CA1122657A - Pipe surface testing carriage - Google Patents
Pipe surface testing carriageInfo
- Publication number
- CA1122657A CA1122657A CA317,260A CA317260A CA1122657A CA 1122657 A CA1122657 A CA 1122657A CA 317260 A CA317260 A CA 317260A CA 1122657 A CA1122657 A CA 1122657A
- Authority
- CA
- Canada
- Prior art keywords
- pipe
- detector
- mounting means
- rail structures
- detector mounting
- 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.)
- Expired
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
- G01N27/9013—Arrangements for scanning
- G01N27/902—Arrangements for scanning by moving the sensors
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An apparatus for determining the precise location of faults in a pipeline, e.g. for use after a travelling pig has indicated the area of a pipeline containing a fault, comprises rail structures, the ends of which are received in end pieces.
The end pieces receive releasable buckled straps, by means of which the apparatus may be releasably secured to a pipeline.
A detector mounting means is movable along the rails, and carries a detector such as a gaussmeter, in a slot extending across the detector mounting means. The bottom surface of the detector mounting means receives the sensor at a constant spacing from the pipe surface, so that the detector can be moved across the pipe surface, by moving the detector assembly along the rail structures and by moving the detector along the detector mounting means, to determine the location of surface imperfections.
An apparatus for determining the precise location of faults in a pipeline, e.g. for use after a travelling pig has indicated the area of a pipeline containing a fault, comprises rail structures, the ends of which are received in end pieces.
The end pieces receive releasable buckled straps, by means of which the apparatus may be releasably secured to a pipeline.
A detector mounting means is movable along the rails, and carries a detector such as a gaussmeter, in a slot extending across the detector mounting means. The bottom surface of the detector mounting means receives the sensor at a constant spacing from the pipe surface, so that the detector can be moved across the pipe surface, by moving the detector assembly along the rail structures and by moving the detector along the detector mounting means, to determine the location of surface imperfections.
Description
"" ~122657 This invention relates to testing of metal structures, and more particularly to methods and apparatus for detectingand locating faults such as "hard spots" in metal pipelines.
A hard spot in a metal pipeline wall is a structure defect which is formed in the pipe during its manu-facture. For-example, it may be formed by accidental cooling of a spot on the metal during fabrication of the pipe, e.g.
by cold water splashing onto a hot pipe. In any event, hard 10 spots are a point of weakness in the pipeline structure, and will deteriorate with age. They are a particular problem in pipelines conducting natural gas, since they tend to be attacked by the hydrogen in the gas. Gas-conducting pipelines frequently operate at elevated pressures, e.g. 1000 psi, and so faults such as hard spots need to be located, and eliminated, after the pipeline has been installed above or below ground.
It is known common practice to use a pig for ` detecting faults in pipelines from the inside of the pipe.
The pig is conveyed along the inside of the pipel-ine, e.g. by 20 the gas flow itself. The pig bears a magnetic coil detector, an odometer and recorder. It measures the magnetic properties of the pipeline, by inducing a magnetic field in the .
.
~226S7 portion of the pipeline being surveyed, and it detects devia-tions from normal readings of magnetic flux caused by faults such as hard spots. It records the locations of such faults and reports them Then it is necessary to unearth and expose the pipe at the location indicated by the pig, and eliminate the fault.
As a result of the use of the travelling pig detector, the operator gets to know the location of a fault such as a hard spot, to within about a one-foot length of the pipe. The pig detector is not normally able to pin-point the fault more exactly than that. Moreover~ it will not indicate the circumferential location of the fault. It is now neces-sary to use another detector to pin-point the fault within the area indicated by the pig.
One form of such detector which is commercially available is a portable Rockwell hardness tester, which probes the pipe surface to determine hardness. For this to be used, the pipe surface must first be stripped of its protective coating (normally asphalt) and scoured. Such operations, followed by probing into the metal to determine its hardness, require the closing down of pressurized flows in the pipeline.
Another form of detector for surveying restricted surface areas of the pipe, following the use of the pig with its magnetic induction system, is a gaussmeter, which measures magnetic properties of the metal. In fact, the gaussmeter l~ZZ657 determines the residual magnetism left in the pipe wall, as a result of the previous passage of the pig which applied a magnetic field to the pipe wall. The harder steel of a hard spot in the pipe gives a greater degree of residual magnetism than the surrounding steel. Measurements with a gaussmeter as normally conducted are however imprecise and unsatisfactory.
