KR101568127B1 - device for inspecting an welding part - Google Patents

Abstract

The present invention relates to an apparatus for inspecting a welded portion of a boiler tube according to a new type which can accurately confirm whether or not a welding material of a wrong material is used, and an inspection method using the same.
To this end, the present invention provides a detection probe for detecting a magnetic field change with respect to a welded portion of a boiler tube and converting the magnetic field into a digital value, And a conversion program for converting the digital value provided from the detection probe into a magnetic permeability and providing the conversion rate, wherein the average magnetic permeability is confirmed on the basis of the magnetic permeability for each inspection frequency by the detection probe, and the use of the non- A controller that is programmed to make a determination as to whether or not the non-recommended electrode is to be used and to determine a region of use of the non-recommended electrode; And a display unit for displaying a graph of the permeability for each inspection frequency of the detection probe provided by the controller and displaying the result information determined by the controller. Is provided.

Description

Technical Field [0001] The present invention relates to a device for inspecting a welding portion of a boiler tube,

The present invention relates to an inspection apparatus and an inspection method for inspecting a defect on a welded portion, and more particularly, to an inspection apparatus and an inspection method for inspecting whether or not a welding material of a wrong material is correctly used, To an apparatus for inspecting a welding portion of a boiler tube and to an inspection method using the same.

Generally, boiler tubes used in thermal power plants are not made of the same material for all parts in order to save costs, but the main parts exposed to high temperature are formed of austenitic material such as stainless steel, and non-main parts are made of carbon steel Ferrite-based material.

Accordingly, the boiler tube is made up of a plurality of welded portions connecting the stainless steel and the carbon steel. If a damage occurs to any one of the welded portions, the entire power plant is stopped, do.

Therefore, after the welding work has been performed on the boiler tube in the past, it is essential to inspect the welded portion for defects.

The inspection of the welding portion of the boiler tube is largely performed by Radiographic Examination (RT), Ultrasonic Examination (UT) and Eddy Current Examination (ECT).

At this time, the radiographic inspection and the ultrasonic inspection are easily used to identify defects such as the presence of foreign substances or defects in the welding area, but it is not easy to precisely confirm the material of the welding electrodes.

For example, welding to the connection region between the stainless steel and the carbon steel can be prevented by using an austenitic welding rod to prevent damage such as cracking due to thermal stress. However, when such an austenitic welding rod is used, As the cost increased, the worker often used carbon steel type ferritic welding electrodes without using the austenitic welding electrodes due to intentional or accidental mistakes, but the precise inspection was not carried out.

Accordingly, in order to confirm the material of the above-described welding rod, a work of confirming whether ferrite or austenite is used as a magnetic material is further performed manually.

However, the welding of the boiler tube is usually carried out three times such as the super-layer, the middle layer and the surface layer, and when the ferrous material is welded to the super-layer or the middle layer, confirmation of the weld material using the ferro- There is a problem.

Of course, in the past, a technique has been proposed in which an inspection of whether a dissimilar metal material is mixed on a welded portion using an eddy current inspection method as disclosed in Japanese Patent Application Laid-Open No. 10-2012-0052394 has been proposed.

However, the above-mentioned prior art is merely a method of judging whether or not a dissimilar metallic material is mixed by additionally providing a permanent magnet to generate and acquire an eddy current signal, so that the actual welding of the boiler tube uses a ferrite- But it can not be used for distinguishing whether an austenitic electrode is used or not.

Furthermore, the above-described conventional techniques also have a disadvantage in that it is impossible to judge separately whether a welded portion exists in a superstructure, an intermediate layer or a surface layer.

SUMMARY OF THE INVENTION The present invention has been made in order to solve various problems of the prior art described above, and it is an object of the present invention to provide a welded part inspection apparatus for a boiler tube according to a new form, And an inspection method using the same.

