CA1161115A - Pipeline inspection and maintenance method - Google Patents
Pipeline inspection and maintenance methodInfo
- Publication number
- CA1161115A CA1161115A CA000357174A CA357174A CA1161115A CA 1161115 A CA1161115 A CA 1161115A CA 000357174 A CA000357174 A CA 000357174A CA 357174 A CA357174 A CA 357174A CA 1161115 A CA1161115 A CA 1161115A
- Authority
- CA
- Canada
- Prior art keywords
- pipeline
- route
- feature
- observed
- magnetometer
- 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
Links
- 238000007689 inspection Methods 0.000 title claims abstract description 10
- 238000000034 method Methods 0.000 title claims description 28
- 238000012423 maintenance Methods 0.000 title abstract description 4
- 230000007797 corrosion Effects 0.000 claims abstract description 5
- 238000005260 corrosion Methods 0.000 claims abstract description 5
- 238000005272 metallurgy Methods 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000008569 process Effects 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 238000009412 basement excavation Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000003550 marker Substances 0.000 description 2
- 230000008439 repair process Effects 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 241000518994 Conta Species 0.000 description 1
- 241000282887 Suidae Species 0.000 description 1
- 241000193803 Therea Species 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- GWUSZQUVEVMBPI-UHFFFAOYSA-N nimetazepam Chemical compound N=1CC(=O)N(C)C2=CC=C([N+]([O-])=O)C=C2C=1C1=CC=CC=C1 GWUSZQUVEVMBPI-UHFFFAOYSA-N 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
- F17D5/02—Preventing, monitoring, or locating loss
- F17D5/06—Preventing, monitoring, or locating loss using electric or acoustic means
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A magnetometer is moved along the route of a pipeline and the output of the magnetometer is observed to identify pipeline characteristics. Used with a buried pipeline the magnetometer is moved over the surface of the overlay to identify and locate girth welds, pipeline fittings and accoutrements, changes in pipeline metallurgy such as occur with large hard spots and changes in wall thickness as occur in extensive and severe corrosion.
Similar functions can be performed with underwater pipelines using a magnetometer which is located in an appropriate container and trolled along the route of the pipeline by a vessel. The pipeline is formed of pipe sections which are arranged in an identifiable pattern according to their magnetic characteristics to facilitate inspection and maintenance.
A magnetometer is moved along the route of a pipeline and the output of the magnetometer is observed to identify pipeline characteristics. Used with a buried pipeline the magnetometer is moved over the surface of the overlay to identify and locate girth welds, pipeline fittings and accoutrements, changes in pipeline metallurgy such as occur with large hard spots and changes in wall thickness as occur in extensive and severe corrosion.
Similar functions can be performed with underwater pipelines using a magnetometer which is located in an appropriate container and trolled along the route of the pipeline by a vessel. The pipeline is formed of pipe sections which are arranged in an identifiable pattern according to their magnetic characteristics to facilitate inspection and maintenance.
Description
~6~
This ,inyention ~ conce~ned With the ~nspection ~nd m~intenance o~ pipelines~ Over land areas pipelines are usually buried under a three or four foot overlay or, where ground conditions preclude ~ur,vlng the line, as for example in frigid zones or over ri~ers, it is supported aboveground on spaced support structures, Pipelines conveying materials underwater are usually protectively coated~ as for example with concrete, and are submerged to lie on the lake or sea~ed.
Whatevex the environment of the pipeline~ the risk o~ pipeline ~ilu~e i~ ever p~esent ~nd the conseyuences o~ such failure are potentially grave.
As a result, it is desirable to inspect the pipeline ~s it is installed and thereafter to perform regular inspec-tions to detect any weaknesses prior to failure.
It has been generally recognized that effective inspection of pipeline from the outside of the line is not possible because of the necessarily great spacing between the sensor used for the inspection and the line, because of the large background fields produced by the mass of the line and by earth and because of the impracticability of passing an external sensor over the line. Thus the most widely accepted inspection technique is to pass a pig through the pipeline, the pig having one or more instruments for detecting such weaknesses as areas of corrosion, pitting or out-of-round conditions.