The gaussmeter is not sufficiently sensitive to operate through the corrosion-protective asphalt coating of the pipeline, so that the coating must be removed from the area to be tested.
This entails abrading and scouring of the pipe surface which is liable to upset the residual magnetic field left in the pipe by the pig. The magnetic readings given by the gaussmeter are highly sensitive to variation in the separation between the magnetic probe on the gaussmeter and the metallic pipe surface.
It is an object of the present invention to provide a novel apparatus for detecting faults in metal pipes.
According to the present invention, there is provided a pipe surface testing apparatus comprising at least two side rail structures adapted to extend axially along the limited extent of the exterior of a pipe under test;
first and second end pieces fixedly receiving therein opposed ends of said rail structures, each said end piece having a lowermost surface adapted to be received against the outer surface of the pipe under test;
detector mounting means mounted on said rail 11226~7 structures and movable therealong, said detector mounting means extending circumferentially with respect to the pipe to span the gap between said rail structures;
the lowermost surface of the detector mounting means presented towards the pipe surface having a plurality of zones each with a surface location adapted to be spaced an equal radial distance from the pipe surface when said end pieces are received against the outer surface of the pipe under test;
a detector assembly, including a sensing means, movably mounted on said detector mounting means for movement in a direction transverse to the direction of extent to the rail structures, and having a mounting position in each zone of the lowermost surface thereof in which the detector assembly may be mounted so that the sensing means registers with the surface location of said zone to be disposed the same radial distance from the pipe surface in each of the mounting positions;
releasable securing means for releasably securing the apparatus to the pipe, with the lowermost surfaces of said end pieces received against the outer surface of the pipe.
By means of the apparatus of the present invention, a limited section of the pipe surface may be scanned for imperfections such as hard spots, conveniently and accurately.
The detector assembly, which may include a gaussmeter or other known form of detector can be moved axially of the pipe surface by moving the detector mounting means along the rail structures.
~ ZZ~;57 It can be moved circumferentially of the pipe by moving it along the detector mounting means. A next adjacent section of the pipe surface can be scanned by releasing the releasable securing means and moving the entire apparatus to another pipe surface section. The sensing means of the detector is at all times positioned the same radial distance from the pipe surface.
The accuracy and sensitivity of the measurements is enhanced, to the extent that removal of external coatings form the pipe prior to using the apparatus becomes much less important.
The size of the apparatus is suitably from about 1-4 feet in length, with a rail separation of 4-12 inches. Such an apparatus can readily scan the pipe section indicated by the pig as containiny a fault, and speedily pinpoint the precise location of the previously indicated fault.
In the preferred embodiment of the invention, the lowermost surface of the detector mounting means, instead of being curved on a radius corresponding to that of the pipe surface, has a series of stepped formations, the edges of - which extend radially to define an edge of the zone. A part of the surface of each zone lies on a circle concentric with the cylindrical pipe surface. Then the detector assembly can be mounted in each zone with an edge thereof against the step formation, and the sensing means registering with that part of the surface on the concentric circle, so that the sensing means is always positioned the same radial distance from the ~122~:iS7 pipe surface. Such a structure provides for more positive positioning of the detector mounting means and consequently more accurate determination and recording of the precise location of a surface fault in the pipe. ~oreover, it is simpler and more economical to manufacture a detector mounting with an accurately finished stepped lower surface than an accurately finished curved lower surface.
The lowermost surface of the end piece which is received against the pipe surface normally constitutes the lower structural surface of the piece itself. Preferably however, there are included in the end pieces a plurality of adjustable levelling screws permitting the apparatus to be adjusted against the pipe surface to ensure t~at the detector mounting means for the side rail structures is disposed with its mounting zones at an equal distance above the pipe exterior surface. The releasable securing means, which are suitably flexible buckled straps encircling the pipe, are then tightened to hold the apparatus firmly against the pipe surface, levelled or otherwise correctly adjusted by the preset position of the levelling screws.
Also in a preferred embodiment, one of the side rail structures comprises a lead screw upon which the detector mounting means is threadably mounted. The lead screw can be driven by hand or powered means to rotate it and cause axial movement of the detector mounting means down the pipe. The l~Z~6~7 detector mounting means is suitably slidable along the other rail structure.
