JP2016138770A - Inspection method and inspection system for adhesive strength of inner surface vinyl chloride lined steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method that enables a nondestructive inspection of adhesive force of all inner surface polyvinyl chloride-lining steel pipes in one batch.SOLUTION: The adhesive force inspection method for the inner surface polyvinyl chloride-lining steel pipe according to the present invention includes: a step of heating, with use of an induction heating coil, one batch of a steel pipe group formed with a plurality of steel pipes inserted inside a polyvinyl chloride pipe so as to be approximately parallel to each other, to allow the polyvinyl chloride pipe to expand, thereby causing the polyvinyl chloride pipe to adhere to an inner surface of the steel pipe such that plural numbers of the inner surface polyvinyl chloride-lining steel pipes are obtained, and in said process, measuring a surface temperature of the steel pipe group with use of a thermal image measuring apparatus that is installed at least at one of an upper part and a lower part of the steel pipe group; and a step of evaluating the adhesive force between the steel pipes and the polyvinyl chloride pipe in each of the obtained inner surface polyvinyl chloride-lining steel pipes on the basis of a result of the measurement by the thermal image measuring apparatus.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inspection method and an inspection system for evaluating the adhesive force between an inner surface vinyl chloride lined steel pipe including a steel pipe and a vinyl chloride pipe bonded to the inner surface of the steel pipe.

  The inner surface vinyl chloride lined steel pipe is, for example, as described in Patent Document 1, in which a vinyl chloride pipe is bonded to the inner surface of the steel pipe, and is used in piping facilities such as water supply and drainage. With the vinyl chloride pipe with the outer surface coated with adhesive, the vinyl chloride pipe is heated and expanded with the adhesive coming into contact with the steel pipe. Adhesive strength is exerted on the inner surface, and an inner surface vinyl chloride lined steel pipe is obtained.

As a method of inspecting the adhesive strength of an inner surface vinyl chloride lining steel pipe with a steel pipe and a vinyl chloride tube, an inspection sample prepared by cutting the inner surface vinyl chloride lining steel tube into a length of 20 mm is prepared. A method is known in which a load is punched with a punching tester and the load at that time is measured. This method is stipulated in JWWA standard hard vinyl chloride lined steel pipe (JWWA K116). In this standard, if the load is 20 N / cm ² or more, it is considered acceptable. It is necessary to confirm and guarantee that the inner surface vinyl chloride lined steel pipe to be manufactured has an adhesive strength exceeding this standard. Therefore, at least one pipe is extracted from one batch of manufactured inner surface vinyl chloride lined steel pipe and shipped after being subjected to the above inspection.

JP 2002-257265 A

  Since the above inspection method is a destructive inspection, only a part of the inner surface vinyl chloride lining steel pipe in one batch can be used as a test body, and the entire product cannot be inspected. Moreover, the adhesive force of only a small part (20 mm cut out) of the inner surface vinyl chloride lined steel pipe is measured.

  However, there is no confirmation that the adhesion at the test site is a typical result that can guarantee the adhesion of all internal vinyl chloride lined steel tubes in one batch. Since heating by the induction heating coil is heating by radiant heat, it must be said that the accuracy of heating is not very high. For this reason, it has been found that the adhesive force varies depending on the location of each of the plurality of inner surface vinyl chloride lining steel pipes or even within one inner surface vinyl chloride lining steel pipe. For this reason, it has been recognized that it is possible to grasp whether or not an appropriate adhesive force is obtained in all the parts of all the inner surface vinyl chloride lining steel pipes in one batch, which leads to higher reliability of the product.

  An object of this invention is to provide the inspection method and inspection system which can test | inspect non-destructively the adhesive force of all the inner surface vinyl chloride lining steel pipes in 1 batch in view of the said subject.

  The present inventor has intensively studied to solve the above problems, and in the process of induction heating, the surface temperature of the steel pipe is measured in a non-contact manner by a thermal image measuring device. It was found that there is a correlation between the adhesive strength and the adhesive strength. Then, based on this measurement result, it came to recognition that the adhesive force of an inner surface vinyl chloride lining steel pipe could be evaluated, and completed this invention.

