GB2159954A - Apparatus, system and method for detecting a discontinuity in a pipe or conduit - Google Patents

Apparatus, system and method for detecting a discontinuity in a pipe or conduit Download PDF

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Publication number
GB2159954A
GB2159954A GB08414408A GB8414408A GB2159954A GB 2159954 A GB2159954 A GB 2159954A GB 08414408 A GB08414408 A GB 08414408A GB 8414408 A GB8414408 A GB 8414408A GB 2159954 A GB2159954 A GB 2159954A
Authority
GB
United Kingdom
Prior art keywords
conduit
pipe
discontinuity
sensor
output
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.)
Withdrawn
Application number
GB08414408A
Other versions
GB8414408D0 (en
Inventor
Richard Ward
Callegero Condello
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Gas Corp
Original Assignee
British Gas Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by British Gas Corp filed Critical British Gas Corp
Priority to GB08414408A priority Critical patent/GB2159954A/en
Publication of GB8414408D0 publication Critical patent/GB8414408D0/en
Publication of GB2159954A publication Critical patent/GB2159954A/en
Withdrawn legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws

Abstract

Apparatus for locating a discontinuity such as a joint or crack in a metal pipe or conduit from the interior of the pipe or conduit, comprises means in the form of a magnet 2 for inducing a magnetic field in the pipe or conduit and a sensor 3 exhibiting the Hall effect, whereby any change in electrical output from the sensor 3 owing to a discontinuity in the pipe or conduit can be monitored. The sensor 3 comprises two Hall effect devices the output of one of which is inverted to cancel one induced magnetic pole. The apparatus includes a pre op-amp 4 which is connected to external equipment including a logic circuit to monitor the signal. There may be four such apparatus mounted around a pipe-line pig. The pig may tow a sealing pig. <IMAGE>