In order to achieve the above object, according to the present invention, there is provided a welding probe inspection apparatus for detecting a change in magnetic field with respect to a welded portion of a boiler tube and converting the detected magnetic field into a digital value, A conversion program for converting a digital value provided from the detection probe into a magnetic permeability and providing a conversion rate of the digital value provided by the detection probe; And a judgment program for judging whether the non-recommended electrode is used or not and judging whether the non-recommended electrode is used; And a display unit for displaying a graph of the permeability for each inspection number of the detection probe provided from the conversion program of the controller and displaying the result information determined by the determination program of the controller.

Here, a detection rod for generating a magnetic field change due to the influence of a magnetic field on a welded portion of the boiler tube, and a plurality of winding coils disposed adjacent to the detection rod and arranged in parallel to each other, An oscillator circuit for applying a signal of a sinusoidal wave to the winding coil and a winding coil of two iron cores according to a change in the magnetic field of the detection rod while being wound to collectively surround the outside of the two iron cores A sensing coil for sensing a balance of an applied sinusoidal signal to generate a sensing signal, a phase sensing circuit for measuring a phase and an amplitude of a signal sensed by the sensing coil, A converter for converting the corresponding voltage into a digital value, And a sensor housing in which cows are embedded.

The detection probe is further provided with a temperature sensor, and the conversion program of the controller is programmed to determine a final permeability by compensating a predetermined compensation value according to the sensed temperature from the temperature sensor to the permeability converted from the digital value .

The temperature sensor is provided in a plurality of two or more, and the conversion program of the controller is programmed to determine a compensation value based on an average value of temperature values sensed by the temperature sensors.

According to another aspect of the present invention, there is provided a method of inspecting a welded portion of a boiler tube, the method comprising: a first step of receiving a digital value converted from a voltage value detected by a detection probe by a magnetic field change with respect to a welded portion of the boiler tube; ; Converting a digital value provided from the detection probe into a magnetic permeability through a conversion program, and displaying the graph on a display unit; A third step of judging whether or not a non-recommended electrode is used based on the range of the permeability value for each situation in which the converted permeability value is previously set through the determination program, and determining a used region of the non-recommended electrode; And displaying a result of the determination performed in the third step on the display unit.

Here, the first step is performed a plurality of times while the welded portions of the boiler tubes are varied, and in the second step, the respective permeability ratios of the respective performing order are controlled so as to be displayed in a gross graph, and in the third step, And a determination is made based on a range of a preset permeability value for each situation on the basis of the average value of the permeability ratios of the respective performance orders.

In addition, a temperature sensing value is additionally provided from a temperature sensor provided in the detection probe during the execution of the first step, and the third step is further provided with a temperature sensing value by the compensation value corresponding to the temperature sensing value provided in the first step, Determining a final permeability value by correcting the permeability value provided in step 2 and determining a final permeability value based on the preset range of the permeability value for each situation based on the final permeability value; And performing a judgment on a use site of the recommended electrode.

The digital value of the first stage includes a step of controlling the oscillator circuit to apply a sinusoidal signal to the winding coils of two iron cores arranged in parallel to each other, Measuring a phase and an amplitude of the sensing signal supplied from the sensing coil when the sensing coil senses a balance of the sensing signal and outputting the measured DC value as a DC value; And converting the voltage corresponding to the input voltage to a digital value.

As described above, according to the present invention, there is provided an apparatus for inspecting a welded portion of a boiler tube and a method of inspecting the welded portion of the boiler tube, comprising the steps of sensing a change in a magnetic field of a detection rod caused by a magnetic field, It is possible to accurately determine whether or not the electrode is used and the site of use of the ferrite electrode.

Particularly, since the two iron cores are vertically arranged from the detection rods, it is possible to accurately detect minute changes of the magnetic force lines formed around the detection rods, thereby improving the sensing sensitivity.

In addition, the sensed value is converted into permeability and provided to the inspector. In addition, the use area of the ferrite electrode can be determined based on the result of the inspection while the plurality of inspection sites are different, It can be clearly distinguished from the defect caused by the defect.

