WO2009045015A1 - Apparatus for monitoring damage of pipe - Google Patents

Apparatus for monitoring damage of pipe Download PDF

Info

Publication number
WO2009045015A1
WO2009045015A1 PCT/KR2008/005660 KR2008005660W WO2009045015A1 WO 2009045015 A1 WO2009045015 A1 WO 2009045015A1 KR 2008005660 W KR2008005660 W KR 2008005660W WO 2009045015 A1 WO2009045015 A1 WO 2009045015A1
Authority
WO
WIPO (PCT)
Prior art keywords
pipe
electric current
magnetic saturation
damage
voltage
Prior art date
Application number
PCT/KR2008/005660
Other languages
French (fr)
Inventor
Jang Bom Chai
Young Sun Kim
Original Assignee
M & D Co., Ltd.
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 M & D Co., Ltd. filed Critical M & D Co., Ltd.
Publication of WO2009045015A1 publication Critical patent/WO2009045015A1/en

Links

Classifications

    • 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
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
    • G01N27/9006—Details, e.g. in the structure or functioning of sensors
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
    • 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
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • 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

Definitions

  • the present invention relates to an apparatus for monitoring damage of pipes, and more particularly to a pipe damage monitoring apparatus which easily detects wear of the pipes whose thickness is thinned or damage of the pipes which may occurs on the inner wall of the pipes such as crack of the pipes, by high temperature and high pressure fluid or gas which flows in the pipes.
  • a pipe damage monitoring apparatus using an ultrasonic sensor generates an ultrasonic wave onto surface of a pipe, detects the ultrasonic wave reflected from the inner wall or crack of the pipe, and measures a propagation speed and a reflection time of the ultrasonic wave, to thereby monitor whether or not change of the thickness of the pipe or occurrence of the crack in the pipe happens.
  • the pipe damage monitoring apparatus using the ultrasonic wave makes an ultrasonic generator contact the outer surface of the pipe using a liquid couplant such as gel in order to improve generation of ultrasonic waves on the outer surface of the pipe.
  • the ultrasonic sensor is weak at a high temperature. In the case of a pipe which is applied at a high temperature, it is difficult to use the conventional pipe damage monitoring apparatus using the ultrasonic wave at a state of directly contacting the high temperature pipe. Even though a heat transfer prevention member is attached on the ultrasonic sensor, it is not so good to effectively generate ultrasonic waves due to the couplant which falls down along the outer surface of the pipe.
  • the conventional pipe damage monitoring apparatus using the ultrasonic wave generates an ultrasonic wave onto surface of a pipe, detects the ultrasonic wave reflected from the inner wall or crack of the pipe, and measures a propagation speed and a reflection time of the ultrasonic wave, to thereby monitor whether or not change of the thickness of the pipe or occurrence of the crack in the pipe happens. As a result, it takes much time to detect whether or not the wear of the pipe or the damage of the pipe happens.
  • the pipe damage monitoring apparatus does not need a couplant such as gel but is made to be always mounted in a pipe and directly contact even a high temperature pipe, to thereby easily monitor and quickly detect wear of the pipe or damage of pipe happens.
  • an apparatus for monitoring damage of pipes comprising: a magnetic field generator which generates a magnetic field by an electric current that is generated by a voltage at a pipe monitoring point at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state at the pipe monitoring point; an electric current detector which traces change of the electric current which enables the magnetic field generator to generate the magnetic field and detects a magnetic saturation electric current when the magnetic saturation state has been formed at the pipe monitoring point; and a comparator which compares the magnetic saturation electric current detected from the electric current detector with a reference magnetic saturation electric current of a normal pipe and thus outputs a pipe damage signal if the magnetic saturation electric current is smaller than the reference magnetic saturation electric current.
  • an apparatus for monitoring damage of pipes comprising: a magnetic field generator which generates a magnetic field by an electric current that is generated by a voltage at a pipe monitoring point at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state at the pipe monitoring point; an electric current detector which traces change of the electric current which enables the magnetic field generator to generate the magnetic field and detects a magnetic saturation electric current when the magnetic saturation state has been formed at the pipe monitoring point; a look-up table which stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall and magnitude of crack having occurred in the pipe inner wall; and a pipe damage determination unit which compares the magnetic saturation electric current detected from the electric current detector with the magnetic saturation electric current values stored in the look-up table, to thereby determine a degree of damage of the pipe.
  • the magnetic field generator comprises: an electric power supply which supplies a voltage; a core whose one end contacts the outer wall of the pipe located at one side of the pipe monitoring point and whose other end contacts the outer wall of the pipe located at the other side of the pipe monitoring point; and a coil which is wound around the outer circumferential surface of the core and which generates a closed loop magnetic field in the inside of the core and from one side of the pipe monitoring point to the other side thereof, by the voltage.
