JP6306851B2 - Layer thickness test method for metal multilayer and layer thickness test equipment for metal multilayer - Google Patents

Description

  The present invention relates to a method for testing a thickness of a metal multilayer body and a layer thickness test apparatus for a metal multilayer body. In particular, the present invention relates to a test method for the degree of deterioration of buried piping and an apparatus therefor.

Conventionally, a method of measuring the thickness of a constituent layer of a multilayer body by a nondestructive method has been adopted.
For example, in Japanese Patent Laid-Open No. 60-123712 (Patent Document 1), an ultrasonic probe is installed on the surface of a tube to emit ultrasonic waves in the radial direction and detect a reflected wave from the inner surface of the opposite lining. A method for measuring the inner surface lining thickness is disclosed, wherein the lining thickness is measured from the energy loss of the reflected wave.

  Japanese Patent Application Laid-Open No. 63-3211 (Patent Document 2) discloses a method for measuring the thickness of a fiber-reinforced composite layer formed integrally with a surface of a metal main body and made of a reinforcing fiber and a metal matrix. The ultrasonic wave is transmitted toward the surface of the fiber reinforced resin composite layer and the reflected wave is sequentially received, and the time from the transmission of the ultrasonic wave to the reception of the final reflected wave by the reinforcing fiber is converted into the thickness of the fiber reinforced composite layer. A method for measuring the thickness of a fiber-reinforced composite layer using ultrasonic waves is disclosed.

JP-A-60-123712 Japanese Patent Laid-Open No. Sho 63-3211

The method of patent document 1 measures the thickness of the concrete lining layer of the composite pipe comprised from a metal and concrete. In this method, it is necessary to install a contact-type ultrasonic probe outside the composite tube. Therefore, when applied to the buried pipeline, an excavation work is required. Furthermore, the method of Patent Document 1 is a method of measuring the lining thickness, and does not describe measuring the thickness of the metal layer.
The method of patent document 2 measures the thickness of the fiber reinforcement layer which is an ultrasonic incident side by a water immersion type ultrasonic method. However, it is not described that the thickness of the metal layer as the back layer can be measured.

  The object of the present invention is to provide information on the thickness of a metal layer in a nondestructive manner with respect to a composite layer having a porous layer on the surface of the metal layer, which is considered to have a particularly large attenuation of ultrasonic waves in general technical common sense. It is to provide a method that can be obtained.

(1)
The layer thickness test method for a metal multilayer body according to one aspect is a method for testing the layer thickness of a multilayer body including a metal layer and a porous layer provided on the surface of the metal layer. The layer thickness test method includes a transmitting step for applying an ultrasonic wave transmitted in a direction from the porous layer side to the metal layer side through an aqueous medium; and receiving a reflected wave with respect to the ultrasonic propagation time. A waveform acquisition step of acquiring a waveform of the intensity of the reflected wave; at least a peak of the first interface reflected wave first reflected at the boundary surface between the metal layer and the porous layer from the acquired waveform; and the metal layer A determination step of determining a peak of the first outer surface reflected wave first reflected on the surface opposite to the porous layer; and a detection time difference between the peak of the first interface reflected wave and the peak of the first outer surface reflected wave And a thickness calculating step of calculating the thickness of the metal layer based on the above.

  Thereby, the thickness of the metal layer can be measured by a non-destructive method.

(2)
The layer thickness test method for a metal multilayer body according to one aspect is a method for testing the layer thickness of a multilayer body including a metal layer and a porous layer provided on the surface of the metal layer. The layer thickness test method includes a transmitting step for applying an ultrasonic wave transmitted in a direction from the porous layer side to the metal layer side through an aqueous medium; and receiving a reflected wave with respect to the ultrasonic propagation time. A waveform acquisition step of acquiring a waveform of the intensity of the reflected wave; and when the acquired waveform is detected as a multiple peak due to n-fold reflection (n is an integer of 2 or more) in the metal layer. A determination step of determining at least two peaks of the external reflection wave reflected by the surface of the metal layer opposite to the porous layer from the waveform; and at least arbitrarily selected from the determined peaks of the external reflection wave A thickness calculating step of calculating the thickness of the metal layer based on the detection time of the two peaks.

  Thereby, the thickness of the metal layer can be measured by a non-destructive method.

  The peak of the first interface reflected wave and the peak of the outer surface reflected wave (including the first outer surface reflected wave) are detected in a manner that can be discriminated as a reflected wave. For example, the signal noise ratio (S / N) is It means 2.5 or more, preferably 3 or more.

Porous is a solid material with continuous pores that are connected in three dimensions.
The porous material is caused by the fact that the continuous pores are filled with air with particularly low acoustic impedance (that is, extremely small compared to solids and liquids). Hateful. For this reason, the porous material is not inherently suitable for ultrasonic measurement. In the layer thickness test method of the present invention, an aqueous medium is interposed, the porous layer is impregnated with the aqueous medium, and the continuous pores are filled with water having a higher acoustic impedance (that is, having an acoustic impedance close to a solid). It is. That is, the inside of the continuous pores is replaced with air from water. For this reason, it is conceivable that the ultrasonic impedance is easily transmitted by making the difference in acoustic impedance from the solid constituting the porous material small, and ultrasonic measurement is possible.

(3)
In the layer thickness test method of the present invention, the porous material may be a cement-containing material.
Since the cement-containing material has an acoustic impedance that is particularly close to that of water, the difference in acoustic impedance is reduced by the intervention of the aqueous medium, and ultrasonic measurement becomes easier.

(4)
In the layer thickness test method of this invention, it is preferable that the frequency of the ultrasonic wave transmitted in the transmitting step is 1 MHz or more and 9 MHz or less.

  Thereby, it is easy to obtain a resolution for separating and detecting the peak in the waveform of the reflected wave intensity with respect to the ultrasonic wave propagation time. Therefore, it is easy to acquire the thickness of the metal layer more accurately. Since the ultrasonic wave is easily transmitted through the metal layer, the external surface reflected wave is easily obtained in a highly sensitive state.

(5)
The test target of the layer thickness test method of the present invention may be a composite tube in which a porous layer is lined as a lining layer on the inner peripheral surface of a metal tube. In this case, the ultrasonic wave is transmitted from a probe unit provided inside the composite tube.

The lining layer is a layer which is coated on the surface of a base material (metal in the present invention) relatively thickly to prevent corrosion, abrasion and contamination of the base. The probe unit is a member including at least an ultrasonic probe.
In this case, since the layer thickness test can be performed by inserting the probe portion into the composite pipe filled with water, the excavation work becomes unnecessary particularly when the composite pipe is buried.

(6)
In the transmitting step, ultrasonic waves can be transmitted so as to scan the entire inner circumference of the composite tube while maintaining an angle at which the ultrasonic waves are transmitted perpendicularly to the inner surface of the lining layer.
Note that the distance between the head portion of the probe portion and the inner surface of the lining layer corresponds to the thickness of the intervening aqueous medium. The head portion refers to the outer surface on the ultrasonic wave transmission side in the housing of the ultrasonic probe constituting the probe portion.

  Further, the term “perpendicular to the inner surface of the lining layer” does not mean that the angle is strictly 90 degrees with respect to the tangent line of the inner surface of the lining layer, but 85 degrees or more and 95 degrees or less with respect to the tangent line. The angle which forms is also allowed. Further, it is preferable that the allowable range is 88 degrees or more and 92 degrees or less because the echo height can be reduced to about half of the case where the echo height is 90 degrees (specifically, a decrease of 6 dB).