A specific preferred embodiment of the present invention is illustrated in the accompanying drawings, in which:
FIGURE 1 is a perspective view of an apparatus according to a specific preferred embodiment of the present invention, mounted in position on the exterior of a cylindrical pipe; and FIGURE 2 is a fragmentary sectional view along the line 2-2 of Fig. 1.
Fig. 1 shows a portion of a generally cylindrical pipe 10 with an apparatus according to the invention releasably fastened thereto. The apparatus comprises first and second straight, parallel side rail structures 11, 12. The first side rail structure 11 comprises an elongated bar having a longitudinal slot 13 therein, presenting an upper smooth surface. The second s-~de rail structure 12 comprises a side bar 14 completing the framework of the apparatus, and a lead screw 15 extending alongside the side bar 14 axially of the - 20 pipe 10. The ends of the side rail structures 11, 12 are fixedly received in end pieces 16, 18. Each end piece as an inner generally rectangular plate 20, 22, respectively completing a rectangular framework with the rail structure 11 and side bar 14 of rail structure 12, and an outer, smaller plate 24, 26 respectively, arranged in an upright position on the surface of pipe 10 and parallel to one another. Each end piece 16, 18 is also provided with a respective lower spacer bar 28, 29 extending across the centre lower part of the space between the inner and outer plates thereof, and a pair of upper spacer bars 30, 31 and 32, 33 respectively near the upper corners of the outer plates 24, 26 and extending between the inner and outer plates. The lowermost surface of each end piece 16, 18 is formed by the bottom surface 34 of the inner plates 20, 22, which as illustrated has three straight portions angularly disposed with respect to one another. The centre portion and side portions of this lowermost surface are received in contact against the cylindrical outer surface of the pipe 10. Each inner plate 20, 22 is provided with a pair of adjustable levelling screws 35, 36 and 37, 38 respectively, threadably received in end formations of the inner plates 20, 22 and protruding downwardly therethrough, so that the apparatus as a whole can be adjusted as to height on the pipe surface.
The end pieces 16, 18 are releasably held against the pipe surface by means of respective flexible straps 39, 40 having buckles 41, 42. The straps 39, 40, pass through the space between inner plates 20, 22 and outer plates 24, 26 over the ends of outer spacer bars 30, 31 and 32, 33 respectively, and under the central spacer bars 28, 29 respectively so that they releasably tighten the apparatus onto the pipe surface.
~lZ2~57 By first adjusting the levelling screws to the desired position and then tightening the straps 39, 40, the apparatus is held rigidly in position in the desired location, to permit measurements to be made using it, on the pipe surface.
A detector mounting means 50 in the form of an elongated metal block is mounted for movement along the rail structures 12, 14. ~he end formation 51 of the block 50 passes through and slides along slot 13 in side rail structure 11. At the other endl the block 50 is provided with a screw threaded housing 52 which is threadably received on the lead screw 15. The block 50 thus spans the gap between the rail structures 11, 12. It is provided with a slot 53 which extends through the block 50 and in the circumferential direction with respect to the pipe 10. A detector assembly 54 is mounted in the slot 53, this detector assembly comprising a rod 55, a lower block 56 in the form of a cube, an elongated sensing means 57 protruding downwardly through the rod 55 of block 56, to present a sensor 58 extending a short way below the bottom surface of the block 56. Downwardly extending protrusions 59 are provided at each of the four corners of the lowermost surface of the block 56, protruding downwardly beyond the end of the sensing means 57, to protect the sensor 58 located therebetween from damaging contact with the surface of the pipe 10~ The detector assembly 54 also inciudes a washer 62, an upper knob 64 on the top of l:~Z2657 the rod 57 and a coil spring 66 bearing against the washer 62 and the knob 64. Thus by turning the knob 64, the detector assembly can be clamped in position in slot 54, and released for position adjustment therealong.
The undersurface of the block 50 is formed in a series of zones 68 each defined by a stepped side formation 70 at its outer edge, and a flat top surface 72, extending in a tangential direction with respect to the pipe 10. As shown in Fig. 2, the centre location of each top surface 72 of the zones 68 is the same distance from the surface of the pipe 10, and lies on a circle 74 concentric with the pipe surface. When the block 56 is mounted in each zone, with its side abutting against step 70, the sensor 58 registers with the centre location of the zone. The arrangement of steps 70 thus provides for positive location of the block 56 and sensing means 60 in each zone, with the sensing means 60 spaced the same distance from the pipe surface in each zone. Suitably, the sensing means is spaced about 1/4" from the pipe surface.