The pig may be driven through the pipeline by fluid flowing in the line or it rnay be carried by a crawler which includes drive means. Whichever method is used it is common to have the instruments coupled to a recording device as for example a pen recorder which produces a trace related to some characteristic of the pipeline. As the pig is recovered, the record is inspected and suspect areas of potential weakness identified. It then remains physically to locate the suspect area, assess its siynificance and, if need be, repair it.
Since the rate o~ pXo~ession o~ the pig through the pipeline is rarely~ lf e~err constant~ the trace bears ; little relatlonship to the geoyraphical location o~ the suspect area. Odometers of ~arious kinds have been associated with the pigs in attempts to correlate the pig si~nals with the geographical location of the suspect area indicated by those signals but the odometers are in many instances inherently inaccurate in this environment or quickly become worn or maladjusted. Thus this solution has not proven entirely satisfac-tory. The problem has been exacerbated by the fact that the distances recorded by the odometers are relatively large and by the fact that the pipeline does not usually follow a rectilinear path. Thus the length of pipeline measured by the odometer is not necessarily related to the distance covered by the pipeline.
A common pig is one which e~amines magnetic char-acteristics of the pipeline and moves sensors along the interior wall of that pipeline. The device produces a signal proportional to the flux changes in the fleld produced by the pipeline and a skilled reader of the tra~e produced by the instrument can, in some instances, identify the nature of conditions in the pipeline causing anomalies in that trace. The girth welds between adjacent sections making up the line can also be identified, because there is a change in the metallurgical characteristic of the wall produced during the welding process or because wall thickness changes or because of the surface roughness of the weld. Pipeline fittings c~n also be detected, Other t~pes o~ instxument~
can also identif~ some o~ the~e characte~1stic features.
Thus a co~nt of the num~er o~ girth welds can give a general indicatlon of the geographical location of a suspect part of the line which must be ph~sically inspected. However, because the lengths of the sections making up the pipelines are not constant, because of the larye distances involved and of course because the pipeline does not follow a rectilinear course commonly an error of as much as several hundred feet may occur.
Thus with submerged or buried pipeline the technique which has been adopted involves identifying on the trace a specific feature of the pipeline such as a short pipe section or a fitting closest to the suspect area which must be inspected and measuring the distance between that feature and the suspect area as best one can from the trace either by counting girth welds or by the use of an odometer which will be reasonably accurate over the relatively short distance involved. From a map of the line one may then approximately locate that feature.
The buried line is then excavated, positively to locate the feature and having made that location the distance to the suspect area may be measured off and that area excavated.
Besides being a time consuming and hence costly procedure, there is a substantial element of risk involved in making these two excavations. The excavations are usually made with a hoe or other mechanical digger and the operator may easily err and damage the pip~llne even to the extent of ruptuxing it, With a submerged line it becomes necessary to send down one or more divers to uncover and locate the feature and therea~ter the di~er or divers must move to the suspect section and uncover it.
-The present invention seeks to provide aninspection and maintenance method to alleviate the disadvan-tages of the existing methods, It is recognized that the sections of pipe which are used to form the pipeline become magnetized to a limited extent during the manufacturing or handling processes. Perhaps because of the opinion that the sections when jointed together would lose their magnetism or that joining them would have the effect of forming a single bar magnet of length equal to the overall length of the pipeline, no value or significance has been attributed to this characteristic. On the contrary, it has been considered to be a nuisance by welders joining the sections end to end when their welding rods have been attracted to and have adhered to the ends of the sections and research temporarily to desauss or demagnetize the end portions of sections of pipe to facilitate welding has been undertaken by others.
Fox whateYer ~easonr uniyexs~ it has been reckoned that the an~maly produced ~t ~uch welds could only be observed ~ using ~n inspection pig based on magnetic principles.
I have now discovered that not only do the pipe sections of a pipeline retain their individual bar-magnet characteristics but also that by using a magnetic field responsive means, which in some instances may be a relatively simple device of only routine sensitivity, one may detect the junction between adjacent sections even from a distance of several feet and through an overlay or in water.
