EP0348742A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method for detecting thinned out portion of inner surface or outer surface of pipe
Assignee: JFE Engineering Corp
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Filing: 1989-06-14
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Granted: —
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Expires: 2009-06-14
Abstract
Abstract A method for detecting a thinned out portion on the inner surface or the outer surface of a pipe, which comprises the steps of: heating or cooling a pipe to be tested from the side of the outer surface thereof or the inner surface thereof so that a difference in temperature is produced between a portion of the outer surface or the inner surface of the pipe corresponding to a thinned out portion as a defective portion on the inner surface or the outer surface of the pipe, on the one hand, and a portion of the outer surface or the inner surface of the pipe corresponding to a normal portion of the inner surface or the outer surface of the pipe, on the other hand; then shooting the outer surface or the inner surface of the pipe by means of a thermal imaging system to obtain a thermal image of the difference in temperature; then, calculating a differential value of a temperature distribution of the thermal image of the difference in temperatuee on a line passing the highest temperature point or the lowest temperature point in the thermal image of the difference in temperature; then determining two points of inflection on the both sides of the highest temperature point or the lowest temperature point of the temperature distribution for the thinned out portion, on the basis of the differential value of the temperature distribution; and then detecting an extent of the thinned out portion on the basis of a distance between the two points of inflection of the temperature distribution.
Inventors
- 👤 Yuji C/O Nippon Kokan K.K. Matoba
- 👤 Toshio C/O Nippon Kokan K.K. Koshihara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:36
CPC Classifications
G; G01; G01N; G01N25/00; G01N25/72
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
286 words
A method for detecting a thinned out portion on the inner surface or the outer surface of a pipe, characterized by comprising the steps of: heating or cooling a pipe to be tested from the side of the outer surface thereof or the inner surface thereof so that a difference in temperature is produced between a portion of the outer surface or the inner surface of said pipe corresponding to a thinned out portion as a defective portion on the inner surface or the outer surface of said pipe, on the one hand, and a portion of the outer surface or the inner surface of said pipe corresponding to a normal portion of the inner surface or the outer surface of said pipe, on the other hand; then shooting the outer surface or the inner surface of said pipe by means of a thermal imaging system while said difference in temperature still remains on the outer surface or the inner surface of said pipe, to obtain a thermal image of said difference in temperature; then determining a temperature distribution of said thermal image of said difference in temperature on a line passing the highest temperature point or the lowest temperature point in said thermal image of said difference in temperature; then calculating a differential value of said temperature distribution; then determining two points of inflection on the both sides of said highest temperature point or said lowest temperature point of said temperature distribution for said thinned out portion, on the basis of said calculated differential value of said temperature distribution; and then detecting an extent of said thinned out portion on the basis of a distance between said two points of inflection of said temperature distribution.
Claim 2
Independent Claim
286 words
A method for detecting a thinned out portion on the inner surface or the outer surface of a pipe, characterized by comprising the steps of: heating or cooling a pipe to be tested from the side of the outer surface thereof or the inner surface thereof so that a difference in temperature is produced between a portion of the outer surface or the inner surface of said pipe corresponding to a thinned out portion as a defective portion on the inner surface or the outer surface of said pipe, on the one hand, and a portion of the outer surface or the inner surface of said pipe corresponding to a normal portion of the inner surface or the outer surface of said pipe, on the other hand; then shooting the outer surface or the inner surface of said pipe by means of a thermal imaging system while said difference in temperature still remains on the outer surface or the inner surface of said pipe, to obtain a thermal image of said difference in temperature; then determining a temperature distribution of said thermal image of said difference in temperature on a line passing the highest temperature point or the lowest temperature point in said thermal image of said difference in temperature; then calculating a differential value of said temperature distribution; then determining two points of inflection on the both sides of said highest temperature point or said lowest temperature point of said temperature distribution for said thinned out portion, on the basis of said calculated differential value of said temperature distribution; and then detecting an extent of said thinned out portion on the basis of a distance between said two points of inflection of said temperature distribution.