  Furthermore, a deviation in a radial direction parallel to the tangent line (tangent line on the inner surface of the lining layer on which the ultrasonic wave is incident) from the central axis is allowed from the position where the ultrasonic wave is transmitted. The allowable range of this deviation depends on the water distance, but is within ± 5 mm in the radial direction from the central axis, preferably within ± 3 mm. Thereby, compared with the case where there is no deviation, the echo height can be reduced to about half (decrease by 6 dB as a specific example).

  Thus, the thickness of the entire circumference of the metal tube can be tested.

(7)
In the layer thickness test method of the present invention, the cement-containing substance to be tested may be mortar.

  Thereby, the present invention can realize high versatility, particularly when the test object is a mortar lining pipe.

(8)
In the layer thickness test method of the present invention, the metal layer to be tested may be at least one of cast iron and steel.

  As a result, the present invention can achieve high versatility, particularly when the test object is an embedded lining pipe. It is also useful when the test object is a buried lining steel structure such as an underground tank.

(9)
A layer thickness test apparatus for a metal multilayer according to another aspect is used in the method according to any one of (1) to (8), and includes a probe unit for transmitting ultrasonic waves; a head unit of the probe unit; A separation part that separates the surface of the porous layer; a waveform acquisition part that acquires a waveform of the reflected wave intensity with respect to the ultrasonic propagation time; and at least a boundary surface between the metal layer and the porous layer from the acquired waveform A determination unit for determining a peak of the first interface reflected wave reflected first and a peak of the first outer surface reflected wave first reflected on the surface of the metal layer opposite to the porous layer; And a thickness calculator for calculating the thickness of the metal layer based on the difference in detection time between the peak of the first and the peak of the first external reflection wave.

  Thereby, the thickness of the metal layer can be accurately obtained in a non-destructive manner.

(10)
A layer thickness testing apparatus for a metal multilayer according to still another aspect is used in the method according to any one of (1) to (8), and a probe unit for transmitting ultrasonic waves; and a head unit of the probe unit A separation part that separates the surface of the porous layer from the surface; a waveform acquisition part that acquires a waveform of the reflected wave intensity with respect to the ultrasonic propagation time; and an n-fold reflection (n is the acquired waveform) in the metal layer A determination unit that determines at least two peaks of externally reflected waves that are surface-reflected on the side opposite to the porous layer of the metal layer from the waveform when detected as multiple peaks by an integer of 2 or more); A wall thickness calculating unit that calculates the wall thickness of the metal layer based on the detection time of at least two peaks arbitrarily selected from the determined peak of the external reflection wave.

  Thereby, the thickness of the metal layer can be accurately obtained in a non-destructive manner.

(11)
The layer thickness test apparatus for a metal multilayer body of the present invention may include an angle holding unit that holds an angle at which ultrasonic waves are transmitted perpendicularly to the inner surface of the porous layer.

Thereby, the echo peak can be detected with sufficient intensity.
Note that the angle holding unit may be provided separately from the separation unit, or may be provided as one configuration of the separation unit.

(12)
The apparatus for testing a thickness of a metal multilayer body according to the present invention is a metal composite tube in which a porous layer is lined as a cement-containing lining layer on an inner peripheral surface of a metal tube, and a separation portion is a shaft of the metal composite tube. A moving mechanism capable of traveling in the central direction may be included.

  Thereby, the wall thickness can be tested in the axial direction of the metal tube.

(13)
The apparatus for testing a thickness of a metal multilayer body according to the present invention is a metal composite tube in which a porous layer is lined as a cement-containing lining layer on the inner peripheral surface of a metal tube, and ultrasonic waves are applied to the entire inner periphery of the composite tube. May be configured to be transmitted to scan.

  Thus, the thickness of the entire circumference of the metal tube can be tested.

(14)
The apparatus for testing a thickness of a metal multilayer body according to the present invention is a metal composite tube in which a porous layer is lined as a cement-containing lining layer on an inner peripheral surface of a metal tube, and a probe portion is a shaft of the metal composite tube. It may be provided so as to be rotatable inside the metal composite tube with the core as a rotation axis.

  Thus, the thickness of the entire circumference of the metal tube can be tested. In addition, the layer thickness test apparatus of this invention does not ask | require whether it has the said rotating shaft as a part of mechanical structure. As an example of the case where the layer thickness test apparatus of the present invention does not have the rotating shaft as a part of the mechanical configuration, the separating portion is on the inner periphery of the metal composite tube (that is, the surface of the lining layer is in the circumferential direction). The case where the moving mechanism which can drive along is included is mentioned.

  The apparatus for testing a thickness of a metal multilayer body according to the present invention is a metal composite tube in which a porous layer is lined as a cement-containing lining layer on an inner peripheral surface of a metal tube, and a probe portion is a shaft of the metal composite tube. A refracting part that refracts the transmitted ultrasonic wave so as to be incident on the inner surface of the lining layer is provided with the axis of the composite tube as the rotation axis. It may be provided so as to be rotatable.

  Thereby, it can be transmitted to scan the entire inner circumference of the composite tube. Therefore, the thickness of the entire circumference of the metal tube can be tested.

(15)
The layer thickness test apparatus for a metal multilayer body of the present invention may be set so that the ultrasonic frequency is 1 MHz or more and 9 MHz or less.
Thereby, it is easy to obtain a resolution for separating and detecting the peak in the waveform of the reflected wave intensity with respect to the ultrasonic wave propagation time. Therefore, it is easy to acquire the thickness of the metal layer more accurately. Since the ultrasonic wave is easily transmitted through the metal layer, the external surface reflected wave is easily obtained in a highly sensitive state.

(16)
In the layer thickness test apparatus for a metal multilayer body according to the present invention, the probe portion may include an ultrasonic probe.
This makes it possible to use an ultrasonic probe that is generally used in the water immersion method. The ultrasonic probe is generally an ultrasonic sensor that is housed in a casing by adhering a sound absorbing material and a protective plate to a vibrator having piezoelectric characteristics.

  ADVANTAGE OF THE INVENTION According to this invention, the method which can acquire the information regarding the thickness of a metal layer can be provided by a nondestructive system about the composite layer which has a porous layer on the surface of a metal layer.

It is a schematic diagram which shows an example of the layer thickness test method of this Embodiment. It is a schematic diagram which shows an example of the layer thickness test method of this Embodiment. It is a typical partial enlarged view which shows an example of the layer thickness test method of this Embodiment. It is a typical partial enlarged view which shows an example of the layer thickness test method of this Embodiment. It is a block diagram which shows an example of the principal part of the layer thickness test apparatus of this Embodiment. It is a schematic diagram which shows an example of the detection peak pattern in the layer thickness test method of this Embodiment. It is a schematic diagram which shows the other example of the detection peak pattern in the layer thickness test method of this Embodiment. It is a schematic diagram which shows the further another example of the detection peak pattern in the layer thickness test method of this Embodiment. It is a schematic diagram which shows another example of the layer thickness test method of this Embodiment. 3 is a layer thickness test result obtained in Example 1. 3 is a layer thickness test result obtained in Example 2. 4 is a layer thickness test result obtained in Example 3. 4 is a layer thickness test result obtained in Example 4. 5 is a layer thickness test result obtained in Example 5. It is a layer thickness test result obtained in Example 6. It is a layer thickness test result obtained in Example 7. This is the result obtained in Reference Example 1. 10 is a layer thickness test result obtained in Example 8. 10 is a layer thickness test result obtained in Example 9. It is a layer thickness test result obtained in Example 10. 3 is a layer thickness test result obtained in Example 11. It is a layer thickness test result obtained in Example 12. It is a layer thickness test result obtained in Reference Example 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same elements are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a partially cutaway view schematically showing an example of a layer thickness test method according to the present embodiment. FIG. 2 is a schematic view seen from the axial direction of the lining pipe to be tested in the layer measurement test method of FIG. FIG. 3 is a schematic partially enlarged view showing an example of a layer thickness test method in the present embodiment. FIG. 5 is a block diagram showing a part of the layer thickness test apparatus.

