas cannot be safely treated offshore and in a raw state it may include the combination of carbon dioxide and free water which produces carbonic acid and causes corrosion of steel, especially when the temperature is relatively high as is often the case. The corrosion is augmented by an erosion effect where the rate of flow is high and at bends and over weld beadis or the like where the flow is turbulent.
.
, , , :, , If locali~ed damage to the pipe could be detected before it presents a serious problem, it would be possible to effect repair or to otherwise take corrective measures.
For example, it is possible to move devices known as ~Ipigs~
through a pipe and by moving a series of such pigs through a pipe, it can be cleaned, etched, washed, dehydrated and then coated with a protective coating such as an epoxy. Such a procedure is, of course, relatively expensive especially in that the pipeline cannot be used for an extended period of time, and it is not desirable to utilize the procedure unless and until the necessity therefor can be established by a suitable inspection. Also, even after a protective coating is applied, there is the possibility of breaks in the coating and further periodic inspection is desirable to make certain that the coating is properly protecting the pipe. Accordingly, a reliable and accurate way of inspecting such pipeline for defects would be highly desirable.
As above indicated, prior art techniques are not satisfactory. Magnetic inspection, if properly performed, has many advantages including a high degree of sensitivity to flaws of types which may cause problems and the ability to cover large distances with suitable magnetic recording or other information storage equipment. ~owever, there are disadvantages including the necessity of having operators with a high degree of skill in order to obtain an accurate interpretation of the information obtained.
Ultrasonic techniques have a serious disadvantage in that it is difficult to couple the ultrasonic energy into the wall of a pipe and television techniques have a serious disadvantage, at least in the present state of development, in that a high sensitivity and high resolution is difficult to obtain especially if a substantial length of pipe is to ' -'' :
~ ~3~
be inspected and the information is to be recorded. If the information is to be transmitted through a cable, there is a problem as to loss of sensitivity at great distances and the difficulty in moving a cable having a large mass through a pipeline. Photographic techniques as heretofore proposed have had limitations not recognized in the prior art parti-cularly with respect to obtaining records which can be easily and accurately interpreted and also with respect to reliability.
With regard to specific prior art disclosures, the Nettles et al. United States Patent No. 2,892,150 discloses a device movable through a pipe and including seal or cup members for sealing engagement with the inside of the pipe to permit drive of the device by fluid pressure. A
magnetic testing device is provided for detecting variations in the thickness of the wall of the pipe and indications obtained are recorded on a recording tapeO To correlate the recorded indications with the position of the device while permitting variations in speed, the recording tape is driven from a wheel engaged with the inside surface of the pipe.
The Green et al. United States Patent No. 3,064,127 discloses a pipeline survey instrument in which a survey capsule or "pig" carries cups or sealing flanges engageable with the inside of a pipe so that the capsule may be moved through the pipe by fluid pressure. The capsule carries various instruments for making tests including a radiation analysis assembly for detecting cavities in the pipe wall, a caliper assembly for measuring the inside diameter of the pipe, a water detector and an electric current sensing assembly. In addition, a recording assembly is provided for recording the results of the various measurements. Since , .
the pig may move at various speeds, the recording assembly is driven from a wheel engaged with the inside of the pipe and the measurements are thereby correlated with the distance along the pipe regardless of the speed of movement of the pig.
No camera is carried by the pig of the Green et al.
patent. However, the use of a camera for the internal inspection o~ pipe has been proposed in other prior art references. For example, the Pulfer United States Patent No. 3,244,085 discloses a capsule movable along the inside of a pipe or tube and including a camera and illumination means. Film exposures are taken at spaced locations along the length of the pipe or tube, the direction of each exposure being controlled by a shutter or by control of the duration of the operation of the illumination means.
Another similar disclosure is contained in the Watts et al.
United States Patent No. 3,667,359 in which the camera and illumination means are supported by a pig which carries cups or sealing flanges engageable with the inside of the pipe so as to be movable by fluid pressure, as in the Green et al.
patent. The Watts et al. assembly also includes a wheel engageable with the inside of the pipe and connected to the camera so as to correlate the pictures with the distance along the pipe.
In both the Pulfer and the Watts et al. devices, the pictures are taken from one end of the capsule or pig, the viewing axis of the camera being coincident with the axis of the pipe and the illumination means being posi-tioned radially outside the axis of the camera.
.:
The Watts et al. Patent No. 3,667,359 also dis-closes an arrangement for directing a gas spray across the surface of a lens assembly for preventing fogging thereof.
Summarv of the Invention This invention was evolved with the general object of overcoming the disadvantages of prior art pipeline inspec-tion systems and of providing apparatus which can move within a pipeline and which will detect potentially dangerous flaws with a high degree of reliability and effectiveness and which produces records which ~an be easily and accurately interpreted.
Important facets of the invention relate to the recognition of problems with arrangements such as proposed in the prior art~ One problem relates to the production of photographic records which can be accurately interpreted in a manner such that standards can be established for determining whether a pipe is satisfactory or whether steps should be taken to repair the pipe or otherwise take a cor-rective measure.
In accordance with this invention, an orientation of the viewing axis is used which has been found to produce highly advantageous results. In particular, a viewing axis is provided which is transverse to the axis of the pipe and a generally rectangular image is produced which corresponds to a generally rectangular surface area of the pipe with length and width dimensions, respectively, corresponding to the axial length and arcuate width dimensions of the internal surface area of the pipe.
, ~;3~4 It is found that the orientation in which the viewing axis is normal to the axis of the pipe is highly advantageous in that the relationship between the size of defects and the size of the corresponding portions of the images produced on the developed film is substantially uniform. This is particularly true when the illumination means projects a beam toward the internal surface area of the pipe at a generally uniform acute angle to the axis of the pipe. Thus, the dimensions of shadows produced are generally uniformly proportional to the size of recesses in the internal surface area of the pipeO It is found that such relationships cannot be readily obtained with the second orientation in which the viewing axis is substan-tially coincident with the pipe axis. It is also difficult to obtain uniform illumination such that the size of recorded indications bear a readily determinable relationship to the sizes of the actual recesses in the surface of the pipe.
For these reasons, the first orientation is highly advanta-geous and is much to be preferred over the second orientation.
Further problems which have not been recognized and dealt with relate to those wh~ch arise when extremely long lengths of pipe must be inspected. When many miles of pipe are to be inspected, it is not possible to carry enough film and to otherwise make it possible to photograph all portions of the pipe. In order to make the most effec-tive use of time, equipment, and materials, it i5 found to be highly desirable to restrict the pictures to only those portions of the pipe in which defects are most likely to occur. One portion of the pipe of primary interest is the lower part of the pipe in which water may collect to combine with carbon dioxide and cause corrosion. To restrict the taking of the pictures to the lower portion of the pipe, the camera support is rotatable relative to the axis of the , -pipe, so that it may be weighted to be positioned at a predetermined angular position and thus the camera may be positioned so that the viewing axis is directed straight downwardly or at any desired angular position relative to the pipe. In one type of construction, a support is pro-vided including wheels engaged with the inside of the pipe, and the camera support is journalled through suitable bearings. In another arrangement, an entire pig is so weighted as to assume a predetermined angular position, the camera support being adjustably positionable at a certain angular position relative to the weighted pig.
It is also desirable to record images where there are magnetic discontinuities and magnetic leakage field detector units are provided for use in detecting magnetic discontinuities, such being usable to trigger the operation of the camera.
;
In accordance with a specific feature of the invention, circuitry including a delay circuit is provided for responding to signals produced from the magnetic leakage field detector units to activate the camera and illumination means in a manner such that a picture is produced of the area producing such signals.
; In addition to producing pictures where there are magnetic discontinuities including pipe welds, pictures may be taken at predetermined positions along the pipe suffi-cient in number to insure a high degree likelihood of detecting any problems which might exist while conserving on the amount of film used.
i?3~
~03 Additional features of the invention relate to 04 construction of the apparatus in a manner such that it is very 05 rugged and relia~le and capable of being moved through long 06 lengths of pipeline without damage to the camera and other 07 instrumentation carried by the apparatus and while also avoiding 08 any damage to the pipeline.