Further, the apparatus for inspecting a weld portion of a boiler tube according to the present invention and the inspection method using the same can have a temperature change with respect to a region to be inspected, so that more accurate inspection results can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of a boiler tube inspection apparatus according to an embodiment of the present invention.
2 is a circuit diagram illustrating a detailed structure of a detection probe in a welding site inspection apparatus of a boiler tube according to an embodiment of the present invention.
3 is a flowchart illustrating a method of testing a boiler tube using a welding portion inspection apparatus according to an embodiment of the present invention.
4 is a flowchart illustrating a process of providing a detection value by a detection probe in an inspection method using a welding site inspection apparatus of a boiler tube according to an embodiment of the present invention.
FIG. 5 is a graph illustrating the measurement results of the permeability for each inspection number (inspection site) displayed on the display unit by the welding site inspection apparatus and inspection method of the boiler tube according to the embodiment of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of an apparatus for inspecting a welding portion of a boiler tube and an inspection method using the same will be described with reference to FIGS. 1 to 5.

Prior to the description of the embodiment, the boiler tube 10 is a tube for guiding the flow of a heat fluid used in a thermal power plant or the like, and the carbon steel 12 is welded to a plurality of portions of the stainless steel 11, At this time, a portion where the carbon steel (12) and the stainless steel (11) are connected to each other by welding is referred to as a welded portion (13).

FIG. 1 is a block diagram schematically showing an apparatus for inspecting a welding part of a boiler tube according to an embodiment of the present invention. FIG. 2 is a schematic view of a welding part inspection apparatus of a boiler tube according to an embodiment of the present invention. And is a circuit diagram for explaining the detailed structure of the probe.

As shown in these drawings, an apparatus for inspecting a welding portion of a boiler tube according to an embodiment of the present invention includes a detection probe 100, a controller 200, and a display unit 300, The present invention is characterized in that it is programmed to judge whether or not the non-recommended electrode is used based on the detection value of the magnetic field change by the number of inspections with respect to the welding portion and to judge the used portion of the non-recommended electrode.

This will be described in more detail below for each configuration.

First, the detection probe 100 senses a change in a magnetic field with respect to the welded portion 13 of the boiler tube 10, converts the detected magnetic field into a digital value, and provides the digital value.

Particularly, in the embodiment of the present invention, the detection probe 100 includes a detection rod 160, two iron cores 110 and 120, a sensing coil 130, an oscillator circuit 141, a phase sensing circuit 142, A converter 143 and a sensor housing 150. This makes it possible to judge whether or not a non-recommended electrode is used for the welded portion 13 of the boiler tube 10, It is possible to accurately determine whether to judge the used site and whether mixed materials are mixed.

Here, the detection rod 160 is formed of a permanent magnet, which is provided to cause a change in the magnetic field due to the ferrite material when the ferrite material exists in the welded portion 13 of the boiler tube 10.

The two iron cores 110 and 120 are wound around the winding coils 111 and 121 having phases opposite to each other.

The two iron cores 110 and 120 are made of soft iron mainly used for a conventional electromagnet, and are arranged so as to be parallel to each other.

In addition, the winding coils 111 and 121 wound on the two iron cores 110 and 120 are wound in opposite directions to each other so that the winding coils 111 and 121 have phases opposite to each other.

That is, when the sinusoidal signals, which are derived from the winding coils 111 and 121 wound in opposite directions to each other and are identical but opposite in phase to each other, can be offset from each other, And the balance of the sinusoidal signal is collapsed.

In particular, the two iron cores 110 and 120 are disposed so as to be perpendicular to the axial direction of the detection rod 160. The reason for this is that the two iron cores (110, 120) are arranged at a position where the flow of the detection rod (160) to the magnetic force lines is performed, so that a minute magnetic field change can be detected.

The sensing coil 130 is a coil for generating a sense signal when the balance of the sinusoidal signals induced by the winding coils 111 and 121 of the iron cores 110 and 120 is collapsed.

That is, the sensing coil 130 generates a sensing signal by a change in impedance of each of the coils 111 and 121 due to a change in the magnetic field of the detection rod 160.

