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WO1990004779A1 - Detection de la corrosion du metal - Google Patents

Detection de la corrosion du metal Download PDF

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Publication number
WO1990004779A1
WO1990004779A1 PCT/GB1988/000876 GB8800876W WO9004779A1 WO 1990004779 A1 WO1990004779 A1 WO 1990004779A1 GB 8800876 W GB8800876 W GB 8800876W WO 9004779 A1 WO9004779 A1 WO 9004779A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensors
array
wall
tie
voltages
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.)
Ceased
Application number
PCT/GB1988/000876
Other languages
English (en)
Inventor
Julian Marsden Carroll
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of WO1990004779A1 publication Critical patent/WO1990004779A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
    • 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

Definitions

  • This invention relates to apparatus for and a non- intrusive method of detecting metal corrosion, more especially corrosion which occurs in cavity wall ties.
  • Cavity walls comprise two skins held in fixed relationship by metal ties, either of wire, mild steel strip or cast iron. Such ties commonly corrode with passage of time, eventually to give rise to cracking of the masonry and possible collapse of the wall. It is clearly desirable to replace corroded wall ties before damage can result, but currently the only reliable method of inspecting ties for corrosion is a destructive one, which entails the removal of bricks or other wall blocks to expose the ties to view.
  • apparatus for corrision detection especially detection of corroded wall ties, comprising: i an array of Hall effect sensors;
  • SUBSTITUTE SHEET processing circuitry responsive to the voltages generated at the sensors in the array
  • the principle of the invention is that the patterns of voltages generated within the array of sensors differ between the situation where the field of the permanent magnet is substantially undisturbed, the situation where it is disturbed by the presence in its vicinity of a sound wall tie, and the situation where it is disturbed to a lesser extent by the presence in its vicinity of a corroded tie, due to the reduce ferrous content of the corroded ties.
  • a further aspect of the invention therefore concerns a preferred method of detecting metal corrosion.
  • a method of detecting metal corrosion comprises the steps of:
  • the individual sensor values taken during determination of the reference signal and determination of the measurement signal are stored, the difference values are determined for each sensor, and the difference values are summed.
  • the difference values are determined for each sensor, and the difference values are summed.
  • only the voltages of sensors in the central region of the array may be utilised in this method.
  • the individual sensor voltages are stored for a tie-absent wall position, thereby to establish a background reference pattern, the individual sensor voltages are stored for one or more sound wall tie positions, thereby to establish a mean sound tie reference pattern, the sensor voltage differences for at least some of the sensors are determined to establish a sound tie difference signal pattern, the individual sensor voltages are stored for a suspect wall tie position, thereby to establish a measurement voltage pattern, the sensor voltage differences (for at least some of the sensors) are determined relative to the background reference pattern in order to establish a suspect tie difference signal pattern, and the sound tie difference signal pattern is
  • a background reference pattern is indicated by a minimum sum of the sensor voltages and a sound tie by a maximum value thereof. Centering on a wall tie is indicated by maximum sensor voltages in the central region of the array.
  • a typical sensor array would be a two-dimensional array, having a plurality of sensors extending in two mutually perpendicular directions.
  • the sum of the difference signal voltages from the sound tie may be compared with the sum of the different signal voltages for a suspect tie.
  • a substantial difference in the two sums is indicative of a severely corroded tie.
  • it is badly corroded wall ties which are most important to detect, as distinct from ties suffering from only limited corrosion, and it is an advantage of this invention that the apparatus and method is most sensitive when there is in excess of 50% corrosion.
  • Summation values obtained for corroded wall ties will vary to some extend with position (orientation and depth) of the tie within the wall, but badly corroded ties will always be detectable.
  • an analysis of the pattern of sensor voltages through the array can enable information as to the positioning of the corroded tie to be derived, thus assisting in the work necessary to effect a replacement.
  • the magnet and sensor array may constitute a portable unit, and the processing, measuring and display circuitry may be incorporated in a second unit
  • a power supply preferably of a rechargable kind, is required for the array of Hall effect sensors, and this may also form part of the second unit.
  • At least part of the display equipment may be incorporated in the first unit to facilitate the task of positioning the magnet and array at different sites on the wall.
  • One suitable form of basic display is an LCD meter coupled to the sensors via two rotary switches which in combination select a particular sensor for reading on the meter.
  • Figure 1 is a block circuit diagram of the apparatus
  • Figures 2 to 4 are tables exemplifying results achieved with the exemplary apparatus.
  • the reference 10 denotes a 9 x 7 array of Hall effect sensors, conveniently sprague UGN 3503U linear Hall effect sensors.
  • This array 10 forms part of a sensor head 12 which also includes a ferrite permanent magnet.
  • Figure la shows the circuit element associated with one sensor.
  • the remaining parts of the apparatus are incorporated in a supervisory unit 14 connected to the sensor head 12 by 40- way connectors 16, 40-way cables 18 and 40-way plugs/sockets 20.
  • a controlled power supply ( Figure lb) includes a sealed lead acid battery 22, a battery indicator 24, recharging leads 26, and a d.c/d.c convertor 28.
  • the power supply provides outputs of 0 volts and 5 volts to the sensor head 10.
  • the remainder of the supervisory unit comprises circuitry for processing, measuring and displaying the voltages, , developed at the Hall effect sensors in use.
  • This circuitry includes four stores 32 to 36, two rotary switches 38, 40, the latter forming part of a drive circuit, generally referenced 42, and which includes an arithmetic unit 44, for a digital display module 46.
  • Figures 2 to 4 comprising tables 1, 2 and 3, respectively show the pattern of different signal sensor outputs obtained for a wire tie, a sound cast iron tie, and a corroded cast iron tie.
  • the different signals are obtained by substracting the sensor voltages developed in the presence of a tie from the voltages developed in the absence of a tie, ie, when the field of the permanent magnet is substantially undisturbed.
  • the voltage pattern in the last mentioned case is substantially uniform over the entire array.
  • SUBSTITUTE SHEET can be seen that the highest values are again generally in the centre of the array, the values of the different signals are much reduced, because the disturbance of the magnetic field is substantially less.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Immunology (AREA)
  • Biochemistry (AREA)
  • Pathology (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Ecology (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Environmental Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)