09 In one type of construction, the camera may be moved by means of wheels engaged with the inside surface of the pipe and 11 driven by drive means including an electric motor or other power 12 source. In another type of construction, the camera may be ~13 supported on a pig which is moved through the pipe by a fluid 14 pressure differential on opposite sides thereof. In the ~`15 construction in which wheels are used, the assembly may be 16 connected to a cable and reversing means are provided for 17 automatically reversing the drive when the device is moved a 18 certain distance in the pipe. The drive means may preferably be ~19 operated to a release condition to permit withdrawal of the device through a tether.
21 According to one embodiment of the invention, in pipe 22 inspection apparatus, a device is arranged to be inserted into a 23 pipe for longitudinal movement therewithin. Photographic camera 24 apparatus is carried by the device including film storage and transport apparatus arranged for feeding film through an image ` 26 area and optical apparatus for projecting to the image area an , 27 image from an internal surface area of the pipe. Illumination 28 apparatus illuminates the internal surface area of the pipe, and ~29 operating apparatus operates the film storage and transport ~30 apparatus and the illumination apparatus during movement of the 31 device along the pipe for recording on the film a sequence of 32 images of the internal surface of the pipe. Drive apparatus 33 including drive wheel apparatus engages the inside surface of the 34 pipe and motive power apparatus rotates the drive wheel apparatus to move the device along the pipe. Connection apparatus is 36 adapted for connecting a tether to the device for withdrawal of 37 the device from the pipe independently of the drive apparatus.
38 The drive apparatus is operable between a drive condition wherein 01 - 8a ~
~02 -~03 the drive wheel apparatus are in pressure engagement with the ~04 inside surface and are coupled to the motive power apparatus to 05 develop a relatively high frictional force opposing movement of 06 the device by the tether and a release condition in which the ~07 frictional force is reduced to a relatively low value, and 08 apparatus interconnecting the connection apparatus with the drive 09 apparatus for operating the drive apparatus to the release condition in response to application of a predetermined force by ~11 the tether.
12 According to a further embodiment, reversing apparatus 13 is operable upon movement of the device through substantially a 14 predetermined distance along the pipe for reversing the drive apparatus to effect movement of the pipe in a reverse direction.
16 The reversing apparatus is comprised of apparatus for developing ~17 an electrical pulse in response to movement of the device through ~18 a certain distance. Counter apparatus counts a predetermined `;~19 number of the pulses to develop a reversing signal, and apparatus responsive to the reversing signal reverses the drive apparatus.
21 According to a further embodiment, in pipe inspection 22 apparatus, a device is arranged to be moved downward through a 23 vertically extending pipe section and thence into a horizontal -24 pipe section for longitudinal horizontal movement therein. The ~25 device is comprised of photographic camera apparatus including ~26 apparatus defining a rectangular image area, film storage and 27 transport apparatus arranged for feeding film through the image 28 area and optical apparatus for projecting an image to the image 29 area. The optical apparatus is arranged to project the image ~30 along a viewing axis from an internal surface area of the pipe 31 with the viewing axis being normal to the axis of the pipe and 32 with the generally rectangular image being produced in the image - 33 area which corresponds to a generally rectangular internal ` 34 surface area of the pipe and which has length and width dimensions respectively corresponding to the axial length and 36 arcuate width dimensions of the internal surface area.
37 Illumination apparatus illuminates the internal surface area of 38 the pipe. Operating apparatus operates the film storage and . ~
, ' ', ~ , .
1~3~
01 ~ 8b -03 transport apparatus and illumination apparatus during movement of 04 the device along the pipe for recording on the film a plurality 05 of images corresponding to axially spaced generally rectangularly " 06 surface areas of the pipe. The illumination apparatus is spaced `~ 07 axially from the viewing axis and is arranged to project light ; 08 toward the internal surface area of the pipe in a direction at a 09 substantially uniform acute angle to the axis of the pipe and with substantially uniform intensity, the relationship between 11 the direction of the light and the surface of the pipe being 12 substantially uniform throughout all of the internal surface of 13 the pipe such that shadows are produced across recesses in the 14 internal surface area of the pipe and such that there is a substantially uniform relationship between the size of the images ~- 16 of the shadows and the size of corresponding recesses in the ~17 internal surface area. Engagement apparatus including at least 18 two axially spaced cup members defining resilient annular flanges 19 are in engagment with axially spaced portions of the inside surface of the pipe. A central housing section supports the ~21 camera and illumination apparatus therewithin. A pair of cup ~22 member support structures is secured to opposite ends of the 23 central housing section for support of the central housing ; 24 section from the cup members. The viewing axis is approximately mid-way between the cup member support structures. Weight 26 apparatus operative under the force of gravity urges the device 27 toward a certain angular position when moving longitudinally 28 through a horizontal pipe section and places the viewing axis at
2~ a predetermined angular position relative to the pipe.
This invention contemplates other objects, features and ` 31 advantages which will become more fully apparent from the 32 following description taken in conjunction with the accompany ~33 drawings.
34 Brief Description o~ the Drawings FIGURE 1 is a side ele~Jational view, partly in section, 36 illustrating pipe inspection apparatus constructed in accordance ~37 with the invention;
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This invention contemplates other objects, features and ` 31 advantages which will become more fully apparent from the 32 following description taken in conjunction with the accompany ~33 drawings.
34 Brief Description o~ the Drawings FIGURE 1 is a side ele~Jational view, partly in section, 36 illustrating pipe inspection apparatus constructed in accordance ~37 with the invention;
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g FIGURE 2 illustrates diagrammatically in side elevation the positioning of camera and strobe light units of the apparatus in relation to the pipe;
FIGURE 3 is another diagrammatic view looking from a position as indicated by line III-III of Figure 2;
FIGURE 4 is a sectional view taken substantially . along line IV-IV of Figure l;
` FIGURE 5 is a top plan view of another form of ii^~! apparatus constructed in accordance with the invention;
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~, 10 FIGURE 6 is a side elevational view of the apparatus , of Figure 5;
FIGURE 7 is a side elevational view of another form of apparatus according to the invention;
, .
FIGURE 8 is a sectional view taken substantially along line VIII-VIII of Figure 7;
- FIGURF 9 is a schematic electrical diagram for the apparatus of Figures 7 and 8;
~ FIGURE 10 is a view illustrating a modified apparatus ;: constructed in accordance with the invention, shown moving ~ 20 through a bend portion of a pipeline;
~,, FIGURE 11 is a side elvational view of a drive unit of the apparatus of Figure 10; and FIGURE 12 is a schematic electrical diagram of the apparatus of Figures 10 and 11.
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;`` ~escription of Preferred Embodiments Reference numeral 10 generally designates a pipe inspection apparatus constructed in accordance with the principles of this invention. The illustrated apparatus 10 is in the form of a "pig" device similar to those used for , cleaning, washing and coating pipes and it includes two rear-; ward cups 11 and 12 and two forward cups 13 and 14 which are respectively disposed behind and in front of a central housing section 15 in which a camera assembly 16 is sup-ported. The cups 11-14 are of a resilient elastomeric material and define flanges for resilient sealing engagement with the inside surface 17 of a pipe 18, permitting the apparatus to be driven by the pressure of gas pumped through the pipe 18 or by the pressure of compressed air or the like pumped into the pipe 18. The pipe 18 may, for example, be used to carry raw natural gas from an off-shore location to an on-shore processing station and the apparatus 10 is designed to produce high resolution photographs which will reveal erosion and corrosion at pipe bends, pitting at ~ 20 circumferential welds and heat-affected areas and corrosion ;~ such as caused by puddles at low pipe line areas.
