Abstract:
A pipe damage detection apparatus and method are disclosed. The pipe damage detection apparatus includes an ultrasonic supply unit configured to supply an ultrasonic signal to a pipe; an ultrasonic reception unit configured to receive the ultrasonic signal of the pipe; and an analysis unit configured to analyze the ultrasonic signal received by the ultrasonic reception unit, and determine whether the pipe is damaged. The pipe damage detection apparatus and method can detect whether a pipe that is difficult for an inspector to access because it is coated with an insulating material or buried in the ground is damaged.

Description:
FIELD OF THE TECHNOLOGY 
       [0001]    The following relates to a pipe damage detection apparatus and method, and more particularly, to a pipe damage detection apparatus and method capable of detecting whether underground pipes and inner pipes of nuclear power plant and chemical plant facilities are damaged. 
       BACKGROUND 
       [0002]    Generally, infrastructure facilities such as bridges, large facilities, underground utilities, etc. are becoming larger and modernized according to the development of society in order to meet various requirements of members of society. 
         [0003]    Accordingly, various new technologies, new methods, new materials, etc. are being introduced, and the need for verification of stability, etc., which is prerequisite for introducing them, is being required. 
         [0004]    Recently, a laser ultrasonic apparatus is used to diagnose structures. The laser ultrasonic apparatus radiates a strong pulse laser beam on the surface of an object, generates an ultrasonic signal, and detects whether the object is damaged by measuring the ultrasonic signal propagated or reflected from the object. 
         [0005]    Meanwhile, a technique serving as background to the present invention entitled “Inspection apparatus and method using laser” is disclosed in Korean Patent No. 10-1072802 registered on Oct. 6, 2011. 
       SUMMARY 
       [0006]    An aspect relates to a pipe damage detection apparatus and method capable of safely detecting whether a pipe with a high temperature condition used in nuclear power generation facilities and plant facilities or underground pipes is damaged. 
         [0007]    According to another aspect, there is provided a pipe damage detection apparatus, including: an ultrasonic supply unit configured to supply an ultrasonic signal to a pipe; an ultrasonic reception unit configured to receive the ultrasonic signal of the pipe; and an analysis unit configured to analyze the ultrasonic signal received by the ultrasonic reception unit, and determine whether the pipe is damaged. 
         [0008]    The ultrasonic supply unit may include: a generation unit configured to generate a laser beam; a supply unit including one end which is connected to the generation unit, and configured to supply the laser beam; and a guide unit connected to the other end of the supply unit, mounted on the pipe, and configured to guide the laser beam to the pipe. 
         [0009]    The supply unit may be an optical fiber. 
         [0010]    The guide unit may include: a guide pipe connected to the supply unit, in contact with the pipe, and configured to guide the laser beam; a guide lens built in the guide pipe, and configured to adjust focus of the laser beam; a guide plate coupled with the guide pipe, formed to protrude in a lateral direction, and in contact with the pipe; and a guide belt formed to cover the guide plate and the pipe, and formed so that the guide plate is coupled with the pipe. 
         [0011]    The ultrasonic reception unit may include: a light source unit configured to generate a laser beam; a transfer unit connected to the light source unit, and configured to transfer the laser beam; a detection unit connected to the transfer unit, mounted on the pipe, and configured to detect the laser beam; and a reception unit connected to the transfer unit, and configured to receive the laser beam and transfer information regarding the ultrasonic signal to the analysis unit. 
         [0012]    The detection unit may include: a detection pipe connected to the transfer unit, in contact with the pipe, and configured to guide the laser beam; a detection lens built in the detection pipe, and configured to adjust focus of the laser beam; a detection filter built in the detection pipe, and configured to block infrared radiant heat coming from the pipe; a detection plate coupled with the detection pipe, formed to protrude in a lateral direction, and in contact with the pipe; and a detection belt formed to cover the detection plate and the pipe, and formed so that the detection plate is coupled with the pipe. 
         [0013]    The transfer unit may be an optical fiber. 
         [0014]    According to another aspect, there is provided a pipe damage detection method, including: supplying, by an ultrasonic supply unit, an ultrasonic signal to a pipe; receiving, by an ultrasonic reception unit, the ultrasonic signal of the pipe; and analyzing, by an analysis unit, the ultrasonic signal and determining whether the pipe is damaged. 
         [0015]    The ultrasonic supply unit may change a guide point along a circumferential surface of the pipe, and the ultrasonic reception unit may change a detection point along the circumferential surface of the pipe. 
         [0016]    When determining, by the analysis unit, of whether the pipe is damaged, includes: calculating a damage index; and analyzing an outlier based on the damage index, wherein the damage index is obtained by following equations: 
         [0000]    
       
