JP2017122694A - Pipe inspection method and pipe inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe inspection method and a pipe inspection device which can accurately detect the center position of a pipe even in such a state that a heat insulating material is wound around an outer surface of the pipe, so as to be able to improve the accuracy of thickness measurement.SOLUTION: In a pipe inspection method, after the deviation of the center of a pipe (1) inside a covering material is measured from a plurality of different directions by using a radiation having linearity, the thickness of the pipe (1) is measured on the basis of a center position (O1) of the pipe (1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pipe inspection method and a pipe inspection apparatus for inspecting a pipe in which a covering material such as a heat insulating material is wound.

  If piping used in plant equipment is worn or corroded due to its usage, and the thickness of the piping is reduced, there is a risk of leakage of fluid or gas flowing inside the piping leading to a major accident. Therefore, it is necessary to accurately know the thickness attenuation state of the pipe.

  Incidentally, as disclosed in Patent Document 1, the pipe is covered with a heat insulating material or an exterior plate. In Patent Document 1, it is possible to measure the wall thickness of a pipe in which a heat insulating material is wound. However, in order to improve the pipe wall thickness measurement accuracy, it is necessary to accurately detect the arrangement of the pipes inside the heat insulating material. I must.

Japanese Patent No. 5375541 Japanese Patent No. 5400704

  However, due to various factors such as the installation status of the pipe and the material and form of the heat insulating material wound around the pipe, the pipe as the measurement object may be displaced inside the heat insulating material.

  Patent Document 2 discloses an invention relating to a pipe center position detection device. In Patent Document 2, a transmission image is captured, the edge position of the pipe, the shape information of the pipe, and the distance between the irradiation position and the detection element are specified based on the transmission image, and the center position of the pipe is determined based on these information. Looking for.

  However, in Patent Document 2, complicated image processing is required to specify the edge position from the transmission image. In other words, in order to enlarge and project an image, the relative position of the pipe to the radiation source must be specified in advance, and it is difficult to accurately determine the relative position. (See paragraph number [0027] and after).

  Therefore, the present invention has been made in view of such problems, and the object of the present invention is to accurately detect the center position of a pipe even in a state where a heat insulating material or the like is wound around the outer surface of the pipe. It is possible to provide a pipe inspection method and a pipe inspection apparatus capable of improving the thickness measurement accuracy.

  In the pipe inspection method according to the present invention, the thickness of the pipe is determined based on the center position of the pipe after measuring the center deviation of the pipe inside the coating material from a plurality of different directions using radiation having linearity. Is measured. Thereby, even if the pipe is wound with a covering material such as a heat insulating material, the center position of the pipe can be detected with high accuracy, and therefore the accuracy of measuring the thickness of the pipe can be improved as compared with the conventional case.

  In the present invention, it is preferable that a plurality of end positions are specified at different positions on the outer peripheral surface of the pipe, and the center deviation of the pipe is detected based on each end position. In the present invention, even when a covering material such as a heat insulating material is wound around the pipe, a plurality of end positions can be obtained with high accuracy, and the center position detection accuracy can be improved.

  In the present invention, while translating the radiation irradiation position between the outside of the end position and the inner wall thickness, a radiation transmission curve for the irradiation position is obtained, and among the radiation transmission curves, It is preferable that the irradiation position indicating the center of the inclined straight line region inclined at a constant change amount is defined as the end position. As described above, in the present invention, a radiation transmission curve with respect to the irradiation position is acquired while the radiation irradiation position is translated in the vicinity of the end position of the pipe. At this time, if the radiation is applied to the pipe, the radiation is shielded by the pipe, but the region where the amount of transmission (count number) of the radiation changes constantly due to the relationship between the radiation line width and the irradiation position on the pipe (inclined straight line) Region) is obtained. And in this invention, the irradiation position which shows the center of an inclination straight line area | region can be prescribed | regulated as an edge part position. For this reason, a plurality of end positions can be obtained easily and appropriately.

  In the present invention, it is preferable to measure the center deviation of the pipe from at least two directions orthogonal to the pipe. Thereby, the center position of piping can be calculated | required accurately and easily.

  In the present invention, it is preferable that the thickness of the pipe is measured based on the center position after correcting the position of the center position of the pipe based on the measurement result of the center deviation. As a result, the pipe can be centered at the time of the wall thickness measurement. Therefore, the pipe wall thickness measurement can be performed as it is, and the pipe wall thickness measurement can be performed easily and appropriately.

  Further, in the step of measuring the wall thickness of the pipe according to the present invention, the radiation irradiation direction is at least three directions, and the radiation is irradiated so that the intersection of each irradiation direction is located within the wall thickness of the pipe. It is preferable to calculate the thickness of the pipe at the intersection point based on the transmission amount. Thus, in the present invention, the thickness of the pipe can be measured with high accuracy by the three beam method.

  Further, in the step of measuring the wall thickness of the pipe according to the present invention, radiation is radiated so as to pass through the center position of the pipe, the amount of the radiation transmitted is obtained, and the thickness of the pipe is calculated based on the amount of transmission. You can also

  The pipe inspection apparatus according to the present invention includes a radiation source that emits linear radiation and a detector that detects the radiation, and includes at least a detection function unit for measuring a center position of the pipe, and the detection function unit. A ring member that is rotatably supported around a pipe, and the detection function unit is moved straight from a position away from the pipe to a position where the radiation source and the detector face each other through the pipe. And a linear movement mechanism capable of As described above, according to the pipe inspection apparatus of the present invention, the detection function unit is rotated around the pipe by the ring member and the linear movement mechanism, and is opposed to the pipe from the position away from the pipe (retreat position). By moving straight to the position, the center deviation of the pipe can be detected from a plurality of different directions, and the thickness of the pipe can be accurately measured based on the center position of the pipe.

  In the present invention, a plurality of support legs that support the outer surface of the covering material that covers the pipe is provided between the ring member and the covering material, and at least two of the support legs and the covering material It is preferable that an adjustment mechanism capable of correcting movement of the ring member side in a state where the support position is fixed is provided. Thereby, while being able to perform centering of piping with high precision, the fixed support by a support leg part can be performed appropriately.

  Moreover, in this invention, it is preferable that the said adjustment mechanism is provided in the said at least 2 of the said support leg parts. Thereby, the movement correction | amendment by the side of a ring member can be implemented simply.

  In the present invention, it is preferable that the detection function unit also serves for measuring the thickness of the pipe. In the present invention, after the center position of the pipe is obtained by the detection function section for measuring the center position, the thickness can be measured by replacing with the detection function section for measuring the wall thickness of the pipe. By using a detection function unit that combines both for measuring and for wall thickness measurement, both the center position and the wall thickness of the pipe can be measured with high accuracy and speed with a small number of parts.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is the state by which coating | covering materials, such as a heat insulating material, were wound around the outer surface of piping, it becomes possible to detect the center position of piping accurately and can improve thickness measurement precision.