  • the core has a magnetic flux density larger than that of the pipe at the magnetic saturation state so that the magnetic saturation state cannot be produced.
  • an apparatus for monitoring damage of pipes generates a magnetic field into the inner wall of a pipe to be monitored at a pipe monitoring point to then form a magnetic saturation state at the pipe monitoring point, and detects change of an electric current at the magnetic saturation state, to thereby monitor whether or not wear of the pipe or damage of pipe happens.
  • the pipe damage monitoring apparatus according to the present invention does not need a couplant such as gel but is made to be always mounted in a pipe and directly contact even a high temperature pipe, to thereby easily monitor and quickly detect wear of the pipe or damage of pipe happens.
  • FIG. 1 is a schematic diagram of a pipe damage monitoring apparatus according to an embodiment of the present invention.
  • FIG. 2 is a schematic view showing a closed loop magnetic field at a core and a pipe monitoring point
  • FIG. 3 is a waveform diagram showing a magnetic saturation property at a piping monitoring point
  • FIG. 4 is a waveform diagram showing change of electric current flowing in a coil due to damage of a pipe
  • FIG. 5 is a waveform diagram showing respective magnetic saturation properties of a cast iron plate and a silicon steel plate.
  • FIG. 6 is a schematic diagram of a pipe damage monitoring apparatus according to another embodiment of the present invention. Best Mode for Carrying Out the Invention
  • FIG. 1 is a schematic diagram of a pipe damage monitoring apparatus according to an embodiment of the present invention
  • FIG. 2 is a schematic view showing a closed loop magnetic field at a core and a pipe monitoring point.
  • an apparatus for monitoring damage of pipes includes: a magnetic field generator 10 which generates a magnetic field (CM) by an electric current that is generated by a voltage at a pipe monitoring point (P) at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state (PSM) at the pipe monitoring point (P); an electric current detector 20 which traces change of the electric current which enables the magnetic field generator 10 to generate the magnetic field (CM) and detects a magnetic saturation electric current (SI) when the magnetic saturation state (PSM) has been formed at the pipe monitoring point (P); and a comparator 30 which compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with a reference magnetic saturation electric current (RSI) of a normal pipe and thus outputs a pipe damage signal (PDS) if the magnetic saturation electric current (SI) is smaller than the reference magnetic saturation electric current (RSI).
  • CM magnetic field
  • PDS reference magnetic saturation electric current
  • FIG. 6 is a schematic diagram of a pipe damage monitoring apparatus according to another embodiment of the present invention.
  • an apparatus for monitoring damage of pipes includes: a magnetic field generator 10 which generates a magnetic field (CM) by an electric current that is generated by a voltage at a pipe monitoring point (P) at which damage of an inner wall 110 of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state (PSM) at the pipe monitoring point (P); an electric current detector 20 which traces change of the electric current which enables the magnetic field generator 10 to generate the magnetic field (CM) and detects a magnetic saturation electric current (SI) when the magnetic saturation state (PSM) has been formed at the pipe monitoring point (P); a look-up table 40 which stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall 110 and magnitude of crack having occurred in the pipe inner wall 110; and a pipe damage determination unit 50 which compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with the magnetic saturation electric current values stored in the look-up table 40, to
  • the magnetic field generator 10 includes: an electric power supply 11 which supplies a voltage; a core 13 whose one end 13a contacts the outer wall of the pipe located at one side 110a of the pipe monitoring point (P) and whose other end 13b contacts the outer wall of the pipe located at the other side 110b of the pipe monitoring point (P); and a coil 15 which is wound around the outer circumferential surface of the core 13 and which generates a closed loop magnetic field in the inside of the core 13 and from one side 110a of the pipe monitoring point (P) to the other side 110b thereof, by the voltage.
  • the core 13 has a magnetic flux density larger than that of the pipe 100 at the magnetic saturation state (PSM) so that the magnetic saturation state (PSM) cannot be produced.
  • the voltage output from the electric power supply 11 may be a direct- current (DC) voltage or an alternating-current (AC) voltage, but it is preferable that the voltage output from the electric power supply 11 may be a direct-current (DC) voltage in order to make an electric current (I) flowing in the coil 15 passes to coil 15 have a stabilized and constant value.
  • DC direct- current
  • AC alternating-current
  • a magnetic field generator 10 including an electric power supply 11, a core 13 and a coil 15 is made to contact a pipe monitoring point (P) in order to detect wear of a pipe 100 or occurrence of crack that is, damage of the pipe 100 along the outer wall of the pipe 100. That is, one end 13a of the core 13 is made to contact the outer wall of the pipe 100 located at one side 110a of the pipe monitoring point (P) and the other end 13b of the core 13 is made to contact the outer wall of the pipe 100 located at one side 110b of the pipe monitoring point (P). Then, the magnetic field generator 10 is fixed onto the pipe 100 using a string (not shown).