The sensing coil 130 is wound to collectively surround the outer circumference of the two iron cores 110 and 120, and is configured to sense a change in the magnetic field of the two iron cores 110 and 120.

The oscillator 141 is a circuit for applying a sinusoidal signal to the winding coils 111 and 121.

The phase sensitive detector 142 is a circuit for measuring the phase and the amplitude of the signal sensed by the sensing coil 130. In this case, an amplifier 143 is additionally provided between the sensing coil 130 and the phase sensing circuit 142 so that phase and amplitude measurement of the sensing signal provided from the sensing coil 130 is performed by the phase sensing circuit 142 ) To be more accurate.

The converter 143 is an analog to digital converter that converts a voltage corresponding to the DC value output through the phase sensing circuit 142 into a digital value.

The sensor housing 150 is a part forming an outer appearance of the detection probe 100 and includes various components such as the above-described iron cores 110 and 120, the sensing coil 130 and various circuits 141, 142 and 143 It protects from external environment.

It is preferable that the sensor housing 150 is formed in a pen structure for the convenience of the operator. In this case, the tip of the detection rod 160 is exposed to the outside of the sensor housing 150 do.

Next, the controller 200 is configured to receive data through the RS232 communication with the detection probe 100, and further, various programs for processing and processing the received data.

The controller 200 is provided with a conversion program 210 for converting a digital value provided from the detection probe 100 into a magnetic permeability and providing the digital value to the controller 200. The controller 200 calculates an average permeability A judgment program 220 for judging whether or not a non-recommended electrode is used based on the average permeability, whether a foreign substance is present or not, and a used region of a non-recommended electrode are installed.

In particular, the permeability to be converted by the conversion program 210 is a value set by dividing the magnitude of the voltage into a range of 0 to 100, where 0 is the sensing coil 160, And 100 denotes a value obtained by converting the voltage value of the sensing signal output from the sensing coil 130 into the permeability when the sensing rod 160 is brought into contact with the ferromagnetic body. .

Next, the display unit 300 displays various data processed by the controller 200 and / or data received from the detection probe 100.

Particularly, the display unit 300 includes a role of an oscilloscope that graphically displays the permeability of the detection probe 100 provided by the controller 200 for each inspection frequency, And a monitor for displaying the image.

Meanwhile, the measurement value sensed by the above-described detection probe 100 may be drifted by an external temperature. That is, there is a fear that the measurement value changes according to the internal environment of the inspection site or the temperature change of the boiler tube 10, so that it is impossible to check the defect based on the measured value or check the defective position accurately.

Accordingly, in the embodiment of the present invention, the detection probe 100 is further provided with a temperature sensor 170, and the conversion program 210 of the controller 200 controls the temperature sensor 170 To compensate a preset compensation value according to the sensed temperature and to determine the final permeability.

That is, the influence of the temperature on the measured value is confirmed in advance, and the compensated value corresponding to the temperature is set in advance and the compensated value is added to the measured value based on the temperature sensed by the temperature sensor 170 So that accurate inspection can always be performed regardless of the ambient temperature.

It is most preferable that the temperature sensor 170 is configured to sense the temperature of the detection rod 160 while being in contact with the outer circumferential surface of the detection rod 160 among the inside of the sensor housing 150.

The conversion program 210 of the controller 200 may be configured such that the compensation value is determined based on the average value of the temperature values sensed by the respective temperature sensors 170 It is more preferable to be programmed. It is preferable that a plurality of temperature sensors 170 are provided in the outer circumferential surface of the detection rod 160 in consideration of the fact that the temperature of the measurement region may vary according to the contact angle of the detection rod 160, So that the temperature of the measurement site can be accurately measured regardless of the contact angle of the detection rod 160.

Hereinafter, an inspection method using the apparatus for inspecting a welding portion of a boiler tube according to an embodiment of the present invention will be described in more detail with reference to the flowchart of FIG.

First, when power is supplied to the inspection apparatus, a sinusoidal signal is applied from the oscillator circuit 141 constituting the detection probe 100 to the winding coils 111 and 121 of the two iron cores 110 and 120 (S110).