  As shown in FIGS. 1 and 2, a test target of the layer thickness test apparatus 100 in the layer thickness test method is a lining pipe 500. The lining pipe 500 is such that a cement-containing layer 520 is lined on the inner surface of a metal pipe 510 and embedded in the ground. For example, plumbing of waterworks, sewage, industrial water and agricultural water is included.

Examples of the material of the metal tube 510 include iron (particularly cast iron) and steel.
Cast iron is an iron-carbon alloy containing about 2.0% or more of carbon. Generally, the carbon content is 2.0% or more and 4.5% or less and silicon is 0.5% or more and 3.0% or less, manganese is 1.0% or less, phosphorus and / or sulfur is 0.1%. In many cases, it also contains about% (% is based on weight).

Types of cast iron include white cast iron, mottled cast iron and gray cast iron as normal cast iron, and reinforced cast iron as tough cast iron, spheroidal graphite cast iron (for example, nodular cast iron, ductile cast iron), malleable cast iron and alloys Cast iron is mentioned. In the case of water pipes, specifically, Japanese Industrial Standards (JIS G 5521, 5522, 5523, 5524, 5526, 5527), Japan Waterworks Association Standards (JWSA G 102, 103, 105, 106, 108, 109, 110, 111, 113, 114, 114-2), Japan Sewerage Association Standard (JSWAS G-1, G-2), Japan Ductile Iron Pipe Association Standard (JDPA G 1001, 1002,
1003, 1004, 1007, 1008, 1009, 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017,
1018, 1019, 1020, 1021, 1022, 1024, 1025, 1026, 1027, 1028, 1029, 1030, 1031,
1032, 1033, 1034, 1035, 1036, 1037, 1038, 1039, 1040, 1041, 1042, 1043, 1044,
1045, 1046, 1047, 1048).

  Steel is an iron-carbon based alloy containing about 2.0% or less of carbon (% is based on weight). Examples include carbon steel and stainless steel.

  Moreover, the nominal diameter of the metal pipe 510 is, for example, 100 or more, more specifically, 100 or more and 300 or less.

  The material of the cement-containing layer 520 may be any lining material containing cement. Examples of the cement include pollite cement, mixed cement (for example, blast furnace cement, fly ash cement, silica cement), eco cement, hydrated cement, and unhydrated cement. Typical pollite cements fire a mixture of limestone and clay, silica, and iron oxide, and clinker such as tricalcium silicate, dicalcium silicate, tricalcium aluminate, iron tetracalcium aluminate After that, a small amount of gypsum was added to the clinker and pulverized. In addition to the components described above, air and / or water may be present in the cement.

  The cement-containing layer 520 is a layered material made of the above-described cement. In materials containing cement, examples of materials mixed with cement include fine aggregates such as sand, coarse aggregates such as gravel and crushed stone, and admixtures. More specifically, materials containing cement include mortar and concrete (eg, fresh concrete, hardened concrete).

  In general, mortar is obtained by adding a fine aggregate alone to cement or adding both a fine aggregate and an admixture to cement. In the case of water pipes, specifically, it is stipulated in Japan Industrial Standard (JIS A5314), Japan Waterworks Association Standard (JWWA A 107, JWWA A 113), Japan Ductile Iron Pipe Association Standard (JDPA Z 2013, JDPA Z 2015), etc. ing. When the blending ratio of the cement and fine aggregate is 1: 1.5 or more and 1: 3.5 or less as a composition in a healthy state (that is, an undegraded state), and an admixture is blended , Is defined as 15% or less relative to the cement mass (% is based on weight).

  Further, the cement-containing layer 520 may have another coating layer or seal coat on the inner surface of the layer of cement-containing material. The material of the further another coating layer includes, for example, a resin, more specifically, an acrylic resin and a vinyl chloride resin.

  As shown in FIGS. 1 and 2, the lining pipe 500 is filled with water W. The layer thickness test apparatus 100 is disposed inside the lining pipe 500. The layer thickness test apparatus 100 includes a probe unit 110, a holding unit 120, and a separation unit 130. Furthermore, as shown in FIG. 5, the layer thickness test apparatus 100 includes a waveform acquisition unit 150, a determination unit 160, a thickness calculation unit 170, and a display unit 180.

  As shown in FIG. 2, the probe unit 110 includes an ultrasonic probe 111, a sensor holder 112 that holds the ultrasonic probe 111 toward the cement-containing layer 520 at one end, and the other end of the sensor holder 112. And an arm member 113 that couples the part to the holding part 120. The ultrasonic probe 111, the sensor holder 112, and the arm member 113 are arranged so as to be coaxial with the lining tube 500 in the radial direction.

  The ultrasonic probe 111 shown in FIG. 2 generates an ultrasonic wave and transmits / receives an ultrasonic beam. The ultrasonic probe 111 mainly includes an acoustic lens, an acoustic matching layer (matching layer), a vibrator (element), and a backing (damper) in a housing.

The acoustic lens is provided to focus the ultrasonic beam using refraction and improve the resolution. A concave lens is generally used as the acoustic lens. The sound speed of the acoustic lens is about 2000 m / sec or more and 3000 m / sec or less, and an acrylic resin or polystyrene resin is used as the material.
The acoustic matching layer (matching layer) is also called a λ / 4 layer. In order to reduce the acoustic impedance difference between the transducer and the specimen and to efficiently transmit and receive ultrasonic waves, the multilayer arrangement is used.
The vibrator (element) transmits and receives ultrasonic waves. It is a so-called transducer that vibrates when a voltage is applied to generate ultrasonic waves, and generates a voltage when vibrated. It is also called a piezoelectric element, and is composed of a material having a piezo effect (piezoelectric effect). A typical example of such a material is quartz, and more generally, PZT (lead zirconate titanate). Other examples include PVDF (polyvinylidene fluoride).
The backing (damper) is disposed on the back surface of the vibrator, and suppresses the propagation of ultrasonic waves to the rear. This contributes to shortening the pulse width.

  Examples of the ultrasonic probe include a focus type probe and a straight type probe. The focus type probe is designed so that a transmitted ultrasonic wave is temporarily focused at a point at a certain distance (see reference symbol D in FIG. 1) from the head unit. In the focus type probe, ultrasonic waves transmitted from each point of the head unit are transmitted in such a way that they are not parallel but gather toward the point. The rectilinear probe is designed so that ultrasonic waves transmitted from each point of the head part are parallel. In order to obtain a sharp peak, a focus type probe is preferable.

In the present embodiment, a single probe method, that is, a method using one transmission / reception integrated ultrasonic probe 111 is illustrated, but the present invention is not limited to this.
For example, a two-probe method, that is, a method using a transmitting probe and a receiving probe may be used. The transmitting probe and the receiving probe may be functionally and physically separated from each other. In this case, the transmitting probe and the receiving probe are oblique to the tangent to the inner surface of the lining layer (that is, more than 0 degrees 90 degrees). The ultrasonic wave is transmitted from the transmitting probe so that the incident angle is less than 50 degrees, and the reflected wave reflected obliquely (that is, with a reflection angle of more than 0 degrees and less than 90 degrees) is received by the receiving probe. Can do.
In addition, a method of using a plurality of transmission / reception integrated sensors may be used. Further, a method using a plurality of two-probe methods may be used.