Abstract

L'appareil décrit sert à détecter du métal corrodé, et en particulier des ancres murales corrodées. On prévoit un réseau de détecteurs à effet de Hall (10), reliés par le champ magnétique d'un aimant permanent, et les sorties provenant des détecteurs sont multipliées par des dispositifs (30, 32, 34, 36, 44) et amplifiées par un amplificateur (42) permettant la mise sous tension d'un module d'alimentation (46) d'un compteur. Les modèles des tensions générées à l'intérieur du réseau des capteurs diffèrent selon les situations, qui sont au nombre de trois: (1) situation où le champ de l'aimant permanent est en substance non perturbé, (2) situation où le champ est perturbé par la présence d'une ancre murale en bon état et (3) situation où le champ est perturbé dans une moindre mesure par la présence d'une ancre corrodée, cette perturbation étant due à la teneur ferreuse réduite de l'ancre corrodée. Dans un procédé de détection d'ancres murales corrodées, une unité contenant le réseau de détecteurs à effet de Hall et l'aimant permanent est placée adjacente à un mur, dans une position où l'aimant est plus éloigné du mur que les détecteurs, et l'unité est déplacée dans une position par rapport au mur où les détecteurs présentent un certain modèle de tension, puis un signal de référence est produit par traitement de la tension des détecteurs. L'unité est ensuite déplacée dans une position où les détecteurs présentent un modèle de tension différent et les tensions des détecteurs sont à nouveau traitées de façon à produire un signal de mesure, le signal de référence et le signal de mesure étant ensuite comparés.
PCT/GB1988/000876 1987-04-15 1988-10-18 Detection de la corrosion du metal Ceased WO1990004779A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8709033A GB2203549B (en) 1987-04-15 1987-04-15 Metal corrosion detection

Publications (1)

Publication Number Publication Date
WO1990004779A1 true WO1990004779A1 (fr) 1990-05-03

Family

ID=10615875

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1988/000876 Ceased WO1990004779A1 (fr) 1987-04-15 1988-10-18 Detection de la corrosion du metal

Country Status (2)

Country Link
GB (1) GB2203549B (fr)
WO (1) WO1990004779A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001069204A3 (fr) * 2000-03-14 2002-01-24 British Nuclear Fuels Plc Ameliorations apportees ou relatives a l'analyse de courant
US6861853B2 (en) 2000-03-14 2005-03-01 British Nuclear Fuels Plc Investigating corrosion
US6982563B2 (en) 2000-11-09 2006-01-03 British Nuclear Fuels Plc Monitoring of corrosion induced loss of material by means of a plurality of electrical resistance measurements (field signature method, electrical resistance tomography)
CN101788521A (zh) * 2010-03-19 2010-07-28 南京工业大学 金属腐蚀状况在线检测方法及其检测仪器