A motor 76 e.g. an electric motor is mounted on the - outside end of end piece 16, spaced therefrom to allow passage of strap 39. The end of the lead screw 15 is journalled in - end plate 20 of end piece 16, and is received in driving engagement with motor 76, so that the lead screw may be rotated therewith. At its other end, beyond end plate 22 of end piece 18, the lead screw is received in a rotation counter such as a Helipot (trade mark~, to sense and record the .
position of the threaded housing 52 of the detector mounting means 50 therealong. This information is electrically fed from the Helipot to a suitable recorder, e.g. an X-Y plotter, along with other information received from the sensor, to give a plot of readings for assistance in identifying the precise location of an anomaly on the surface of the pipe 10.
The operation of the apparatus of the~invention will be apparent from the foregoing de~ription and drawings. By movement of the detector assembly 54 in slot 53, the area within the rail structures 11, 12 and end frames 20, 22 can be surveyed by sensor 58, and accurate readings of its characteristics can be obtained. Then the releasable straps 39, 40 can be loosened and the apparatus moved to another location on the pipe surface to repeat the operation. Once a conventional moving detector such as a pig has recorded the presence of a fault within a certain short length of the pipe the apparatus according to the invention can be readily used to pin-point the fault. The readings obtained using the apparatus of the invention are accurate and reliable, since the sensing means is positively positioned at precise locations, and ensured to be mounted the same distance from the pipe surface at each test location. The need to scour, abrade and clean the exterior pipe surface is substantially reduced. The apparatus is small and readily portable, and at the same time simple but efficient to use.
.
112~7 Whilst a specific preferred embodiment of the invention has been described and illustrated in detail, it will of course be understood that this is illustrative and by way of example only and should not be construed as limiting.
Variations thereof will be apparent without departing from the scope of the invention. The scope of the invention is limited only by the appended claims.
A hard spot in a metal pipeline wall is a structure defect which is formed in the pipe during its manu-facture. For-example, it may be formed by accidental cooling of a spot on the metal during fabrication of the pipe, e.g.
by cold water splashing onto a hot pipe. In any event, hard 10 spots are a point of weakness in the pipeline structure, and will deteriorate with age. They are a particular problem in pipelines conducting natural gas, since they tend to be attacked by the hydrogen in the gas. Gas-conducting pipelines frequently operate at elevated pressures, e.g. 1000 psi, and so faults such as hard spots need to be located, and eliminated, after the pipeline has been installed above or below ground.
It is known common practice to use a pig for ` detecting faults in pipelines from the inside of the pipe.
The pig is conveyed along the inside of the pipel-ine, e.g. by 20 the gas flow itself. The pig bears a magnetic coil detector, an odometer and recorder. It measures the magnetic properties of the pipeline, by inducing a magnetic field in the .
.
~226S7 portion of the pipeline being surveyed, and it detects devia-tions from normal readings of magnetic flux caused by faults such as hard spots. It records the locations of such faults and reports them Then it is necessary to unearth and expose the pipe at the location indicated by the pig, and eliminate the fault.
As a result of the use of the travelling pig detector, the operator gets to know the location of a fault such as a hard spot, to within about a one-foot length of the pipe. The pig detector is not normally able to pin-point the fault more exactly than that. Moreover~ it will not indicate the circumferential location of the fault. It is now neces-sary to use another detector to pin-point the fault within the area indicated by the pig.
One form of such detector which is commercially available is a portable Rockwell hardness tester, which probes the pipe surface to determine hardness. For this to be used, the pipe surface must first be stripped of its protective coating (normally asphalt) and scoured. Such operations, followed by probing into the metal to determine its hardness, require the closing down of pressurized flows in the pipeline.
Another form of detector for surveying restricted surface areas of the pipe, following the use of the pig with its magnetic induction system, is a gaussmeter, which measures magnetic properties of the metal. In fact, the gaussmeter l~ZZ657 determines the residual magnetism left in the pipe wall, as a result of the previous passage of the pig which applied a magnetic field to the pipe wall. The harder steel of a hard spot in the pipe gives a greater degree of residual magnetism than the surrounding steel. Measurements with a gaussmeter as normally conducted are however imprecise and unsatisfactory.