It is a longitudinal cross-sectional view which shows piping of the measuring object by which the heat insulating material was wound. It is a schematic diagram which shows the measurement process of the center shift | offset | difference of piping in the Y direction in this Embodiment. It is a schematic diagram which shows the measurement process of the center shift | offset | difference of piping in the X direction in this Embodiment. It is a schematic diagram of a radiation transmission curve. It is a schematic diagram which shows a radiation source, a detector, and the radiation irradiated toward a detector from a radiation source. It is a perspective view of the piping inspection apparatus of this Embodiment. It is the elements on larger scale which expanded and showed a part of piping inspection device. It is a fragmentary top view which shows the center position measurement process to the Y direction by a piping inspection apparatus. It is a fragmentary top view which shows the center position measurement process to the X direction by a piping inspection apparatus. It is a fragmentary top view which shows the state which moved the detection function part linearly to the Y direction with respect to piping using the linear movement mechanism of a piping inspection apparatus. It is a partial top view which shows the state which correct | amended the installation position of piping based on the measured center deviation | shift amount of piping. It is a fragmentary top view which shows the thickness measurement process by a piping inspection apparatus. It is a fragmentary perspective view which shows an example of the support leg part in this Embodiment. It is explanatory drawing for demonstrating the thickness measuring method by a three beam system. It is explanatory drawing for demonstrating the thickness measuring method by a thickness sum total system. It is explanatory drawing which shows the relationship between piping with respect to a reference position, and the irradiation position of a radiation. It is a graph which shows the relationship between the distance from the reference position of the radiation irradiation position with respect to several piping from which thickness differs, and a count number (measurement value). It is a graph which shows the relationship between the distance from the reference position of the radiation irradiation position with respect to several piping from which thickness differs, and a count number (measurement value). From the reference position (piping center) of the radiation irradiation position when the detection function unit is rotated to 0 degrees, 90 degrees, 180 degrees, and 270 degrees with respect to the piping with the heat insulating material using SPCC as the exterior plate. It is a graph which shows the relationship between distance and a count number (measurement value). When the detection function unit is rotated to 0, 90, 180, and 270 degrees with respect to the piping with the heat insulating material using aluminum for the exterior plate, the radiation irradiation position from the reference position (piping center) It is a graph which shows the relationship between distance and a count number (measurement value).

  Hereinafter, an embodiment of the present invention (hereinafter abbreviated as “embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the meaning.

  FIG. 1 is a longitudinal sectional view showing a pipe to be measured around which a heat insulating material is wound. The pipe 1 shown in FIG. 1 has a cylindrical shape, but is not limited to a cylindrical shape, and may be a polygonal cylindrical shape or the like. The cross section shown in FIG. 1 has shown the longitudinal cross section cut | disconnected along the thickness direction of the piping 1 in parallel. 1 is defined as the X direction, and the longitudinal direction (the vertical direction of the sheet) of the cross section illustrated in FIG. 1 is defined as the Y direction. The X direction and the Y direction are orthogonal to each other. Moreover, although the material of the piping 1 is not specifically limited, For example, it is formed with stainless steel or carbon steel.

As shown in FIG. 1, a heat insulating material 2 as a covering material is wound around the outer peripheral surface 1 a of the pipe 1, and the measurer cannot confirm the arrangement of the pipe 1 inside the heat insulating material 2 from the outside. . The heat insulating material 2 is formed of a material having high heat insulation properties, and is not particularly limited, but is formed of, for example, CaSiO ₂ or glass wool. Moreover, in this Embodiment, it applies also to the form which a coating | covering material coat | covers a part instead of the whole outer peripheral surface 1a of the piping 1. FIG. When the heat insulating material 2 is glass wool, the center deviation of the pipe 1 is likely to occur. On the other hand, when the heat insulating material 2 is formed of CaSiO ₂ , although the center shift is less likely to occur than glass wool, there is a possibility that the center shift may occur depending on the use situation and the like. Position measurement is important.

  In the present embodiment, the surface of the heat insulating material 2 may be covered with an exterior plate (not shown). The exterior plate is made of aluminum, cold rolled steel plate (SPCC), or the like.

  In FIG. 1, the center position O1 of the pipe 1 is located away from the center position O2 of the heat insulating material 2. Thus, the pipe 1 is housed in a state of being shifted in the heat insulating material 2.

  In the present embodiment, as shown in FIG. 1, even if the heat insulating material 2 is wound around the outer peripheral surface 1a of the pipe 1, the center deviation of the pipe 1 inside the heat insulating material 2 can be measured with high accuracy. Thereby, after specifying the center position O1 of the piping 1, it is possible to shift to the wall thickness measurement.

  In the present embodiment, before measuring the wall thickness of the pipe 1, the center deviation of the pipe 1 inside the heat insulating material 2 is measured from a plurality of different directions using radiation having linearity. Here, “different directions” refer to two or more different directions in a direction orthogonal to the central axis of the pipe 1 (that is, a direction in which the center position O1 is connected to the direction perpendicular to the paper surface). For example, as shown in FIG. 1, the center position O1 of the pipe 1 can be accurately identified by obtaining the center shift amounts G1 and G2 of the pipe 1 with respect to a plurality of orthogonal X and Y directions. can do. As shown in FIG. 1, if the center position O2 of the heat insulating material 2 is considered as the center position (virtual center position) of the pipe 1, the center shift amounts G1 and G2 of the pipe 1 are actually the XY coordinates of the center position O2. This is the difference from the XY coordinates of the center position O1 of the pipe 1 of FIG.

  As described above, in the present embodiment, the center position O1 of the pipe 1 is detected by obtaining the center deviation of the pipe 1 inside the heat insulating material 2 from a plurality of different directions with respect to the pipe 1, and the center deviation is measured. The direction is not limited to two directions and can be three or more directions. By increasing the measurement direction of the center deviation with respect to the pipe 1, the center position detection accuracy can be further improved. However, even if the number is increased too much, the measurement becomes complicated, and if a certain number of center shift data is prepared, the center position accuracy does not change much even if the center shift data is further increased. It is preferable that: Further, it is preferable that the measurement directions are shifted by an equal angle. Further, as shown in FIG. 1, it is preferable to measure the center deviation of at least two directions (X direction and Y direction) orthogonal to the pipe 1. Thereby, the center position of the pipe 1 can be obtained accurately and easily.

  In the present embodiment, the thickness of the pipe 1 is measured based on the specified center position O1 of the pipe 1. In the present embodiment, the thickness measurement method is not particularly limited, and an existing method can be used. A specific thickness measuring method will be described later.