  • the pipe 100 may be made of a cast iron material.
  • the core 13 may be made of a silicon steel plate whose magnetic flux density (T) is larger than that of the cast iron tube.
  • PSM magnetic saturation
  • magnetic saturation means that the magnetic flux density (T) reaches a saturation point "A" on a magnetic saturation curve even if the electric current flowing in the coil 15 is continuously made to increase, and then the magnetic flux density (T) in a magnetic body is not linearly increased but is saturated. That is, if the electric current flowing in the coil 15 is made to increase before intensity of the magnetic field reaches a point "B,” the magnetic flux density (T) is linearly increased according to the electric current flowing in the coil 15. However, if intensity of the magnetic field reaches a point "B,” the magnetic flux density (T) is not increased any more but saturated, even if the electric current flowing in the coil 15 is continuously made to increase.
  • a permeability is decreased if magnetic saturation (PSM) occurs at the pipe monitoring point (P).
  • PSM magnetic saturation
  • reluctance of a magnetic circuit increases, and inductance which is flux linkage of the coil 15 decreases due to the increase of the reluctance of the magnetic circuit. Accordingly, impedance of the coil 15 decreases.
  • the electric current flowing in the coil 15 sharply increases at a point in time where magnetic saturation occurs at the pipe monitoring point (P), as illustrated in FIG. 4.
  • a curve ⁇ represents an electric current waveform of a normal pipe having no wear of the pipe or the crack of the pipe along the inner wall of the pipe. It can be seen from the curve ⁇ of FIG. 4 that electric current sharply increases due to magnetic saturation on the inner wall of the pipe, at a point in time of t3. It can be also seen from a curve ® of FIG.
  • the voltage output from the electric power supply 11 is applied to the coil 15 and then the voltage is made to slowly increase.
  • a magnetic field (CM) occurs in the core 13 by electric current flowing in the coil 15.
  • a closed loop magnetic field directing a route of a portion of one side 110a of the pipe monitoring point (P) contacting one end 13a of the core 13, the inner wall 110 of the pipe, the other side 110b of the pipe monitoring point (P) contacting the other end 13b of the core 13, and the other end 13b of the core 13, is formed by the magnetic field of the core 13.
  • the magnetic field becomes a magnetic saturation state (PSM) at the pipe monitoring point (P) on the inner wall 110 of the pipe.
  • PSM magnetic saturation state
  • the electric current detector 20 traces the electric current flowing in the coil 15, and detects a magnetic saturation electric current (SI) at the electric current value of the sharply increased electric current, that is, at the magnetic saturation state (PSM) of the pipe monitoring point (P).
  • a comparator 30 compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with a reference magnetic saturation electric current (RSI) of a normal pipe and thus outputs an activated pipe damage signal (PDS) if the magnetic saturation electric current (SI) is smaller than the reference magnetic saturation electric current (RSI), and a deactivated pipe damage signal (PDS) if the magnetic saturation electric current (SI) equals the reference magnetic saturation electric current (RSI).
  • a direct-current (DC) voltage is used as the voltage output from the electric power supply 11 instead of alternating-current (AC) voltage, and the DC voltage is made to slowly increase. Then, a penetration depth of the magnetic field (CM) which occurs at the pipe monitoring point (P) may become deeper.
  • FIG. 6 is a schematic diagram of a pipe damage monitoring apparatus according to another embodiment of the present invention.
  • the operation of the pipe damage monitoring apparatus shown in FIG. 6 equals that of FIG. 1.
  • the pipe damage monitoring apparatus of FIG. 6 includes a look-up table 40 and a pipe damage determination unit 50, instead of the comparator 30 of FIG. 1.
  • the look-up table 40 stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall 110 and magnitude of crack having occurred in the pipe inner wall 110, and a pipe damage determination unit 50 compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with the magnetic saturation electric current values stored in the look-up table 40, to thereby determine a degree of damage on the inner wall of the pipe. That is, the pipe damage determination unit 50 can determine how much thickness of the pipe inner wall 110 is thinned due to wear of the pipe, or how many degrees a crack occurs on the pipe inner wall 110.
  • SI magnetic saturation electric current
  • the core 13 should use a material whose magnetic flux density at the time of magnetic saturation is larger in comparison with the pipe 100. Since ordinary pipes 100 are made of cast iron, the core 13 is preferably made of a silicon steel plate whose magnetic flux density at the time of magnetic saturation is larger than the cast iron. More preferably, the core 13 is formed of a lamination of the silicon steel plates.
  • an apparatus for monitoring damage of pipes can be applied to easily detect wear of the pipes whose thickness is thinned or damage of the pipes which may occurs on the inner wall of the pipes such as crack of the pipes, by high temperature and high pressure fluid or gas which flows in the pipes.