Since the winding coils 111 and 121 of the two iron cores 110 and 120 are configured to be wound in opposite directions to each other, sinusoidal signals having phases exactly opposite to each other are applied to the winding cores 110 and 120, Are not canceled each other, so that they have no influence on the sensing coil 130 wound to collectively surround the two iron cores 110 and 120.

In this initial state, the setting of the initial reference is performed using the reference specimen (not shown) before performing the inspection of the welded portion of the boiler tube 10.

That is, the detection rod 160 constituting the detection probe 100 is brought into contact with the reference specimen and the corresponding state is set as the reference value, so that the reference value can be set so that the influence of the magnetic field which may be present in the air is ignored . At this time, it is preferable that the reference specimen is made of an austenitic copper block having no magnetic property so that the permeability value obtained when the detection rod 160 is brought into contact with the reference specimen is set to zero.

Next, when the reference setting is completed, the controller 200 receives measurement data measured by the detection probe 100 and converted into a digital value (S100).

At this time, the inspector checks whether the detection rod 160 of the detection probe 100 is in contact with or adjacent to the side of the welded portion 13 of the boiler tube 10 that is positioned on the portion where the stainless steel 11 is located It is preferable to allow the inspection to proceed. This is because when the welded portion 13 of the boiler tube 10 is inspected for the portion where the carbon steel 12 is located or the intermediate portion between the carbon steel 12 and the stainless steel 11 It is highly likely that the detection of the permeability by the carbon steel 12 is undesirable.

According to the above-described operation of the inspector, in the detection probe 100, when the welding part 13 of the boiler tube 10 is used as an austenitic welding rod or a ferritic welding rod, do.

That is, if the welding part 13 is made of an austenitic welding rod, even if the detection rod 160 of the detection probe 100 is brought close to the welding part 13, the winding coil of the two iron cores 110 and 120 111, and 121 are offset from each other to maintain the same balance, the sensing coil 130 wound to collectively surround the two iron cores 110 and 120 does not generate a sensing signal, 0 < / RTI >

On the other hand, when the ferrite welding electrode is used as the welding portion 13, since a magnetic field is present at the welding portion by the welding rod of the waste light system, if the detecting rod 160 is adjacent to the welding portion 13, And the balance of the sinusoidal signals applied to the winding coils 111 and 121 of the two iron cores 110 and 120 is collapsed due to the change of the magnetic field.

Accordingly, the sensing coil 130, which is positioned to surround the two iron cores 110 and 120, generates a sensing signal by balance disruption of the sinusoidal signal. In addition, The phase sensing circuit 142 measures the phase and amplitude of the received sensing signal and outputs it as a DC value (S130). Then, the voltage corresponding to the output DC value is converted from the converter 143 to a digital value S140), the measurement data is generated.

Of course, even if an austenitic welding electrode is used, the balance of the sinusoidal signals is finely collapsed due to the influence of the carbon steel adjacent to the welding site, and the sensing area of the sensing coil 130 A signal may be generated.

Considering that the sensing signal by the sensing coil 130 is different according to the magnitude of the magnetic field provided from the welding portion 13, the phase and amplitude of the sensing signal measured by the phase sensing circuit 142 The value of the final measurement data is provided differently depending on the magnitude of the magnetic field.

Particularly, considering that the amplifier 144 is further provided between the phase sensing circuit 142 and the sensing coil 130, the sensing signal sensed through the sensing coil 130 is amplified by the amplifier 144 The phase and amplitude of the sensing signal can be confirmed by being provided to the phase sensing circuit 142 in an amplified state.

When the controller 200 receives the measurement data from the detection probe 100 as described above, the controller 200 converts the digital value of the measurement data into the magnetic permeability through the conversion program 210, And displayed on the display unit 300 (S200).

At the same time, the controller 200 determines whether the non-recommended electrode is used based on the converted permeability value through the determination program 220, and determines the used region of the non-recommended electrode.