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The camera assembly 16 includes a lens disposed above a protective glass plate 2~ held by a support 21 on a horizontal wall portion 22 of the section 15. To illu-minate the surface of the pipe, a pair of strobe lights are provided behind a pair of ports 23 and 24 which are disposed on inclined wall portions 25 and 26 of the central housing section 17, the ports 23 and 24 having ylass windows for transmission of light therethrough.
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As diagrammatically shown in Figures 2 and 3, the camera assembly 18 includes a camera 28 having a lens 29 which projects an image to a film plane at which a film 30 is moved from a supply reel 31 to a take-up reel 32, suitable electrically operated drive means being provided for driving the take-up reel 32 to advance the film 30 for taking each picture. With this arrangement, and with the viewing axis of the camera, indicated by broken line 34, being normal to ~` the axis of the pipe, a generally rectangular image is projected to an image area of the film 30 which corresponds `~ to a generally rectangular internal surface area of the ` pipe. The image has length and width dimensions which respectively correspond to the axial length and arcuate width dimensions of the internal surface area. Thus, as indicated diagrammatically by lines 35 and 36 in Figure 2, the forward and rearward limits of the rectangular image area on the film may correspond to rearward and forward ` limits of a generally rectangular surface area of the ~ internal surface 17 of the pipe 18. As indicated by lines ; 20 37 and 38 in Figure 3, the side limits of the rectangular image area of the film 30 may correspond to arcuately spaced limits of a generally rectangular surface area of the internal surface 17 of the pipe 18.
As also shown diagrammatically in Figure 2, strobe lights 39 and 40 are mounted behind the ports 23 and 24 to project beams of light along axes as indicated by -broken lines 41 and 42. Each strobe light is spaced axially from the viewing axis and each projects a beam of light toward the internal surface area of the pipe which is to be photographed, along an illumination direction at an acute angle to the axis of the pipe.
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The arrangement with the viewing axis of the camera at right angles to the axis of the pipe, thereby producing a generally rectangular image corresponding to a generally rectangular internal surface area of the pipe, is highly advantageous in that the relationship between the size of defects and the size of the corresponding indica-tion on the film is substantially uniform. As a result, standards can be established for determining whether a pipe can be passed as being satisfactory or whether remedial action should be taken to repair or service the pipe. The necessity ~or requiring an inspector of the film to exercise critical judgment is minimized.
The illumination of the surface area of the pipe as disclosed is also advantageous for similar reasons, it being noted that the relationship between the direction of the light and the surface of the pipe is substantially uniform throughout the entire internal surface area of the pipe which corresponds to the image produced.
Since the internal surface area of the pipe which is photographed is of limited angular extent, it is important that the portion photographed be selectable and identifiable.
It is also found to be important that the pictures be taken in an angular direction which has the greatest likelihood of ":
producing indications of any critical defects which may exist.
In inspecting horizontal runs of pipelines such as used for , conveying raw natural gas, it is found that the lower portion of the internal surface of the pipe is generally of primary /- interest because liquids can accumulate to cause corrosion .' of the pipe under certain conditions. In accordance with ,i, :',' :
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the invention, the apparatus 10 is weighted in a manner such that the viewing axis 34 of the camera may be in a vertical plane through the axis of the device or at any desired angle relative to such a vertical plane.
In Figure 1, a rearward cup assembly including the rearward cups 11 and 12 and associated elements is shown in section. As illustrated, a spacer structure 44 is sandwiched between the cups 11 and 12 and a holding ring 45 is disposed against the rear side of the rear cup 11 while a plate 46 is disposed against the forward face of the cup 12. The forward face of the plate 46 is recessed to receive the rearward end of the central housing section 15, a radially inwardly facing annular shoulder 47 being provided which engages a rear end of an annular flange portion 48 of the central housing section 15. Four bolts 49 are provided having head portions engaging the plate 46 and having shank portions extending through the cup 12, spacer structure 44, cup 11, plate 45 and washers 50 with nuts 51 being threaded on the rearward terminal ends of the shank portions of the bolts 49.
The forward cup assembly which includes cups 13 and 14 is similar to the rearward cup assembly and includes a spacer structure 52 similar to the spacer structure 44, a ring 53 similar to the ring 45 and four bolts 55.
To hold the rearward and forward cup assemblies against the rearward and forward ends of the central housing section, four elongated bolts 58 are provided which have shank portions extending through the forward cup assembly, r .
thence through sleeves 59 positioned between the rearward end of the forward cup assembly and the plate 46 at the forward end of the rearward cup assembly, thence through the rearward cup assembly and through washers 60 with nuts 61 being threaded on the rearward terminal ends of the elongated bolts 58.
The spacer structure 44 is formed from a pair of rings ~3 and 64 and a plurality of spacer sleeves 62 through which the shank portions of the connecting bolts 49 and 58 extend. To weight the apparatus so as to cause it to assume a predetermined angular position, a weight member 66 of semi-cylindrical shape is located between the rings 63 and 64. The weight member 66 is of a heavy material, prefer-ably lead, and a similar weight member is preferably included in the forward cup assembly.
For most applications, the viewing axis of the camera is preferably at a six o'clock position so as to be in a vertical plane through the axis of the apparatus and so as to produce photographs of the bottom of the pipe where corrosion may be produced as the result of the accumulation of liquid, particularly in low pipeline areas. However, the viewing axis may be positioned at any desired angular posi-tion. To adjust the viewing axis of the camera, the nuts 61 may be loosened and the central housing section 15 may then be rotated to the desired angular position relative to the weights of the cup assemblies a~ter which the nuts 61 may be tightened to securely lock the housing section 15 in the desired angular position.
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The illustrated apparatus may be propelled by the pressure of a gaseous medium in the pipeline, either the natural gas or other product normally carried by the pipe-line or compressed air or the like introduced into the pipeline. The illustrated apparatus may thus be self-pro-pelled or it may, in the alternative, be propelled by a towing pig in which case cups of the apparatus may be provided with openings or grooves for passage of the gaseous medium past the apparatus to the towing pig.
In the apparatus 10 of Figures 1-4, the entire apparatus is rotated to a predetermined angular position whereby the force of gravity acts on the weights which are positioned to place the center of gravity of apparatus to the offset of the angular position. It is also possible to support the camera for rotation by the pipe axis to a predetermined angular position while supporting the camera from support means non-rotatably engaged with the inside surface of the pipe. Referring to Figures 5 and 6, refer-ence numeral 6~ generally designates an apparatus in which the camera is supported for rotation about the pipe axis from the support structure non-rotatably engaged with the pipe.
The apparatus 68 is in the form of a camera unit and it includes a camera 70 which includes electrically operated film storage and -transport means whereby photo-graphic film is moved from a supply reel within one end ,.
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portion 71 of a housing 72 to a take-up reel within an opposite end portion 73 of the housing 72. The camera 70 further includes a lens assembly 74 which operates to project an image of the inside surface of the pipe onto a section of the film positioned at an image area interme-diate the supply and take-up reels.
To illuminate the inside surface of the pipe, an electrically operated strobe flash unit 76 is provided arranged to project a beam of light along an axis 77 which intersects the central axis of the lens 74, indicated by reference numeral 78, at a point on the inside surface of the pipe.
The orientation of the illumination and lens axes 77 and 78 are of substantial importance. Preferably, the lens axis is generally normal to the inside surface of the pipe, i.e., at substan~ially a right angle to the pipe axis and the illumination axis is at an acute angle, preferably on the order of 45 degrees or less. Corrosion pits or the like cast shadows such that from inspection of a developed picture, an accurate estimate can be made with xespect to the depth of a pit or the like and as to whether it neces-sitates a repair opera~ion on the pipe.
A counter 80 is energized from pulses generated in response to movemen~ of the apparatus within the pipe and registers the distance traveled, being disposed within the field of ~iew of the lens 74 so as to record the posi-tion in each film frame.