Landscapes

  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

Provided is an apparatus for monitoring damage of pipes, which includes: a magnetic field generator (10) which generates a magnetic field (CM) by an electric current that is generated by a voltage at a pipe monitoring point (P) at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state (PSM) at the pipe monitoring point (P); an electric current detector (20) which traces change of the electric current which enables the magnetic field generator (10) to generate the magnetic field (CM) and detects a magnetic saturation electric current (SI) when the magnetic saturation state (PSM) has been formed at the pipe monitoring point (P); and a comparator (30) which compares the magnetic saturation electric current (SI) detected from the electric current detector (20) with a reference magnetic saturation electric current (RSI) of a normal pipe and thus outputs a pipe damage signal (PDS) if the magnetic saturation electric current (SI) is smaller than the reference magnetic saturation electric current (RSI).

Description

Description
APPARATUS FOR MONITORING DAMAGE OF PIPE
Technical Field
[1] The present invention relates to an apparatus for monitoring damage of pipes, and more particularly to a pipe damage monitoring apparatus which easily detects wear of the pipes whose thickness is thinned or damage of the pipes which may occurs on the inner wall of the pipes such as crack of the pipes, by high temperature and high pressure fluid or gas which flows in the pipes. Background Art
[2] In general, pipes or tubes play a very important role of transporting fluid or gas in almost all industrial facilities or daily lives.
[3] In the case of the pipes or tubes, wear of the pipes whose thickness is thinned or damage of pipes which may occurs on the inner wall of the pipes such as crack which deteriorates mechanical properties of the pipes, may happen by high temperature and high pressure fluid or gas which flows in the pipes. The wear of the pipes or the damage of pipes may cause serious economical and manpower loss. Accordingly, it is necessary to have to monitor whether or not pipes are damaged.
[4] In the conventional cases, ultrasonic sensors have been used for monitoring whether or not wear of the pipes or damage of pipes exists in the pipes. A pipe damage monitoring apparatus using an ultrasonic sensor generates an ultrasonic wave onto surface of a pipe, detects the ultrasonic wave reflected from the inner wall or crack of the pipe, and measures a propagation speed and a reflection time of the ultrasonic wave, to thereby monitor whether or not change of the thickness of the pipe or occurrence of the crack in the pipe happens.
[5] The pipe damage monitoring apparatus using the ultrasonic wave makes an ultrasonic generator contact the outer surface of the pipe using a liquid couplant such as gel in order to improve generation of ultrasonic waves on the outer surface of the pipe.
[6] The ultrasonic sensor is weak at a high temperature. In the case of a pipe which is applied at a high temperature, it is difficult to use the conventional pipe damage monitoring apparatus using the ultrasonic wave at a state of directly contacting the high temperature pipe. Even though a heat transfer prevention member is attached on the ultrasonic sensor, it is not so good to effectively generate ultrasonic waves due to the couplant which falls down along the outer surface of the pipe.
[7] In addition, even in the case that the conventional pipe damage monitoring apparatus using the ultrasonic wave is used for a pipe which is applied at a low temperature, the couplant between the outer surface of the pipe and the ultrasonic sensor is dried or disappears according to lapse of time. As a result, if a given time passes, the ultrasonic wave is not transferred into the inside of the pipe, to thereby cause the conventional pipe damage monitoring apparatus using the ultrasonic wave not to monitor whether or not the wear of the pipe or the damage of the pipe happens.
[8] In addition, the conventional pipe damage monitoring apparatus using the ultrasonic wave generates an ultrasonic wave onto surface of a pipe, detects the ultrasonic wave reflected from the inner wall or crack of the pipe, and measures a propagation speed and a reflection time of the ultrasonic wave, to thereby monitor whether or not change of the thickness of the pipe or occurrence of the crack in the pipe happens. As a result, it takes much time to detect whether or not the wear of the pipe or the damage of the pipe happens.
Disclosure of Invention Technical Problem
[9] Therefore, to solve the above problems, it is an object of the present invention to provide an apparatus for monitoring damage of pipes which generates a magnetic field into the inner wall of a pipe to be monitored at a pipe monitoring point to then form a magnetic saturation state at the pipe monitoring point, and detects change of an electric current at the magnetic saturation state, to thereby monitor whether or not wear of the pipe or damage of pipe happens. As a result, the pipe damage monitoring apparatus according to the present invention does not need a couplant such as gel but is made to be always mounted in a pipe and directly contact even a high temperature pipe, to thereby easily monitor and quickly detect wear of the pipe or damage of pipe happens. Technical Solution
[10] To accomplish the above object of the present invention, according to an aspect of the present invention, there is provided an apparatus for monitoring damage of pipes, the pipe damage monitoring apparatus comprising: a magnetic field generator which generates a magnetic field by an electric current that is generated by a voltage at a pipe monitoring point at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state at the pipe monitoring point; an electric current detector which traces change of the electric current which enables the magnetic field generator to generate the magnetic field and detects a magnetic saturation electric current when the magnetic saturation state has been formed at the pipe monitoring point; and a comparator which compares the magnetic saturation electric current detected from the electric current detector with a reference magnetic saturation electric current of a normal pipe and thus outputs a pipe damage signal if the magnetic saturation electric current is smaller than the reference magnetic saturation electric current.
[11] According to another aspect of the present invention, there is provided an apparatus for monitoring damage of pipes, the pipe damage monitoring apparatus comprising: a magnetic field generator which generates a magnetic field by an electric current that is generated by a voltage at a pipe monitoring point at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state at the pipe monitoring point; an electric current detector which traces change of the electric current which enables the magnetic field generator to generate the magnetic field and detects a magnetic saturation electric current when the magnetic saturation state has been formed at the pipe monitoring point; a look-up table which stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall and magnitude of crack having occurred in the pipe inner wall; and a pipe damage determination unit which compares the magnetic saturation electric current detected from the electric current detector with the magnetic saturation electric current values stored in the look-up table, to thereby determine a degree of damage of the pipe.
[12] Preferably but not necessarily, the magnetic field generator comprises: an electric power supply which supplies a voltage; a core whose one end contacts the outer wall of the pipe located at one side of the pipe monitoring point and whose other end contacts the outer wall of the pipe located at the other side of the pipe monitoring point; and a coil which is wound around the outer circumferential surface of the core and which generates a closed loop magnetic field in the inside of the core and from one side of the pipe monitoring point to the other side thereof, by the voltage.