  As described above, in the present embodiment, even when the pipe 1 is wound around the heat insulating material 2, the center position O1 of the pipe 1 can be specified with high accuracy. It can be improved compared to

  Next, a specific method for detecting the center position of the pipe will be described with reference to FIGS. In FIGS. 2 and 3, a part of the piping is shown in an enlarged manner. In addition, the heat insulating material and the exterior plate will be described in the drawings.

  In FIG. 2A, the radiation source 10 and the detector (sensor) 11 are arranged at a position retracted in the upward direction in the figure with respect to the pipe 1. The radiation source 10 and the detector 11 are in a positional relationship facing each other in the X direction, and the radiation source 10 and the detector 11 are supported so as to be movable in parallel in the Y1-Y2 direction orthogonal to the X direction. . In FIG. 2, the upper direction of the paper is displayed as Y1 and the lower direction of the paper is displayed as Y2 with respect to the Y direction.

  As shown in FIG. 2A, the irradiation center line C1 of the radiation R emitted from the radiation source 10 is a direction parallel to the X direction. Although the radiation source 10 is not limited, for example, a cesium radiation source can be used. The detector 11 includes a scintillator, a light guide, a photomultiplier tube, and the like. When the radiation R enters the scintillator from the detection surface of the detector 11, the scintillator responds to the radiation and emits light. This light is converted into a detection pulse (electron signal) which is a current pulse by a photomultiplier tube and output. Then, the control unit counts the detection pulses.

  As shown in FIG. 2A, the radiation R has a predetermined line width W1. In FIG. 2A, the line width W1 is shown as a constant width, but actually, it is detected from the radiation source 10 as shown in FIG. The line width W2 of the radiation R is gradually spread toward the container 11 and irradiated.

  As shown in FIG. 5, a collimator 12 having a constant opening width (opening diameter) is disposed at the irradiation port of the radiation source 10. As shown in FIG. 5, the detector (sensor) 11 is provided with a detection surface 11 a having a predetermined size. As shown in FIG. 5, the detection surface 11 a is wider than the opening width of the collimator 12. As shown in FIG. 5, the radiation R is emitted from the radiation source 10 toward the detector 11, but the radiation outer edge RO that spreads outside the detection surface 11 a is not detected by the detector 11. The radiation RC indicated by the solid line shown in FIG. As shown in FIG. 5, since the detection surface 11a of the detector 11 is wider than the opening width of the collimator 12, the line width W2 of the radiation RC is widened toward the detector 11, but the description is simplified. Therefore, in FIG. 2, the line width W1 is described as a constant width. The detection surface 11a of the detector 11 can pick up more radiation R from the radiation source 10 when it is wider than the opening width of the collimator 12. Therefore, even if the radiation intensity is relatively weak, the center position can be detected appropriately. However, the detection accuracy tends to decrease as the detection surface 11a becomes wider. On the other hand, if the size of the detection surface 11a and the opening width of the collimator 12 are reduced, the detection accuracy is improved. However, unless the radiation intensity is increased, detection itself is impossible. For this reason, it is necessary to adjust the size of the detection surface 11a and the opening width of the collimator 12 based on the usable radiation intensity. For example, the ratio of the length of the detection surface 11a to the opening width of the collimator 12 is adjusted to about 4 to 10.

  Further, “radiation having linearity” means that the irradiation center line C1 is a substantially straight line as shown in FIG. 2A.

  As shown in FIG. 2B from the state of FIG. 2A, the radiation source 10 and the detector 11 are gradually brought closer to the pipe 1 (moved in the Y2 direction). Eventually, the pipe-side lower end (the lower end of the drawing) 3 of the line width W1 of the radiation R comes into contact with the end position 4 of the outer peripheral surface 1a of the pipe 1 corresponding to the most protruding portion when viewed from the radiation R side. In the stage of FIG. 2B, the radiation R irradiated from the radiation source 10 reaches the detector 11 without being blocked by the pipe 1.

  FIG. 4 is a schematic diagram of a radiation transmission curve. The horizontal axis shown in FIG. 4 indicates the position of the irradiation center line C <b> 1 with respect to the pipe 1. The vertical axis in FIG. 4 is the amount of radiation R transmitted, and specifically shows the count number (detection pulse) detected by the detector 11. The larger the count number, the larger the transmission amount.

  A region α shown in FIG. 4 indicates a detection state in a range from FIG. 2A to FIG. 2B. That is, in FIGS. 2A to 2B, there is no shielding against the radiation R irradiated from the radiation source 10 toward the detector 11. Therefore, as shown on the vertical axis in FIG. 4, a count value having a large value and a substantially constant value is obtained.

  Subsequently, as shown in FIGS. 2B to 2C, when the radiation source 1 and the detector 11 are further moved in the Y2 direction, the radiation lower region 5 positioned below the paper surface from the irradiation center line C1 of the radiation R becomes a pipe. 1 is gradually shielded. For this reason, the radiation amount (transmission amount) reaching the detector 11 gradually decreases, and the count number obtained by the detector 11 gradually decreases as shown in the region β shown in FIG.

  The boundary position P1 between the region α and the region β illustrated in FIG. 4 indicates the position in FIG. 2B where the pipe-side lower end 3 of the line width W1 of the radiation R is in contact with the end position 4 of the outer peripheral surface 1a of the pipe 1.

  Subsequently, as shown in FIGS. 2C to 2D, the radiation source 1 and the detector 11 are further moved in the Y2 direction. Then, since the radiation upper region 6 positioned on the upper side of the drawing with respect to the radiation center line C1 of the radiation R is gradually shielded by the pipe 1, the radiation amount (transmission amount) reaching the detector 11 is further reduced. As shown in the region β shown in FIG. 4, the number of counts obtained by the detector 11 is further reduced.

  In FIG. 2D, the entire area of the line width W1 of the radiation R is in a positional relationship facing the pipe 1. Even if the radiation source 1 and the detector 11 are further moved in the Y2 direction from FIG. 2D, they are detected by the detector 11. The number of counts to be obtained is very small (or 0), and the region γ in FIG. 4 with little change is obtained.

  The boundary position P3 between the region β and the region γ shown in FIG. 4 indicates the position in FIG. 2D where the entire region of the line width W1 of the radiation R is in a positional relationship facing the outer peripheral surface 1a of the pipe 1.

  In FIG. 4, the count values of the regions α and γ are constant, but this is only a schematic diagram, and in practice, some fluctuations are observed as shown in the experimental data described later. It is done. However, the variation in the region α and the region γ is smaller than the change in the region β described below, or the variation varies randomly, so that it can be distinguished from the region β that shows a constant change amount.

  A region β exists between the region α and the region γ of the radiation transmission curve shown in FIG. As shown in FIG. 4, the region β is an inclined linear region that is inclined at a constant change amount with respect to the position change of the irradiation center line C <b> 1 with respect to the pipe 1 (hereinafter sometimes referred to as an inclined linear region β). . In addition, as shown in the experiment mentioned later, it turns out that the substantially same result is obtained even if the thickness of the piping 1 differs in the inclination linear area | region (beta).