Claim 3
Independent Claim
463 words
A method for detecting a thinned out portion on the inner surface or the outer surface of a pipe, characterized by comprising the steps of: heating or cooling a pipe to be tested from the side of the outer surface thereof or the inner surface thereof so that a difference in temperature is produced between a portion of the outer surface or the inner surface of said pipe corresponding to a thinned out portion as a defective portion on the inner surface or the outer surface of said pipe, on the one hand, and a portion of the outer surface or the inner surface of said pipe corresponding to a normal portion of the inner surface or the outer surface of said pipe, on the other hand; then shooting the outer surface or the inner surface of said pipe by means of a thermal imaging system while said difference in temperature still remains on the outer surface or the inner surface of said pipe, to obtain a thermal image of said difference in temperature; then determining a temperature distribution of said thermal image of said difference in temperature on a line passing the highest temperature point or the lowest temperature point in said thermal image of said difference in temperature; then calculating a differential value of said temperature distribution; then determining two points of inflection on the both sides of said highest temperature point or said lowest temperature point of said temperature distribution for said thinned out portion, on the basis of said calculated differential value of said temperature distribution; then detecting an extent of said thinned out portion on the basis of a distance between said two points of inflection of said temperature distribution; on the other hand, heating or cooling an experimental pipe having an artificial thinned out portion of a prescribed extent and a prescribed depth on the inner surface or the outer surface of said experimental pipe, from the side of the outer surface thereof or the inner surface thereof, to previously determine a heat analysis data concerning the relationship between the highest temperature or the lowest temperature of a portion of the outer surface or the inner surface of said experimental pipe corresponding to said artificial thinned out portion on the inner surface or the outer surface of said experimental pipe, the extent of said artificial thinned out portion, and the depth of said artificial thinned out portion; and then detecting a depth of said thinned out portion on the basis of said extent of said thinned out portion detected by said distance between said two points of inflection of said temperature distribution, said highest temperature point or said lowest temperature point in said thermal image of said difference in temperature, and said previously determined heat analysis data.
Claim 4
Independent Claim
463 words
A method for detecting a thinned out portion on the inner surface or the outer surface of a pipe, characterized by comprising the steps of: heating or cooling a pipe to be tested from the side of the outer surface thereof or the inner surface thereof so that a difference in temperature is produced between a portion of the outer surface or the inner surface of said pipe corresponding to a thinned out portion as a defective portion on the inner surface or the outer surface of said pipe, on the one hand, and a portion of the outer surface or the inner surface of said pipe corresponding to a normal portion of the inner surface or the outer surface of said pipe, on the other hand; then shooting the outer surface or the inner surface of said pipe by means of a thermal imaging system while said difference in temperature still remains on the outer surface or the inner surface of said pipe, to obtain a thermal image of said difference in temperature; then determining a temperature distribution of said thermal image of said difference in temperature on a line passing the highest temperature point or the lowest temperature point in said thermal image of said difference in temperature; then calculating a differential value of said temperature distribution; then determining two points of inflection on the both sides of said highest temperature point or said lowest temperature point of said temperature distribution for said thinned out portion, on the basis of said calculated differential value of said temperature distribution; then detecting an extent of said thinned out portion on the basis of a distance between said two points of inflection of said temperature distribution; on the other hand, heating or cooling an experimental pipe having an artificial thinned out portion of a prescribed extent and a prescribed depth on the inner surface or the outer surface of said experimental pipe, from the side of the outer surface thereof or the inner surface thereof, to previously determine a heat analysis data concerning the relationship between the highest temperature or the lowest temperature of a portion of the outer surface or the inner surface of said experimental pipe corresponding to said artificial thinned out portion on the inner surface or the outer surface of said experimental pipe, the extent of said artificial thinned out portion, and the depth of said artificial thinned out portion; and then detecting a depth of said thinned out portion on the basis of said extent of said thinned out portion detected by said distance between said two points of inflection of said temperature distribution, said highest temperature point or said lowest temperature point in said thermal image of said difference in temperature, and said previously determined heat analysis data.