[13] Preferably but not necessarily, when the pipe monitoring point is at the magnetic saturation state by an increase of the voltage, the core has a magnetic flux density larger than that of the pipe at the magnetic saturation state so that the magnetic saturation state cannot be produced.
Advantageous Effects
[14] As described above, an apparatus for monitoring damage of pipes according to the present invention generates a magnetic field into the inner wall of a pipe to be monitored at a pipe monitoring point to then form a magnetic saturation state at the pipe monitoring point, and detects change of an electric current at the magnetic saturation state, to thereby monitor whether or not wear of the pipe or damage of pipe happens. As a result, the pipe damage monitoring apparatus according to the present invention does not need a couplant such as gel but is made to be always mounted in a pipe and directly contact even a high temperature pipe, to thereby easily monitor and quickly detect wear of the pipe or damage of pipe happens. Brief Description of the Drawings
[15] The above and/or other objects and/or advantages of the present invention will become more apparent by describing the preferred embodiments thereof in detail with reference to the accompanying drawings in which:
[16] FIG. 1 is a schematic diagram of a pipe damage monitoring apparatus according to an embodiment of the present invention;
[17] FIG. 2 is a schematic view showing a closed loop magnetic field at a core and a pipe monitoring point;
[18] FIG. 3 is a waveform diagram showing a magnetic saturation property at a piping monitoring point;
[19] FIG. 4 is a waveform diagram showing change of electric current flowing in a coil due to damage of a pipe;
[20] FIG. 5 is a waveform diagram showing respective magnetic saturation properties of a cast iron plate and a silicon steel plate; and
[21] FIG. 6 is a schematic diagram of a pipe damage monitoring apparatus according to another embodiment of the present invention. Best Mode for Carrying Out the Invention
[22] Hereinbelow, an apparatus for monitoring damage of pipes according to preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals denote like elements through the following embodiments.
[23] FIG. 1 is a schematic diagram of a pipe damage monitoring apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view showing a closed loop magnetic field at a core and a pipe monitoring point.
[24] As illustrated in FIGS 1 and 2, an apparatus for monitoring damage of pipes, according to an embodiment of the present invention includes: a magnetic field generator 10 which generates a magnetic field (CM) by an electric current that is generated by a voltage at a pipe monitoring point (P) at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state (PSM) at the pipe monitoring point (P); an electric current detector 20 which traces change of the electric current which enables the magnetic field generator 10 to generate the magnetic field (CM) and detects a magnetic saturation electric current (SI) when the magnetic saturation state (PSM) has been formed at the pipe monitoring point (P); and a comparator 30 which compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with a reference magnetic saturation electric current (RSI) of a normal pipe and thus outputs a pipe damage signal (PDS) if the magnetic saturation electric current (SI) is smaller than the reference magnetic saturation electric current (RSI).
[25] FIG. 6 is a schematic diagram of a pipe damage monitoring apparatus according to another embodiment of the present invention.
[26] As illustrated in FIG. 6, an apparatus for monitoring damage of pipes, according to another embodiment of the present invention includes: a magnetic field generator 10 which generates a magnetic field (CM) by an electric current that is generated by a voltage at a pipe monitoring point (P) at which damage of an inner wall 110 of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state (PSM) at the pipe monitoring point (P); an electric current detector 20 which traces change of the electric current which enables the magnetic field generator 10 to generate the magnetic field (CM) and detects a magnetic saturation electric current (SI) when the magnetic saturation state (PSM) has been formed at the pipe monitoring point (P); a look-up table 40 which stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall 110 and magnitude of crack having occurred in the pipe inner wall 110; and a pipe damage determination unit 50 which compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with the magnetic saturation electric current values stored in the look-up table 40, to thereby determine a degree of damage of the pipe.
[27] In addition, the magnetic field generator 10 includes: an electric power supply 11 which supplies a voltage; a core 13 whose one end 13a contacts the outer wall of the pipe located at one side 110a of the pipe monitoring point (P) and whose other end 13b contacts the outer wall of the pipe located at the other side 110b of the pipe monitoring point (P); and a coil 15 which is wound around the outer circumferential surface of the core 13 and which generates a closed loop magnetic field in the inside of the core 13 and from one side 110a of the pipe monitoring point (P) to the other side 110b thereof, by the voltage.
[28] In addition, when the pipe monitoring point (P) is at the magnetic saturation state
(PSM) by an increase of the voltage, the core 13 has a magnetic flux density larger than that of the pipe 100 at the magnetic saturation state (PSM) so that the magnetic saturation state (PSM) cannot be produced.
[29] In addition, the voltage output from the electric power supply 11 may be a direct- current (DC) voltage or an alternating-current (AC) voltage, but it is preferable that the voltage output from the electric power supply 11 may be a direct-current (DC) voltage in order to make an electric current (I) flowing in the coil 15 passes to coil 15 have a stabilized and constant value.
[30] Operations of the pipe damage monitoring apparatuses according to the respective embodiments of the present invention having the above-described structures will follow with reference to the accompanying drawings.
[31] As illustrated in FIGS. 1 and 2, a magnetic field generator 10 including an electric power supply 11, a core 13 and a coil 15 is made to contact a pipe monitoring point (P) in order to detect wear of a pipe 100 or occurrence of crack that is, damage of the pipe 100 along the outer wall of the pipe 100. That is, one end 13a of the core 13 is made to contact the outer wall of the pipe 100 located at one side 110a of the pipe monitoring point (P) and the other end 13b of the core 13 is made to contact the outer wall of the pipe 100 located at one side 110b of the pipe monitoring point (P). Then, the magnetic field generator 10 is fixed onto the pipe 100 using a string (not shown).
[32] The voltage output from the electric power supply 11 is made to slowly increase. Accordingly, an electric current flows in the coil 15. As a result, a closed loop magnetic field is formed in the inside of the core 13 and at the pipe monitoring point (P) located on the inner wall of the pipe 100, by the electric current applied to the coil 15, as illustrated in FIG. 2.
[33] As illustrated in FIG. 5, the pipe 100 may be made of a cast iron material. In the case that the pipe 100 is made of a cast iron tube, the core 13 may be made of a silicon steel plate whose magnetic flux density (T) is larger than that of the cast iron tube. In this case, if the voltage output from the electric power supply 11 is continuously made to increase, magnetic saturation (PSM) is accomplished at the pipe monitoring point (P) of the pipe 100 whose magnetic flux density (T) at the time of the magnetic saturation is smaller than that of the core 13 earlier than that of the inside of the core 13, as illustrated in FIG. 2.