That is, the converted permeability value and the predetermined permeability value are compared with each other (S400) to determine whether the non-recommended electrode is used or not and the used region of the non-recommended electrode.

At this time, the permeability value for each situation set in the judgment program 220 is set to be equal to or higher than 61 (hereinafter, referred to as a first set permeability) when a non-recommended electrode is used in the surface layer, (Hereinafter referred to as " second set permeability ") when the non-recommended electrode is used, and the permeability when the non-recommended electrode is used in the second layer is set to 20 to 40 , Hereinafter referred to as " third set permeability "), the permeability value converted by the conversion program 210 is in the range of any one of the first set permeability, the second set permeability, and the third set permeability (S510, S520, S530) whether the non-recommended electrode is used or not and whether the non-recommended electrode is used.

If the permeability below the third predetermined permeability is confirmed, it is determined that the use of the non-recommended electrode is judged to be due to the influence of the carbon steel adjacent to the weld region 13 (S540).

Then, the controller 200 displays on the display unit 300 whether or not the recommended non-recommended electrode is used and the non-recommended electrode is used (S600), thereby allowing the inspector to accurately recognize the non-recommended electrode.

On the other hand, whether or not to use the non-recommended electrode by the confirmation of the permeability and the determination of the use site of the non-recommended electrode is not terminated by a single inspection but is performed for the plurality of locations around the welded portion 13 of the boiler tube 10 Ensure that the inspection is performed.

That is to say, a plurality of measurement data are provided from the detection probe 100 by sequentially or in close contact with the detection rods 160 of the detection probes 100 while varying the welding site 13 of the boiler tube 10 And the ratio of the permeability of each non-recommended electrode to that of the non-recommended electrode is determined based on the average value of the permeabilities, Can be performed.

This is because if it is determined that a non-recommended electrode is used only as a result of inspection of any one of the welded portions 13 and if the use of the non-recommended electrode is set to be made, This is because there is a possibility of being confused with the case where it exists and the accurate judgment can not be made.

If a foreign matter (dissimilar metal material) exists in the welded portion 13, the permeability value in a similar range is not generated in all of the plurality of inspections, but only in a specific order of inspections, Since the permeability value is generated, the presence or absence of the foreign matter can be determined according to the variation frequency of the permeability value.

Of course, as described above, when a plurality of inspection is performed while the inspection site is varied, the permeability that is confirmed at each inspection is displayed in a gross display by the execution sequence, so that the inspector can accurately recognize the inspection result of each site . This is the same as the portion shown in the example of FIG.

Meanwhile, while the inspection of the magnetic permeability of the welded portion 13 by the detection probe 100 and the controller 200 as described above is being performed, the controller 200 controls the temperature sensor 170 provided in the detection probe 100 And the final permeability value is determined (S300) by correcting the permeability value by the compensation value corresponding to the temperature sensing value thus provided (S300). Based on the final permeability value, It is more desirable to make a determination based on the range of values whether to use the non-recommended electrode or to determine where to use the non-recommended electrode.

As a result, the apparatus for inspecting a welded portion of a boiler tube according to an embodiment of the present invention and the inspection method using the same are capable of reducing the influence of a change in the magnetic field of the detection rod 160 due to a magnetic field provided at the welded portion 13 on the iron cores 110 and 120 Sensing and measuring the temperature of the ferritic electrode can be used to determine whether the ferritic electrode is used or not.

Particularly, since the two iron cores 110 and 120 are vertically disposed from the detection rods 160, it is possible to accurately detect minute changes in the magnetic force lines formed around the detection rods 160, thereby improving the sensing sensitivity do.

In addition, the sensed value is converted into permeability and provided to the inspector. In addition, the use area of the ferrite electrode can be determined based on the result of the inspection while the plurality of inspection sites are different, Can be clearly distinguished from the defects caused by the defects.

Furthermore, since the apparatus for inspecting a welding portion of a boiler tube according to an embodiment of the present invention and the inspection method using the same can be considered together with the temperature change of the inspection site, more accurate inspection results can be obtained.

