GB2394042A - Method and apparatus for the inspection of surfaces - Google Patents
Method and apparatus for the inspection of surfaces Download PDFInfo
- Publication number
- GB2394042A GB2394042A GB0223749A GB0223749A GB2394042A GB 2394042 A GB2394042 A GB 2394042A GB 0223749 A GB0223749 A GB 0223749A GB 0223749 A GB0223749 A GB 0223749A GB 2394042 A GB2394042 A GB 2394042A
- Authority
- GB
- United Kingdom
- Prior art keywords
- irregularities
- points
- image
- measured
- responses
- 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.)
- Granted
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4427—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with stored values, e.g. threshold values
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/954—Inspecting the inner surface of hollow bodies, e.g. bores
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/11—Analysing solids by measuring attenuation of acoustic waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/01—Indexing codes associated with the measuring variable
- G01N2291/012—Phase angle
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/01—Indexing codes associated with the measuring variable
- G01N2291/014—Resonance or resonant frequency
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/01—Indexing codes associated with the measuring variable
- G01N2291/015—Attenuation, scattering
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/044—Internal reflections (echoes), e.g. on walls or defects
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/26—Scanned objects
- G01N2291/263—Surfaces
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Acoustics & Sound (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
A method of inspecting a regular surface such as a pipe, which comprises transmitting a signal to the surface, detecting and measuring reflected signal responses from various points on the surface and comparing the measured responses with expected values for the respective points. Points where differences occur between the measured responses and expected values are then identified as irregularities in the surface and the irregularities are analysed to determine their nature.
Description
Method and Apparatus for the Inspection of Surfaces The present invention
relates to the inspection of surfaces in order to detect flaws, cracks, protrusions, blemishes, irregularities, discontinuities, 5 inconsistencies or any unexpected features. The invention is particularly applicable to the inspection of pipelines and tubes, especially their inner surfaces, but is also relevant to the study of surfaces more generally. Thus, the techniques are applicable to any body with a surface which is continuous and regular, such as tanks, containers and enclosures [and even parts of the body 10 such as veins, arteries and organs such as the heart and lungs].
Currently, the inspection of submarine pipelines to identify leaks, cracks or other damage is carried out from the outside. This is difficult and costly in that it requires a manned or remotely operated submarine vehicle. In the case of the 15 underground pipelines, it is impossible to carry out a study without excavation.
It is an object of the present invention to provide a system for inspecting a continuous regular surface in order to detect irregularities.
20 It is a more specific object to provide a system for inspecting submarine pipelines in order to detect cracks, leaks or other irregularities.
It is a still further object to provide a system for inspecting a pipeline in order to detect internal deposits or damage.
According to one aspect of the invention, there is provided a method of inspecting a regular surface, which comprises: transmitting a signal to the surface; detecting and measuring reflected signal responses from various points on the surface; comparing the measured responses with expected values for the
respective points; identifying points where differences occur between the measured responses and expected values as irregularities in the surface; and analysing the irregularities to determine their nature.
5 According to another aspect of the invention, there is provided apparatus for inspecting a regular surface which comprises: means for transmitting a signal to the surface; means for detecting and measuring reflected signal responses from various points on the surface; means for comparing the measured responses with expected values for the respected points; means for identifying 10 points where differences occur between the measured responses and expected values as irregularities in the surface; and means for analysing the irregularities to determine their nature.
In this way any departure from the regularity of the surface can be identified.
15 The departures from surface regularity can be flaws, cracks, protrusions, blemishes, discontinuities or any unexpected features. Having identified these irregularities, their co-ordinates can be recorded in a memory so that subsequent study can be concentrated on these "degraded zones".
20 Any suitable measuring device may be employed, for example an acoustic or coherent light (laser)-based device or a magnetic device. The measurement data may be used to create a visual image of the surface. The image, whether visual or otherwise may be a digital image.