[34] As illustrated in FIG. 3, magnetic saturation means that the magnetic flux density (T) reaches a saturation point "A" on a magnetic saturation curve even if the electric current flowing in the coil 15 is continuously made to increase, and then the magnetic flux density (T) in a magnetic body is not linearly increased but is saturated. That is, if the electric current flowing in the coil 15 is made to increase before intensity of the magnetic field reaches a point "B," the magnetic flux density (T) is linearly increased according to the electric current flowing in the coil 15. However, if intensity of the magnetic field reaches a point "B," the magnetic flux density (T) is not increased any more but saturated, even if the electric current flowing in the coil 15 is continuously made to increase.
[35] A permeability is decreased if magnetic saturation (PSM) occurs at the pipe monitoring point (P). Thus, reluctance of a magnetic circuit increases, and inductance which is flux linkage of the coil 15 decreases due to the increase of the reluctance of the magnetic circuit. Accordingly, impedance of the coil 15 decreases. As a result, the electric current flowing in the coil 15 sharply increases at a point in time where magnetic saturation occurs at the pipe monitoring point (P), as illustrated in FIG. 4. [36] In the case that thickness of a pipe is thinned due to a long use of the pipe, wear of the pipe occurs on the inner wall of the pipe or crack occurs on the inner wall of the pipe, that is, damage of the pipe occurs in the pipe, magnetic saturation is accomplished at a damaged portion OP) earlier in comparison with a normal pipe. That is, as illustrated in FIG. 4, a curve © represents an electric current waveform of a normal pipe having no wear of the pipe or the crack of the pipe along the inner wall of the pipe. It can be seen from the curve © of FIG. 4 that electric current sharply increases due to magnetic saturation on the inner wall of the pipe, at a point in time of t3. It can be also seen from a curve ® of FIG. 4 that wear of a pipe or crack of the pipe occurs along the inner wall of the pipe, to thus produce magnetic saturation on the inner wall of the pipe and to thus cause the electric current to be sharply increased, and magnetic saturation of the curve ® has occurred earlier in comparison with the curve ©. It can be also seen from a curve © of FIG. 4 that magnetic saturation has occurred earlier in comparison with the normal pipe and thus the inner wall of the pipe has been damaged. That is, it can be seen that damage of the inner wall of the pipe has been m ore serious in the case of the curve ® in comparison with that of the curve ©.
[37] Therefore, in the case of the pipe damage monitoring apparatus according to the present invention, the voltage output from the electric power supply 11 is applied to the coil 15 and then the voltage is made to slowly increase. A magnetic field (CM) occurs in the core 13 by electric current flowing in the coil 15. A closed loop magnetic field directing a route of a portion of one side 110a of the pipe monitoring point (P) contacting one end 13a of the core 13, the inner wall 110 of the pipe, the other side 110b of the pipe monitoring point (P) contacting the other end 13b of the core 13, and the other end 13b of the core 13, is formed by the magnetic field of the core 13. When the voltage output from the electric power supply 11 is made to continuously increase, the magnetic field becomes a magnetic saturation state (PSM) at the pipe monitoring point (P) on the inner wall 110 of the pipe. When magnetic saturation occurs at the pipe monitoring point (P), the electric current flowing in the coil 15 sharply increases. The electric current detector 20 traces the electric current flowing in the coil 15, and detects a magnetic saturation electric current (SI) at the electric current value of the sharply increased electric current, that is, at the magnetic saturation state (PSM) of the pipe monitoring point (P). A comparator 30 compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with a reference magnetic saturation electric current (RSI) of a normal pipe and thus outputs an activated pipe damage signal (PDS) if the magnetic saturation electric current (SI) is smaller than the reference magnetic saturation electric current (RSI), and a deactivated pipe damage signal (PDS) if the magnetic saturation electric current (SI) equals the reference magnetic saturation electric current (RSI). [38] A direct-current (DC) voltage is used as the voltage output from the electric power supply 11 instead of alternating-current (AC) voltage, and the DC voltage is made to slowly increase. Then, a penetration depth of the magnetic field (CM) which occurs at the pipe monitoring point (P) may become deeper.
[39] Therefore, the comparator 30 cannot distinguish how much the inner wall of a pipe
110 is damaged, but it can only determine whether or not thickness of the inner wall 110 of the pipe decreases, wear of the pipe occurs, and occurrence of crack along the inner wall of the pipe exists.
[40] FIG. 6 is a schematic diagram of a pipe damage monitoring apparatus according to another embodiment of the present invention. The operation of the pipe damage monitoring apparatus shown in FIG. 6 equals that of FIG. 1. However, the pipe damage monitoring apparatus of FIG. 6 includes a look-up table 40 and a pipe damage determination unit 50, instead of the comparator 30 of FIG. 1.
[41] The look-up table 40 stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall 110 and magnitude of crack having occurred in the pipe inner wall 110, and a pipe damage determination unit 50 compares the magnetic saturation electric current (SI) detected from the electric current detector 20 with the magnetic saturation electric current values stored in the look-up table 40, to thereby determine a degree of damage on the inner wall of the pipe. That is, the pipe damage determination unit 50 can determine how much thickness of the pipe inner wall 110 is thinned due to wear of the pipe, or how many degrees a crack occurs on the pipe inner wall 110.
[42] In the case of the pipe damage monitoring apparatus according to the present invention, magnetic saturation should not occur in the core 13 earlier than the pipe inner wall 110 according to an increase of the voltage output from the electric power supply 11, but magnetic saturation should occur in the pipe inner wall 110 earlier than the core 13. Thus, the core 13 should use a material whose magnetic flux density at the time of magnetic saturation is larger in comparison with the pipe 100. Since ordinary pipes 100 are made of cast iron, the core 13 is preferably made of a silicon steel plate whose magnetic flux density at the time of magnetic saturation is larger than the cast iron. More preferably, the core 13 is formed of a lamination of the silicon steel plates. Mode for the Invention
[43] As described above, the present invention has been described with respect to particularly preferred embodiments. However, the present invention is not limited to the above embodiments, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention. Thus, the protective scope of the present invention is not defined within the detailed description thereof but is defined by the claims to be described later and the technical spirit of the present invention. Industrial Applicability
[44] As described above, an apparatus for monitoring damage of pipes according to the present invention can be applied to easily detect wear of the pipes whose thickness is thinned or damage of the pipes which may occurs on the inner wall of the pipes such as crack of the pipes, by high temperature and high pressure fluid or gas which flows in the pipes.