Contrary to other experts belief that the magnetic anomaly representing a girth weld in a buried line could not be detected from aboveground, because the anomaly would be lost in the noise produced by earth field and by the field produced by the rnass of the pipeline, I
have found that not only can I clearly identify that anomaly but I can also identify other features such as fittings and changes in pipeline metallurgy and wall thickness including some which may be dejects such as large hard spots and severe and extensive corrosion.
Accordingly there is provided according to this invention a pipeline inspection and maintenance method comprising moving a magnetic field responsive ~evice along the ~ou~e o~ eline ~nd obse~ying the output of that device to ldentify pipellne ch~r~cteristics.
Accordin~ to anotAer aspect of this invention there is provided a method of inspecting and maintaining a pipeline which comprises mov~ng a magnetic field responsive device o~er the course Of a p~peline, identifying the location of a specific feature of that pipeline and using that location as a datum from which to locate a suspect area of the pipeline.
Using the technique of this invention in a buried line one would examine a record produced by a pig and identify a suspect portion of the line and the nearest specific or characterising feature of the pipeline such as a short section, a fitting, as for example a drip, or a junction or intersection. The distance between the specific feature and the suspect portion is noted either from a record produced from an odometer on the pig or by counting girth welds as recorded by the pig and thereafter consult-ation of a map of the line gives an approximate location of the specific feature. The pipeline is then examined in that location by following its course with a magnetic field responsive device such as for exarnple a magnetometer or an inclinometer (dip needle). This examination will reveal the precise location of the specific feature and thereaftex it is a simple matter to move from that feature to the suspect portion of the pipeline. This procedure lS
will elimin~te the dan~e~ou$~ ti~le con,sumin~ and hence, - costl~, procedure o~ exca~at~,n~ the p~,pe ~n two locations.
The method is also available for use with submerged pipeline. In such instances a sensor is enclosed within a conta~ner suitable for trolling along the route of the pipeline, the position of the container beiny controlled for example by reference to a depth guage.
The position of the pipeline is first determined by crossing the route of the pipeline and placing marker buoys as the magnetic field sensiti~e device detects the pipeline.
Thereafter the container is trolled over the route of the line and some small distance above it and the location of a specific feature of that line positive]y established.
It has also been observed that the signal produced by the magnetic field responsive device as it passes over a junction between the ends of adjacent pipe sections which are of like polarity is markedly greater than when the device is passed over a junction of which the ends of adjacent sections are of opposite polarity. Thus i~ is proposed according to this invention to identify the polarity of the ends of the sections as the line is assembled (which can be done for example using a simple compass) and r~rder the sections so that there is a junction of adjacent like poles at regular intervals along the route of the pipeline.
Such functions~provide a very readily identifiable specific feature of the pipeline.
~ 8 A typical magnetometer use~ul in the methods according to this invent~on ~s a portable proton magnetometer.
A speci~ic model is that availa~le from ~arringer Research Limited of Rexdale, Ontario, and which i5 identified by that company as their Model GM-122. That type of magnetometer comprises a proton rich fluid such as keroséne and means for inducing a field in it. This causes the protons to align along the maynetic field vector and when the field is removed the protons act as elementary gyroscopes and begin precessing around the remaining magnetic field, i.e. that of the earth and,in its application herein,also that of the pipeline.
The precession frequency is directly proportional to the field and can be read with a high degree of accuracy.
Embodiments of the invention are illustrated, very schematically, in the accompanying drawings in which:
Figure 1 is illustrative of the present invention as applied to buried pipeline; and Figure 2 is illustrative of the present invention as applied to submerged pipeline.
In the method illustrated schematically in Figure 1 a wheeled non-magnetic vehicle V is used in inspecting and maintaining a pipeline P buried at a depth of two or three feet below the surface of the ground. The vehicle includes a magnetometer having a sensor 10, a power supply 12, a console 14 and a recorder, if necessary, at 16.
To in,spect the line ~r$tl~ ~ Pi~ i~ p~$ed through it ~nd a txace is~ p~oduced whlch wlll indic~te , the,~existence of a suspect part o~ the pipe which should be excavated and physically examined. That tra`de will also give an indication of a speci~ic identlfying characteristic of the pipeline and its location within the pipeline relative to the suspect area. That iaentifying feature can be approximately located from a map of the pipeline.