The gaussmeter is not sufficiently sensitive to operate through the corrosion-protective asphalt coating of the pipeline, so that the coating must be removed from the area to be tested.
This entails abrading and scouring of the pipe surface which is liable to upset the residual magnetic field left in the pipe by the pig. The magnetic readings given by the gaussmeter are highly sensitive to variation in the separation between the magnetic probe on the gaussmeter and the metallic pipe surface.
It is an object of the present invention to provide a novel apparatus for detecting faults in metal pipes.
According to the present invention, there is provided a pipe surface testing apparatus comprising at least two side rail structures adapted to extend axially along the limited extent of the exterior of a pipe under test;
first and second end pieces fixedly receiving therein opposed ends of said rail structures, each said end piece having a lowermost surface adapted to be received against the outer surface of the pipe under test;
detector mounting means mounted on said rail 11226~7 structures and movable therealong, said detector mounting means extending circumferentially with respect to the pipe to span the gap between said rail structures;
the lowermost surface of the detector mounting means presented towards the pipe surface having a plurality of zones each with a surface location adapted to be spaced an equal radial distance from the pipe surface when said end pieces are received against the outer surface of the pipe under test;
a detector assembly, including a sensing means, movably mounted on said detector mounting means for movement in a direction transverse to the direction of extent to the rail structures, and having a mounting position in each zone of the lowermost surface thereof in which the detector assembly may be mounted so that the sensing means registers with the surface location of said zone to be disposed the same radial distance from the pipe surface in each of the mounting positions;
releasable securing means for releasably securing the apparatus to the pipe, with the lowermost surfaces of said end pieces received against the outer surface of the pipe.
By means of the apparatus of the present invention, a limited section of the pipe surface may be scanned for imperfections such as hard spots, conveniently and accurately.
The detector assembly, which may include a gaussmeter or other known form of detector can be moved axially of the pipe surface by moving the detector mounting means along the rail structures.
~ ZZ~;57 It can be moved circumferentially of the pipe by moving it along the detector mounting means. A next adjacent section of the pipe surface can be scanned by releasing the releasable securing means and moving the entire apparatus to another pipe surface section. The sensing means of the detector is at all times positioned the same radial distance from the pipe surface.
The accuracy and sensitivity of the measurements is enhanced, to the extent that removal of external coatings form the pipe prior to using the apparatus becomes much less important.
The size of the apparatus is suitably from about 1-4 feet in length, with a rail separation of 4-12 inches. Such an apparatus can readily scan the pipe section indicated by the pig as containiny a fault, and speedily pinpoint the precise location of the previously indicated fault.
In the preferred embodiment of the invention, the lowermost surface of the detector mounting means, instead of being curved on a radius corresponding to that of the pipe surface, has a series of stepped formations, the edges of - which extend radially to define an edge of the zone. A part of the surface of each zone lies on a circle concentric with the cylindrical pipe surface. Then the detector assembly can be mounted in each zone with an edge thereof against the step formation, and the sensing means registering with that part of the surface on the concentric circle, so that the sensing means is always positioned the same radial distance from the ~122~:iS7 pipe surface. Such a structure provides for more positive positioning of the detector mounting means and consequently more accurate determination and recording of the precise location of a surface fault in the pipe. ~oreover, it is simpler and more economical to manufacture a detector mounting with an accurately finished stepped lower surface than an accurately finished curved lower surface.
The lowermost surface of the end piece which is received against the pipe surface normally constitutes the lower structural surface of the piece itself. Preferably however, there are included in the end pieces a plurality of adjustable levelling screws permitting the apparatus to be adjusted against the pipe surface to ensure t~at the detector mounting means for the side rail structures is disposed with its mounting zones at an equal distance above the pipe exterior surface. The releasable securing means, which are suitably flexible buckled straps encircling the pipe, are then tightened to hold the apparatus firmly against the pipe surface, levelled or otherwise correctly adjusted by the preset position of the levelling screws.