  As shown in FIGS. 1 and 2, the holding part 120 is provided so as to be interposed between both parts in order to hold the probe part 110 and the separating part 130. Further, in the case of FIGS. 1 and 2, the probe unit 110 and the separation unit 130 are maintained so that the angle (vertical) of the probe unit 110 with respect to the tangent TL (see FIG. 2) of the inner peripheral surface of the cement-containing layer 520 is kept constant. Can also be connected. As shown in FIG. 2, the holding unit 120 includes a rotating shaft 121 and a cylindrical casing 122 that are arranged so as to be coaxial with the axis of the lining pipe 500.

  As shown in FIGS. 1 and 2, the rotary shaft 121 has one end fixed to the arm member 113 of the probe unit 110 and the other end supported at the axial center position of the cylindrical casing 122. It is rotationally driven by a motor (not shown) accommodated therein. Thus, along with the rotation of the rotating shaft 121, the ultrasonic probe 111 is kept on the inner peripheral surface of the cement-containing layer 520 while maintaining an angle (perpendicular) to the cement-containing layer 520 surface via the arm member 113. Rotate along (arrows in FIGS. 1 and 2).

  As shown in FIG. 1 and FIG. 2, the separation unit 130 separates the head part (part where ultrasonic waves are transmitted) of the ultrasonic probe 111 of the probe unit 110 and the surface of the cement-containing layer 520. Is provided. The distance D (see FIG. 1) between the head portion of the ultrasonic probe 111 of the probe unit 110 and the cement-containing layer 520 is the wavelength of the transmitted ultrasonic wave and the characteristic (straight line) of the ultrasonic probe 111. There is no particular limitation as it may differ depending on the type and the focus type. For example, from the viewpoint of easily maintaining good detection sensitivity, the distance D can be set to 5 mm or more.

  As shown in FIG. 2, the separation portion 130 includes three parallel link mechanisms 131 that can radially expand radially outward on the inner periphery of the cement-containing layer 520 and radially contract radially inward, and each parallel link. It includes a wheel 135 provided outside the mechanism 131 in the axial direction of the lining pipe 500 (see FIG. 1) and capable of traveling in the axial direction.

As shown in FIG. 1, the parallel link mechanism 131 includes a connecting ring 132, a cross arm 133, and a link plate 134.
Two connecting rings 132 are provided in the axial direction of the cylindrical casing 122, one is fitted on the outer peripheral surface of the cylindrical casing 122, and the other is slidable on the outer peripheral surface of the cylindrical casing 122 in the axial direction. It is loosely fitted. As shown in FIG. 2, each of the connecting rings 132 has three connecting protrusions for connecting the cross arm 133 projecting radially on the surface.

  The cross arm 133 can change the crossing angle of a pair of arms, and as shown in FIG. 1, one end of each arm is connected to each of the two connecting rings 132. The link plate 134 connects the other end of the cross arm 133 and connects a pair of wheels 135 to each other. In the link plate 134, one connecting position of the other end of the cross arm 133 is fixed, and the other connecting position is slidable in the axial direction of the lining pipe 500.

  As shown in FIG. 1 and FIG. 2, the spacing portion 130 is crossed so that the three pairs of wheels 135 abut against the cement-containing layer 520 and the axis of the cylindrical casing 122 coincides with the axis of the lining pipe 500. By adjusting the crossing angle of the arms 133, the state in which the ultrasonic probe 111 of the probe unit 110 and the cement-containing layer 520 are separated from each other is maintained.

  FIG. 3 is an enlarged schematic view of the ultrasonic probe 111 and a part of the lining tube 500 when the layer thickness test is performed. As shown in FIG. 3, an ultrasonic wave (transmitted wave E) is transmitted from the head portion of the ultrasonic probe 111. The transmitted wave E is transmitted so as to be perpendicular to the tangent TL of the inner peripheral surface s of the cement-containing layer 520.

  The wavelength of the transmitted ultrasonic wave is particularly limited because it can vary depending on the characteristics (linear type and focal type) of the ultrasonic probe 111, the distance between the head portion of the ultrasonic probe 111 and the surface of the cement-containing layer 520, and the like. Is not to be done. For example, the lower limit value of the wavelength of the ultrasonic wave is 1 MHz or more, and 1.5 MHz, and further 2 MHz is preferable. The upper limit of the wavelength of the ultrasonic wave is, for example, 10 MHz, more preferably 9 MHz, further 7.5 MHz, further 5 MHz, and further 3.5 MHz. When the above range is exceeded, the sensitivity tends to be low with respect to the signal noise ratio (S / N ratio). Below the above range, the dead zone (that is, the skirt width of each peak) becomes wide, the layer thickness measurement accuracy tends to decrease, and the layer thickness measurable range tends to narrow.

  In an example of the model case brought about by the layer thickness test, as shown in FIG. 3, the transmitted wave E reaches the outer surface b of the metal tube 510, and the inner peripheral surface s of the cement-containing layer 520, the cement-containing layer. 520 and the metal pipe 510 boundary surface i, and the outer surface b of the metal tube 510, the reflected wave RS reflected by the inner peripheral surface s, the first reflected wave RI1 first reflected by the boundary surface i, and The first reflected wave RB1 first reflected by the outer surface b is received by the ultrasonic probe 111.

Further, FIG. 4 schematically shows an ultrasonic reflection path when multiple echo peaks are acquired by multiple reflection in the metal layer 510.
When generalizing that the transmitted wave E is reflected n times in the metal layer 510 (n is an integer of 2 or more, the same applies hereinafter), the reflected wave reflected at the (n-1) th time on the outer surface b. Is the (n-1) th reflected wave RB (n-1), and the (n-1) th reflected wave RB (n-1) is reflected at the boundary surface i, so that the nth reflected wave RB (n-1) is reflected again on the outer surface b The reflected wave that has been reflected is the nth reflected wave RBn.
Therefore, the reflected wave first reflected by the outer surface b of the metal layer 510 is referred to as the first reflected wave RB1, and the reflected wave RB1 is reflected at the boundary surface i by the second reflection on the outer surface b. The reflected wave reflected again is referred to as a second reflected wave RB2. In addition, when the number of the reflected light is not particularly limited, it is simply described as a reflected wave RB.

  The received signal is processed into a waveform of reflected wave intensity with respect to propagation time in the waveform acquisition unit 150 (see FIG. 5). More specifically, the received wave (reflected wave RS, RI1, RB1 in the case of FIG. 3) is amplified by a signal amplifier, noise is removed by a band pass filter or the like, digitized by an A / D converter, and thereafter The waveform is acquired by performing an averaging process of adding and averaging the digitized waveforms on the same time axis. The acquired waveform is stored together with the measurement position information. The acquired waveform can be displayed on the display unit 180.

  FIG. 6 schematically shows a peak pattern (reflected wave intensity with respect to propagation time) in this model case. FIG. 6 shows the propagation time on the horizontal axis and the signal intensity on the vertical axis. As shown in FIG. 6, three echo peaks are detected with separable resolution. More specifically, the reflected wave RS reflected by the inner peripheral surface s of the cement-containing layer 520 is detected as the reflected wave having the shortest propagation time. The first reflected wave RI1 reflected first at the boundary surface i is detected as the reflected wave having the second longest propagation time. As a reflected wave having the third longest propagation time, the first reflected wave RB1 first reflected by the outer surface b is detected.

  Further, in some cases, multiple echo peaks including two or more reflected waves RB may be obtained by multiple reflection in the metal layer 510. That is, the (n−k + 1) th reflected wave RB (n−k + 1), the (n−k + 2) th reflected wave RB (n−k + 2), the (n−k) th reflected wave RB (n−k), (n−k + 3) reflected wave RB (n−k + 3), (n−k + 4) th reflected wave RB (n−k + 4)... may be acquired (k is an integer of 1 or more. The same applies hereinafter. .) In this case, the multiplex composed mainly of the first reflected wave RB1 and the second reflected wave by detecting the second reflected wave RB2 (see FIG. 3) secondly reflected by re-reflection on the outer surface b. There is a tendency that echo peaks are often acquired.