         
           
             
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         [0017]    where f i  and f j  represent measurement signals measured in two paths having the same phase,  f i    represents an average value of f i , σf j  represents standard deviation of f i , N represents the number of data points in a time domain of the measured f j , and {tilde over (t)} represents time delay. 
         [0018]    The pipe damage detection apparatus and method can accurately detect the damage of a pipe which is difficult for an inspector to access because it is coated with an insulating material or buried in the ground. 
         [0019]    The pipe damage detection apparatus and method can perform accurate detection on a pipe with a high temperature used in a nuclear power plant facility or a chemical plant facility. 
       BRIEF DESCRIPTION 
       [0020]      FIG. 1  is a schematic diagram illustrating a pipe damage detection apparatus according to an exemplary embodiment of the present invention. 
         [0021]      FIG. 2  is a schematic diagram illustrating a guide unit of a pipe damage detection apparatus according to an exemplary embodiment of the present invention. 
         [0022]      FIG. 3  is a schematic diagram illustrating a detection unit of a pipe damage detection apparatus according to an exemplary embodiment of the present invention. 
         [0023]      FIG. 4  is a schematic flowchart for describing a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0024]      FIG. 5  is a flowchart for describing an operation in which an analysis unit detects whether a pipe is damaged in a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0025]      FIGS. 6 to 8  are schematic diagrams illustrating an ultrasonic signal path according to a guide point of an ultrasonic supply unit and a detection point of an ultrasonic reception unit when a pipe is not damaged in a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0026]      FIGS. 9 to 14  are schematic diagrams for describing a stepwise outlier analysis in a pipe damage detection method according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION 
       [0027]    Hereinafter, a radiation detector according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Thicknesses of lines or sizes of components shown in the figures may be exaggeratedly illustrated for clarity and convenience of description. Further, the terminology described below may be defined by considering a function in the present, and may differ according to an intention or custom of a user or an operator. Accordingly, the definitions with respect to the terminology may be determined based on overall content of the present specification. 
         [0028]      FIG. 1  is a schematic diagram illustrating a pipe damage detection apparatus according to an exemplary embodiment of the present invention,  FIG. 2  is a schematic diagram illustrating a guide unit of a pipe damage detection apparatus according to an exemplary embodiment of the present invention, and  FIG. 3  is a schematic diagram illustrating a detection unit of a pipe damage detection apparatus according to an exemplary embodiment of the present invention. 
         [0029]    A pipe damage detection apparatus  1  according to an exemplary embodiment of the present invention may include an ultrasonic supply unit  10 , an ultrasonic reception unit  20 , and an analysis unit  30 . 
         [0030]    The ultrasonic supply unit  10  may be mounted on a pipe  50 , radiate a laser beam on the pipe  50 , and generate an ultrasonic signal. At this time, the ultrasonic supply unit  10  may generate the ultrasonic signal along a circumferential surface at any one point of the pipe  50 . 
         [0031]    The ultrasonic reception unit  20  may radiate the laser beam on the pipe  50 , and receive the ultrasonic signal of the pipe  50  included in a reflected laser beam. At this time, the ultrasonic reception unit  20  may detect the ultrasonic signal along the circumferential surface at another point of the pipe  50 . 
         [0032]    The analysis unit  30  may analyze the ultrasonic signal received by the ultrasonic reception unit  20 , and determine whether the pipe  50  is damaged. 
         [0033]    The ultrasonic supply unit  10  according to the exemplary embodiment of the present invention may include a generation unit  11 , a supply unit  12 , and a guide unit  13 . 
         [0034]    The generation unit  11  may generate the laser beam, and the supply unit  12  may supply the laser beam generated in the generation unit  11 . One end of the supply unit  12  may be connected to the generation unit  11 , and the other end of the supply unit  12  may be connected to the guide unit  13 . 