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The camera 70 is secured to a frame 81 which carries caster wheel assemblies 82, 83 and 84 at one end thereof. At the opposite end thereof, the camera support frame 51 is hingedly connected through a hinge pin 85 to a plate 86 which is hingedly connected through a pin 87 to a second plate 88 which, in turn, is connected through a third pin ~9 to a support plate 90, the axes of the pins 85 and 87 being in spaced parallel relation and the axis of the pin 89 being at risht angles ~o the axes of the pins 85 and 87. A coiled tension spring 91 is secured between an outer end of the camera support frame 81 and the support plate 90 to normally hold the end o~ the camera frame 81 and the plates 86, 88 and 90 against one another as shown.
In moving through ~urns or bends in the pipe, the camera frame 81 may, if necessary, pivot relative to plate 86 about the axis of pin 85 or the camera frame and the plate 86 may together pivot relative to the plate 88 and the axis of the pin 87 or the camera frame 81 and plates 86 and B8 may pivot relative to the plate 90 about the axis of the pin 89.
The support plate 90 carries the strobe unit 76 and the counter 80 and is supported through a pair of posts 92 and 93 from a frame 94 which is journalled within a cylindrical housing 95 for movement about the axis of the cylindrical housing 95, preferably with one ball-bearing assembly 96 being provided at one end of the housing 95 and another similar assembly being provided at the other end. Suitable slip rings are pro~ided within the cylin-drical shell or housing 95 for transmission of electrical control signals to the camera 70, strobe unit 76 and counter 80.
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To support the housing 95 for movement within the pipe, it carries three wheel assemblies 98 spaced equi-angularly, 120 degrees from each other, each including a frame 100 extending longitudinally in generally parallel relation to the axis of the housing 95 and carrying a pair of wheels 101 and 102 at the opposite ends thereof, the frame 100 being supported from the housing 95 through compression sprinas 103, 104 and ].05, operative to urge the wheels 101 and 102 into engagement with the inside surface of the pipe.
The apparatus 68 may be propelled by means of a motor-driven drive unit as disclosed in our prior copending application or it may be propelled by a suitable towing pig.
For such purposes, a bar 106 is connected through a U-joint 107 to one end of the housing 95.
Figure 7 shows a modified form of apparatus which is in the form of a camera unit 110 similar to the camera unit 68 of Pigur~s 5 and 6 and having a camera 111 on a frame 112 which is supported ~hrough a hinge assembly from a support plate 114 which is supported through posts 115 and 116 from a frame journalled in a housing 117. Housing 117 is supported for movement wi~hin a pipe 113 through three wheel assemblies 119, each including a frame 120 which carries wheels 121 and 122 and which is connected to the housing 117 through compression springs 123, 124 and 125. A flash unit 126, corresponding to flash unit 76, s mounted on the support plate 114.
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Magnetic detection means are provided for sensing inhomogeneities in the pipe. In the illustrated arrangement~
three units 127, 128 and 129 are provided, each of which extends arcuately, the three units being offset axially and being in overlapping relation to cover an arcuate distance corresponding ~o the arcua~e dimension of the effective field of view of the camera. The units 127-129 may have the same construction and may be resiliently supported in substantially the same way. Unit 127 may, for example, include an arcuate core 131 of permanently magnetized material and of generally U-shaped cross-sectional form with a coil 132 wound thereon.
When the unit moves over a corrosion pit or other discontin-uity in pipe 118, the magnetic linkage field of the permanent magnet core 131 changes, inducing a corresponding electrical signal in the coil 132. Core 131 is supported from the sup-port plate through springs 133 and 134 for resiliently yieldable contact with the inside of pipe 118.
The camera unit 110 also incorporates means for sensing changes in the internal dimensions or configuration of the pipe such as caused by indentations, bends or obstruc-tions. Such means include three switch units 136, each associated with ~he ~rame 120 of one of the wheel assemblies 119 to be actuated when the fra~e is moved radially inwardly a predetermined e~tent.
Figure 9 is a schematic diagram of the electrical connection of units of the camera unit 110 of Figures 7 and ~. The magnetic leakage field de~ector units 127~129 are ~3~53~4 connected through amplifiers 137-139 and through circuitry 140 to a threshold detector 141 which develops an output signal in response to a leakage field signal having an amplitude greater than a predetermined amplitude.
The output signal so developed is applied to a delay circuit 142 which after a certain delay, propor~ional to the speea of travel of the appar~tus, applies a signal to the strobe unit 126 of the camera unit 110 so as to take a picture of the portion of the pipe which produced the signal de~eloped by the magnetic detection circuit. The signal applied to the strobe is also applied through a delay circuit 144 to a film advance control 145 of the camera of the unit 110.
~he switch units 136 are connected through circuitry 146 to another delay circuit 147 which after a certain delay, proportional to the speed of travel of the apparatus, applies a signal to the strobe unit 126 and also to the delay circuit 144. It is noted ~hat the direction of movement of the unit 110 is assumed to be to the right as viewed in Figure 7 so that the dimensional and magnetic detector means is ahead of the camera unit.
The arrangement of Flgures 7~ 8 and 9 is par-ticularly advantageous in inspection of long pipeline runs, in which it is desirable to avoid unnecessary consumption of film and to restrict the picture-taking to those sections of the pipe which are of possible interest as indicated by dimensional changes or the presence of magnetic discontinuities.
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It may be noted that the camera in any case may be rotated about the axis of the pipe to various positions and/or suitable split mirrors or other optical elements may be used to effect taking of the picture of the entire internal surface of the pipe. In most applications, however, the taking of pictures may be restricted to the lower part of the inside surface of the pipe, where corrosion is apt to occur because of the accumulation of liquid, and the apparatus of Figures 1-4 is advantageous in this respect.
The apparatus of Figures 1-4 is also advantageous in that the camera and the strobe lights are supported in well-protected positions behind glass windows of the ports in the central housing section 15. It is further noted that with the central housing section being disposed between the forward and rearward cup assemblies, a protected region is provided for the taking of the pictures. The arrangement thus serves to minimize problems with interference due to puddles of liquid in the pipe, splashing of liquids and liquid droplets or vapors in the air or gas in the pipe.
Z0 Reference numeral 150 generally designates a modi-fied type pipe inspection apparatus constructed in accordance with the principles of this invention. The apparatus 150 is shown in a bend of a pipe 157 which may, for example, be a bend at the lower end of a vertical pipe section which extends down from an off-shore station.
The illustrated apparatus 150 includes a camera unit 152 and a drive unti 153 with a coupling therebetween including a bar 154 having opposite ends coupled to the units 152 and 153 through U-joints 155 and 156.
The illustrated drive unit 153 includes three motor-driven wheel assemblies 158 each including a pair of wheels 159 on a shaft 160 driven through a gear reduction unit 161 from an electric motor 162. The housing of each motor 162 is hingedly connected to a frame member 164 through a pin 165 and at the opposite end, a compression spring 166 acts between a pin 167 carried by the frame member 164 and a socket member 168 which is secured to the housing of the gear reduction unit 161, the wheels 159 being urged radially outwardly into pressure engage-ment with the inside surface of the pipe 151. Pin 167 may be withdrawn for release of pressure as hereinafter described.
The three wheel assemblies 168 are preferably in equi-angularly spaced relation, 120 degrees from each other.
At the opposite end of the drive unit, three idler wheel assemblies 170 are provided, each including a pair of wheels 171 urged radially outwardly by a spring 172, the assemblies 170 being preferably spaced e~ui-angularly, 120 degrees from each other. A battery unit 174 is carried by the frame of the drive unit 153 between the motor-driven wheel assemblies 158 and ~he idler wheel assemblies 170 and an electrical control unit 175 is carried on a projecting frame member 176. A hook 177 is provided on the terminal end of the frame member 176 for connection to a tether cable 178.
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The camera unit 152 includes a camera 180 (Figure 12) which includes electrically operated film storage and transport means whereby photographi~ film i5 moved from a supply reel 181 within one end portion of a housing 182 to a take-up reel 183 within an opposite end portion of the housing 182. The camera 180 further includes a lens assembly 184 which operates to project an image of the inside surface of the pipe onto a section of the film positioned at an image area intermediate the supply and take-up reels.