Description

SPECIFICATION Apparatus, system and method for detecting a discontinuity in a pipe or conduit The invention relates to an apparatus, system and a method for detecting a discontinuity in a pipe or conduit, such as a gas main.
Various methods such as the use of close circuit television have been used to detect surface discontinuities such as joints, cracks, fissures and the like in the walls of pipes and conduits, but such methods, particularly the use of close circuit television are time-consuming and expensive.
It is an object of the invention to seek to mitigate these disadvantages.
According to one aspect of the invention there is provided apparatus for locating a discontinuity such as a joint or crack in a metal pipe or conduit from the interior of the pipe or conduit, comprising a means for inducing a magnetic field in the pipe or conduit and a sensor exhibiting the Hall effect, whereby any change in electrical output from the sensor owing to a discontinuity in the pipe or conduit can be monitored.
The means for inducing a magnetic field may comprise a permanent magnet.
There may be electrical/electronic circuitry for driving the Hall effect sensor, which circuitry may be connectible in use with equipment externally of the pipe of conduit for monitoring any change in output from the sensor.
The sensor may comprise two Hall effect devices with matched outputs.
The electrical/electronic circuitry may comprise two operational amplifiers which are connected in a differential configuration, whereby to cancel the effect of variations on temperature in the respective outputs of the two Hall effect devices.
The circuitry may be connectible by a cable to the external equipment.
The external equipment may comprise an operational amplifier for receiving the output from the sensor.
One of the operational amplifier inputs from the Hall effect devices may be controllably offset, whereby to set up the apparatus for use in different types of pipe, for example mild steel, cast iron etc.
This output from the operational amplifier may be fed to a voltage analog indicator and to a logic device.
The logic device may include means to provide an audible warning when the sensor detects a discontinuity.
There may be spaced rotatable means for engaging the inner surface of the pipe or conduit, whereby the apparatus can be drawn therethrough.
The rotatable means may be spaced apart wheels.
The apparatus may be mounted on a non-electrically or magnetically conductive carrier.
The carrier may be plastic.
There may be resilient mounts whereby the apparatus is mounted on the carrier.
According to a second aspect of the invention there is provided a system for detecting a discontinuity such as a joint or crack in a metal pipe or conduit from the interior of the pipe or conduit, comprising a carrier for being drawn through the pipe or conduit, apparatus as hereinbefore defined carried by the carrier, external equipment for monitoring the output of the sensor and means connecting the sensor and the external equipment.
Preferably the means connecting the sensor and the external equipment is an elongated electrical connector.
The electrical connector may be a cable.
There may be a plurality of apparatuses as hereinbefore defined carried by the carrier.
There may be four apparatuses spaced equidistantly round the outer surface of the carrier.
According to a third aspect of the invention there is provided a method for locating a discontinuity such as a joint or crack in a metal pipe or conduit, comprising inserting apparatus as hereinbefore defined into the pipe or conduit, moving the apparatus through the pipe or conduit and monitoring the output from the sensor whereby to detect any change in the output resulting from the presence of a discontinuity.
The method may comprise the step of feeding the output to external monitoring equipment.
The method may comprise the step of providing an audible signal resulting from a change in the output.
A plurality of outputs may be obtained and those outputs may be selectively monitored whereby to confirm the presence of a joint or crack.
Apparatus embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings.
Brief description of drawings Figure 1 is a side view of apparatus according to the invention with parts broken away for clarity; Figure 2 is a sectional view of a carrier with four apparatuses according to Figure 1 spaced equidistantly therearound; Figure 3 is a plan view, partly broken away, of the carrier according to Figure 2; Figure 4 is a block diagram of circuitry which can be used with the apparatus of Figure 1; and Figure 5 shows schematically the apparatus of Figure 1 in use in a pipe with a graphical representation of output voltage as a joint is located.
Referring to the drawings, Figure 1 shows apparatus 1 for locating a discontinuity such as a joint or crack in a metal pipe or conduit from the interior of the pipe of conduit, comprising a means in the form of a magnet 2 for inducing a magnetic field in the pipe or conduit, and a sensor 3 exhibiting the Hall effect, whereby any change in electrical output from the sensor owing to a discontinuity in the pipe or conduit can be monitored.
The apparatus 1 comprises a skid or elongate member 4 which has rotatable means in the form of spaced wheels 5 for mounting the apparatus 1 on the interior surface of a pipe or conduit for passage thereover as the apparatus 1 is drawn through the pipe or conduit.
The magnet 2 is a permanent magnet which comprises in the embodiment described a plurality of ceramic discs.
The sensor 3 comprises two matched Hall effect devices, the devices being matched so that both voltage outputs are of the same magnitude, one being inverted to cancel the effect of one magnetically induced pole of the pipe.
The apparatus 1 also includes electrical/electronic circuitry in the form of two operational amplifiers or pre op-amps 6, which are electrically wired in a differential configuration (a half bridge arrangement) to cancel the effects of variations in temperature on the outputs of the two Hall effect devices.
In the embodiment described, a system for detecting discontinuities comprises four apparatuses spaced circumferentially round a carrier in the form of two spaced circular mountings 7 and 8 the whole arrangement effectively comprising a pig which can be drawn through the pipe or conduit.
Each apparatus 1 is resiliently mounted on the carrier 7, 8 by a spring loaded bolt 9, whereby smooth passage along the pipe is obtained even when the wheels 5 pass over surface irregularities or disconformities such as bumps (Figure 3).
The pre op-amps 6 of each apparatus 1 are connected by a cable 10 to external monitoring equipment 11 which also drives the Hall effect devices 3.
The length of the cable 10 depends on the length of pipe or conduit to be traversed, for example 100 metres.
The outputs from the two Hall effect devices of each sensor are fed to an operational amplifier 12 of the external equipment 11. One of the outputs (or looking at it another way, one of the op-amp 12 inputs) is given a controllable offset by say a potentiometer 13, for setting up the sysem incorporating the apparatuses for use in pipes or conduits of different construction, for example mild steel, cast iron or other metal. The output of the op-amp is connected to a + 10 volt analog indicator 14 and through a logic system 15 which can be connected to a circuit to provide an audible indication of when the sensors detect a discontinuity.The circuit comprises a buzzer 16 selection circuit and provides not only the audible indication of the detection of a discontinuity, but also allows the operator externally of the pipe or conduit to check as to whether a visual indication on the indicator from one sensor 3 is in fact indication of a joint or crack rather than a branch line of the pipe. The operator can check by selecting one or more of the readings from the four sensors to confirm the presence of the discontinuity.
Passage of the apparatus 1 along the interior of a pipe 17 is shown in Figure 5 with the change in voltage on the graph being indicated with refer ence letters which correspond with the reference letters used to indicate the position of the apparatus. Thus 'A' indicates the position and the voltage at the position to the left of the joint 18, as viewed in Figure 5, the apparatus moving from left to right as viewed in that figure.
In a system for sealing a joint or crack, the pig can tow a sealing pig which when located over the joint or discontinuity 18 (after passage of the pig thereover and hence detection by an operator) can be actuated to seal the joint or crack.
It will be understood that in every case as the apparatus 1 passes over the discontinuity a disturbance in the magnetic field is produced by the discontinuity and thus affects the output of the Hall effect devices, which can then be monitored as described to indicate the presence of the discontinuity.
However, the apparatus 1 also functions when stationary.