Claims

Claims
[1] An apparatus for monitoring damage of pipes, the pipe damage monitoring apparatus comprising: a magnetic field generator which generates a magnetic field by an electric current that is generated by a voltage at a pipe monitoring point at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state at the pipe monitoring point; an electric current detector which traces change of the electric current which enables the magnetic field generator to generate the magnetic field and detects a magnetic saturation electric current when the magnetic saturation state has been formed at the pipe monitoring point; and a comparator which compares the magnetic saturation electric current detected from the electric current detector with a reference magnetic saturation electric current of a normal pipe and thus outputs a pipe damage signal if the magnetic saturation electric current is smaller than the reference magnetic saturation electric current.
[2] The pipe damage monitoring apparatus according to claim 1, wherein the magnetic field generator comprises: an electric power supply which supplies a voltage; a core whose one end contacts the outer wall of the pipe located at one side of the pipe monitoring point and whose other end contacts the outer wall of the pipe located at the other side of the pipe monitoring point; and a coil which is wound around the outer circumferential surface of the core and which generates a closed loop magnetic field in the inside of the core and from one side of the pipe monitoring point to the other side thereof, by the voltage.
[3] The pipe damage monitoring apparatus according to claim 3, wherein when the pipe monitoring point is at the magnetic saturation state by an increase of the voltage, the core has a magnetic flux density larger than that of the pipe at the magnetic saturation state so that the magnetic saturation state cannot be produced.
[4] The pipe damage monitoring apparatus according to claim 2 or 3, wherein the pipe is made of cast iron and the core is made of a silicon steel plate.
[5] The pipe damage monitoring apparatus according to any one of claims 1 to 3, wherein the voltage is a DC voltage.
[6] An apparatus for monitoring damage of pipes, the pipe damage monitoring apparatus comprising: a magnetic field generator which generates a magnetic field by an electric current that is generated by a voltage at a pipe monitoring point at which damage of an inner wall of a pipe is monitored, and increases the voltage persistently to thus form a magnetic saturation state at the pipe monitoring point; an electric current detector which traces change of the electric current which enables the magnetic field generator to generate the magnetic field and detects a magnetic saturation electric current when the magnetic saturation state has been formed at the pipe monitoring point; a look-up table which stores a number of preset magnetic saturation electric current values according to change of thickness of the pipe inner wall and magnitude of crack having occurred in the pipe inner wall; and a pipe damage determination unit which compares the magnetic saturation electric current detected from the electric current detector with the magnetic saturation electric current values stored in the look-up table, to thereby determine a degree of damage of the pipe.
[7] The pipe damage monitoring apparatus according to claim 6, wherein the magnetic field generator comprises: an electric power supply which supplies a voltage; a core whose one end contacts the outer wall of the pipe located at one side of the pipe monitoring point and whose other end contacts the outer wall of the pipe located at the other side of the pipe monitoring point; and a coil which is wound around the outer circumferential surface of the core and which generates a closed loop magnetic field in the inside of the core and from one side of the pipe monitoring point to the other side thereof, by the voltage.
[8] The pipe damage monitoring apparatus according to claim 6, wherein when the pipe monitoring point is at the magnetic saturation state by an increase of the voltage, the core has a magnetic flux density larger than that of the pipe at the magnetic saturation state so that the magnetic saturation state cannot be produced.
[9] The pipe damage monitoring apparatus according to claim 7 or 8, wherein the pipe is made of cast iron and the core is made of a silicon steel plate.
[10] The pipe damage monitoring apparatus according to any one of claims 6 to 8, wherein the voltage is a DC voltage.
PCT/KR2008/005660 2007-09-29 2008-09-24 Apparatus for monitoring damage of pipe WO2009045015A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2007-0098507 2007-09-29
KR1020070098507A KR20090033294A (en) 2007-09-29 2007-09-29 Pipe damage monitor