  And P2 which shows the center position of inclination linear area | region (beta) has the positional relationship which the irradiation center line C1 just contact | abutted to the edge part position 4 of the outer peripheral surface 1a of the piping 1 (refer FIG. 2C). Accordingly, the position P2 shown in FIG. 4 can be defined as the end position 4 of the outer peripheral surface 1a of the pipe 1.

  Therefore, by the center position measurement step shown in FIG. 2, the radiation transmission curve of FIG. 4 is obtained, and the end position 4 can be derived from the center position (P2) of the inclined linear region β. Thereby, the Y coordinate of the end position 4 can be obtained.

  Although illustration of the heat insulating material 2 and an exterior board is abbreviate | omitted in FIG. 2, even if the heat insulating material 2 and an exterior board exist, the radiation R permeate | transmits the part of the thermal insulation material 2 and an exterior board, and there is almost no shielding effect. In an experiment to be described later, an experiment using aluminum or SPCC for the exterior plate was performed, but it has been confirmed that the inclined linear region β can be appropriately obtained even by a difference in the material of the exterior plate. Therefore, a radiation transmission curve similar to that shown in FIG. 4 or a radiation transmission curve having at least an inclined linear region β can be obtained, and thereby the end position 4 can be obtained.

  3, the radiation source 10 and the detector (sensor) 11 are rotated by 90 degrees with respect to FIG. 2, and the radiation source 10 and the detector 11 are supported so as to be movable in the X1-X2 direction. In FIG. 3, the right direction on the paper surface is distinguished from X1 and the left direction on the paper surface is distinguished from X2 with respect to the X direction.

  In FIG. 3A, a radiation source 10 and a detector (sensor) 11 are arranged at a position retracted rightward in the drawing with respect to the pipe 1. As shown in FIG. 3A, the irradiation center line C1 of the radiation R emitted from the radiation source 10 is a direction parallel to the Y direction. As shown in FIG. 2A, the radiation R has a predetermined line width W1.

  The source 1 and the detector 11 are gradually brought closer to the pipe 1 from the state of FIG. 3A (moved in the X2 direction). Eventually, the pipe-side left end 7 of the line width W1 of the radiation R comes into contact with the end position 8 of the outer peripheral surface 1a of the pipe 1 corresponding to the most protruding portion when viewed from the radiation R side. At this stage, the radiation R irradiated from the radiation source 10 reaches the detector 11 without being blocked by the pipe 1. Therefore, the region α shown in FIG. 4 can be obtained.

  When the radiation source 10 and the detector 11 are further moved in the X2 direction, the left radiation region 9 located on the left side of the drawing with respect to the irradiation center line C1 of the radiation R is gradually shielded by the pipe 1. For this reason, the radiation amount (transmission amount) reaching the detector 11 gradually decreases, and the count number obtained by the detector 11 gradually decreases as shown in the region β shown in FIG.

  FIG. 3B shows a state in which the irradiation center line C1 is in contact with the end position 8 of the pipe 1. Further, the source 10 and the detector 11 are moved in the X2 direction from FIG. 3B. Then, the radiation right part region 13 located on the right side of the drawing with respect to the irradiation center line C1 of the radiation R is gradually shielded by the pipe 1 this time. For this reason, the amount of radiation (transmission amount) reaching the detector 11 is further reduced, and the count number obtained by the detector 11 is further reduced as shown in the region β shown in FIG.

  Thus, the same radiation transmission curve as that in FIG. 4 can be obtained in the measurement process of FIG. Therefore, the X coordinate of the end position 8 can be derived from the center position (P2) of the inclined linear region β in FIG.

  As described above, the end position 8 obtained in FIG. 3 is at a position rotated by 90 degrees with respect to the end position 4 obtained in FIG.

  In the present embodiment, as shown in FIGS. 2 and 3, the XY coordinates of the plurality of end positions 4 and 8 are specified at different positions on the outer peripheral surface 1 a of the pipe 1. Based on the end positions 4 and 8, the center deviation of the pipe 1 in the X direction and the Y direction can be detected. For example, the coordinates of the end position are measured at four points of 0 degree, 90 degrees, 180 degrees, and 270 degrees. At this time, for example, the Y coordinates of the end positions existing on both sides in the Y direction are detected at the rotation positions of 0 degrees and 180 degrees, and at the rotation positions of 90 degrees and 270 degrees, for example, on both sides in the X direction. Each X coordinate of the existing end position is detected. Based on the coordinates of these end positions, the center position O1 of the pipe 1 can be calculated, and the amount of center deviation within the heat insulating material 2 of the pipe 1 (center deviation amounts G1 and G2 shown in FIG. 1) can be obtained. . As shown in FIGS. 2 and 3, when only two end positions 4 and 8 are measured, if the diameter of the pipe 1 is known, the end positions facing the end positions 4 and 8 respectively. Therefore, it is possible to obtain the center deviation amounts G1 and G2 of the pipe 1 shown in FIG.

  Further, in the present embodiment, as shown in FIG. 1, it is preferable to measure the center shift amounts G1 and G2 of the pipe 1 from at least the X direction and the Y direction, which are two orthogonal directions. Thereby, the center position O1 of the pipe 1 can be obtained accurately and easily.

  Next, the pipe inspection apparatus according to the present embodiment will be described. FIG. 6 is a perspective view of the pipe inspection apparatus according to the present embodiment. FIG. 7 is a partially enlarged plan view showing a part of the pipe inspection apparatus in an enlarged manner.

  As shown in FIGS. 6 and 7, the pipe inspection apparatus 100 according to the present embodiment includes a detection function unit 101, a ring member 102 that rotatably supports the detection function unit 101, and the detection function unit 101 that moves straight with respect to the pipe. And a rectilinear movement mechanism 103 that can be moved.

  As shown in FIGS. 6 and 7, the detection function unit 101 supports a radiation source 10 that emits linear radiation, a detector (sensor) 11 that detects radiation, and the radiation source 10 and the detector 11. And a supporting member 104 configured to be configured. The radiation source 10 and the detector 11 are arranged to face each other with a predetermined gap L. The gap L is supported on the inner side of the ring member 102, and a covering material such as a heat insulating material or an exterior plate is provided on the pipe. It is made wider than the diameter D2 of the object 120 to be measured in the rolled state.