Thereafter the vehicle V is used to follow the route of the pipeline with magnetometer 10 and that will positively and accurately locate the identifying characteristic., Thereafter it is a simple matter to move along the pipeline the distance indicated from the pig trace to the suspect part or area.
In Figure 2 there is illustrated the method as applied to a pipeline P subrnerged under water of which the surface is inaicated at S, the pipeline lying on the bed of that body of water. A vessel 10 is used to troll a container 12 within which a magnetometer sensor is disposed.
The sensor may be provided with skids or the like so that it may be moved along the bed of the body of water or it may be provided with a depth controlling vane 22 operated in response to a depth guage or similar device on the vessel 10. In operation the pipeline is first located with the magnetometer by criss-crossing it and marker buoys are put out to mark the pipeline. Thereafter the container 20 and with it the magnetorneter is caused to follow the route of the pipeline and locate an identifying characteristic _ 10 _ featuxe of the Pipeline in much the same manne~ ~s desc~ibed here~hove w-ith reference to Figure 1, Di~ers m~ then moVe d~rectl~ to a suspect reg~on of the pipeline and effect inspect~on and, if need be, repair~
When using a magnetometer or other sensitive magnetic field responsive device ~t is possible to detect magnetic field anomalies such as are produced by areas of the pipeline of different metallurgical characteristics, as for example hard spots. Further it is possible to detect magnetic field anomalies produced by reduced wall thickness of the pipeline as result from severe and extensive corrosion of the pipeline.
As noted hereabove the pipe joints which make up the pipeline are magnetized during production and handling and form relatively weak bar magnets. The field anomaly produced by adjacent pipe sections which are butted with like poles together is noticably more pronounced than those formed with unlike or opposite poles together. Thus it is preferred that certain joints at regularly spaced intervals along the route of the pipeline be ones at which the end portions of the sections are of like polarity and that the joints in between should be of opposite polarity. The joints of like polarity provide a very easily identifiable specific feature of the pipeline.
- 11 ~
~ 6~
It will be appreciated that the present invention is subject to various modifications. The form of the magnetometer may be chosen according to the particular conditions encountered, It may be possible in certain instances to use a simple inclinometer. Further although simple wheeled structures have been illustrated in the methods applied to land area pipelines, it will be recog-nized that it is possible to use a hand held magnetometer with any appropriate support means and it is also possible to suspend a magnetometer from, for example a helicopter and perform the inspection process by flying along the route of the pipeline.
This ,inyention ~ conce~ned With the ~nspection ~nd m~intenance o~ pipelines~ Over land areas pipelines are usually buried under a three or four foot overlay or, where ground conditions preclude ~ur,vlng the line, as for example in frigid zones or over ri~ers, it is supported aboveground on spaced support structures, Pipelines conveying materials underwater are usually protectively coated~ as for example with concrete, and are submerged to lie on the lake or sea~ed.
Whatevex the environment of the pipeline~ the risk o~ pipeline ~ilu~e i~ ever p~esent ~nd the conseyuences o~ such failure are potentially grave.
As a result, it is desirable to inspect the pipeline ~s it is installed and thereafter to perform regular inspec-tions to detect any weaknesses prior to failure.
It has been generally recognized that effective inspection of pipeline from the outside of the line is not possible because of the necessarily great spacing between the sensor used for the inspection and the line, because of the large background fields produced by the mass of the line and by earth and because of the impracticability of passing an external sensor over the line. Thus the most widely accepted inspection technique is to pass a pig through the pipeline, the pig having one or more instruments for detecting such weaknesses as areas of corrosion, pitting or out-of-round conditions.
The pig may be driven through the pipeline by fluid flowing in the line or it rnay be carried by a crawler which includes drive means. Whichever method is used it is common to have the instruments coupled to a recording device as for example a pen recorder which produces a trace related to some characteristic of the pipeline. As the pig is recovered, the record is inspected and suspect areas of potential weakness identified. It then remains physically to locate the suspect area, assess its siynificance and, if need be, repair it.