  In the model case of FIG. 6, the echo peak of each reflected wave RS, RI1, RB1 is displayed as a single peak of normal distribution, but it is not limited to such a shape. The echo peak may be an aspect in which at least the echo peaks of the first reflected waves RI1 and RB1 necessary for measuring the thickness of the metal tube 510 are detected so as to be distinguishable from each other. For example, the aspect which formed the peak group by the synthesized wave by interference of the reflected wave which reflected the same interface for the echo peak may be sufficient. Each echo peak of the reflected waves RS, RI1, RB1 has, for example, an S / N ratio of 2.5 or more, preferably 3 or more.

  In the determination unit 160 (see FIG. 5), at least the first reflected waves RI1, RB1 or at least two reflected waves RB among the reflected waves RB in the case of n-layer reflection in the metal layer 510 are determined as peaks. It is determined whether or not detection has been made with possible resolution, or resolution and S / N ratio (for example, S / N ratio is 2.5 or more, preferably 3 or more).

  For example, when a peak pattern (echo peak of reflected waves RS, RI1, RB1) as shown in FIG. 6 is detected in a distinguishable manner, the thickness of the metal tube 510 of the lining tube 500 is such that the thickness can be obtained. It can be judged that.

  Similarly, when the echo peaks of two or more reflected waves RB are detected in a distinguishable manner, it can be determined that the thickness of the metal layer 510 of the lining tube 500 is such that the thickness can be obtained.

  In the case of the peak pattern as shown in FIG. 6, the thickness calculation unit 170 (see FIG. 5) further reduces the propagation time difference (μ seconds) between the first reflected wave RB1 and the first reflected wave RI1 to 1/2. The thickness of the metal tube 510 is calculated by multiplying by the speed of sound.

  Similarly, when two or more reflected wave RB peaks are detected in a distinguishable manner, a pair of (two) reflected wave RB peaks arbitrarily selected from the detected reflected wave RB peaks are used. Based on the difference in propagation time, the thickness of the metal layer can be calculated.

  For example, when the (n−k) th reflected wave RB (n−k) and the (n−k + 1) th reflected wave RB (n−k + 1) are used, the (n−k) th reflected wave RB (n−k) is used. And the (n−k + 1) th reflected wave RB (n−k + 1), the thickness of the metal tube 510 is calculated by multiplying the difference in propagation time (μ seconds) by 1/2 and the sound velocity.

  Further, for example, when the (n−k) th reflected wave RB (n−k) and the (n−k + 3) th reflected wave RB (n−k + 3) are used, the (n−k) th reflected wave RB (n−k) ) And the (n−k + 3) reflected wave RB (n−k + 3) by multiplying the difference in propagation time (μ seconds) by 1/3, and further multiplying by 1/2 and the sound velocity, the thickness of the metal tube 510 is increased. Calculate the thickness.

  In addition, when there are a plurality of patterns for selecting a pair of reflected waves RB from the peaks of two or more reflected waves RB detected in a distinguishable manner, a value obtained by calculating the plurality of patterns and averaging the calculation results May finally be the thickness of the metal tube 510.

  Alternatively, for two or more reflected waves RB arbitrarily selected from the peaks of the two or more reflected waves RB detected in a distinguishable manner, first, the relationship of the propagation time to the path distance of the reflected wave RB is determined by the least square method or the like. By approximating the linear function, the coefficient of the approximated linear function is calculated as an average value of the time during which the reflected wave RB travels once between the boundary surface i and the outer surface b of the metal layer 510, and then calculated. The thickness of the metal layer 510 may be obtained by multiplying the average value by 1/2 and the sound speed.

  The determination result by the determination unit 160 and / or the result of the wall thickness calculation unit 170 can be displayed on the display unit 180.

FIG. 7 shows the peak pattern in another example of the model case that results from the layer thickness test.
In FIG. 7, the echo peak of the reflected wave RS is detected in a separable manner, whereas the echo peak of the first reflected wave RI1 and the first reflected wave RB1 cannot be separated.

  When the peak pattern as shown in FIG. 7 is detected, it can be determined that the metal tube 510 of the lining tube 500 has been thinned to such an extent that it cannot be measured. On the other hand, the cement-containing layer 520 is not deteriorated, or even if it is deteriorated, it is determined that the degree is small enough to allow the transmission wave E to enter the cement-containing layer 520. can do.

  In the example of FIGS. 6 and 7, the aspect in which the thickness of the metal tube 510 is measured based on the detection peaks of the first reflected wave RI1 and the first reflected wave RB1 is shown. However, the second reflection is performed together with the first reflected wave RB1. When the wave RB2 (see FIG. 3) is detected with a detectability that can be distinguished from each other (for example, the S / N ratio is 2.5 or more, preferably 3 or more), the first reflected wave RB1 and the second reflected wave RB2 Similarly, the thickness of the metal tube 510 can be measured based on the detected peak.

FIG. 8 shows a peak pattern in yet another example of a model case caused by the layer thickness test.
In FIG. 8, only the echo peak of the reflected wave RS is detected. When the peak pattern as shown in FIG. 8 is detected, it can be determined that the deterioration of at least the cement-containing layer 520 of the lining pipe 500 is advanced. The state where the deterioration of the cement-containing layer 520 is advanced is a state where the transmitted wave E does not enter the cement-containing layer 520 due to at least one of an increase in porosity, a decrease in the weight ratio of cement, and a decrease in calcium concentration. Say. Examples of the degree of deterioration of the cement-containing layer 520 when such a peak pattern is generated include a case where the weight ratio of cement is 20% by weight or less and / or a case where the calcium concentration is 100,000 ppm or less. . In addition, the cement-containing layer 520 may have a porosity of 0.5% or more.

  Moreover, in the above-mentioned example, the ultrasonic probe 111 of the probe part 110 fixed to the rotating shaft 121 is rotated along the inner peripheral surface of the cement-containing layer 520 (an arrow in FIGS. 1 and 2). However, it is not limited to this aspect. For example, the probe unit 110 including the ultrasonic probe 111 that is not fixed to the rotating shaft 121 may be self-propelled while maintaining a distance and an angle (perpendicular) with respect to the cement-containing layer 520 surface.

  Further, as in the layer thickness test apparatus 100 a which is another example of the layer thickness test apparatus 100 shown in FIG. 9, the ultrasonic probe 111 a of the probe unit 110 a fixed to the non-rotating axis is connected to the lining tube 500. An ultrasonic wave may be provided so as to be transmitted in the axial direction from the axial position. In this case, the mirror 140 that refracts the ultrasonic wave transmitted from the ultrasonic probe 111a so as to be incident at a predetermined angle (perpendicular) with respect to the inner surface of the cement-containing layer 520 causes the axis to rotate. Are provided so as to be rotatable (arrows in FIG. 9).

  In the above example, the aspect in which the layer thickness test is performed on the lining pipe 500 on which the cement-containing layer 520 having a curved surface is lined is shown, but the present invention is not limited to this aspect. For example, a layer thickness test may be performed on a metal multilayer body in which a cement-containing layer having a flat surface is laminated so that the surface opposite to the surface is in contact with the metal surface.

  Further, in the above-described example, the aspect in which the porous layer provided on the surface of the metal tube 510 is the cement-containing layer 520 is shown, but the porous layer is not limited to the cement-containing substance.