Also in a preferred embodiment, one of the side rail structures comprises a lead screw upon which the detector mounting means is threadably mounted. The lead screw can be driven by hand or powered means to rotate it and cause axial movement of the detector mounting means down the pipe. The l~Z~6~7 detector mounting means is suitably slidable along the other rail structure.
A specific preferred embodiment of the present invention is illustrated in the accompanying drawings, in which:
FIGURE 1 is a perspective view of an apparatus according to a specific preferred embodiment of the present invention, mounted in position on the exterior of a cylindrical pipe; and FIGURE 2 is a fragmentary sectional view along the line 2-2 of Fig. 1.
Fig. 1 shows a portion of a generally cylindrical pipe 10 with an apparatus according to the invention releasably fastened thereto. The apparatus comprises first and second straight, parallel side rail structures 11, 12. The first side rail structure 11 comprises an elongated bar having a longitudinal slot 13 therein, presenting an upper smooth surface. The second s-~de rail structure 12 comprises a side bar 14 completing the framework of the apparatus, and a lead screw 15 extending alongside the side bar 14 axially of the - 20 pipe 10. The ends of the side rail structures 11, 12 are fixedly received in end pieces 16, 18. Each end piece as an inner generally rectangular plate 20, 22, respectively completing a rectangular framework with the rail structure 11 and side bar 14 of rail structure 12, and an outer, smaller plate 24, 26 respectively, arranged in an upright position on the surface of pipe 10 and parallel to one another. Each end piece 16, 18 is also provided with a respective lower spacer bar 28, 29 extending across the centre lower part of the space between the inner and outer plates thereof, and a pair of upper spacer bars 30, 31 and 32, 33 respectively near the upper corners of the outer plates 24, 26 and extending between the inner and outer plates. The lowermost surface of each end piece 16, 18 is formed by the bottom surface 34 of the inner plates 20, 22, which as illustrated has three straight portions angularly disposed with respect to one another. The centre portion and side portions of this lowermost surface are received in contact against the cylindrical outer surface of the pipe 10. Each inner plate 20, 22 is provided with a pair of adjustable levelling screws 35, 36 and 37, 38 respectively, threadably received in end formations of the inner plates 20, 22 and protruding downwardly therethrough, so that the apparatus as a whole can be adjusted as to height on the pipe surface.
The end pieces 16, 18 are releasably held against the pipe surface by means of respective flexible straps 39, 40 having buckles 41, 42. The straps 39, 40, pass through the space between inner plates 20, 22 and outer plates 24, 26 over the ends of outer spacer bars 30, 31 and 32, 33 respectively, and under the central spacer bars 28, 29 respectively so that they releasably tighten the apparatus onto the pipe surface.
~lZ2~57 By first adjusting the levelling screws to the desired position and then tightening the straps 39, 40, the apparatus is held rigidly in position in the desired location, to permit measurements to be made using it, on the pipe surface.
A detector mounting means 50 in the form of an elongated metal block is mounted for movement along the rail structures 12, 14. ~he end formation 51 of the block 50 passes through and slides along slot 13 in side rail structure 11. At the other endl the block 50 is provided with a screw threaded housing 52 which is threadably received on the lead screw 15. The block 50 thus spans the gap between the rail structures 11, 12. It is provided with a slot 53 which extends through the block 50 and in the circumferential direction with respect to the pipe 10. A detector assembly 54 is mounted in the slot 53, this detector assembly comprising a rod 55, a lower block 56 in the form of a cube, an elongated sensing means 57 protruding downwardly through the rod 55 of block 56, to present a sensor 58 extending a short way below the bottom surface of the block 56. Downwardly extending protrusions 59 are provided at each of the four corners of the lowermost surface of the block 56, protruding downwardly beyond the end of the sensing means 57, to protect the sensor 58 located therebetween from damaging contact with the surface of the pipe 10~ The detector assembly 54 also inciudes a washer 62, an upper knob 64 on the top of l:~Z2657 the rod 57 and a coil spring 66 bearing against the washer 62 and the knob 64. Thus by turning the knob 64, the detector assembly can be clamped in position in slot 54, and released for position adjustment therealong.