Since the rate o~ pXo~ession o~ the pig through the pipeline is rarely~ lf e~err constant~ the trace bears ; little relatlonship to the geoyraphical location o~ the suspect area. Odometers of ~arious kinds have been associated with the pigs in attempts to correlate the pig si~nals with the geographical location of the suspect area indicated by those signals but the odometers are in many instances inherently inaccurate in this environment or quickly become worn or maladjusted. Thus this solution has not proven entirely satisfac-tory. The problem has been exacerbated by the fact that the distances recorded by the odometers are relatively large and by the fact that the pipeline does not usually follow a rectilinear path. Thus the length of pipeline measured by the odometer is not necessarily related to the distance covered by the pipeline.
A common pig is one which e~amines magnetic char-acteristics of the pipeline and moves sensors along the interior wall of that pipeline. The device produces a signal proportional to the flux changes in the fleld produced by the pipeline and a skilled reader of the tra~e produced by the instrument can, in some instances, identify the nature of conditions in the pipeline causing anomalies in that trace. The girth welds between adjacent sections making up the line can also be identified, because there is a change in the metallurgical characteristic of the wall produced during the welding process or because wall thickness changes or because of the surface roughness of the weld. Pipeline fittings c~n also be detected, Other t~pes o~ instxument~
can also identif~ some o~ the~e characte~1stic features.
Thus a co~nt of the num~er o~ girth welds can give a general indicatlon of the geographical location of a suspect part of the line which must be ph~sically inspected. However, because the lengths of the sections making up the pipelines are not constant, because of the larye distances involved and of course because the pipeline does not follow a rectilinear course commonly an error of as much as several hundred feet may occur.
Thus with submerged or buried pipeline the technique which has been adopted involves identifying on the trace a specific feature of the pipeline such as a short pipe section or a fitting closest to the suspect area which must be inspected and measuring the distance between that feature and the suspect area as best one can from the trace either by counting girth welds or by the use of an odometer which will be reasonably accurate over the relatively short distance involved. From a map of the line one may then approximately locate that feature.
The buried line is then excavated, positively to locate the feature and having made that location the distance to the suspect area may be measured off and that area excavated.
Besides being a time consuming and hence costly procedure, there is a substantial element of risk involved in making these two excavations. The excavations are usually made with a hoe or other mechanical digger and the operator may easily err and damage the pip~llne even to the extent of ruptuxing it, With a submerged line it becomes necessary to send down one or more divers to uncover and locate the feature and therea~ter the di~er or divers must move to the suspect section and uncover it.
-The present invention seeks to provide aninspection and maintenance method to alleviate the disadvan-tages of the existing methods, It is recognized that the sections of pipe which are used to form the pipeline become magnetized to a limited extent during the manufacturing or handling processes. Perhaps because of the opinion that the sections when jointed together would lose their magnetism or that joining them would have the effect of forming a single bar magnet of length equal to the overall length of the pipeline, no value or significance has been attributed to this characteristic. On the contrary, it has been considered to be a nuisance by welders joining the sections end to end when their welding rods have been attracted to and have adhered to the ends of the sections and research temporarily to desauss or demagnetize the end portions of sections of pipe to facilitate welding has been undertaken by others.
Fox whateYer ~easonr uniyexs~ it has been reckoned that the an~maly produced ~t ~uch welds could only be observed ~ using ~n inspection pig based on magnetic principles.
I have now discovered that not only do the pipe sections of a pipeline retain their individual bar-magnet characteristics but also that by using a magnetic field responsive means, which in some instances may be a relatively simple device of only routine sensitivity, one may detect the junction between adjacent sections even from a distance of several feet and through an overlay or in water.
Contrary to other experts belief that the magnetic anomaly representing a girth weld in a buried line could not be detected from aboveground, because the anomaly would be lost in the noise produced by earth field and by the field produced by the rnass of the pipeline, I
have found that not only can I clearly identify that anomaly but I can also identify other features such as fittings and changes in pipeline metallurgy and wall thickness including some which may be dejects such as large hard spots and severe and extensive corrosion.
Accordingly there is provided according to this invention a pipeline inspection and maintenance method comprising moving a magnetic field responsive ~evice along the ~ou~e o~ eline ~nd obse~ying the output of that device to ldentify pipellne ch~r~cteristics.