  Furthermore, in the above-described example, the layer thickness test apparatus 100 exemplifies a mode in which the probe unit 110 is coupled to the separation unit 130 via the holding unit 120. However, the present invention is not limited to this mode. For example, the layer thickness test apparatus 100 may have a configuration in which the probe unit is directly connected to the separation unit. In this case, the spacing portion may have a function of keeping the angle of the probe portion perpendicular to the surface of the cement-containing layer or the tangent to the surface.

  As described above, according to the layer thickness test using the layer thickness test apparatuses 100 and 100a, when at least the peaks of the first reflected waves RI1 and RB1 (for example, the peak pattern in FIG. 6) are observed in the waveform acquisition step, It can be determined that the metal tube 510 has a thickness that allows thickness measurement. In this case, the wall thickness of the metal tube 510 can be accurately obtained by multiplying the detection time difference between the peak of the first reflected wave RB1 and the peak of the first reflected wave RI1 by the speed of sound.

  In addition, when the peak pattern of FIG. 7 is observed, it can be determined that the thickness reduction of the metal tube 510 is large. When the peak pattern in FIG. 8 is observed, it can be determined that at least the degree of deterioration of the cement-containing layer 520 is large.

  According to the layer thickness test using the layer thickness test apparatus 100, 100a, the measurement target is the lining pipe 500 in which the cement-containing layer 520 is lined on the inner peripheral surface of the metal pipe 510, and the transmitted wave E is generated inside the composite pipe. Since the transmission is transmitted from the ultrasonic probes 111 and 111a of the probe units 110 and 110a of the provided layer thickness test apparatuses 100 and 100a, the layer thickness is obtained in a state where the lining pipe 500 is embedded and the water W is filled therein. A test can be performed. For this reason, it is possible to perform a layer thickness test without performing a cutting operation.

  According to the layer thickness test using the layer thickness test apparatus 100, 100a, the entire inner circumference of the lining pipe 500 is maintained while maintaining the positional relationship in which the transmitted wave E is transmitted perpendicularly to the inner surface of the cement-containing layer 520. It can be transmitted to scan. Therefore, the thickness of the entire circumference of the metal tube 510 can be tested.

  According to the layer thickness test using the layer thickness test apparatus 100, 100a, when the frequency of the ultrasonic wave (transmitted wave E) transmitted in the transmitting step is 1 MHz or more and 9 MHz or less, the thickness of the metal tube 510 is accurately determined. Easy to get.

  According to the layer thickness test using the layer thickness test apparatus 100, 100a, since the thickness D of the aqueous medium interposed in the transmission step is 5 mm or more and 60 mm or less, the transmission wave E is easily transmitted through the metal tube 510, The reflected wave RB is easily obtained in a highly sensitive state.

  According to the layer thickness test using the layer thickness test apparatus 100, 100a, the test object is the lining pipe 500 lined with the metal pipe 510 cement-containing layer 520 typified by a cast iron pipe, so that high versatility is realized. be able to.

  The layer thickness test apparatus 100, 100a includes probe portions 110, 110a for transmitting ultrasonic waves, a separation portion 130 for separating the head portions of the probe portions 110, 110a and the surface of the cement-containing layer 520, and ultrasonic propagation. The waveform acquisition unit 150 includes a waveform acquisition unit 150 that acquires a waveform of reflected wave intensity with respect to time, and a determination unit 160 that determines whether or not the number of reflected wave peaks in the waveform is three or more. If at least the peaks of the first reflected waves RI1 and RB1 (for example, the peak pattern of FIG. 6) are observed, it can be determined that the metal tube 510 has a thickness that allows thickness measurement. In this case, the thickness calculator 170 can accurately acquire the thickness of the metal tube 510 by multiplying the detection time difference between the peak of the first reflected wave RB1 and the peak of the first reflected wave RI1 by the speed of sound. .

  The layer thickness test apparatus 100 can test the thickness of the entire circumference of the metal tube 510 because the probe unit 110 is provided so as to be rotatable inside the lining tube 500 about the axis of the lining tube 500. it can.

  In the layer thickness test apparatus 100a, the mirror 140 is provided with the probe portion 110a at the axial center of the lining tube 500 and refracts so as to be perpendicularly incident on the inner surface of the cement-containing layer 520. Therefore, the thickness of the entire circumference of the metal tube 510 can be tested.

  In the present invention, the metal pipe 510 corresponds to the “metal layer”, the cement-containing layer 520 corresponds to the “porous layer”, the lining pipe 500 corresponds to the “multi-layer body”, and the water W is the “aqueous medium”. The boundary surface i between the cement-containing layer and the metal tube corresponds to “the boundary surface between the metal layer and the porous layer”, and the outer surface b of the metal tube is “opposite to the porous layer of the metal layer” The first reflected wave RB1 corresponds to the “first outer surface”, the first reflected wave RI1 corresponds to the “first interface reflected wave”, and the first reflected wave RB1 corresponds to the “first outer surface”. Corresponding to “reflected wave”, reflected wave RB corresponds to “outer surface reflected wave”, inner peripheral surface s corresponds to “inner peripheral surface”, layer thickness test apparatus 100 corresponds to “layer thickness test apparatus”, The probe unit 110 corresponds to a “probe unit”, the separation unit 130 corresponds to a “separation unit”, the waveform acquisition unit 150 corresponds to a “waveform acquisition unit”, The unit 160 corresponds to the “determination unit”, the wall thickness calculation unit 170 corresponds to the “wall thickness calculation unit”, the wheel 135 corresponds to the “movement mechanism”, and the ultrasonic probe 111 corresponds to the “ultrasonic probe”. Corresponds to "child".

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.

  A healthy pipe of JWWA A107, A113 predetermined mortar lining ductile cast iron pipe (the thickness of the mortar lining layer is about 7 mm) was prepared, and a part of the metal was thinned to prepare a sample pipe. The sample tube used in Examples 1 to 7 has a nominal diameter of 250. The thinning process was performed by counterboring, and the flat bottom surface of the counterbored hole with a diameter of 20 mm was defined as the thinned part. As for the thickness reduction of the thinned portion, the metal thickness is 50% of the healthy portion. The layer thickness test was performed by filling the sample tube with water and inserting the layer thickness test apparatus 100.

[Example 1]
In this example, the layer thickness test was performed with a transmission frequency of 1.0 MHz, a characteristic of the ultrasonic probe of a straight traveling type, and a water distance (distance D in FIGS. 1 and 3) of 15 mm. The oscillogram obtained for the healthy part is shown in FIG. 10 (a), and the oscillogram obtained for the thinned part is shown in FIG. 10 (b). 10A and 10B, the horizontal axis represents the relative value of the layer thickness based on the propagation time, and the vertical axis represents the relative intensity of the signal. S represents the peak of the reflected wave reflected on the inner peripheral surface of the cement-containing layer, I represents the first reflected wave first reflected at the interface between the cement-containing layer and the metal tube, and B ₁ and F represents the first reflected wave first reflected on the outer surface of the metal tube. B ₂ is a second reflected wave reflected again on the second outside surface of the metal pipe by first reflected wave is reflected at the boundary surface. The same applies to the subsequent oscillograms.

[Example 2]
A layer thickness test was performed in the same manner as in Example 1 except that the transmission frequency was changed to 2.25 MHz. The oscillogram obtained for the healthy part is shown in FIG. 11 (a), and the oscillogram obtained for the thinned part is shown in FIG. 11 (b).

[Example 3]
A layer thickness test was performed in the same manner as in Example 1 except that the transmission frequency was changed to 3.5 MHz. The oscillogram obtained for the healthy part is shown in FIG. 12 (a), and the oscillogram obtained for the thinned part is shown in FIG. 12 (b).

[Example 4]
A layer thickness test was performed in the same manner as in Example 1 except that the transmission frequency was changed to 5.0 MHz. The oscillogram obtained for the healthy part is shown in FIG. 13 (a), and the oscillogram obtained for the thinned part is shown in FIG. 13 (b).