Claim 5
Dependent Claim
184 words
The method as claimed in Claim 1 or 2, characterized by: shooting, prior to said heating or said cooling of said pipe from the side of the outer surface thereof or the inner surface thereof, the outer surface or the inner surface of said pipe by means of said thermal imaging system, to obtain a thermal image which shows a pseudo defective portion including adhesion of foreign matters or presence of a thinned out portion on the outer surface or the inner surface of said pipe; then obtaining said thermal image of said difference in temperature, said thermal image of said difference in temperature including said thermal image showing said pseudo defective portion in addition to a thermal image showing said thinned out portion as said defective portion; then eliminating said thermal image showing said pseudo defective portion from said thermal image of said difference in temperature including said thermal image showing said pseudo defective portion; and then determining said temperature distribution of said thermal image of said difference in temperature from which said thermal image showing said pseudo defective portion has been eliminated.
Claim 6
Dependent Claim
498 words
The method as claimed in Claim 1 or 2, characterized by: shooting, prior to said heating or said cooling of said pipe from the side of the outer surface thereof or the inner surface thereof, the outer surface or the inner surface of said pipe by means of said thermal imaging system, to obtain a thermal image which shows a pseudo defective portion including adhesion of foreign matters or presence of a thinned out portion on the outer surface or the inner surface of said pipe; then determining a temperature distribution of said thermal image showing said pseudo defective portion on a line passing the highest temperature point or the lowest temperature point in said thermal image showing said pseudo defective portion; then calculating a differential value of said temperature distribution of said thermal image showing said pseudo defective portion; then determining two points of inflection on the both sides of said highest temperature point or said lowest temperature point of said temperature distribution for said pseudo defective portion, on the basis of said calculated differential value of said temperature distribution of said thermal image showing said pseudo defective portion; then obtaining said thermal image of said difference in temperature, said thermal image of said difference in temperature including said thermal image showing said pseudo defective portion in addition to a thermal image showing said thinned out portion as said defective portion; then determining a temperature distribution of each of said thermal image showing said pseudo defective portion and said thermal image showing said thinned out portion, on a line passing the highest temperature point or the lowest temperature point in said thermal image showing each of said pseudo defective portion and said thinned out portion, in said thermal image of said difference in temperature including said thermal image showing said pseudo defective portion; then calculating a differential value of each of said temperature distribution of said thermal image showing said pseudo defective portion and said temperature distribution of said thermal image showing said thinned out portion; then determining two points of inflection on the both sides of said highest temperature point or said lowest temperature point of said temperature distribution for each of said pseudo defective portion and said thinned out portion, on the basis of said calculated differential value of each of said temperature distribution of said thermal image showing said pseudo defective portion and said temperature distribution of said thermal image showing said thinned out portion; then eliminating said two points of inflection of said pseudo defective portion, as determined from said thermal image showing said pseudo defective portion, from said respective two points of inflection of said pseudo defective portion and said thinned out portion, as determined from said thermal image of said difference in temperature including said thermal image showing said pseudo defective portion; and then detecting an extent of said thinned out portion, on the basis of a distance between said two points of inflection of said thinned out portion thus obtained.
Claim 7
Dependent Claim
65 words
The method as claimed in Claim 1 or 2, wherein: the outer surface of said pipe is exposed; said thinned out portion exists on the inner surface of said pipe; said pipe is heated or cooled from the side of the outer surface thereof or the inner surface thereof; and the outer surface of said pipe is shot by means of said thermal imaging system.
Claim 8
Dependent Claim
61 words
The method as claimed in Claim 1 or 2, wherein: the outer surface of said pipe is not exposed; said thinned out portion exists on the outer surface of said pipe; said pipe is heated or cooled from the side of the inner surface thereof; and the inner surface of said pipe is shot by means of said thermal imaging system.
References Cited (Backward Citations)
No citation records indexed.
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