Publications (1)

Publication Number Publication Date
WO2009045015A1 true WO2009045015A1 (en) 2009-04-09

Family

ID=40526397

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2008/005660 WO2009045015A1 (en) 2007-09-29 2008-09-24 Apparatus for monitoring damage of pipe

Country Status (2)

Country Link
KR (1) KR20090033294A (en)
WO (1) WO2009045015A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20200095053A (en) 2019-01-31 2020-08-10 주식회사 코아칩스 Wireless displacement sensor system installed outside of pipe and operation method of the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1151907A (en) * 1997-08-04 1999-02-26 Tokyo Gas Co Ltd Damaged position probing method for concealed pipeline
KR20010019866A (en) * 1999-08-31 2001-03-15 이구택 Signal Processing Method for DC Magnetic Flux Leakage
JP2006010646A (en) * 2004-06-29 2006-01-12 Tokyo Electric Power Co Inc:The Method and apparatus for detecting degradation of inner surface of steel pipe

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1151907A (en) * 1997-08-04 1999-02-26 Tokyo Gas Co Ltd Damaged position probing method for concealed pipeline
KR20010019866A (en) * 1999-08-31 2001-03-15 이구택 Signal Processing Method for DC Magnetic Flux Leakage
JP2006010646A (en) * 2004-06-29 2006-01-12 Tokyo Electric Power Co Inc:The Method and apparatus for detecting degradation of inner surface of steel pipe

Also Published As

Publication number Publication date
KR20090033294A (en) 2009-04-02

Similar Documents

Publication Publication Date Title
JP2016008964A (en) Device and method for detecting thickness reduction pulse, using eddy current probe
CN203479275U (en) High-temperature resistant electromagnetic ultrasonic thickness measurement probe
US20160069841A1 (en) NOVEL SEGMENTED STRIP DESIGN FOR A MAGNETOSTRICTION SENSOR (MsS) USING AMORPHOUS MATERIAL FOR LONG RANGE INSPECTION OF DEFECTS AND BENDS IN PIPES AT HIGH TEMPERATURES
CN112903162A (en) Method for evaluating residual stress distribution characteristics of natural gas pipeline circumferential weld by using coercive force
EP2390639A2 (en) Laser shock peening measurement system and method
CN105954362B (en) The supersonic guide-wave generator quickly detected for pipeline
JP5634072B2 (en) Piping / equipment monitoring device and method
CN104198580A (en) Magnetostriction wave guide sensor and heat exchange tube defect detecting system comprising sensor
WO2009045015A1 (en) Apparatus for monitoring damage of pipe
WO2009045020A1 (en) Apparatus for monitoring damage of pipe
KR20110087477A (en) Apparatus and method for detecting the wall thinning of pipeline using pulse magnetic field
JP5313117B2 (en) Corrosion inspection system, corrosion inspection apparatus, and corrosion inspection method
JP2000131008A (en) Apparatus for detecting deposit quantity of magnetic body
JP2011075499A (en) Method and device for inspecting reduced-thickness of piping using electromagnetic ultrasonic wave
KR101823318B1 (en) Monitoring system for rotation of plumbing
JP5470191B2 (en) Corrosion state monitoring method and monitoring system for cathode anticorrosion management probe
JP5031314B2 (en) Electromagnetic ultrasonic sensor and electromagnetic ultrasonic detection system
EP3246684A1 (en) Systems and methods for determining mechanical stress of machinery
Zhong et al. Excitation power design base on series resonant electromagnetic ultrasonic sensor for pipeline NDT
JPH0694383A (en) Double tube type sea-water introduction tube for sea-water heat exchanger
CN207018827U (en) A kind of ultrasound damage device of water supply line
CN216485552U (en) Pipeline surveys clamp with safety protection structure
KR101807859B1 (en) Electromagnetic flowmeter for non-conducting fluid
CN215064395U (en) High-temperature ultrasonic probe integrating temperature detection
JP2000162082A (en) Acoustic leak monitoring apparatus

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 08835979

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 08835979

Country of ref document: EP

Kind code of ref document: A1