25 The signal responses may be measured in terms of quantity andlor quality.
Preferably, the measuring device measures the distance between a reference position and series of points on the surface and the measured distances are compared with expected distances whereby differences between the measured and expected values represent irregularities, and the expected distance
measurements correspond to a constant distance or a regularly varying distance. The reference position from which measurements are taken may be a single 5 fixed point or may be a set of points. The set of points may represent a series of positions on a measuring device from which measurements are taken and/or may result from movement of the measuring device. In the latter case the set of points may correspond to the axis of a pipe or tube; the axis may be straight or curved. The measurements in this case would preferably be radius 10 measurements or measurements along radii.
In the case of a pipe or tube, the measuring device could be moved along the tube to take measurements which would effectively map the entire inner surface or only a part of it. In one embodiment, several radial measurements 15 are taken sequentially at successive axial positions. Alternatively, the several measurements could be taken simultaneously, or these arrangements could be combined with sets of simultaneous measurements being taken sequentially at any radial position.
20 In another embodiment, radial measurements at different circumferential angular positions are taken as the measuring device moves so that the measurement points are arranged on a helical path. This technique could also be employed with a measuring device capable of taking several measurements simultaneously. The measurements can be taken at a relatively coarse resolution, such as tom or preferably lmm in a preliminary or detection sweep. If a degraded zone is detected, the resolution of the measurements in that zone can be made finer in a secondary or investigative sweep, for example 1 mm, more preferably 0.1 mm in
order that the degraded zone can be characterised more closely. The secondary sweep can be made automatically during the primary sweep or may be conducted subsequently, possibly following a manual study of the primary sweep data. Alternatively, all the measurements may be made in a single 5 sweep and the analysis carried out later. In general, the resolution of the distance measurements will be in the range 10 mm to 0.1 mm.
In one possible alternative system, a visual image of the surface is first created using for example a camera, and this is used to identify areas including 10 irregularities. These areas may be identified visually by skilled operatives or may be identified using digital (or analogue) analysis techniques. When they have been identified, these areas with irregularities are subjected to a more detailed surface inspection as described above.
15 In some cases, the distances to a surface will be expected to be constant and so any deviation in the measured distance from the expected value will represent an irregularity. The inside of a pipe might fall into this category. In other cases, the distances to a surface may change in a regular or predictable fashion and so an irregularity will be represented by a deviation from an expected but 20 varying value. The inside of a vessel or a non-circular pipe [or an organ in a body] might fall into this category.
The irregularities, for example in a pipe, can take various forms and will therefore have different parameters or properties. The combination of these 25 properties will be characteristic of the type of irregularity. By measuring those various properties a series of attributes are created. Depending upon the measurement technique, those attributes might include frequency, amplitude, intensity, energy, coherency and so on. By analysing the attributes, irregularities can be located or identified and the type of irregularity can be
classified or even singled out. Examples of these properties include depth, length, width, orientation, frequency, gradient and shape, and also whether they intrude or protrude. Once an irregularity has been identified and classified it can be repaired as appropriate, possibly by equipment carried by a transport 5 device or possibly by separate dedicated repair equipment.
The techniques of the present invention are particularly suitable for use with a neural network since all the measurement data and/or the attributes can be supplied to the neural network which can detect and classify any degraded 10 zone. The neural network would normally be trained (supervised neural network) to detect and classify the irregularity and/or identify the type of degradation. The neural network can operate both in a supervised or unsupervised mode. In the supervised mode, the classification system can be tuned to changing user needs due to differences in surfaces and developing 15 experience. The neural network can be trained on examples given by the user; the input for training can be raw data or the attributes.
As can be appreciated, the method and apparatus of the present invention allow surface damage to be detected and assessed in situations where this is currently 20 either impossible or impractical, because the inspection data volume is very large and/or because the degradation is hardly visible in terms of single attributes/measurements. In particular, the invention allows detection, decision making and repair of damage to pipelines and tubes in a far more convenient way than is presently possible.
Effectively, therefore, the present invention allows the inspection of surfaces in space and time with many measurements of the surface conditions being combined by neural network. Normally the measurements are transformed to "attributes" which enhance or reflect the surface conditions. Then the
attributes can be used to classify the damage due to degradation and the appropriate action can be taken.