         [0035]    In this case, an optical fiber that can be survived under extreme environments such as a high temperature, radiation, corrosion, etc. may be used as the supply unit  12 . Since the optical fiber itself has low resistance, the optical fiber may suppress loss of the laser beam, and may be widely used in the extreme environments. 
         [0036]    The guide unit  13  may be mounted on the pipe  50 , and guide the laser beam to the pipe  50 . The guide unit  13  according to the exemplary embodiment of the present invention may include a guide pipe  131 , a guide lens  132 , a guide plate  133 , and a guide belt  134 . 
         [0037]    The guide pipe  131  may be connected to the supply unit  12 , and be in contact with the pipe  50 . The guide pipe  131  may have a cylindrical shape in which the inside is hollow, and guide the laser beam. 
         [0038]    In this case, a guide connector  121  may be provided at the other end of the supply unit  12 . The guide connector  121  may be coupled with the other end of the supply unit  12  and inserted into the guide pipe  131 , and may guide the laser beam to the guide pipe  131 . 
         [0039]    The guide connector  121  may have a screw thread formed on the outer surface, and may be screw-coupled with the guide pipe  131 . 
         [0040]    The guide lens  132  may be built in the guide pipe  131 . The guide lens  132  may be coupled with an inner surface of the guide pipe  131 , and may adjust focus of the laser beam so that the laser beam is focused on an ultrasonic guide point of the pipe  50 . 
         [0041]    The guide plate  133  may be coupled with the guide pipe  131 , and formed to protrude in a lateral direction. The guide plate  133  may have a curvature corresponding to the outer surface so that the guide plate  133  is in contact with the pipe  50 . 
         [0042]    The guide belt  134  may be formed to cover the outer surfaces of the guide plate  133  and the pipe  50 . The guide belt  134  may limit movement of the guide pipe  131  by fixing the guide plate  133  to be in close contact with the pipe  50 . 
         [0043]    In this case, the guide pipe  131  may be moved along the circumferential surface of the pipe  50 , and the guide point of the pipe  50  may be varied. 
         [0044]    The ultrasonic reception unit  20  according to the exemplary embodiment of the present invention may include a light source unit  21 , a transfer unit  22 , a detection unit  23 , and a reception unit  24 . 
         [0045]    The light source unit  21  may generate the laser beam, one end of the transfer unit  22  may be connected to the light source unit  21 , the other end of the transfer unit  22  may be connected to the detection unit  23 , and the transfer unit  22  may transfer the laser beam. 
         [0046]    In this case, an optical fiber with durability in extreme environments such as a high temperature, radiation, corrosion, etc. may be used as the transfer unit  22 . Since the optical fiber itself has low resistance, the optical fiber may suppress loss of the laser beam and may be widely used in the extreme environments. 
         [0047]    The detection unit  23  may be mounted on the pipe  50 , and may detect the laser beam. That is, the detection unit  23  may guide the laser beam of the light source unit  21  to reach the pipe  50 , and detect the laser beam reflected from the pipe  50  and including the ultrasonic signal of the pipe  50 . 
         [0048]    The reception unit  24  may be connected to the transfer unit  22 , may receive the laser beam, and may transfer information regarding the ultrasonic signal of the pipe  50  to the analysis unit  30 . 
         [0049]    That is, the reception unit  24  may digitize the ultrasonic signal of the pipe  50 , and transfer the digitized ultrasonic signal to the analysis unit  30 . The analysis unit  30  may analyze the transferred ultrasonic signal, and determine whether the pipe  50  is damaged. 
         [0050]    The detection unit  23  according to the exemplary embodiment of the present invention may include a detection pipe  231 , a detection lens  232 , a detection filter  233 , a detection plate  234 , and a detection belt  235 . 
         [0051]    The detection pipe  231  may be coupled with the transfer unit  22 , and be in contact with the pipe  50 . The detection pipe  231  may have a cylindrical shape in which the inside is hollow, and may guide the laser beam. 