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To illuminate the inside surface of the pipe, an electrically operated strobe flash unit 186 is provided arranged to project a beam of light along an axis 187 which intersects the central axis of the lens 184, indicated by reference numeral 188, at a point on the inside surface of the pipe.
The orientation of the illumination and lens axes 187 and 188 are of substantial importance. Preferably, the lens axis is generally normal to the inside surface of the pipe, i.e., at substantially a right angle to the pipe axis and the illumination axis is at an acute angle, preferably on the order of 45 degrees or less. Corrosion pits or the like cast shadows such that from inspection of a developed picture, an accurate estimate can be made with respect to the depth of a pit or the like and as to whether it necessi-tates a repair operation on the pipe.
A counter 190 is energized from pulses generated in response to movement of the apparatus within the pipe and registers the distance travelled, being disposed ~ithin the field of view of the lens 184 so as to record the position in each film frame.
The camera 180 is secured to a fra~e 191 which may carry suitable caster wheel assemblies at one end thereof, using a construction such as shown in Figures 5 and 6, for example.
Figure 12 is a schematic diagram of electrical cir-cuitry for the apparatus 150. Control circuitry 196 is connected through lines 198l 199 and 200 to the camera 180, strobe unit 186 and counter 190 and is also connected to a switch device 202 which is operated from one of the wheels ~ .
engaged with the inside surface of the pipe, such as one of the idler wheels 171 and which generates a pulse in response to rotation of the wheel through a certain angle and thereby in response to movement of the apparatus a certain distance.
Electronic counter means are provided in the control circuitry l99 to apply a triggering signal to the strobe unit 186 after a certain number of such pulses. After a certain delay, indexing pulses are applied to the counter l90 and also to film drive means of the camera 180.
Motor control circuitry 204 is provided which is connected to the battery unit 174 and to the drive motors 162 and also to the control circuitry 196 and a start switch 206. With the apparatus disposed in one end of a pipeline or in a launching pipe section which feeds into a pipeline, the start switch 206 is depressed to cause energization of the drive motors 162 and to initiate movement of the apparatus along the pipeline. The apparatus may continue movement until it reaches the other end of a pipeline. Alternatively, counter means within the motor control circuitry 204 may respond to signals from the control circuitry 196 to operate after a certain number of pulses are applied and thereby after the--apparatus travels a certain distance, to reverse the polarity of the voltages applied to the motors 162 and to cause the apparatus to move in the reverse direction and return to its initial position. This automatic reversing feature is highly advantageous in that the portion of a pipeline extending only a relatively short distance such as from 1,000 to 2,000 feet away from an offshore station may be inspected. Many of the problems which can be detected by the apparatus are found within such a relatively short distance frorn offshore stations and the use of the apparatus in this way is thus highly productive. Also, it does not require that the apparatus be capable of travelllng very large distances.
A very high degree of reliability can be obtained with drive means such as illustrated but it is nevertheless desirable to provide a back-up in the event of failure of the drive means, and it is for this reason that the hook 177 is provided for connection to the tether cable 178, so that the apparatus can be withdrawn by means of the cable 178.
It is noted that the motor-driven wheel assemblies 158 desirably include the gear reduction units 161 which allow the motors to be operated at relatively high speeds so as to be of relatively small si~e. With such gear reduction units, however, it is found that in case of deenergization of the motors, the high degree of friction is encountered when attempting to move the apparatus by means of the tether cable 178. In accordance with a specific feature, a spring 210 is provided in the connection between the cable 178 and the hook 177 and three lines 211 are provided between the cable 178 and the pins 167 of the drive wheel assemblies.
When the tension in the cable 178 reaches a predetermined level, the spring 210 is stretched to an extent such that the cable 178 acts through the lines 211 to retract the pins 167 and to allow the inner ends of the springs to move inwardly and thus release the pressure applied by the wheels 159. Accordingly, the apparatus can be readily withdrawn, friction being minimized.
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g FIGURE 2 illustrates diagrammatically in side elevation the positioning of camera and strobe light units of the apparatus in relation to the pipe;
FIGURE 3 is another diagrammatic view looking from a position as indicated by line III-III of Figure 2;
FIGURE 4 is a sectional view taken substantially . along line IV-IV of Figure l;
` FIGURE 5 is a top plan view of another form of ii^~! apparatus constructed in accordance with the invention;
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~, 10 FIGURE 6 is a side elevational view of the apparatus , of Figure 5;
FIGURE 7 is a side elevational view of another form of apparatus according to the invention;
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FIGURE 8 is a sectional view taken substantially along line VIII-VIII of Figure 7;
- FIGURF 9 is a schematic electrical diagram for the apparatus of Figures 7 and 8;
~ FIGURE 10 is a view illustrating a modified apparatus ;: constructed in accordance with the invention, shown moving ~ 20 through a bend portion of a pipeline;
~,, FIGURE 11 is a side elvational view of a drive unit of the apparatus of Figure 10; and FIGURE 12 is a schematic electrical diagram of the apparatus of Figures 10 and 11.
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;`` ~escription of Preferred Embodiments Reference numeral 10 generally designates a pipe inspection apparatus constructed in accordance with the principles of this invention. The illustrated apparatus 10 is in the form of a "pig" device similar to those used for , cleaning, washing and coating pipes and it includes two rear-; ward cups 11 and 12 and two forward cups 13 and 14 which are respectively disposed behind and in front of a central housing section 15 in which a camera assembly 16 is sup-ported. The cups 11-14 are of a resilient elastomeric material and define flanges for resilient sealing engagement with the inside surface 17 of a pipe 18, permitting the apparatus to be driven by the pressure of gas pumped through the pipe 18 or by the pressure of compressed air or the like pumped into the pipe 18. The pipe 18 may, for example, be used to carry raw natural gas from an off-shore location to an on-shore processing station and the apparatus 10 is designed to produce high resolution photographs which will reveal erosion and corrosion at pipe bends, pitting at ~ 20 circumferential welds and heat-affected areas and corrosion ;~ such as caused by puddles at low pipe line areas.
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The camera assembly 16 includes a lens disposed above a protective glass plate 2~ held by a support 21 on a horizontal wall portion 22 of the section 15. To illu-minate the surface of the pipe, a pair of strobe lights are provided behind a pair of ports 23 and 24 which are disposed on inclined wall portions 25 and 26 of the central housing section 17, the ports 23 and 24 having ylass windows for transmission of light therethrough.
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As diagrammatically shown in Figures 2 and 3, the camera assembly 18 includes a camera 28 having a lens 29 which projects an image to a film plane at which a film 30 is moved from a supply reel 31 to a take-up reel 32, suitable electrically operated drive means being provided for driving the take-up reel 32 to advance the film 30 for taking each picture. With this arrangement, and with the viewing axis of the camera, indicated by broken line 34, being normal to ~` the axis of the pipe, a generally rectangular image is projected to an image area of the film 30 which corresponds `~ to a generally rectangular internal surface area of the ` pipe. The image has length and width dimensions which respectively correspond to the axial length and arcuate width dimensions of the internal surface area. Thus, as indicated diagrammatically by lines 35 and 36 in Figure 2, the forward and rearward limits of the rectangular image area on the film may correspond to rearward and forward ` limits of a generally rectangular surface area of the ~ internal surface 17 of the pipe 18. As indicated by lines ; 20 37 and 38 in Figure 3, the side limits of the rectangular image area of the film 30 may correspond to arcuately spaced limits of a generally rectangular surface area of the internal surface 17 of the pipe 18.
As also shown diagrammatically in Figure 2, strobe lights 39 and 40 are mounted behind the ports 23 and 24 to project beams of light along axes as indicated by -broken lines 41 and 42. Each strobe light is spaced axially from the viewing axis and each projects a beam of light toward the internal surface area of the pipe which is to be photographed, along an illumination direction at an acute angle to the axis of the pipe.