Claims (28)

1. Apparatus for locating a discontinuity such as a joint or crack in a metal pipe or conduit from the interior of the pipe or conduit, comprising a means for inducing a magnetic field in the pipe or conduit and a sensor exhibiting the Hall effect, whereby any change in electrical output from the sensor owing to a discontinuity in the pipe or conduit can be monitored.
2. Apparatus according to Claim 1, the means for inducing a magnetic field comprising a permanent magnet.
3. Apparatus according to Claim 2, including electrical/electronic circuitry for driving the Hall effect sensor, which circuitry is connectible in use with equipment externally of the pipe or conduit for monitoring any change in output from the sensor.
4. Apparatus according to Claim 3, the sensor comprising two Hall effect devices with matched outputs.
5. Apparatus according to Claim 4, the electrical/electronic circuitry comprising two operational amplifiers which are connected in a differential configuration, whereby to cancel the effect of variations in temperature on the respective outputs of the two Hall effect devices.
6. Apparatus according to Claim 5, the circuitry being connectible by a cable to the external equip ment.
7. Apparatus according to Claim 6, the external equipment comprising an operational amplifier for receiving the output from the sensor.
8. Apparatus according to Claim 7, one of the operational amplifier inputs from the Hall effect devices being controllably offset.
9. Apparatus according to Claim 8, the output from the operational amplifier being fed to a voit age analog indicator and to a logic device.
10. Apparatus according to Claim 9, the logic device including means to provide an audible warning when the sensor detects a discontinuity.
11. Apparatus according to any preceding claim, including spaced rotatable means for engag ing the inner surface of the pipe or conduit, whereby the apparatus can be drawn therethrough.
12. Apparatus according to Claim 11, the rotata ble means being spaced apart wheels.
13. Apparatus according to any preceding claim, mounted on a non-electrically or magnetically conductive carrier.
14. Apparatus according to Claim 13, the carrier being plastic.
15. Apparatus according to Claim 13 or Claim 14, including resilient mounts whereby the apparatus is mounted on the carrier.
16. Apparatus for locating a discontinuity such as a joint or crack in a metal pipe or conduit from the interior of the pipe or conduit, substantially as hereinbefore described with reference to the accompanying drawings.
17. A system for detecting a discontinuity such as a joint or crack in a metal pipe or conduit frorn the interior of the pipe or conduit, comprising a carrier for being drawn through the pipe or conduit, apparatus according to any preceding claim carried by the carrier, external equipment for monitoring the output of the sensor and means connecting the sensor and the external equipment.
18. A system according to Claim 17, the means connecting the sensor and the external equipment being an elongated electrical connector.
19. A system according to Claim 18, the electrical connector being a cable.
20. A system according to claim 18 or Claim 19, there being a plurality of apparatuses according to any of Claims 1 to 16 carried by the carrier.
21. A system according to Claim 20, there being four apparatuses spaced equidistantly round the outer surface of the carrier.
22. A sytem for detecting a discontinuity such as a joint or crack in a pipe or conduit, substantially as hereinbefore described with reference to the accompanying drawings.
23. A method for locating a discontinuity such as a joint or crack in a metal pipe or conduit, comprising inserting apparatus according to Claim 1 into the pipe or cona'uit, moving the apparatus through the pipe or conduit and monitoring the output from the sensor whereby to detect any change in the output resulting from the presence of a discontinuity.
24. A method according to Claim 23, comprising the step of feeding the output to external monitoring equipment.
25. A method according to Claim 24, comprising the step of providing an audible signal resulting from a change in the output.
26. A method according to Claim 25, in which a plurality of outputs are obtained and those outputs are selectively monitored whereby to confirm the presence of a joint or crack.
27. A method according to Claim 23, substantially as described.
28. A method of sealing a discontinuity such as a joint or crack in a pipe or conduit, comprising the steps of detecting a discontinuity by a method according to any of Claims 23 to 27, passing a sealing device along the pipe or conduit behind the apparatus, and actuating that device to seal the discontinuity when it is adjacent the discontinuity.
GB08414408A 1984-06-06 1984-06-06 Apparatus, system and method for detecting a discontinuity in a pipe or conduit Withdrawn GB2159954A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08414408A GB2159954A (en) 1984-06-06 1984-06-06 Apparatus, system and method for detecting a discontinuity in a pipe or conduit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08414408A GB2159954A (en) 1984-06-06 1984-06-06 Apparatus, system and method for detecting a discontinuity in a pipe or conduit

Publications (2)

Publication Number Publication Date
GB8414408D0 GB8414408D0 (en) 1984-07-11
GB2159954A true GB2159954A (en) 1985-12-11