Accordin~ to anotAer aspect of this invention there is provided a method of inspecting and maintaining a pipeline which comprises mov~ng a magnetic field responsive device o~er the course Of a p~peline, identifying the location of a specific feature of that pipeline and using that location as a datum from which to locate a suspect area of the pipeline.
Using the technique of this invention in a buried line one would examine a record produced by a pig and identify a suspect portion of the line and the nearest specific or characterising feature of the pipeline such as a short section, a fitting, as for example a drip, or a junction or intersection. The distance between the specific feature and the suspect portion is noted either from a record produced from an odometer on the pig or by counting girth welds as recorded by the pig and thereafter consult-ation of a map of the line gives an approximate location of the specific feature. The pipeline is then examined in that location by following its course with a magnetic field responsive device such as for exarnple a magnetometer or an inclinometer (dip needle). This examination will reveal the precise location of the specific feature and thereaftex it is a simple matter to move from that feature to the suspect portion of the pipeline. This procedure lS
will elimin~te the dan~e~ou$~ ti~le con,sumin~ and hence, - costl~, procedure o~ exca~at~,n~ the p~,pe ~n two locations.
The method is also available for use with submerged pipeline. In such instances a sensor is enclosed within a conta~ner suitable for trolling along the route of the pipeline, the position of the container beiny controlled for example by reference to a depth guage.
The position of the pipeline is first determined by crossing the route of the pipeline and placing marker buoys as the magnetic field sensiti~e device detects the pipeline.
Thereafter the container is trolled over the route of the line and some small distance above it and the location of a specific feature of that line positive]y established.
It has also been observed that the signal produced by the magnetic field responsive device as it passes over a junction between the ends of adjacent pipe sections which are of like polarity is markedly greater than when the device is passed over a junction of which the ends of adjacent sections are of opposite polarity. Thus i~ is proposed according to this invention to identify the polarity of the ends of the sections as the line is assembled (which can be done for example using a simple compass) and r~rder the sections so that there is a junction of adjacent like poles at regular intervals along the route of the pipeline.
Such functions~provide a very readily identifiable specific feature of the pipeline.
~ 8 A typical magnetometer use~ul in the methods according to this invent~on ~s a portable proton magnetometer.
A speci~ic model is that availa~le from ~arringer Research Limited of Rexdale, Ontario, and which i5 identified by that company as their Model GM-122. That type of magnetometer comprises a proton rich fluid such as keroséne and means for inducing a field in it. This causes the protons to align along the maynetic field vector and when the field is removed the protons act as elementary gyroscopes and begin precessing around the remaining magnetic field, i.e. that of the earth and,in its application herein,also that of the pipeline.
The precession frequency is directly proportional to the field and can be read with a high degree of accuracy.
Embodiments of the invention are illustrated, very schematically, in the accompanying drawings in which:
Figure 1 is illustrative of the present invention as applied to buried pipeline; and Figure 2 is illustrative of the present invention as applied to submerged pipeline.
In the method illustrated schematically in Figure 1 a wheeled non-magnetic vehicle V is used in inspecting and maintaining a pipeline P buried at a depth of two or three feet below the surface of the ground. The vehicle includes a magnetometer having a sensor 10, a power supply 12, a console 14 and a recorder, if necessary, at 16.
To in,spect the line ~r$tl~ ~ Pi~ i~ p~$ed through it ~nd a txace is~ p~oduced whlch wlll indic~te , the,~existence of a suspect part o~ the pipe which should be excavated and physically examined. That tra`de will also give an indication of a speci~ic identlfying characteristic of the pipeline and its location within the pipeline relative to the suspect area. That iaentifying feature can be approximately located from a map of the pipeline.
Thereafter the vehicle V is used to follow the route of the pipeline with magnetometer 10 and that will positively and accurately locate the identifying characteristic., Thereafter it is a simple matter to move along the pipeline the distance indicated from the pig trace to the suspect part or area.
In Figure 2 there is illustrated the method as applied to a pipeline P subrnerged under water of which the surface is inaicated at S, the pipeline lying on the bed of that body of water. A vessel 10 is used to troll a container 12 within which a magnetometer sensor is disposed.