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The arrangement with the viewing axis of the camera at right angles to the axis of the pipe, thereby producing a generally rectangular image corresponding to a generally rectangular internal surface area of the pipe, is highly advantageous in that the relationship between the size of defects and the size of the corresponding indica-tion on the film is substantially uniform. As a result, standards can be established for determining whether a pipe can be passed as being satisfactory or whether remedial action should be taken to repair or service the pipe. The necessity ~or requiring an inspector of the film to exercise critical judgment is minimized.
The illumination of the surface area of the pipe as disclosed is also advantageous for similar reasons, it being noted that the relationship between the direction of the light and the surface of the pipe is substantially uniform throughout the entire internal surface area of the pipe which corresponds to the image produced.
Since the internal surface area of the pipe which is photographed is of limited angular extent, it is important that the portion photographed be selectable and identifiable.
It is also found to be important that the pictures be taken in an angular direction which has the greatest likelihood of ":
producing indications of any critical defects which may exist.
In inspecting horizontal runs of pipelines such as used for , conveying raw natural gas, it is found that the lower portion of the internal surface of the pipe is generally of primary /- interest because liquids can accumulate to cause corrosion .' of the pipe under certain conditions. In accordance with ,i, :',' :
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the invention, the apparatus 10 is weighted in a manner such that the viewing axis 34 of the camera may be in a vertical plane through the axis of the device or at any desired angle relative to such a vertical plane.
In Figure 1, a rearward cup assembly including the rearward cups 11 and 12 and associated elements is shown in section. As illustrated, a spacer structure 44 is sandwiched between the cups 11 and 12 and a holding ring 45 is disposed against the rear side of the rear cup 11 while a plate 46 is disposed against the forward face of the cup 12. The forward face of the plate 46 is recessed to receive the rearward end of the central housing section 15, a radially inwardly facing annular shoulder 47 being provided which engages a rear end of an annular flange portion 48 of the central housing section 15. Four bolts 49 are provided having head portions engaging the plate 46 and having shank portions extending through the cup 12, spacer structure 44, cup 11, plate 45 and washers 50 with nuts 51 being threaded on the rearward terminal ends of the shank portions of the bolts 49.
The forward cup assembly which includes cups 13 and 14 is similar to the rearward cup assembly and includes a spacer structure 52 similar to the spacer structure 44, a ring 53 similar to the ring 45 and four bolts 55.
To hold the rearward and forward cup assemblies against the rearward and forward ends of the central housing section, four elongated bolts 58 are provided which have shank portions extending through the forward cup assembly, r .
thence through sleeves 59 positioned between the rearward end of the forward cup assembly and the plate 46 at the forward end of the rearward cup assembly, thence through the rearward cup assembly and through washers 60 with nuts 61 being threaded on the rearward terminal ends of the elongated bolts 58.
The spacer structure 44 is formed from a pair of rings ~3 and 64 and a plurality of spacer sleeves 62 through which the shank portions of the connecting bolts 49 and 58 extend. To weight the apparatus so as to cause it to assume a predetermined angular position, a weight member 66 of semi-cylindrical shape is located between the rings 63 and 64. The weight member 66 is of a heavy material, prefer-ably lead, and a similar weight member is preferably included in the forward cup assembly.
For most applications, the viewing axis of the camera is preferably at a six o'clock position so as to be in a vertical plane through the axis of the apparatus and so as to produce photographs of the bottom of the pipe where corrosion may be produced as the result of the accumulation of liquid, particularly in low pipeline areas. However, the viewing axis may be positioned at any desired angular posi-tion. To adjust the viewing axis of the camera, the nuts 61 may be loosened and the central housing section 15 may then be rotated to the desired angular position relative to the weights of the cup assemblies a~ter which the nuts 61 may be tightened to securely lock the housing section 15 in the desired angular position.
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The illustrated apparatus may be propelled by the pressure of a gaseous medium in the pipeline, either the natural gas or other product normally carried by the pipe-line or compressed air or the like introduced into the pipeline. The illustrated apparatus may thus be self-pro-pelled or it may, in the alternative, be propelled by a towing pig in which case cups of the apparatus may be provided with openings or grooves for passage of the gaseous medium past the apparatus to the towing pig.
In the apparatus 10 of Figures 1-4, the entire apparatus is rotated to a predetermined angular position whereby the force of gravity acts on the weights which are positioned to place the center of gravity of apparatus to the offset of the angular position. It is also possible to support the camera for rotation by the pipe axis to a predetermined angular position while supporting the camera from support means non-rotatably engaged with the inside surface of the pipe. Referring to Figures 5 and 6, refer-ence numeral 6~ generally designates an apparatus in which the camera is supported for rotation about the pipe axis from the support structure non-rotatably engaged with the pipe.
The apparatus 68 is in the form of a camera unit and it includes a camera 70 which includes electrically operated film storage and -transport means whereby photo-graphic film is moved from a supply reel within one end ,.
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portion 71 of a housing 72 to a take-up reel within an opposite end portion 73 of the housing 72. The camera 70 further includes a lens assembly 74 which operates to project an image of the inside surface of the pipe onto a section of the film positioned at an image area interme-diate the supply and take-up reels.
To illuminate the inside surface of the pipe, an electrically operated strobe flash unit 76 is provided arranged to project a beam of light along an axis 77 which intersects the central axis of the lens 74, indicated by reference numeral 78, at a point on the inside surface of the pipe.
The orientation of the illumination and lens axes 77 and 78 are of substantial importance. Preferably, the lens axis is generally normal to the inside surface of the pipe, i.e., at substan~ially a right angle to the pipe axis and the illumination axis is at an acute angle, preferably on the order of 45 degrees or less. Corrosion pits or the like cast shadows such that from inspection of a developed picture, an accurate estimate can be made with xespect to the depth of a pit or the like and as to whether it neces-sitates a repair opera~ion on the pipe.
A counter 80 is energized from pulses generated in response to movemen~ of the apparatus within the pipe and registers the distance traveled, being disposed within the field of ~iew of the lens 74 so as to record the posi-tion in each film frame.
- ".
, ; , .
, ~' .
The camera 70 is secured to a frame 81 which carries caster wheel assemblies 82, 83 and 84 at one end thereof. At the opposite end thereof, the camera support frame 51 is hingedly connected through a hinge pin 85 to a plate 86 which is hingedly connected through a pin 87 to a second plate 88 which, in turn, is connected through a third pin ~9 to a support plate 90, the axes of the pins 85 and 87 being in spaced parallel relation and the axis of the pin 89 being at risht angles ~o the axes of the pins 85 and 87. A coiled tension spring 91 is secured between an outer end of the camera support frame 81 and the support plate 90 to normally hold the end o~ the camera frame 81 and the plates 86, 88 and 90 against one another as shown.
In moving through ~urns or bends in the pipe, the camera frame 81 may, if necessary, pivot relative to plate 86 about the axis of pin 85 or the camera frame and the plate 86 may together pivot relative to the plate 88 and the axis of the pin 87 or the camera frame 81 and plates 86 and B8 may pivot relative to the plate 90 about the axis of the pin 89.
The support plate 90 carries the strobe unit 76 and the counter 80 and is supported through a pair of posts 92 and 93 from a frame 94 which is journalled within a cylindrical housing 95 for movement about the axis of the cylindrical housing 95, preferably with one ball-bearing assembly 96 being provided at one end of the housing 95 and another similar assembly being provided at the other end. Suitable slip rings are pro~ided within the cylin-drical shell or housing 95 for transmission of electrical control signals to the camera 70, strobe unit 76 and counter 80.
.
.
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To support the housing 95 for movement within the pipe, it carries three wheel assemblies 98 spaced equi-angularly, 120 degrees from each other, each including a frame 100 extending longitudinally in generally parallel relation to the axis of the housing 95 and carrying a pair of wheels 101 and 102 at the opposite ends thereof, the frame 100 being supported from the housing 95 through compression sprinas 103, 104 and ].05, operative to urge the wheels 101 and 102 into engagement with the inside surface of the pipe.