100. Detection probes 110, 120. Iron core
111, 121. Winding coil 130. Sensing coil
141. Oscillator circuit 142. Phase sensing circuit
143. Converter 144. Amplifier
150. Sensor housing 160. Detection rod
170. Temperature sensor 200. Controller
210. Conversion program 220. Judgment program
300. Display unit

Claims (8)

A detection probe for detecting a magnetic field change due to the influence of a magnetic field on a welded portion of a boiler tube and converting the detected magnetic field change into a digital value,
A conversion program for converting a digital value provided from the detection probe into a magnetic permeability and providing a conversion rate of the digital value provided by the detection probe; And a judgment program for judging whether the non-recommended electrode is used or not and judging whether the non-recommended electrode is used; And,
And a display unit for displaying a graph of the permeability for each inspection number of the detection probe provided from the conversion program of the controller and displaying the result information determined by the determination program of the controller,
The detection probe
A detection rod for generating a magnetic field change by an influence of a magnetic field on a welded portion of the boiler tube,
Two iron cores positioned adjacent to the detection rods and arranged side by side so as to be parallel to each other and having winding coils wound in opposite directions to each other and having phases opposite to each other,
An oscillator circuit for applying a signal of a sine wave to the winding coil,
A sensing coil wound around the outer periphery of the two iron cores for collectively covering the sensing coil and sensing a balance of a sine wave signal applied to the winding coils of the two iron cores according to a change in the magnetic field of the detection rod,
A phase sensing circuit for measuring a phase and an amplitude of a signal sensed by the sensing coil,
A converter for converting a voltage corresponding to a DC value output through the phase detection circuit into a digital value;
And a sensor housing which forms an outer appearance of the boiler tube and incorporates the respective components. delete The method according to claim 1,
The detection probe further includes a temperature sensor,
Wherein the conversion program of the controller is programmed to determine a final permeability by compensating a preset compensation value according to the sensed temperature from the temperature sensor to the permeability converted from the digital value,
The temperature sensor is provided in a plurality of two or more,
Wherein the conversion program of the controller is programmed to determine a compensation value based on an average value of temperature values sensed by the temperature sensors. delete A first step of receiving a converted digital value from a voltage value detected by a detection probe by a magnetic field change with respect to a welded portion of the boiler tube;
Converting a digital value provided from the detection probe into a magnetic permeability through a conversion program, and displaying the graph on a display unit;
A third step of judging whether or not a non-recommended electrode is used based on the range of the permeability value for each situation in which the converted permeability value is previously set through the determination program, and determining a used region of the non-recommended electrode; And,
And displaying a result of the determination performed in the third step on the display unit,
The digital value of the first step is
A step of applying a sinusoidal signal to the winding coils of two iron cores arranged in parallel to each other by controlling the oscillator circuit and having opposite phases to each other,
When the balance of the sinusoidal signals with respect to the winding coils of the two iron cores due to the magnetic field changes is collapsed and the sensing coil senses this, the sensing signal is supplied from the sensing coil. The phase and amplitude of the sensing signal thus supplied And outputting the measured value as a DC value;
And converting the voltage corresponding to the output DC value from a converter to a digital value. 6. The method of claim 5,
Wherein the first step is performed a plurality of times with different welding positions of the boiler tubes,
In the second step, the respective performance ratios of the respective performance orders are collectively graphically displayed and controlled to be displayed,
Wherein the third step is controlled so as to make a determination based on a predetermined range of the permeability value for each situation based on the average value of the respective permeability ratios of the respective execution orders. 6. The method of claim 5,
Wherein a temperature sensing value is additionally provided from a temperature sensor provided in the detection probe during the first step,
In the third step,
Determining a final permeability value by correcting the permeability value converted and provided in the second step by a compensation value corresponding to the temperature sensing value provided in the first step;
Determining whether the non-recommended electrode is used based on the predetermined range of the permeability value for each situation based on the final permeability value, and determining whether the non-recommended electrode is used. Welding site inspection method of tube. delete

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