  As shown in FIGS. 6 and 7, the support member 104 includes a base portion 105, a radiation source side arm 106 attached to one end portion of the base portion 105, and a detection attached to the other end portion of the base portion 105. A container-side arm 107. The radiation source 10 is attached to the distal end of the radiation source side arm 106, and the detector 11 is attached to the distal end of the detector side arm 107. As shown in FIG. 7, the radiation source side arm 106 and the detector side arm 107 are provided so as to extend in the Y direction. The direction in which the radiation source 10 and the detector 11 face each other is the X direction orthogonal to the Y direction. The direction (X direction) in which the radiation source 10 and the detector 11 face each other coincides with the direction of the irradiation center line C1 (see FIG. 2) of the radiation R.

  As shown in FIGS. 6 and 7, two rail members 110 and 111 extending in the Y direction, which is the same direction as the radiation source side arm 106 and the detector side arm 107, are provided on the back surface side of the base portion 105. They are arranged at intervals in the X direction. These rail members 110 and 111 are fixedly supported by a support frame body 112. The support frame body 112 is fixedly connected to the base portion 105. Further, as shown in FIG. 7, a roller support 113 is provided at a position facing the ring member 102 of the support frame 112, and two rollers 114 and 115 are rotatably supported on the roller support 113. Has been.

  The ring member 102 has a ring structure having a perfect circular constant width, and is provided with a ring-shaped protrusion 116 along the circumferential direction. A ring-shaped table portion 117 having a flat surface that is one step lower than the ring-shaped ridge portion 116 is provided on the outer side of the ring-shaped ridge portion 116 in the same circumferential direction. Rollers 114 and 115 are arranged at the level difference between the ring-shaped protrusion 116 and the ring-shaped table 117. As shown in FIG. 7, the roller support 113 is provided with an extending portion 119 extending in the direction of the inner wall surface 118 of the ring member 102, and the roller 140 is disposed at the distal end portion of the extending portion 119. As shown in FIGS. 6 and 7, the ring member 102 has a ring-shaped table portion 141 having a flat surface that is one step lower than the ring-shaped protrusion 116 along the circumferential direction inside the ring-shaped protrusion 116. Is provided. Then, the roller 140 is disposed at the level difference between the ring-shaped protrusion 116 and the ring-shaped table 141. The roller 140 disposed on the inner side is located in the middle of the rollers 114 and 115 disposed on the outer side.

  The detection function unit 101 can be rotated along the circumferential direction of the ring member 102 by the rotation of the rollers 114, 115, and 140. By the rotation mechanism using the rollers 114, 115, and 140 shown in FIG. 7, the detection function unit 101 goes around the ring member 102 in the opposing direction (the direction of the interval L shown in FIG. 7) between the radiation source 10 and the detector 11. It is possible to rotate 360 degrees in between.

  As shown in FIG. 6, a rail moving body 143 having a through hole through which the rail members 110 and 111 pass is provided on the back surface of the base portion 105. The rail members 110 and 111 and the rail moving body 143 constitute a rectilinear movement mechanism 103 that can linearly move the detection function unit 101 in the front-rear direction. For example, screws (ball screws) are cut on the surfaces of the rail members 110 and 111, and the detection function unit 101 can be moved straight in the front-rear direction by using a driving force from a driving generator (not shown). .

  As shown in FIG. 7, the inner diameter D1 of the ring member 102 is larger than the diameter D2 of the outer peripheral surface 120a of the DUT 120. Therefore, the measurement object 120 is installed inside the inner diameter D1 of the ring member 102, and the center position measurement and the wall thickness measurement of the pipe are performed on the measurement object 120.

  First, detection of the center position of the pipe executed using the pipe inspection apparatus 100 shown in FIGS. 6 and 7 will be described.

  As shown in FIG. 8, the DUT 120 is arranged inside the ring member 102, and the outer peripheral surface 120 a of the DUT 120 is fixedly supported by, for example, four support legs 121 and 122. In FIG. 7, the support leg portions 121 and 122 are omitted.

  The structure of the support leg 121 will be described with reference to FIGS. As shown in FIG. 8, the support legs 121 are located on both sides in the Y direction with respect to the measurement object 120. As shown in FIGS. 8 and 13, the support leg 121 is adjusted to a contact portion 149 that contacts the outer peripheral surface 120a of the object 120 to be measured, an adjustment shaft 154 connected to the contact portion 149, and a through hole. An adjustment bearing 155 that is fixedly supported by the ring member 102 through the shaft 154 and a head 156 that is positioned at the tip of the adjustment shaft 154 are configured.

  As shown in FIG. 13, the adjustment bearing 155 is provided with a rectangular through hole 155a extending in the X direction. A block body 157 is attached to the adjustment shaft 154. The width dimension of the block body 157 in the Z direction (direction perpendicular to the X direction and the Y direction) is substantially the same as the width dimension of the through hole 155a in the Z direction. Moreover, the width dimension of the X direction of the block body 157 is shorter than the width dimension of the X direction of the through-hole 155a, and is about half the width dimension of the through-hole 155a in FIG.

  As shown in FIG. 13, the block body 157 is provided with a long hole 157a penetrating in the X direction. As shown in FIG. 13, a rail shaft 158 is inserted into the long hole 157 a, and retaining portions 159 are provided at both ends of the rail shaft 158. The block body 157 and the rail shaft 158 are fixed. As shown in FIG. 13, the length dimension of the rail shaft 158 in the X direction is longer than the width dimension between both sides of the outer surface in the X direction of the adjustment bearing 155. Accordingly, as shown in FIG. 13, the rail shaft 158 has a portion 158 a that protrudes outward from the outer surface of the adjustment bearing 155.

  As shown in FIG. 13, the block body 157 has a protruding portion 160 protruding in the Z direction on the abutting portion 149 side. On the other hand, a step 161 is provided in a portion of the through hole 155a that faces the protrusion 160. The protrusion 160 is supported so as to slide on the surface of the step 161.

  As shown in FIG. 13, the block body 157 is smaller than the width dimension in the X direction of the through hole 155 a, and the rail shaft 158 is longer than the adjustment bearing 155. For this reason, the block body 157 can be relatively moved in the X direction within the allowable movement range of the through hole 155a together with the rail shaft 158. The block body 157 and the rail shaft 158 are moved by, for example, a configuration in which the hole into which the rail shaft 158 of the adjustment bearing 155 is inserted and the rail shaft 158 are screwed and fitted to each other, so that the retaining portion 159 is inserted. Realized by turning. In this embodiment, the “adjustment mechanism” includes the adjustment bearing 155, the block body 157, and the rail shaft 158, but the configuration of the adjustment mechanism is not limited.

  As shown in FIG. 13, scales are provided on the surface of the adjustment bearing 155 and the surface of the adjustment shaft 154, so that the movement distances in the X direction and the Y direction can be known.

  Next, the support legs 122 positioned on both sides in the X direction with respect to the measurement object 120 will be described. As shown in FIGS. 6 and 8, the support leg portion 122 is adjusted to a contact portion 150 that contacts the outer peripheral surface 120 a of the object 120 to be measured, an adjustment shaft 151 connected to the contact portion 150, and a through hole. An adjustment bearing 152 that is fixedly supported by the ring member 102 through the shaft 151 and a head 153 that is positioned at the tip of the adjustment shaft 151 are configured.