         [0052]    In this case, a detection connector  221  may be provided at one end of the transfer unit  22 . The detection connector  221  may be coupled with the one end of the transfer unit  22  and inserted into the detection pipe  231 , and may guide the laser beam radiated to the pipe  50  or reflected from the pipe  50  in the corresponding direction. 
         [0053]    The detection connector  221  may have a screw thread formed on the outer surface, and the detection pipe  231  may be screw-coupled with the detection pipe  231 . 
         [0054]    The detection lens  232  may be built in the detection pipe  231 . The detection lens  232  may be coupled with an inner surface of the detection pipe  231 , and may adjust focus of the laser beam. 
         [0055]    The detection filter  233  may be built in the detection pipe  231 . The detection filter  233  may be coupled with the inner surface of the detection pipe  231 , and may prevent heat damage by blocking infrared radiant heat coming from the pipe  50 . 
         [0056]    In this case, the detection lens  232  may be arranged adjacent to the pipe  50 , and the detection filter  233  may be arranged adjacent to the detection connector  221 . 
         [0057]    The detection plate  234  may be coupled with the detection pipe  231 , and formed to protrude in a lateral direction. The detection plate  234  may have a curvature corresponding to the outer surface so that the detection plate  234  is in contact with the pipe  50 . 
         [0058]    The detection belt  235  may be formed to cover outer surfaces of the detection plate  234  and the pipe  50 . The detection belt  235  may limit movement of the detection pipe  231  by fixing the detection plate  234  to be in close contact with the pipe  50 . 
         [0059]    In this case, since the detection pipe  231  moves along the circumferential surface of the pipe  50 , a detection point of the pipe  50  may be varied. 
         [0060]    A pipe damage detection method according to an exemplary embodiment of the present invention having the construction described above will be schematically described below. 
         [0061]      FIG. 4  is a schematic flowchart for describing a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0062]    Referring to  FIG. 4 , the ultrasonic supply unit  10  may supply the ultrasonic signal to the pipe  50  (S 10 ). That is, when the laser beam generated in the ultrasonic supply unit  10  reaches the guide point of the pipe  50 , the ultrasonic signal may be generated in the pipe  50 . 
         [0063]    After the ultrasonic signal is supplied to the pipe  50 , the ultrasonic reception unit  20  may receive the ultrasonic signal generated in the pipe  50  (S 20 ). 
         [0064]    After the ultrasonic reception unit  20  receives the ultrasonic signal, the analysis unit  30  may analyze the ultrasonic signal, and determine whether the pipe  50  is damaged (S 30 ). 
         [0065]      FIG. 5  is a flowchart for describing an operation in which an analysis unit detects whether a pipe is damaged in a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0066]    Referring to  FIG. 5 , the analysis unit  30  may calculate a damage index (DI) (S 31 ), perform an outlier analysis based on the calculated DI, and determine whether the pipe  50  is damaged (S 32 ). 
         [0067]    Hereinafter, the DI and the outlier analysis will be described in detail. 
         [0068]    The ultrasonic supply unit  10  may change the guide point along the circumferential surface of the pipe  50 , and the ultrasonic reception unit  20  may change the detection point along the circumferential surface of the pipe  50 . 
         [0069]      FIGS. 6 to 8  are schematic diagrams illustrating an ultrasonic signal path according to a guide point of an ultrasonic supply unit and a detection point of an ultrasonic reception unit when a pipe is not damaged in a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0070]    Referring to  FIGS. 6 to 8 , when considering axial symmetry of the ultrasonic signal in a plane view of the pipe  50  without damage, every ultrasonic signal should be the same in the ultrasonic path having the same phase and the same length. 
         [0071]    The following Equation 1 represents several examples of signal combinations showing sameness. 
         [0000]      (a) Signal  A   1   B   1 =Signal  A   2   B   2 = . . . =Signal  A   n−1   B   n−1 =Signal  A   n   B   n ; 
         [0000]      (b) Signal  A   1   B   2 =Signal  A   2   B   1 = . . . =Signal  A   n−1   B   n =Signal  A   n   B   n−1 ; 
         [0000]      (c) Signal  A   1   B   3 =Signal  A   3   B   1 = . . . =Signal  A   n−2   B   n =Signal  A   n   B   n−2 ;   Equation 1
 