The undersurface of the block 50 is formed in a series of zones 68 each defined by a stepped side formation 70 at its outer edge, and a flat top surface 72, extending in a tangential direction with respect to the pipe 10. As shown in Fig. 2, the centre location of each top surface 72 of the zones 68 is the same distance from the surface of the pipe 10, and lies on a circle 74 concentric with the pipe surface. When the block 56 is mounted in each zone, with its side abutting against step 70, the sensor 58 registers with the centre location of the zone. The arrangement of steps 70 thus provides for positive location of the block 56 and sensing means 60 in each zone, with the sensing means 60 spaced the same distance from the pipe surface in each zone. Suitably, the sensing means is spaced about 1/4" from the pipe surface.
A motor 76 e.g. an electric motor is mounted on the - outside end of end piece 16, spaced therefrom to allow passage of strap 39. The end of the lead screw 15 is journalled in - end plate 20 of end piece 16, and is received in driving engagement with motor 76, so that the lead screw may be rotated therewith. At its other end, beyond end plate 22 of end piece 18, the lead screw is received in a rotation counter such as a Helipot (trade mark~, to sense and record the .
position of the threaded housing 52 of the detector mounting means 50 therealong. This information is electrically fed from the Helipot to a suitable recorder, e.g. an X-Y plotter, along with other information received from the sensor, to give a plot of readings for assistance in identifying the precise location of an anomaly on the surface of the pipe 10.
The operation of the apparatus of the~invention will be apparent from the foregoing de~ription and drawings. By movement of the detector assembly 54 in slot 53, the area within the rail structures 11, 12 and end frames 20, 22 can be surveyed by sensor 58, and accurate readings of its characteristics can be obtained. Then the releasable straps 39, 40 can be loosened and the apparatus moved to another location on the pipe surface to repeat the operation. Once a conventional moving detector such as a pig has recorded the presence of a fault within a certain short length of the pipe the apparatus according to the invention can be readily used to pin-point the fault. The readings obtained using the apparatus of the invention are accurate and reliable, since the sensing means is positively positioned at precise locations, and ensured to be mounted the same distance from the pipe surface at each test location. The need to scour, abrade and clean the exterior pipe surface is substantially reduced. The apparatus is small and readily portable, and at the same time simple but efficient to use.
.
112~7 Whilst a specific preferred embodiment of the invention has been described and illustrated in detail, it will of course be understood that this is illustrative and by way of example only and should not be construed as limiting.
Variations thereof will be apparent without departing from the scope of the invention. The scope of the invention is limited only by the appended claims.
Claims (8)
1. A pipe surface testing apparatus comprising:
at least two side rail structures adapted to extend axially along the limited extent of the exterior of a pipe under test;
first and second end pieces fixedly receiving therein opposed ends of said rail structures, each said end piece having a lowermost surface adapted to be received against the outer surface of the pipe under test;
detector mounting means mounted on said rail structures and movable therealong, said detector mounting means extending circumferentially with respect to the pipe to span the gap between said rail structures;
the lowermost surface of the detector mounting means presented towards the pipe surface having a plurality of zones each with a surface location adapted to be spaced an equal radial distance from the pipe surface when said end pieces are received against the outer surface of the pipe under test;
a detector assembly, including a sensing means, movably mounted on said detector mounting means for movement in a direction transverse to the direction of extent to the rail structures, and having a mounting position in each zone of the lowermost surface thereof in which the detector assembly may be mounted so that the sensing means registers with the surface location of said zone to be disposed the same radial distance from the pipe surface in each of the mounting positions;
releasable securing means for releasably securing the apparatus to the pipe, with the lowermost surfaces of said end pieces received against the outer surface of the pipe.
at least two side rail structures adapted to extend axially along the limited extent of the exterior of a pipe under test;
first and second end pieces fixedly receiving therein opposed ends of said rail structures, each said end piece having a lowermost surface adapted to be received against the outer surface of the pipe under test;
detector mounting means mounted on said rail structures and movable therealong, said detector mounting means extending circumferentially with respect to the pipe to span the gap between said rail structures;
the lowermost surface of the detector mounting means presented towards the pipe surface having a plurality of zones each with a surface location adapted to be spaced an equal radial distance from the pipe surface when said end pieces are received against the outer surface of the pipe under test;
a detector assembly, including a sensing means, movably mounted on said detector mounting means for movement in a direction transverse to the direction of extent to the rail structures, and having a mounting position in each zone of the lowermost surface thereof in which the detector assembly may be mounted so that the sensing means registers with the surface location of said zone to be disposed the same radial distance from the pipe surface in each of the mounting positions;
releasable securing means for releasably securing the apparatus to the pipe, with the lowermost surfaces of said end pieces received against the outer surface of the pipe.