[Example 5]
A layer thickness test was performed in the same manner as in Example 1 except that the transmission frequency was changed to 7.5 MHz. The oscillogram obtained for the healthy part is shown in FIG. 14 (a), and the oscillogram obtained for the thinned part is shown in FIG. 14 (b).

[Example 6]
A layer thickness test was performed in the same manner as in Example 1 except that the transmission frequency was changed to 10 MHz. The oscillogram obtained for the healthy part is shown in FIG. 15 (a), and the oscillogram obtained for the thinned part is shown in FIG. 15 (b).

[Example 7]
A layer thickness test was conducted in the same manner as in Example 1 except that the transmission frequency was changed to 2.25 MHz and the characteristics of the ultrasonic probe were of the focus type. The oscillogram obtained for the healthy part is shown in FIG. 16 (a), and the oscillogram obtained for the thinned part is shown in FIG. 16 (b).

[Reference Example 1]
Prepare a test piece of mortar-lined ductile cast iron pipe (half pipe of sample pipe with nominal diameter of 250), and change the water distance (corresponding to distance D in FIGS. 1 and 3) in the range of 10 mm to 200 mm and oscillogram And the measurement sensitivity was evaluated. The equipment used is an ultrasonic flaw detector epoch 4 manufactured by Olympus, and the probe has a focus type, a transmission frequency of 2.25 MHz, a vibrator diameter of 12.7 mm, and a focusing point of 50.8 mm. The evaluation of the measurement sensitivity was based on the sensitivity obtained by adjusting the bottom echo detected when the water distance was set to 10 mm to 80% on the display. FIG. 17 shows the change in echo height with respect to the water distance.

  The results of measuring the water distance from 10 mm to 60 mm in 10 mm increments and the water distance from 60 mm to 200 mm in 20 mm increments were all good in sensitivity. As shown in FIG. 17, it was found that the bottom echo becomes high and the sensitivity is particularly good in the range where the water distance is 10 mm or more and 100 mm or less. On the other hand, in the range of more than 100 mm and not more than 200 mm, the bottom echo gradually decreased and the sensitivity tended to decrease. However, when the water distance of 50 mm where the sensitivity is particularly good is compared with the case of the water distance of 200 mm where the sensitivity is the lowest, the sensitivity difference is 6 dB, which does not greatly affect the measurement.

[Example 8]
A healthy pipe of a mortar-lined ductile cast iron pipe (nominal diameter 250) of JWWA A107, A113 was prepared, and a part of the metal was thinned to prepare a plurality of sample pipes having different thinning degrees. The thinning process was performed by counterboring, and the flat bottom surface of the counterbored hole with a diameter of 20 mm was defined as the thinned part. The thickness reduction of the metal thickness in the thinned portion of the sample tube is 30%, 50%, 60%, and 75% of the healthy portion, respectively. A layer thickness test was performed on the healthy part and the thinned part. The layer thickness test was performed by filling the sample tube with water and using the layer thickness test apparatus 100 under the conditions of a transmission frequency of 2.25 MHz, using a focal probe, and a water distance of 45 mm.

  FIG. 18 shows the relationship between the metal thickness measured by the layer thickness test (water immersion method) and the actual metal thickness. As shown in FIG. 18, the measurement error was about 0.1 mm for thinning, indicating the accuracy of the layer thickness test of the present invention.

[Example 9]
A mortar ductile cast iron pipe (nominal diameter 150), which has passed 27 years after laying, was obtained, and a layer thickness test was conducted under the conditions of a transmission frequency of 2.25 MHz, using a focal probe, and a water distance of 45 mm.
FIG. 19 shows an oscillogram obtained by the layer thickness test. As shown in FIG. 19, a good oscillogram was obtained in the same manner as when the layer thickness test was performed on the healthy pipe (Example 1 to Example 8).

[Example 10]
A mortar ductile cast iron pipe (nominal diameter 150) 1 m, which has passed 27 years after laying, was obtained, and further subjected to artificial thinning of 2.0 mm and 3.0 mm to prepare a sample pipe. The layer thickness test was performed under the conditions in Example 5 by filling the sample tube with water and inserting the layer thickness test apparatus 100. In the present example, the ultrasonic probe 111 was rotated along the circumferential direction of the inner peripheral surface of the sample tube with the rotational speed of the motor accommodated in the cylindrical casing 122 being 60 rpm.

  The result of the thinning evaluation of the sample tube according to this example is shown in FIG. In FIG. 20, the horizontal axis represents the rotational distance (mm) in the circumferential direction, and the vertical axis represents the amount of thinning (mm). The rotational distance in the circumferential direction indicates the circumferential distance of the outer peripheral surface of the sample tube. As shown in FIG. 20, 1.4 mm natural thinning is observed at a rotational distance of 55 mm, 2.0 mm artificial thinning is observed at a rotational distance of 80 mm, and 3.0 mm at a rotational distance of 200 mm. Artificial thinning was observed.

[Example 11]
A mortar-lined ductile cast iron pipe (nominal diameter 250) having an original wall thickness of 7.7 mm was subjected to a layer thickness test under the conditions of a transmission frequency of 2.25 MHz, a focus type probe, and a water distance of 45 mm. FIG. 21 shows the obtained oscillogram. As FIG. 21 shows, since the detected peak was two, it turned out that the cast iron part of the pipe | tube used for the layer thickness test has remarkably thinned. Actually, when the thickness of the cast iron portion of the pipe subjected to the layer thickness test was directly measured, it was 1.9 mm, and the thickness reduction rate (thickness standard) was 75%.

[Example 12]
A mortar ductile cast iron pipe (nominal diameter 200), which has passed 50 years after laying, was subjected to a layer thickness test under the conditions of a transmission frequency of 2.25 MHz, a focus type probe, and a water distance of 45 mm. FIG. 22 shows the obtained oscillogram. As FIG. 22 shows, since the detected peak was one, it turned out that the lining layer of the pipe | tube used for the layer thickness test has deteriorated notably. In fact, the mortar porosity, cement weight ratio, and calcium concentration were directly measured on the lining portion of the tube subjected to the layer thickness test.

(Measurement method of porosity)
As an X-ray CT system, μB3500 manufactured by Matsusada Precision Co., Ltd. was used, and the lining layer was converted to 3D under measurement conditions of 300 data / 360 ° (taken 300 transmission images per rotation). The porosity was calculated using VG Studio (Volume Graphics) CTX / defect extraction option as dedicated analysis software.

(Measurement method of cement weight ratio)
First, the specimen in the mortar layer was dried at 85 ° C. for 1 hour with a drier, and the dried specimen was crushed into small pieces with a hammer. About 10 g of a sample was weighed into a crucible weighed after drying, 50 ml of 15% HCl was added, a large sample piece was crushed with a glass rod, and sonicated (10 min). The immersion state was maintained for 2 days, and then the specimen was transferred to a weighed 50 ml centrifuge tube. Centrifugation was performed at 3000 rpm for 5 min.

  The solid was washed with pure water until neutral (centrifugation 3000 rpm, 2 min x 7 to 10 times), and the solid was dried together with the centrifuge tube in a gear oven (50 ° C). After weighing the whole centrifuge tube, the sand ratio was calculated.