Automated inspection is preferred since the measurements taken of the surface 5 could result in a "picture" as large as 1 O,OOOm by 2m. In this regard the use of a neural network is particularly suitable. It also enables the several attributes to be combined, so increasing the changes of detection compared to the use of a single attribute, and can provide automated classification.
10 Repeated measurements may also be desirable since they can reveal changes in a surface and may therefore be more sensitive to surface degradation/anomalies. This is analogous to seismic time lapse monitoring.
The system may make use of detection combined with visualization. Detected 15 surface regions can be quickly localised and the operatives can spend time on examining degradation instead of on finding it. Advanced visualization can develop the understanding/experience so that classification can be improved.
Attributes are developed and the neural network is trained by the user as the user's experience with surface conditions develops. Damage classification and 20 reporting can then be automated.
Claims (27)
1. A method of inspecting a regular surface, which comprises: transmitting a signal to the surface; detecting and measuring reflected signal responses from 5 various points on the surface; comparing the measured responses with expected values for the respective points; identifying points where differences occur between the measured responses and expected values as irregularities in the surface; and analysing the irregularities to determine their nature.
10
2. A method as claimed in Claim 1, in which the measurements are taken using a measuring device working on the basis of coherent light or acoustics or magnetism.
3. A method as claimed in Claim 1, in which the signal responses are 15 measured in terms of quantity and/or quality.
4. A method as claimed in Claim 3, in which the measuring device measures the distance between a reference position and series of points on the surface and the measured distances are compared with expected distances 20 whereby differences between the measured and expected values represent irregularities.
5. A method as claimed in Claim 4, in which the expected distance measurements correspond to a constant distance or a regularly varying 25 distance.
6. A method as claimed in Claim 5, in which the resolution of the distance measurements is in the range lOmm to 0. lmm.
7. A method as claimed in any preceding Claim, which includes creating a representation of at least a portion of the surface using the measured responses.
8. A method as claimed in Claim 7, in which the creation of a 5 representation from the measured responses includes the creation of a visual representation.
9. A method as claimed in Claim 7 or 8, in which the representation created is a digital image.
10. A method as claimed in any preceding Claim, which comprises: applying one or more measuring techniques to the irregularities, thereby creating one or more attributes, and analysing the attributes.
15
11. A method as claimed in Claim 10, in which the irregularities include properties selected from depth, length, width, orientation, frequency, gradient and shape, and the attributes used are selected from distance frequency, amplitude, phase, intensity, energy and coherency.
20
12. A method as claimed in Claim 10 or Claim 11, which includes associating a type of degradation with a particular attribute or combination of attributes in order to enable the type of degradation to be determined from the analysis of the irregularities.
25
13. A method as claimed in Claim 12, in which comprises training a neural network to detect and classify particular attributes or combinations of attributes associated with irregularities as representing particular types of degradation.
14. A method as claimed in any preceding Claim, in which the surface is the interior of a pipe or tube.
15. A method as claimed in any of Claims 4 to 14, in which the reference 5 position is a single fixed point or a set of points.
16. A method as claimed in Claim 15, in which the reference position is the axis of the pipe or tube, and the distance measurements are radii.
10
17. A method as claimed in any Claims 14 to 16, in which the measurements are taken by a measuring device which is moved along the pipe or tube.
18. A method as claimed in any preceding Claim, in which an image of the 15 surface is created prior to inspecting the surface, and the image is used to identify an area of the surface which is to be subjected to the inspection.
19. A method as claimed in Claim 18, in which the image is a visual image.
20 20. A method as claimed in Claim 18 or Claim 19, in which the identification is carried out visually by an operative.
21. A method as claimed in Claim 18 or Claim 19, in which the identification is carried out by a digital analysis.
22. Apparatus for inspecting a regular surface which comprises: means for transmitting a signal to the surface; means for detecting and measuring reflected signal responses from various points on the surface; means for comparing the measured responses with expected values for the respected
points; means for identifying points where differences occur between the measured responses and expected values as irregularities in the surface; and means for analysing the irregularities to determine their nature.
5
23. Apparatus as claimed in Claim 22, in which the measuring means comprises a measuring device working on the basis of coherent light, acoustics, or magnetism.