  As shown in FIG. 8, the contact part 150 is a flat plate-like highly rigid member, and is formed long in the Y direction as shown in FIG.

  As shown in FIG. 8, the support legs 121 and 122 are arranged on the lines from the center O3 of the ring member 102 in the X direction and the Y direction at the initial position. Therefore, each support leg 121, 122 is arranged at a position rotated 90 degrees from the center O3. That is, as shown in FIG. 8, the intersection of the straight line in the Y direction passing through the center of the pair of support legs 121 at the initial position and the straight line in the X direction passing through the center of the pair of support legs 122 is exactly the ring This is a state that coincides with the center position O3 of the member 102.

  The support mechanism for the DUT 120 is mainly, for example, a support leg 121 that supports the DUT 120 from the vertical direction (Y direction) on the paper surface, and supports from the horizontal direction (X direction) on the paper surface. 122 is provided as an auxiliary.

  In FIG. 8, the ring member 102 has a perfect circle shape, and the center position of the object 120 to be measured fixedly supported inside the ring member 102 (the center position O2 of the heat insulating material 2) is the center position O3 of the ring member 102. It is in a consistent state.

  On the other hand, as shown in FIG. 8, the center position O1 of the pipe 1 arranged inside the heat insulating material 2 is in a state of being shifted from the center positions O2 and O3.

  In FIG. 8, the radiation source 10 and the detector 11 are arranged to face each other in the X direction, and as shown in FIG. 10A, the source 10 and the detector 11 are separated from the pipe 1 (retreated position). 10B, the linear source 10 and the detector 11 are moved straight in the Y direction through the pipe 1 to a position where the radiation source 10 and the detector 11 face each other. Then, during linear movement, while irradiating the radiation R from the radiation source 10 in the X direction, the radiation R is detected by the detector 11 to obtain the radiation transmission curve shown in FIG. In FIG. 10A, the radiation source 10 and the detector 11 are in a positional relationship facing each other via the heat insulating material 2. At this time, since the radiation R passes through the heat insulating material 2, the region α shown in FIG. 4 is obtained. . When the radiation source 10 and the detector 11 are linearly moved upward in the figure from the state of FIG. 10A, the radiation R is gradually applied to the pipe 1, and the inclined linear region β and region γ shown in FIG. 4 can be obtained. The center position of the inclined straight line region β can be defined as the end position 123 (see FIG. 10) of the pipe 1.

  9, the source 10 and the detector 11 are rotated 90 degrees counterclockwise from the position shown in FIG. 8, and the source 10 and the detector 11 are separated from the pipe 1 in the same manner as in FIG. 10. From the position (retracted position) to the position where the radiation source 10 and the detector 11 are opposed to each other via the pipe 1, the linear movement mechanism 103 is used to move straight in the X direction. Thereby, the radiation transmission curve shown in FIG. 4 can be obtained. Then, the end position 124 (see FIG. 10) can be detected from the center position of the inclined linear region β of the radiation transmission curve.

  For example, the end positions of the four points are detected while rotating the radiation source 10 and the detector 11 by 90 degrees with respect to the pipe 1. The center position O1 of the pipe 1 can be detected from the XY coordinates of these end positions, and the center shift amounts in the X direction and Y direction of the pipe 1 inside the heat insulating material 2 can be obtained.

  Next, the position correction of the center position O3 of the ring member 102 is performed based on the center shift amount of the pipe 1. First, in the present embodiment, support between the contact portion 149 of each support leg 121 that supports the object to be measured 120 (the pipe 1 wound with the heat insulating material 2) from the Y direction and the outer peripheral surface 120a of the object 120 to be measured. The position remains fixed. Then, the ring member 102 is moved by a predetermined distance in the X direction so that the center position O3 of the ring member 102 coincides with the center position O1 of the pipe 1 (see FIG. 11). The adjustment bearing 155 of the support leg 121 is fixed to the ring member 102, and the adjustment bearing 155 has a through hole 155 a that can move the ring member 102 in the X direction with respect to the adjustment shaft 154 ( (See FIG. 13). Therefore, the ring member 102 can be moved in the X direction by the space width in the X direction provided in the through hole 155a. The moving distance of the ring member 102 in the X direction can be determined by a scale displayed on the surface of the adjustment bearing 155 shown in FIG. Further, the length dimension in the Y direction of each support leg 121 is also adjusted so that the center position O3 of the ring member 102 matches the center position O1 of the pipe 1. At this time, the moving distance of the ring member 102 in the Y direction can be determined by a scale displayed on the surface of the adjustment shaft 154 shown in FIG.

  As described above, using the adjustment mechanism of each support leg 121, the ring member 102 is moved in the X direction while the support position between the contact portion 149 of the support leg 121 and the outer peripheral surface 120a of the object 120 to be measured is fixed. Then, the position is corrected by moving in the Y direction. As described above, the position of the ring member 102 is adjusted by the support legs 121 arranged in the vertical direction (Y direction) with respect to the object 120 to be measured, and then the left and right direction (X direction) of the object 120 to be measured. ), The contact portion 150 of each support leg 122 is pressed against the outer peripheral surface 120a of the object 120 to be measured, and the object 120 is supplementarily supported by each support leg 122. At this time, the contact portion 150 of the support leg portion 122 has a flat plate shape extending in the Y direction. For this reason, the outer peripheral surface 120a can be fixedly supported by the adjustment mechanism by the support leg 121 even if the support leg 122 moves together with the ring member 102 in the Y direction.

  As described above, the measurement object 120 can be appropriately fixed and supported by the support legs 121 and 122 even when the ring member 102 moves in the X direction and the Y direction with respect to the measurement object 120.

  In addition, the structure of the support leg parts 121 and 122 in this Embodiment is an example. For example, all of the support legs that support the DUT 120 may be the support legs 121 shown in FIG. In the present embodiment, it is only necessary to provide at least a pair of support legs 121 that support the DUT 120 from the Y direction, and the support legs 122 may not be provided. However, by providing the support leg portion 122 in addition to the support leg portion 121, the support mechanism for the object 120 to be measured can be made more stable.