The apparatus 68 may be propelled by means of a motor-driven drive unit as disclosed in our prior copending application or it may be propelled by a suitable towing pig.
For such purposes, a bar 106 is connected through a U-joint 107 to one end of the housing 95.
Figure 7 shows a modified form of apparatus which is in the form of a camera unit 110 similar to the camera unit 68 of Pigur~s 5 and 6 and having a camera 111 on a frame 112 which is supported ~hrough a hinge assembly from a support plate 114 which is supported through posts 115 and 116 from a frame journalled in a housing 117. Housing 117 is supported for movement wi~hin a pipe 113 through three wheel assemblies 119, each including a frame 120 which carries wheels 121 and 122 and which is connected to the housing 117 through compression springs 123, 124 and 125. A flash unit 126, corresponding to flash unit 76, s mounted on the support plate 114.
,'' ' ' ~:
:
Magnetic detection means are provided for sensing inhomogeneities in the pipe. In the illustrated arrangement~
three units 127, 128 and 129 are provided, each of which extends arcuately, the three units being offset axially and being in overlapping relation to cover an arcuate distance corresponding ~o the arcua~e dimension of the effective field of view of the camera. The units 127-129 may have the same construction and may be resiliently supported in substantially the same way. Unit 127 may, for example, include an arcuate core 131 of permanently magnetized material and of generally U-shaped cross-sectional form with a coil 132 wound thereon.
When the unit moves over a corrosion pit or other discontin-uity in pipe 118, the magnetic linkage field of the permanent magnet core 131 changes, inducing a corresponding electrical signal in the coil 132. Core 131 is supported from the sup-port plate through springs 133 and 134 for resiliently yieldable contact with the inside of pipe 118.
The camera unit 110 also incorporates means for sensing changes in the internal dimensions or configuration of the pipe such as caused by indentations, bends or obstruc-tions. Such means include three switch units 136, each associated with ~he ~rame 120 of one of the wheel assemblies 119 to be actuated when the fra~e is moved radially inwardly a predetermined e~tent.
Figure 9 is a schematic diagram of the electrical connection of units of the camera unit 110 of Figures 7 and ~. The magnetic leakage field de~ector units 127~129 are ~3~53~4 connected through amplifiers 137-139 and through circuitry 140 to a threshold detector 141 which develops an output signal in response to a leakage field signal having an amplitude greater than a predetermined amplitude.
The output signal so developed is applied to a delay circuit 142 which after a certain delay, propor~ional to the speea of travel of the appar~tus, applies a signal to the strobe unit 126 of the camera unit 110 so as to take a picture of the portion of the pipe which produced the signal de~eloped by the magnetic detection circuit. The signal applied to the strobe is also applied through a delay circuit 144 to a film advance control 145 of the camera of the unit 110.
~he switch units 136 are connected through circuitry 146 to another delay circuit 147 which after a certain delay, proportional to the speed of travel of the apparatus, applies a signal to the strobe unit 126 and also to the delay circuit 144. It is noted ~hat the direction of movement of the unit 110 is assumed to be to the right as viewed in Figure 7 so that the dimensional and magnetic detector means is ahead of the camera unit.
The arrangement of Flgures 7~ 8 and 9 is par-ticularly advantageous in inspection of long pipeline runs, in which it is desirable to avoid unnecessary consumption of film and to restrict the picture-taking to those sections of the pipe which are of possible interest as indicated by dimensional changes or the presence of magnetic discontinuities.
~ ,: : -, ~;3~
It may be noted that the camera in any case may be rotated about the axis of the pipe to various positions and/or suitable split mirrors or other optical elements may be used to effect taking of the picture of the entire internal surface of the pipe. In most applications, however, the taking of pictures may be restricted to the lower part of the inside surface of the pipe, where corrosion is apt to occur because of the accumulation of liquid, and the apparatus of Figures 1-4 is advantageous in this respect.
The apparatus of Figures 1-4 is also advantageous in that the camera and the strobe lights are supported in well-protected positions behind glass windows of the ports in the central housing section 15. It is further noted that with the central housing section being disposed between the forward and rearward cup assemblies, a protected region is provided for the taking of the pictures. The arrangement thus serves to minimize problems with interference due to puddles of liquid in the pipe, splashing of liquids and liquid droplets or vapors in the air or gas in the pipe.
Z0 Reference numeral 150 generally designates a modi-fied type pipe inspection apparatus constructed in accordance with the principles of this invention. The apparatus 150 is shown in a bend of a pipe 157 which may, for example, be a bend at the lower end of a vertical pipe section which extends down from an off-shore station.
The illustrated apparatus 150 includes a camera unit 152 and a drive unti 153 with a coupling therebetween including a bar 154 having opposite ends coupled to the units 152 and 153 through U-joints 155 and 156.
The illustrated drive unit 153 includes three motor-driven wheel assemblies 158 each including a pair of wheels 159 on a shaft 160 driven through a gear reduction unit 161 from an electric motor 162. The housing of each motor 162 is hingedly connected to a frame member 164 through a pin 165 and at the opposite end, a compression spring 166 acts between a pin 167 carried by the frame member 164 and a socket member 168 which is secured to the housing of the gear reduction unit 161, the wheels 159 being urged radially outwardly into pressure engage-ment with the inside surface of the pipe 151. Pin 167 may be withdrawn for release of pressure as hereinafter described.
The three wheel assemblies 168 are preferably in equi-angularly spaced relation, 120 degrees from each other.
At the opposite end of the drive unit, three idler wheel assemblies 170 are provided, each including a pair of wheels 171 urged radially outwardly by a spring 172, the assemblies 170 being preferably spaced e~ui-angularly, 120 degrees from each other. A battery unit 174 is carried by the frame of the drive unit 153 between the motor-driven wheel assemblies 158 and ~he idler wheel assemblies 170 and an electrical control unit 175 is carried on a projecting frame member 176. A hook 177 is provided on the terminal end of the frame member 176 for connection to a tether cable 178.
.
The camera unit 152 includes a camera 180 (Figure 12) which includes electrically operated film storage and transport means whereby photographi~ film i5 moved from a supply reel 181 within one end portion of a housing 182 to a take-up reel 183 within an opposite end portion of the housing 182. The camera 180 further includes a lens assembly 184 which operates to project an image of the inside surface of the pipe onto a section of the film positioned at an image area intermediate the supply and take-up reels.
. ~ , . . .......................... .
-~ ~
.
To illuminate the inside surface of the pipe, an electrically operated strobe flash unit 186 is provided arranged to project a beam of light along an axis 187 which intersects the central axis of the lens 184, indicated by reference numeral 188, at a point on the inside surface of the pipe.
The orientation of the illumination and lens axes 187 and 188 are of substantial importance. Preferably, the lens axis is generally normal to the inside surface of the pipe, i.e., at substantially a right angle to the pipe axis and the illumination axis is at an acute angle, preferably on the order of 45 degrees or less. Corrosion pits or the like cast shadows such that from inspection of a developed picture, an accurate estimate can be made with respect to the depth of a pit or the like and as to whether it necessi-tates a repair operation on the pipe.
A counter 190 is energized from pulses generated in response to movement of the apparatus within the pipe and registers the distance travelled, being disposed ~ithin the field of view of the lens 184 so as to record the position in each film frame.
The camera 180 is secured to a fra~e 191 which may carry suitable caster wheel assemblies at one end thereof, using a construction such as shown in Figures 5 and 6, for example.
Figure 12 is a schematic diagram of electrical cir-cuitry for the apparatus 150. Control circuitry 196 is connected through lines 198l 199 and 200 to the camera 180, strobe unit 186 and counter 190 and is also connected to a switch device 202 which is operated from one of the wheels ~ .
engaged with the inside surface of the pipe, such as one of the idler wheels 171 and which generates a pulse in response to rotation of the wheel through a certain angle and thereby in response to movement of the apparatus a certain distance.