The sensor may be provided with skids or the like so that it may be moved along the bed of the body of water or it may be provided with a depth controlling vane 22 operated in response to a depth guage or similar device on the vessel 10. In operation the pipeline is first located with the magnetometer by criss-crossing it and marker buoys are put out to mark the pipeline. Thereafter the container 20 and with it the magnetorneter is caused to follow the route of the pipeline and locate an identifying characteristic _ 10 _ featuxe of the Pipeline in much the same manne~ ~s desc~ibed here~hove w-ith reference to Figure 1, Di~ers m~ then moVe d~rectl~ to a suspect reg~on of the pipeline and effect inspect~on and, if need be, repair~
When using a magnetometer or other sensitive magnetic field responsive device ~t is possible to detect magnetic field anomalies such as are produced by areas of the pipeline of different metallurgical characteristics, as for example hard spots. Further it is possible to detect magnetic field anomalies produced by reduced wall thickness of the pipeline as result from severe and extensive corrosion of the pipeline.
As noted hereabove the pipe joints which make up the pipeline are magnetized during production and handling and form relatively weak bar magnets. The field anomaly produced by adjacent pipe sections which are butted with like poles together is noticably more pronounced than those formed with unlike or opposite poles together. Thus it is preferred that certain joints at regularly spaced intervals along the route of the pipeline be ones at which the end portions of the sections are of like polarity and that the joints in between should be of opposite polarity. The joints of like polarity provide a very easily identifiable specific feature of the pipeline.
- 11 ~
~ 6~
It will be appreciated that the present invention is subject to various modifications. The form of the magnetometer may be chosen according to the particular conditions encountered, It may be possible in certain instances to use a simple inclinometer. Further although simple wheeled structures have been illustrated in the methods applied to land area pipelines, it will be recog-nized that it is possible to use a hand held magnetometer with any appropriate support means and it is also possible to suspend a magnetometer from, for example a helicopter and perform the inspection process by flying along the route of the pipeline.
Claims (8)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of inspecting and maintaining a pipeline including the steps of passing an inspection pig through the pipeline and making a record of the pipeline characteristics observed by said pig including areas of said pipeline suspected of weakness and of specific identifiable features of the pipeline; recording the output of an odometer carried by said pig so that the observed characteristics can be related to said recording of the output of the odometer; moving a magnetic field responsive device along the route of the pipeline and exterior to the pipeline, identifying the geographical location of a selected one of said specific identifiable features of the pipeline using that device, correlating that feature with the same feature in the record and observing the distance between that feature and an area of suspected weakness recorded by said odometer and, using the geographical location of said feature as a datum from which to measure off said distance, finding the geographical location of said area suspected of weakness.
2. The method of claim 1 wherein said specific feature is a girthweld.
3. The method of claim 1 or claim 2 wherein said pipeline is a buried pipeline and wherein said magnetic field responsive device is moved along the route of the Pipeline on the surface of the overlay of the pipeline.
4. The method of claim 1 wherein said magnetic field responsive device is a magnetometer.
5. The method of claim 1 or claim 2 wherein said pipeline is a submerged pipeline and wherein said magnetic field responsive device is trolled along the route of the pipeline by a vessel.
6. The method of claim 1 wherein the output of the device is observed to identify metallurgical anomalies indicative of a hard spot in the pipeline and wherein the pipeline is exposed in an area indicated by the device to have such a metallurgical anomaly.
7. The method of claim 1 wherein the output of the device is observed to identify an area of reduced wall thickness of said pipeline indicative of severe corrosion and wherein said pipeline is exposed in an area indicated by the device to have reduced wall thickness.