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238209A2 (en) * 1986-03-17 1987-09-23 United Kingdom Atomic Energy Authority Magnetic discontinuity detection
US5347849A (en) * 1990-08-30 1994-09-20 Tanknology Corporation International Water sensor that detects tank or vessel leakage
US5532587A (en) * 1991-12-16 1996-07-02 Vetco Pipeline Services, Inc. Magnetic field analysis method and apparatus for determining stress characteristics in a pipeline
EP0732595A2 (en) * 1995-03-16 1996-09-18 Eastman Kodak Company Magnetic field detector
GB2301187A (en) * 1995-05-22 1996-11-27 British Gas Plc Locating an anomaly in a lined duct
US7432495B2 (en) 2002-09-02 2008-10-07 Durr Systems, Inc. Sensor arrangement for a coating system
WO2009067769A1 (en) * 2007-11-30 2009-06-04 Asel-Tech Technologia E Automação Ltda. System for locating pigs in single phase and multiphase fluid transport pipelines

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1023067A (en) * 1962-09-28 1966-03-16 Camco Inc Calipering device for determining internal surface dimensions of ferromagnetic tubular structures
GB1169752A (en) * 1965-12-04 1969-11-05 Sumitomo Metal Ind Magnetic Inspecting Apparatus
GB1315468A (en) * 1970-05-06 1973-05-02 Northern Illinois Gas Co Tools for app-ying internal pipe seals
GB1567167A (en) * 1976-04-06 1980-05-14 British Gas Corp Non-destructive testing of pipelines
GB1567166A (en) * 1976-12-16 1980-05-14 British Gas Corp Apparatus and method for the non-destructive testing of ferromagnetic material
GB2055473A (en) * 1979-06-18 1981-03-04 Electric Power Res Inst Method and means for detecting magnetic deposits in tubular plant
GB2056071A (en) * 1979-05-02 1981-03-11 Simmens C Method of and apparatus for testing metal walls, such as ferrous pipes
GB2098335A (en) * 1981-05-08 1982-11-17 Amf Inc Nondestructive inspection apparatus and method

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1023067A (en) * 1962-09-28 1966-03-16 Camco Inc Calipering device for determining internal surface dimensions of ferromagnetic tubular structures
GB1169752A (en) * 1965-12-04 1969-11-05 Sumitomo Metal Ind Magnetic Inspecting Apparatus
GB1315468A (en) * 1970-05-06 1973-05-02 Northern Illinois Gas Co Tools for app-ying internal pipe seals
GB1567167A (en) * 1976-04-06 1980-05-14 British Gas Corp Non-destructive testing of pipelines
GB1567166A (en) * 1976-12-16 1980-05-14 British Gas Corp Apparatus and method for the non-destructive testing of ferromagnetic material
GB2056071A (en) * 1979-05-02 1981-03-11 Simmens C Method of and apparatus for testing metal walls, such as ferrous pipes
GB2055473A (en) * 1979-06-18 1981-03-04 Electric Power Res Inst Method and means for detecting magnetic deposits in tubular plant
GB2098335A (en) * 1981-05-08 1982-11-17 Amf Inc Nondestructive inspection apparatus and method

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238209A2 (en) * 1986-03-17 1987-09-23 United Kingdom Atomic Energy Authority Magnetic discontinuity detection
EP0238209A3 (en) * 1986-03-17 1988-06-22 United Kingdom Atomic Energy Authority Magnetic discontinuity detection
US4814705A (en) * 1986-03-17 1989-03-21 The Secretary Of State For United Kingdom Atomic Energy Authority In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Method and apparatus for magnetic discontinuity detection in a specimen of magnetizable material
US5347849A (en) * 1990-08-30 1994-09-20 Tanknology Corporation International Water sensor that detects tank or vessel leakage
US5532587A (en) * 1991-12-16 1996-07-02 Vetco Pipeline Services, Inc. Magnetic field analysis method and apparatus for determining stress characteristics in a pipeline
EP0732595A2 (en) * 1995-03-16 1996-09-18 Eastman Kodak Company Magnetic field detector
EP0732595A3 (en) * 1995-03-16 1996-10-02 Eastman Kodak Company Magnetic field detector
GB2301187A (en) * 1995-05-22 1996-11-27 British Gas Plc Locating an anomaly in a lined duct
GB2301187B (en) * 1995-05-22 1999-04-21 British Gas Plc Method of and apparatus for locating an anomaly in a duct
US7432495B2 (en) 2002-09-02 2008-10-07 Durr Systems, Inc. Sensor arrangement for a coating system
WO2009067769A1 (en) * 2007-11-30 2009-06-04 Asel-Tech Technologia E Automação Ltda. System for locating pigs in single phase and multiphase fluid transport pipelines

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732 Registration of transactions, instruments or events in the register (sect. 32/1977)
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)