Electronic counter means are provided in the control circuitry l99 to apply a triggering signal to the strobe unit 186 after a certain number of such pulses. After a certain delay, indexing pulses are applied to the counter l90 and also to film drive means of the camera 180.
Motor control circuitry 204 is provided which is connected to the battery unit 174 and to the drive motors 162 and also to the control circuitry 196 and a start switch 206. With the apparatus disposed in one end of a pipeline or in a launching pipe section which feeds into a pipeline, the start switch 206 is depressed to cause energization of the drive motors 162 and to initiate movement of the apparatus along the pipeline. The apparatus may continue movement until it reaches the other end of a pipeline. Alternatively, counter means within the motor control circuitry 204 may respond to signals from the control circuitry 196 to operate after a certain number of pulses are applied and thereby after the--apparatus travels a certain distance, to reverse the polarity of the voltages applied to the motors 162 and to cause the apparatus to move in the reverse direction and return to its initial position. This automatic reversing feature is highly advantageous in that the portion of a pipeline extending only a relatively short distance such as from 1,000 to 2,000 feet away from an offshore station may be inspected. Many of the problems which can be detected by the apparatus are found within such a relatively short distance frorn offshore stations and the use of the apparatus in this way is thus highly productive. Also, it does not require that the apparatus be capable of travelllng very large distances.
A very high degree of reliability can be obtained with drive means such as illustrated but it is nevertheless desirable to provide a back-up in the event of failure of the drive means, and it is for this reason that the hook 177 is provided for connection to the tether cable 178, so that the apparatus can be withdrawn by means of the cable 178.
It is noted that the motor-driven wheel assemblies 158 desirably include the gear reduction units 161 which allow the motors to be operated at relatively high speeds so as to be of relatively small si~e. With such gear reduction units, however, it is found that in case of deenergization of the motors, the high degree of friction is encountered when attempting to move the apparatus by means of the tether cable 178. In accordance with a specific feature, a spring 210 is provided in the connection between the cable 178 and the hook 177 and three lines 211 are provided between the cable 178 and the pins 167 of the drive wheel assemblies.
When the tension in the cable 178 reaches a predetermined level, the spring 210 is stretched to an extent such that the cable 178 acts through the lines 211 to retract the pins 167 and to allow the inner ends of the springs to move inwardly and thus release the pressure applied by the wheels 159. Accordingly, the apparatus can be readily withdrawn, friction being minimized.
, :
Claims (9)
1. In pipe inspection apparatus, a device arranged to be moved down through a vertically extending pipe section and thence into a horizontal pipe section for longitudinal horizontal movement therewithin, said device comprising photographic camera means including means defining a rectangular image area, film storage and transport means arranged for feeding film through said image area and optical means for projecting an image to said image area, said optical means being arranged to project said image along a viewing axis from an internal surface area of the pipe with said viewing axis being normal to the axis of said pipe and with a generally rectangular image being produced in said image area which corresponds to a generally rectangular internal surface area of the pipe and which has length and width dimensions respectively corresponding to the axial length and arcuate width dimensions of said internal surface area, illumination means for illuminating said internal sur-face area of the pipe, operating means for operating said film storage and transport means and said illumination means during movement of said device along the pipe for recording on the film a plurality of images corresponding to axially spaced generally rectangular surface areas of the pipe, said illumination means being spaced axially from said viewing axis and being arranged to project light toward said internal surface area of the pipe in a direction at a substantially uniform acute angle to the axis of the pipe and with substan-tially uniform intensity, the relationship between the direction of the light and the surface of the pipe being substantially uniform throughout all of said internal surface area of the pipe such that shadows are produced across recesses in said internal surface area of the pipe and such that there is a substantially uniform relationship between the size of the images of said shadows and the size of the corresponding recesses in said internal surface area, engage-ment means including at least two axially spaced cup members defining resilient annular flanges in engagement with axially spaced portions of the inside surface of the pipe, a central housing section supporting said camera and illumination means therewithin, a pair of cup member support structures secured to opposite ends of said central housing section for support of said central housing section from said cup members, said viewing axis being approximately mid-way between said cup member support structures, and weight means operative under the force of gravity to urge said device toward a certain angular position when moving longitudinally through a hori-zontal pipe section and to place said viewing axis at a predetermined angular position relative to the pipe.
2. In pipe inspection apparatus as defined in claim 1, said central housing section having ports including windows of solid transparent material for protecting said camera means and said optical means thereof and for protecting said illumination means.
3. In apparatus as defined in claim 1, magnetic detection means carried by said device for developing electrical signals in response to inhomogeneities in the pipe, and means responsive to said electrical signals for controlling said camera and illumination means for recording on the film images of internal surface areas having magnetically detected inhomo-geneities therein.
4. In pipe inspection apparatus as defined in claim 3, said magnetic detection means being forwardly spaced from said camera and illumination means in the direction of movement of said device, and said control means including circuit means for delaying the time of operation of said camera and illumination means in proportion to the speed of movement of said device.
5. In pipe inspection apparatus as defined in claim 1, said viewing axis being placed at a six o'clock position so that said plurality of images correspond to lower rectangular surface areas of the inside of the pipe.
6. In pipe inspection apparatus as defined in claim 5, the resilient annular flange of one of said cup members positioned forwardly in relation to said viewing axis being operative to clear accumulated liquids from the lower surface of the pipe to facilitate obtaining of a clear image thereof.
7. In pipe inspection apparatus, a device arranged to be inserted into a pipe for longitudinal movement there-within, photographic camera means carried by said device including film storage and transport means arranged for feeding film through an image area and optical means for projecting to said image area an image from an internal surface area of the pipe, illumination means for illuminating said internal surface area of the pipe, and operating means for operating said film storage and transport means and said illumination means during movement of said device along the pipe for recording on the film a sequence of images of the internal surface of the pipe, drive means including drive wheel means for engagement with the inside surface of the pipe and motive power means for rotating said drive wheel means to move said device along the pipe, connection means for connecting a tether to said device for withdrawal of said device from the pipe independently of said drive means, said drive means being operable between a drive condition wherein said drive wheel means are in pressure engagement with said inside surface and are coupled to said motive power means to develop a relatively high frictional force opposing movement of the device by the tether and a release condition in which said frictional force is reduced to a relatively low value, and means interconnecting said connec-tion means and said drive means for operating said drive means to said release condition in response to application of a predetermined force by the tether.
8. In apparatus as defined in claim 7, said drive means including spring means for urging said drive wheel means into pressure traction engagement with the inside surface of the pipe, said spring means being operable to a release condition to substantially eliminate said pressure traction engagement.
9. In pipe inspection apparatus, a device arranged to be inserted into a pipe for longitudinal movement there-within, photographic camera means carried by said device including film storage and transport means arranged for feeding film through an image area and optical means for projecting to said image area an image from an internal surface area of the pipe, illumination means for illuminating said internal surface area of the pipe, operating means for operating said film storage and transport means and said illumination means during movement of said device along the pipe for recording on the film a sequence of images of the internal surface of the pipe, drive means including drive wheel means for engagement with the inside surface of the pipe and motive power means for rotating said drive wheel means to move said device along the pipe, reversing means operable upon movement of said device through substantially a predetermined distance along the pipe for reversing said drive means to effect movement of the device in a reverse direction, said reversing means comprising means for developing an electrical pulse in response to movement of said device through a certain distance, counter means for counting a predetermined number of said pulses to develop a reversing signal, and means responsive to said reversing signal to reverse said drive means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15551280A | 1980-06-02 | 1980-06-02 | |
| US155,512 | 1980-06-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153604A true CA1153604A (en) | 1983-09-13 |
Family
ID=22555746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000370419A Expired CA1153604A (en) | 1980-06-02 | 1981-02-09 | Pipeline inspection apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1153604A (en) |
-
1981
- 1981-02-09 CA CA000370419A patent/CA1153604A/en not_active Expired
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