8. The method of claim 1 wherein the output of the device is observed to identify girthweld and wherein pipe sections making it the pipeline ordered so that the sections have adjacent end portions of like magnetic polarity at regularly spaced intervals along the route of the pipeline.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000357174A CA1161115A (en) | 1980-07-28 | 1980-07-28 | Pipeline inspection and maintenance method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000357174A CA1161115A (en) | 1980-07-28 | 1980-07-28 | Pipeline inspection and maintenance method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1161115A true CA1161115A (en) | 1984-01-24 |
Family
ID=4117524
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000357174A Expired CA1161115A (en) | 1980-07-28 | 1980-07-28 | Pipeline inspection and maintenance method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1161115A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| FR2868148A1 (en) * | 2004-03-26 | 2005-09-30 | Enertag Soc Par Actions Simpli | METHOD AND DEVICE FOR LOCATING ANOMALIES LOCATED WITHIN A HOLLOW HOLLOW STRUCTURE |
| FR2913124A1 (en) * | 2007-02-23 | 2008-08-29 | Actavision Sarl | Measuring value i.e. population density, determining method, involves recording physical, geographical and cadastral information, and comparing information to determine measuring value of constraint and compare value with threshold value |
| FR2931924A1 (en) * | 2008-06-02 | 2009-12-04 | Gaz De France | METHOD FOR DETERMINING THE INTEGRITY OF A PRESSURIZED FLUID TRANSPORT STEEL PIPING |
| CN104160203A (en) * | 2011-07-29 | 2014-11-19 | 马来西亚国家石油公司 | System and method for inspecting a subsea pipeline |
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| CN112881520A (en) * | 2021-01-14 | 2021-06-01 | 哈尔滨工业大学 | Underground pipeline defect positioning method based on wavelet transform mode maximum value method |
-
1980
- 1980-07-28 CA CA000357174A patent/CA1161115A/en not_active Expired
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2868148A1 (en) * | 2004-03-26 | 2005-09-30 | Enertag Soc Par Actions Simpli | METHOD AND DEVICE FOR LOCATING ANOMALIES LOCATED WITHIN A HOLLOW HOLLOW STRUCTURE |
| WO2005103554A1 (en) * | 2004-03-26 | 2005-11-03 | Enertag | Method and device for locating anomalies located inside an immersed hollow structure |
| CN100487299C (en) * | 2004-03-26 | 2009-05-13 | 埃内泰格公司 | Method and apparatus for locating anomalies located within a submerged hollow structure |
| FR2913124A1 (en) * | 2007-02-23 | 2008-08-29 | Actavision Sarl | Measuring value i.e. population density, determining method, involves recording physical, geographical and cadastral information, and comparing information to determine measuring value of constraint and compare value with threshold value |
| WO2008107621A3 (en) * | 2007-02-23 | 2008-11-06 | Actavision | Method for determining stress measurement magnitudes for a transportation network and system for implementing same |
| FR2931924A1 (en) * | 2008-06-02 | 2009-12-04 | Gaz De France | METHOD FOR DETERMINING THE INTEGRITY OF A PRESSURIZED FLUID TRANSPORT STEEL PIPING |
| CN104160203A (en) * | 2011-07-29 | 2014-11-19 | 马来西亚国家石油公司 | System and method for inspecting a subsea pipeline |
| EP2737242A4 (en) * | 2011-07-29 | 2016-01-27 | Petroliam Nasional Berhad Petronas | SYSTEM AND METHOD FOR CONTROLLING AN UNDERWATER DRIVING |
| WO2017060846A1 (en) * | 2015-10-09 | 2017-04-13 | Skipper | Modular cart for recording magnetic terrain data, notably for the non-invasive inspection of pipelines or the like |
| FR3042256A1 (en) * | 2015-10-09 | 2017-04-14 | Skipper | MODULAR TROLLEY FOR THE REGISTRATION OF MAGNETIC FIELD DATA, IN PARTICULAR FOR THE NON-INVASIVE CONTROL OF PIPELINES OR THE LIKE |
| US10315675B2 (en) | 2015-10-09 | 2019-06-11 | Skipper Ndt | Modular carriage for recording magnetic terrain data in particular for the non-invasive inspection of pipelines or the same |
| US10823931B2 (en) | 2016-07-28 | 2020-11-03 | Halliburton Energy Services, Inc. | Real-time plug tracking with fiber optics |
| CN112881520A (en) * | 2021-01-14 | 2021-06-01 | 哈尔滨工业大学 | Underground pipeline defect positioning method based on wavelet transform mode maximum value method |
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