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2250097A (en) * 1990-11-07 1992-05-27 Anglo Amer Corp South Africa Testing wire rope for cross section variations and other flaws
DE19654868A1 (de) * 1996-12-24 1998-06-25 Forschungsgesellschaft Fuer In Prüfverfahren zur Erkennung von Korrosion
WO2010117363A1 (fr) 2009-04-09 2010-10-14 Michelin Recherche Et Technique, S.A. Procédé et appareil de détection d'anomalies dans un câble métallique de pneu
CN105067507B (zh) * 2015-08-24 2018-04-06 北京星网锐捷网络技术有限公司 一种腐蚀检测装置及方法
CN105842631B (zh) * 2016-05-10 2018-07-03 青岛理工大学 原电池腐蚀检测装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4087749A (en) * 1977-01-25 1978-05-02 The United States Of America As Represented By The Secretary Of The Army Method and apparatus for normalizing the outputs of sequentially scanned magnetic flaw detectors
US4481809A (en) * 1983-08-29 1984-11-13 Labate M D Method and apparatus for monitoring erosion in gas stirring devices in molten metal ladles
US4531091A (en) * 1982-03-29 1985-07-23 The United States Of America As Represented By The Secretary Of Transportation Magnetic inspection of reinforcing steel using sensor array
DE3418066A1 (de) * 1984-05-16 1985-11-21 Fa. Hermann Nadermann, 4100 Duisburg Korrosions-testgeraet fuer magnetisierbares stahlblech
GB2169084A (en) * 1984-12-21 1986-07-02 Nukem Gmbh A device for the non-destructive testing of ferromagnetic bodies and a process for producing values for adjusting the device into an initial statee for testing determined by the respective test samples
EP0238209A2 (fr) * 1986-03-17 1987-09-23 United Kingdom Atomic Energy Authority Détection de discontinuités magnétiques

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1038037A (fr) * 1976-05-06 1978-09-05 Noranda Mines Limited Dispositif d'essai magnetique pour detecter des defauts dans des objets de forme allongee
GB2012966A (en) * 1977-10-06 1979-08-01 Health & Safety Executive Apparatus for non-destructive testing of elongate objects
GB2108672A (en) * 1981-10-17 1983-05-18 Armstrong Patents Co Ltd Vehicle body repair detector
US4573013A (en) * 1982-03-29 1986-02-25 The United States Of America As Represented By The Secretary Of Transportation Magnetic inspection of reinforcing steel rods in prestressed concrete

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4087749A (en) * 1977-01-25 1978-05-02 The United States Of America As Represented By The Secretary Of The Army Method and apparatus for normalizing the outputs of sequentially scanned magnetic flaw detectors
US4531091A (en) * 1982-03-29 1985-07-23 The United States Of America As Represented By The Secretary Of Transportation Magnetic inspection of reinforcing steel using sensor array
US4481809A (en) * 1983-08-29 1984-11-13 Labate M D Method and apparatus for monitoring erosion in gas stirring devices in molten metal ladles
DE3418066A1 (de) * 1984-05-16 1985-11-21 Fa. Hermann Nadermann, 4100 Duisburg Korrosions-testgeraet fuer magnetisierbares stahlblech
GB2169084A (en) * 1984-12-21 1986-07-02 Nukem Gmbh A device for the non-destructive testing of ferromagnetic bodies and a process for producing values for adjusting the device into an initial statee for testing determined by the respective test samples
EP0238209A2 (fr) * 1986-03-17 1987-09-23 United Kingdom Atomic Energy Authority Détection de discontinuités magnétiques

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001069204A3 (fr) * 2000-03-14 2002-01-24 British Nuclear Fuels Plc Ameliorations apportees ou relatives a l'analyse de courant
US6861853B2 (en) 2000-03-14 2005-03-01 British Nuclear Fuels Plc Investigating corrosion
US6888359B2 (en) 2000-03-14 2005-05-03 British Nuclear Fuels Plc Investigating current
US6982563B2 (en) 2000-11-09 2006-01-03 British Nuclear Fuels Plc Monitoring of corrosion induced loss of material by means of a plurality of electrical resistance measurements (field signature method, electrical resistance tomography)
CN101788521A (zh) * 2010-03-19 2010-07-28 南京工业大学 金属腐蚀状况在线检测方法及其检测仪器

Also Published As

Publication number Publication date
GB2203549B (en) 1991-05-01
GB2203549A (en) 1988-10-19
GB8709033D0 (en) 1987-05-20

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