24. Apparatus as claimed in Claim 22 or Claim 23 in which the measuring 10 device measures distance.
25. Apparatus as claimed in any of Claims 22 to 24, including means for creating an image or a representation of the surface.
15
26. Apparatus as claimed in Claim 25, in which the image is a visual image and the means for creating the image is a camera.
27. Apparatus as claimed in any of Claims l 9 to 23, in which the analysing means comprises a neural network.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0223749A GB2394042B (en) | 2002-10-11 | 2002-10-11 | Method and apparatus for the inspection of surfaces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0223749A GB2394042B (en) | 2002-10-11 | 2002-10-11 | Method and apparatus for the inspection of surfaces |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0223749D0 GB0223749D0 (en) | 2002-11-20 |
| GB2394042A true GB2394042A (en) | 2004-04-14 |
| GB2394042B GB2394042B (en) | 2005-09-07 |
Family
ID=9945796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0223749A Expired - Lifetime GB2394042B (en) | 2002-10-11 | 2002-10-11 | Method and apparatus for the inspection of surfaces |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2394042B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010040719A1 (en) * | 2008-10-10 | 2010-04-15 | European Aeronautic Defence And Space Company Eads France | Method of non-destructive checking using lamb waves to determine zones of a structure comprising defects |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4317632A (en) * | 1979-10-19 | 1982-03-02 | Electric Power Research Institute, Inc. | Method and means for optical inspection of the interior surface of tubing |
| EP0461780A2 (en) * | 1990-06-11 | 1991-12-18 | Hughes Aircraft Company | Infrared holographic defect detector |
| EP0489161A1 (en) * | 1989-08-21 | 1992-06-10 | Hitachi Construction Machinery Co., Ltd. | Ultrasonic flaw detector |
| EP0597639A1 (en) * | 1992-11-12 | 1994-05-18 | Westinghouse Electric Corporation | Non-contact surface flaw detection |
| US5973777A (en) * | 1996-06-25 | 1999-10-26 | Hitachi, Ltd. | Method and apparatus for inspecting defects of surface shape |
| GB2366651A (en) * | 2000-09-08 | 2002-03-13 | Ncr Int Inc | Evaluation system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9215832D0 (en) * | 1992-07-24 | 1992-09-09 | British Nuclear Fuels Plc | The inspection of cylindrical objects |
-
2002
- 2002-10-11 GB GB0223749A patent/GB2394042B/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4317632A (en) * | 1979-10-19 | 1982-03-02 | Electric Power Research Institute, Inc. | Method and means for optical inspection of the interior surface of tubing |
| EP0489161A1 (en) * | 1989-08-21 | 1992-06-10 | Hitachi Construction Machinery Co., Ltd. | Ultrasonic flaw detector |
| EP0461780A2 (en) * | 1990-06-11 | 1991-12-18 | Hughes Aircraft Company | Infrared holographic defect detector |
| EP0597639A1 (en) * | 1992-11-12 | 1994-05-18 | Westinghouse Electric Corporation | Non-contact surface flaw detection |
| US5973777A (en) * | 1996-06-25 | 1999-10-26 | Hitachi, Ltd. | Method and apparatus for inspecting defects of surface shape |
| GB2366651A (en) * | 2000-09-08 | 2002-03-13 | Ncr Int Inc | Evaluation system |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010040719A1 (en) * | 2008-10-10 | 2010-04-15 | European Aeronautic Defence And Space Company Eads France | Method of non-destructive checking using lamb waves to determine zones of a structure comprising defects |
| FR2937136A1 (en) * | 2008-10-10 | 2010-04-16 | Eads Europ Aeronautic Defence | NON-DESTRUCTIVE CONTROL METHOD USING LAMB WAVES FOR DETERMINING ZONES OF A STRUCTURE COMPRISING DEFECTS |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2394042B (en) | 2005-09-07 |
| GB0223749D0 (en) | 2002-11-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) |
Free format text: REGISTERED BETWEEN 20130905 AND 20130911 |
|
| PE20 | Patent expired after termination of 20 years |
Expiry date: 20221010 |