  In this way, after the ring member 102 is moved in the X direction and the Y direction with respect to the object 120 to be measured, the center position O1 of the pipe 1 is corrected relative to the center O3 of the ring member 102. Based on the center position O1 whose position has been corrected, the thickness of the pipe 1 is measured. At this time, as shown in FIG. 12, the detection function unit 101 for center position measurement is replaced with a detection function unit 130 for thickness measurement. The detection function unit 130 includes a radiation source 131 and a detector (sensor) 132 that detects radiation emitted from the radiation source 131. The radiation source 131 and the detector 132 are supported by a support arm 133, and the support arm 133 is supported so as to be rotatable on the circumference of the ring member 102. Or the detection function part 101 for center position measurement can also have a detection function part for thickness measurement. As described above, the detection function unit 101 combines both the center position measurement and the wall thickness measurement, so that both the center position O1 and the wall thickness of the pipe 1 can be measured with high accuracy and speed with a small number of parts. Can do.

  Next, a method for measuring the thickness of the pipe will be described. FIG. 14 is an explanatory diagram for explaining a thickness measuring method by the three beam method. FIG. 14A is a three-beam arithmetic expression diagram, and FIG. 14B is a schematic diagram showing the relationship between the radiation transmission length and the wall thickness.

The three-beam method, firstly, the radiation beam _{(N A, N B, N} C) obtaining a pipe wall thickness measurement of. As shown in FIG. 14A, the pipe 1 is irradiated with radiation while rotating the radiation source 131 and the detector 132 by 120 degrees with respect to the center position O1 of the pipe 1 (center O3 of the ring member 102). Each of R1, R2, and R3 shown in FIG. 14A indicates the radiation direction. At this time, as shown in FIG. 14A, the irradiation direction R1 and the irradiation direction R2, the irradiation direction R2 and the irradiation direction R3, and the irradiation direction R1 and the irradiation direction R3 have intersections in the thickness of the pipe 1, respectively. Radiation is applied to the pipe 1.

The principle of a thickness meter using radiation (γ rays) is to irradiate the object to be measured (piping) and measure the thickness of the object to be measured (piping) from the transmitted radiation. For example, if the thickness of the object to be measured is t, the radiation when there is no object to be measured is N ₀ , and the constant determined by the energy of the radiation and the material of the object to be measured is μ ₀ (absorption coefficient), the attenuation after transmission The radiation N is expressed by the following formula (1).
N = N ₀ e ^{−μ0 t} (1)

When the equation (1) is converted into the equation of the pipe thickness t, the following equation (2) can be obtained.
t = ln (N / KN ₀ ) / (− μ) (2)
Here, K is a combined attenuation amount of the heat insulating material and the exterior plate, and μ is an absorption coefficient of the pipe. That is, if K and μ are known, the thickness of the pipe can be calculated by measuring N ₀ and N.

In this embodiment, using Equation (2) listed above, the measured N ₀ and N by three-beam method, under the relationship shown in FIG. 14B, the following three equations (3), the formula ( 4) Equation (5) can be obtained.
t1 / cos30 ° + t2 / cos30 ° = ln (N _A / (K · N ₀ )) / (− μ)
... (3)
t2 / cos30 ° + t3 / cos30 ° = ln (N _B / (K · N ₀ )) / (− μ)
... (4)
t3 / cos30 ° + t1 / cos30 ° = ln (N _C / (K · N ₀ )) / (− μ)
... (5)

Equations (3), (4), and (5) are converted into equations of thickness t1, thickness t2, and thickness t3, respectively, and the following three equations (6), (7), and (8) can be obtained.
t1 = ((ln (N _A / (K · N ₀ )) / (− μ)) + (ln (N _C / (K · N ₀ )) / (− μ)) − (ln (N _B / ( K · N ₀ )) / (− μ))) · cos 30 ° / 2 (6)
t2 = ((ln (N _A / (K · N ₀ )) / (− μ)) + (ln (N _B / (K · N ₀ )) / (− μ)) − (ln (N _C / ( K · N ₀ )) / (− μ))) · cos 30 ° / 2 (7)
t3 = ((ln (N _B / (K · N ₀ )) / (− μ)) + (ln (N _C / (K · N ₀ )) / (− μ)) − (ln (N _A / ( K · N ₀ )) / (− μ))) · cos 30 ° / 2 (8)

  Then, the wall thickness t1, the wall thickness t2, and the wall thickness t3 can be calculated according to the simultaneous equations of the expressions (6), (7), and (8).

  Alternatively, as shown in FIG. 15, the radiation is irradiated from the radiation source 131 to the detector 132 so as to pass through the center position O <b> 1 of the pipe 1. Based on the amount of transmitted radiation at this time, the total value of the wall thickness t4 and the wall thickness t5 of the pipe can be obtained by the above equation (2). Then, the thickness can be obtained by dividing the total value into two. In the wall thickness measuring method shown in FIG. 15, the wall thickness to be measured is an approximate value. Therefore, when the wall thickness is obtained with high accuracy, the wall thickness measuring method by the three beam method shown in FIG. 14 can be used. preferable. On the other hand, when it is sufficient to know the approximate thickness, the summation method shown in FIG. 15 can be used.

  As shown in FIGS. 14 and 15, when measuring the thickness of the pipe 1, both use the center position O1 of the pipe 1 to define the irradiation conditions from the radiation source 131. In this embodiment, Even when the pipe 1 is wound around the heat insulating material 2, the center position O1 of the pipe 1 can be detected accurately and easily. Therefore, in this Embodiment, it becomes possible to improve the thickness measurement precision of the piping 1 effectively.

  Hereinafter, the present invention will be described in detail with reference to examples carried out in order to clarify the effects of the present invention. In addition, this invention is not limited at all by the following examples.

(Experiment for pipes with different wall thickness)
In the experiment, the end position was detected using the measurement method shown in FIG. In the experiment, a stainless steel pipe having a thickness of 5 mm, a stainless steel pipe having a thickness of 10 mm, and a carbon steel pipe having a thickness of 23 mm were used.

  In this experiment, as shown in FIG. 16, the end position 4 of the outer peripheral surface 1a of the pipe 1 was set as a reference position (0 mm), and the distance in the direction away from the end position 4 was indicated by a negative value. On the other hand, the distance from the end position 4 toward the inside of the pipe 1 is indicated by a positive value.

  As the radiation source 10, a cesium radiation source (10MBq) was used. The detector 11 was a CsI scintillator. As shown in FIG. 2, a radiation transmission curve was obtained while the radiation source 10 and the detector 11 were translated with respect to the pipe 1. The experimental results are shown in FIG.

  As shown in FIG. 17, in the range where the distance from the reference position is ± 4 mm, almost the same linear straight region could be obtained regardless of the thickness of the pipe. In this experiment, since the end position 4 of the outer peripheral surface 1a of the pipe 1 is set as the reference position (0 mm), it has been found that the center position of the inclined linear region indicates the end position 4.

  In the subsequent experiment, the end position was detected using the measurement method shown in FIG. 2 while the end position of the pipe 1 shown in FIG. 16 was moved to the position of −2 mm. The experimental conditions were the same as the experiment shown in FIG. The experimental result is shown in FIG. In FIG. 18, as described above, it is an experimental result in which the end position of the pipe 1 is moved to the position of −2 mm. Therefore, the reference position shown in FIG. 18 is a position shifted by 2 mm from the end position of the pipe 1. Exists.