(Calculation method of calcium concentration)
The supernatant after the above centrifugation treatment was sampled and subjected to ICP analysis (inductively coupled plasma emission spectroscopy). The measurement conditions for ICP analysis are as follows.
・ High frequency output 1.2 kw ・ Spray chamber quartz cyclone chamber ・ Plasma gas flow rate 15 L / min ・ No argon humidifier used ・ Auxiliary gas flow rate 1.5 L / min ・ Analysis wavelength as shown below ・ Carrier gas flow rate 0.9 L / min ・ Integration time 3 seconds, torch quartz torch, 5 repetitions, nebulizer coaxial glass nebulizer, no internal standard correction, ICP emission analysis (SII nanotechnology SPS5100) 2-point qualitative analysis

  As a result of the measurement, the mortar porosity was 1.13%, the cement weight ratio was 18% by weight, and the calcium concentration was 15,782 ppm.

[Reference Example 2]
As a lining layer of a ductile cast iron pipe, a sample pipe (nominal diameter 250) similar to that of Example 1 was prepared except that an epoxy resin powder coating layer (about 2 mm) was coated instead of the mortar lining layer. A layer thickness test was performed on the sample tube using the same equipment as in Reference Example 1 with a water distance of 15 mm. The oscillogram obtained for the healthy part is shown in FIG. 23 (a), and the oscillogram obtained for the thinned part is shown in FIG. 23 (b).

  Preferred embodiments of the present invention are as described above, but the present invention is not limited to them, and various other embodiments are possible without departing from the spirit and scope of the present invention. Furthermore, the operations and effects described in this embodiment are merely examples, and do not limit the present invention.

500 Lining tube 510 Metal tube 520 Cement-containing layer 100 Layer thickness test device 110 Probe unit 111 Ultrasonic probe 130 Separating unit 135 Wheel 140 Mirror 150 Waveform acquisition unit 160 Determination unit 170 Thickness calculation unit W Water s Inner surface i Interface b between the cement-containing layer and the metal tube b Outer surface E of the metal tube Transmitted wave RI1 First interface reflected wave RB1 First outer reflected wave RB2 Second outer reflected wave

Claims (16)

A layer thickness test method for an existing metal multilayer body in which a porous layer is lined on the inner surface of a metal tube,
Filling the interior of the metal multilayer with water;
Arranging a layer thickness test apparatus provided with a probe unit for transmitting ultrasonic waves inside the metal multilayer body;
A transmission step of transmitting an ultrasonic wave from the probe portion of the layer thickness test apparatus toward the inner surface of the metal multilayer body under a condition in which an aqueous medium is interposed;
Receiving a reflected wave of the ultrasonic wave with respect to the propagation time of the ultrasonic wave, and obtaining a waveform of the intensity of the reflected wave;
From the waveform, at least the peak of the first interface reflected wave first reflected at the interface between the metal tube and the porous layer, and the first reflection at the surface of the metal tube opposite to the porous layer. A determination step of determining the peak of the first reflected external wave,
A layer thickness test of the metal multilayer body including a thickness calculating step of calculating a thickness of the metal tube based on a detection time difference between the peak of the first interface reflected wave and the peak of the first outer surface reflected wave Law. A layer thickness test method for an existing metal multilayer body in which a porous layer is lined on the inner surface of a metal tube,
Filling the interior of the metal multilayer with water;
Arranging a layer thickness test apparatus provided with a probe unit for transmitting ultrasonic waves inside the metal multilayer body;
A transmission step of transmitting an ultrasonic wave from the probe portion of the layer thickness test apparatus toward the inner surface of the metal multilayer body under a condition in which an aqueous medium is interposed;
Receiving a reflected wave of the ultrasonic wave with respect to the propagation time of the ultrasonic wave, and obtaining a waveform of the intensity of the reflected wave;
When the waveform is detected as multiple peaks due to n-fold reflection in the metal tube (n is an integer of 2 or more), the waveform is opposite to the porous layer of the metal tube. A determination step of determining at least two peaks of the external reflection wave reflected by the surface;
A thickness calculation step of calculating a thickness of the metal tube based on a detection time of at least two peaks arbitrarily selected from the determined peak of the external reflection wave. Thickness test method. The layer thickness test method of the metal multilayer body according to claim 1 or 2, wherein the existing metal multilayer body is buried in the ground. The layer thickness test method of the metal multilayer body according to any one of claims 1 to 3 , wherein the porous layer contains a cement-containing substance. Wherein the frequency of the ultrasonic waves transmitted in the outgoing process is 1MHz or more 9MHz less, the layer Atsu試test method of the metal multilayer body according to any one of claims 1 to 4. In the transmitting step, the ultrasonic wave is transmitted so as to scan the entire inner periphery of the metal multilayer body while maintaining an angle at which the ultrasonic wave is transmitted perpendicularly to the inner surface of the porous layer. layer Atsu試test method of the metal multilayer body according to any one of 1 to 5. The cement-containing material you containing mortar layer Atsu試test method of the metal multilayer body according to claim 4. Consists of at least one of the metal tube is cast iron and steel, the layer Atsu試test method of the metal multilayer body according to any one of claims 1 to 7. A layer thickness test apparatus for a metal multilayer body used in the method according to claim 1 ,
A probe for transmitting ultrasonic waves;
A spacing portion that separates the head portion of the probe portion and the surface of the porous layer;
A waveform acquisition unit for acquiring a waveform of the intensity of the reflected wave of the ultrasonic wave with respect to a propagation time of the ultrasonic wave;
From the waveform, at least, the peak of the first first interface reflection wave reflected at the boundary surface between the porous layer and the metal tube, and initially reflected by the surface opposite to the porous layer of the metal tube A determination unit for determining a peak of the first external reflection wave;
A thickness calculator for calculating the thickness of the metal tube based on a detection time difference between the peak of the first interface reflected wave and the peak of the first outer reflected wave;
An apparatus for testing the thickness of a metal multilayer body, comprising: A layer thickness test apparatus for a metal multilayer body used in the method according to claim 2 ,
A probe for transmitting ultrasonic waves;
A spacing portion that separates the head portion of the probe portion and the surface of the porous layer;
A waveform acquisition unit for acquiring a waveform of the intensity of the reflected wave of the ultrasonic wave with respect to a propagation time of the ultrasonic wave;
The waveform, n heavy reflection at the metal tube (n is 2 or more an integer) when due detected as multiple peak, from the waveform, opposite to the porous layer of the metal tube A determination unit for determining at least two peaks of the external reflection wave reflected by the surface;
A thickness calculator for calculating the thickness of the metal tube based on the detection time of at least two peaks arbitrarily selected from the determined peak of the external reflection wave;
An apparatus for testing the thickness of a metal multilayer body, comprising: The layer thickness test apparatus of the metal multilayer body of Claim 9 or 10 containing the angle holding part which hold | maintains the angle with which the said ultrasonic wave is transmitted perpendicularly with respect to the inner surface of the said porous layer. The metal multilayer body, wherein the porous layer on the inner peripheral surface of the metal tube is a metal composite pipe lined cement-containing lining layer, the spacing portion, can travel in the axial direction of the metal composite pipe The layer thickness test apparatus for a metal multilayer body according to any one of claims 9 to 11, comprising a simple moving mechanism. The metal multilayer body, wherein the porous layer on the inner peripheral surface of the metal tube is a metal composite pipe lined cement-containing lining layer, the ultrasonic wave, to scan the entire inner periphery of the metal composite pipe The layer thickness test apparatus for a metal multilayer body according to any one of claims 9 to 12, which is transmitted as follows .   The layer thickness test apparatus for a metal multilayer body according to claim 13, wherein the probe portion is provided so as to be rotatable inside the metal composite tube with the axis of the metal composite tube as a rotation axis. The layer thickness test apparatus of the metal multilayer body of any one of Claim 9 to 14 set so that the frequency of the said ultrasonic wave may become 1 MHz or more and 9 MHz or less.   The layer thickness test apparatus for a metal multilayer body according to any one of claims 9 to 15, wherein the probe section includes an ultrasonic probe.