         [0072]    Here, A n  represents various guide points, and B n  represents multiple detection points. 
         [0073]    The pipe damage detection method according to the exemplary embodiment of the present invention may use the fact that the sameness is satisfied in the pipe  50  without damage, but is not satisfied in the pipe  50  with damage. 
         [0074]    For reference, there may be laser paths having various types of sameness according to a value of “n” in addition to Equation 1. 
         [0075]    Meanwhile, the analysis unit  30  may calculate the DI by the following Equation 2 (S 31 ) in the operation (S 30 ) of determining whether the pipe  50  is damaged. 
         [0000]    
       
         
           
             
               
                 
                   
                       
                   
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         [0076]    Here, f i  and f j  represent measurement signals measured in two paths having the same phase,  f i    represents an average value of f i , σf j  represents standard deviation of f i , N represents the number of data points in a time domain of the measured f i , and {tilde over (t)} represents time delay. 
         [0077]    That is, the DI may be a value calculated according to the sameness of the ultrasonic paths described above, and every DI may be close to 0 when the pipe  50  is not damaged. 
         [0078]    When the pipe  50  is damaged, a combination of specific f and f i  may include the measurement signal obtained in a path passing through a damage point of the pipe  50 . Accordingly, when the pipe  50  is damaged, the DI may be increased. 
         [0079]    Meanwhile, after calculating every DI described above, it may be determined whether the pipe  50  is damaged by performing the outlier analysis (S 32 ). 
         [0080]    The outlier analysis may be performed by aligning every DI in ascending order and applying a probability distribution while sequentially increasing the number by one from the smallest DI (for example, from the “1st” DI to the “(m−1)-th” DI), and obtaining a threshold value. 
         [0081]    When comparing the obtained threshold value and a next DI (for example, the “m-th” DI), the DI may be regarded as the outlier and the pipe  50  may be determined to be damaged when the DI is larger than the threshold value. 
         [0082]    For reference, as described above, since the DI is represented as being large when there is a path with damage, the DI being regarded as the outlier may mean that the pipe  50  is damaged. 
         [0083]      FIGS. 9 to 14  are diagrams for schematically describing an outlier analysis in a pipe damage detection method according to an exemplary embodiment of the present invention. 
         [0084]    First, every DI may be aligned in ascending order (1≦m≦N) for the outlier analysis ( FIG. 9 ). 
         [0085]    The probability distribution may be applied to the first DI to the (m−1)-th DI ( FIG. 10 ), and the threshold value corresponding to a confidence interval which is previously defined may be calculated ( FIG. 11 ). 
         [0086]    In this case, the (m−1)-th DI which is first selected may be typically set as half of the number of DIs. 
         [0087]    When the m-th DI is smaller than the threshold value ( FIG. 12 ), the operations described above with reference to  FIGS. 10 and 11  may be repeatedly performed in the same manner with respect to the first to m-th DIs ( FIG. 13 ). 
         [0088]    When the (m+1)-th DI is found to be larger than the threshold value by performing the operation described with reference to  FIG. 13 , the DIs subsequent to the (m+1)-th DI may be regarded as a value affected by every damage path ( FIG. 14 ). 
         [0089]    However, when every DI of the first to N-th DIs is found to be smaller than the threshold value by performing the operations described above, the pipe  50  may be determined not to be damaged. 
         [0090]    Meanwhile, since a range of the DI is from 0 to 1, in order to imitate the distribution of the DI, a beta distribution (introduced by Hayter in 2007) given by the following Equation 4 may be introduced. 
         [0000]    
       
         
           
             
               
                 
                   
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         [0091]    Here, B represent a beta functions, and α and β represent variables determining a shape of the beta distribution. 
         [0092]    When performing a goodness-of-fit test through a Kolmogorov-Smirnov verification method (introduced by Ross in 2004), it will be known that the beta distribution may closely imitate the distribution of the DI of the pipe  50  without damage. 
         [0093]    In this case, the threshold value may be set as a value of 99.7% (3σ) in one side of a confidence interval. 
         [0094]    It will be apparent to those skilled in the art that various modifications can be made to the previously described exemplary embodiments of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover all such modifications provided they come within the scope of the appended claims and their equivalents.