  As shown in FIG. 18, within the range of −6 mm to 2 mm from the reference position, almost the same inclined linear region could be obtained regardless of the thickness of the pipe. Although the center position of the inclined straight line region is a position −2 mm from the reference position, in this experiment, the pipe 1 is moved from the state of FIG. 16 to the position −2 mm as described above. It was found that the center position of the straight line area indicates the end position 4.

  That is, from the above experiment, it has been found that almost the same inclined linear region can be obtained regardless of the thickness of the pipe, and that the end position of the pipe 1 can be obtained from the center position of the inclined linear region. 18 that the end position of the pipe 1 is shifted by -2 mm, that is, the center shift amount is -2 mm, and the end position of the pipe 1 is specified. It was found that the amount of misalignment can be detected.

(Experiment when the measurement direction is changed by 90 degrees)
Subsequently, using a pipe wound with a heat insulating material (thickness 30 mm (130 kg / m ³ )) / exterior plate (0.3 mm (SPCC)), rotation of 0 degrees, 90 degrees, 180 degrees and 270 degrees from the center position A radiation transmission curve was obtained at the corner using the measurement method shown in FIG. The experimental result is shown in FIG. A scale is displayed on the support frame 112 shown in FIG. 7, and the horizontal axis in FIG. 19 is the scale value of the support frame 112. The reference position (0 mm) in FIG. 19 indicates the end position of the heat insulating material.

  As shown in FIG. 19, in the range of −10 mm to 25 mm from the reference position, no large variation is seen in the radiation transmission curve, and the position of 25 mm from the reference position is an inflection point, regardless of the rotation angle up to the range of 35 mm. It was found that an inclined linear region inclined with a substantially constant change amount was obtained. It was found that the inclined linear region was within a range of 25 mm to 35 mm from the reference position, and the center position of the inclined linear region was 30 mm from the reference position. Therefore, it was found that the end position of the pipe was 30 mm from the reference position in any rotation angle measurement. An inflection point is also seen near the reference position. This position is just the position of the outer peripheral surface of the heat insulating material, and the outer peripheral surface of the heat insulating material (0. 3mm) is located. From this, it is considered that the radiation transmission curve as shown in the figure is obtained.

Subsequently, using a pipe wrapped with a heat insulating material (thickness 30 mm (130 kg / m ³ )) / exterior plate (0.3 mm (aluminum)), it is rotated 0, 90, 180, and 270 degrees from the center position. A radiation transmission curve was obtained at the corner using the measurement method shown in FIG. The experimental results are shown in FIG.

  FIG. 20 differs from FIG. 19 in that only the exterior plate is changed and the other experimental conditions are the same as in FIG. Similarly to FIG. 20, it was found from the obtained radiation transmission curve that the inclined linear region was within a range of 25 mm to 35 mm from the reference position, and the central position of the inclined linear region was 30 mm from the reference position. Therefore, it was found that the end position of the pipe was 30 mm from the reference position after measurement at any rotation angle. Further, although an inflection point is also found near the reference position, as described above, this position is just the position of the outer peripheral surface of the heat insulating material, and the outer peripheral surface of the heat insulating material has a greater shielding effect than the heat insulating material. An exterior plate (0.3 mm) is located. Since aluminum has a small atomic number and a small γ-ray shielding effect, it is considered that aluminum has a radiation transmission curve as shown in the figure.

  According to the pipe inspection method of the present invention, the center position and thickness measurement of the pipe can be performed with high accuracy even when the heat insulating material is wound around the pipe. Therefore, even if the pipe is not visible from the appearance, the thickness reduction state of the pipe can be measured appropriately, and the pipe maintenance can be performed appropriately.

DESCRIPTION OF SYMBOLS 1 Piping 2 Heat insulating material 4, 8, 123, 124 End position 10, 131 Radiation source 11, 132 Detector 100 Pipe inspection apparatus 101, 130 Detection function part 102 Ring member 103 Straight movement mechanism 104 Support member 110, 111 Rail member 114, 140 Roller 120 DUT 120a Outer peripheral surface 121, 122 Support leg 149, 150 Abutting portion 151, 154 Adjustment shaft 152, 155 Adjustment bearing 157 Block body

Claims (11)

Using the radiation having linearity, after measuring the center deviation of the pipe inside the coating material from a plurality of different directions, measure the thickness of the pipe based on the center position of the pipe,
A piping inspection method characterized by that.   The pipe inspection method according to claim 1, wherein a plurality of end positions are specified at different positions on the outer peripheral surface of the pipe, and a center shift of the pipe is detected based on each end position.   While translating the radiation irradiation position between the outer side of the end position and the inner wall thickness, a radiation transmission curve for the irradiation position is obtained, and a certain amount of change in the radiation transmission curve is obtained. The pipe inspection method according to claim 2, wherein the irradiation position indicating the center of the inclined linear region inclined at is defined as the end position.   The pipe inspection method according to any one of claims 1 to 3, wherein a center deviation of the pipe is measured from at least two directions orthogonal to the pipe.   5. The thickness of the pipe is measured based on the center position after correcting the position of the center position of the pipe based on the measurement result of the center deviation. The piping inspection method described in 1.   In the step of measuring the thickness of the pipe, the radiation direction is set to at least three directions, and the radiation is irradiated so that the intersection of the irradiation directions is located within the thickness of the pipe. 6. The pipe inspection method according to claim 1, wherein a permeation amount is obtained, and a thickness at the intersection of the pipes is calculated based on the permeation amount.   In the step of measuring the wall thickness of the pipe, radiation is radiated so as to pass through a central position of the pipe to obtain a transmission amount of the radiation, and the thickness of the pipe is calculated based on the transmission amount. The piping inspection method according to any one of claims 1 to 5. A radiation source for irradiating linear radiation, and a detector for detecting the radiation, and at least a detection function unit for measuring the center position of the pipe;
A ring member that rotatably supports the detection function unit around the pipe;
A moving mechanism capable of moving the detection function unit from a position away from the pipe to a position where the radiation source and the detector face each other via the pipe;
A pipe inspection apparatus characterized by comprising:   A plurality of support legs for supporting the outer surface of the covering material covering the pipe is provided between the ring member and the covering material, and a support position between at least two of the support legs and the covering material is fixed. The piping inspection device according to claim 8, wherein an adjustment mechanism capable of correcting movement of the ring member side in a state of being provided is provided.   The pipe inspection apparatus according to claim 9, wherein the adjustment mechanism is provided on the at least two of the support legs. The pipe inspection apparatus according to any one of claims 8 to 10, wherein the detection function unit also serves for measuring the thickness of the pipe.

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