2. The pipe testing apparatus of claim 1, wherein the lowermost surface of the detector mounting means has a plurality of zones defined at one edge by a step formation extending radially with respect to the pipe surface, and having a flat top surface extending in a tangential direction with respect to the pipe surface.
3. The pipe testing apparatus of claim 2, including adjustable levelling means constituting a portion of the lowermost surface of each of said end pieces, for adjusting the level of said rail structures with respect to the pipe surface.
4. The pipe testing apparatus of claim 3, wherein each said top surface of a zone has a surface location at the approximate centre thereof spaced an equal radial distance from the pipe surface, and lying on a circle concentric with that of the pipe surface when the apparatus is mounted in position on the cylindrical surface of a pipe to be tested.
5. The pipe testing apparatus of claim 4, wherein the detector assembly is in the form of a block, engageable against the step side formation of each zone, and against the top tangential wall thereof, for positive positioning with respect to the pipe surface, and carries a sensing means positioned to register with the centre surface of a zone when the block is engaged against the step side formation thereof.
6. The pipe testing apparatus of claim 5, wherein said detector mounting means includes a slot passing there-through and extending transversely with respect to the direction of extent of the rails, said detector assembly being movable along the slot and releasably clampable into position thereon.
7. The pipe testing apparatus of claim 6, wherein the releasable securing means comprise flexible straps, with re-leasable buckles, adapted to pass between the spaced apart inner and outer plates of said end pieces, and engage against end portions of said rails extending between said inner and outer plates.
8. The apparatus according to claim 5, claim 6 or claim 7, wherein one of said rail structures includes a rotatable lead screw threadably engaging an end part of said detector mounting means, said detector mounting means being movable longitudinally of the rail structures by rotation of said lead screw.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA317,260A CA1122657A (en) | 1978-12-01 | 1978-12-01 | Pipe surface testing carriage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA317,260A CA1122657A (en) | 1978-12-01 | 1978-12-01 | Pipe surface testing carriage |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122657A true CA1122657A (en) | 1982-04-27 |
Family
ID=4113055
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA317,260A Expired CA1122657A (en) | 1978-12-01 | 1978-12-01 | Pipe surface testing carriage |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1122657A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2686745A1 (en) * | 1992-01-28 | 1993-07-30 | Westinghouse Electric Corp | Remote controlled apparatus for eddy current and ultrasonic checking of retaining rings of turbogenerators |
| ES2047453A2 (en) * | 1992-01-28 | 1994-02-16 | Westinghouse Electric Corp | Apparatus for remote eddy current and ultrasonic inspection of turbine generator rotor retaining rings |
| EP1262771A2 (en) * | 2001-05-30 | 2002-12-04 | Advanced Engineering Solutions Ltd. | Pipe condition detecting apparatus |
| FR3033895A1 (en) * | 2015-03-18 | 2016-09-23 | Airbus Operations Sas | VERIFICATION TOOL FOR VERIFYING THE STATE OF A VENEER LAYER OF AN ELEMENT |
-
1978
- 1978-12-01 CA CA317,260A patent/CA1122657A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2686745A1 (en) * | 1992-01-28 | 1993-07-30 | Westinghouse Electric Corp | Remote controlled apparatus for eddy current and ultrasonic checking of retaining rings of turbogenerators |
| ES2047453A2 (en) * | 1992-01-28 | 1994-02-16 | Westinghouse Electric Corp | Apparatus for remote eddy current and ultrasonic inspection of turbine generator rotor retaining rings |
| BE1005916A5 (en) * | 1992-01-28 | 1994-03-08 | Westinghouse Electric Corp | Apparatus for remote inspection eddy current and ultrasound crowns deduction turbo-generators. |
| EP1262771A2 (en) * | 2001-05-30 | 2002-12-04 | Advanced Engineering Solutions Ltd. | Pipe condition detecting apparatus |
| FR3033895A1 (en) * | 2015-03-18 | 2016-09-23 | Airbus Operations Sas | VERIFICATION TOOL FOR VERIFYING THE STATE OF A VENEER LAYER OF AN ELEMENT |
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