The present invention has been completed based on the above findings and ideas, and the gist of the present invention is as follows.
(1) A batch of steel pipe groups in which a plurality of steel pipes into which vinyl chloride pipes are inserted are arranged substantially in parallel with each other are heated by an induction heating coil to expand the vinyl chloride pipe, thereby In the process of bonding the vinyl chloride pipe to the inner surface to obtain a plurality of inner surface vinyl chloride lined steel pipes, the surface temperature of the steel pipe group is measured by a thermal image measuring device installed at least above and below the steel pipe group. And a process of
Based on the measurement result by the thermal image measurement device, the step of evaluating the adhesive force between the steel pipe and the vinyl chloride pipe of the obtained individual inner surface vinyl chloride lining steel pipe,
A method for inspecting the adhesive strength of an inner surface vinyl chloride-lined steel pipe.

  (2) In the evaluation step, the maximum temperature of the surface of each steel pipe in the heating process is extracted at a predetermined interval in the extending direction of the steel pipe, and the individual inner surfaces are extracted based on the extracted maximum temperature. The method for inspecting the adhesive strength of an inner surface vinyl chloride lining steel pipe according to (1) above, wherein the adhesive strength of the vinyl chloride lining steel pipe is evaluated.

  (3) In the evaluation step, among the plurality of inner surface vinyl chloride lining steel pipes, all the maximum temperatures extracted in the extending direction are determined to be acceptable, and the others The inspection method of the adhesive force of the inner surface vinyl chloride lining steel pipe according to the above (2), in which it is determined that the material is rejected.

  (4) The method according to any one of (1) to (3), further including a step of marking with a marking device on the inner surface vinyl chloride lining steel pipe determined to be unacceptable after the evaluation step. Inspection method for adhesion of inner surface vinyl chloride lined steel pipe.

(5) an induction heating coil for heating a batch of steel pipe groups in which a plurality of steel pipes into which vinyl chloride pipes are inserted are arranged substantially parallel to each other;
Measuring the surface temperature of the steel pipe group in the process of expanding the vinyl chloride pipe by the heating to adhere the vinyl chloride pipe to the inner surface of the steel pipe and obtaining a plurality of inner surface vinyl chloride lined steel pipes, A thermal image measuring device installed on at least one of the upper and lower sides of the steel pipe group;
Based on the measurement result by the thermal image measuring device, the evaluation unit for evaluating the adhesive force between the steel pipe and the vinyl chloride pipe of the obtained individual inner surface vinyl chloride lining steel pipe,
A system for inspecting the adhesive strength of an inner surface vinyl chloride lined steel pipe, comprising:

(6) It further has a memory for recording a measurement result by the thermal image measurement device,
The evaluation unit extracts, from the memory, the maximum temperature of the surface of each steel pipe in the heating process at predetermined intervals in the extending direction of the steel pipe, and based on the extracted maximum temperature, The inspection system for the adhesive strength of an inner surface vinyl chloride-lined steel pipe according to (5), wherein the adhesive strength of the inner surface vinyl chloride-lined steel tube is evaluated.

  (7) The evaluation unit determines that all the maximum temperatures extracted in the extending direction are equal to or higher than a predetermined temperature among the plurality of inner surface vinyl chloride lining steel pipes, and the others The inspection system for the adhesive strength of the inner surface vinyl chloride lined steel pipe according to the above (6), in which it is determined that the test is rejected.

  (8) The inner surface vinyl chloride lining according to any one of the above (5) to (7), further including a marking device that performs marking on the inner surface vinyl chloride lining steel pipe determined to be rejected by the evaluation unit. Steel pipe adhesion inspection system.

  (9) The inner surface according to any one of (5) to (8), further including a protection mechanism that protects the thermal image measurement device from at least one of heat, steam, and magnetic flux generated from the steel pipe group. Inspection system for adhesive strength of PVC pipes.

  According to the inspection method and inspection system for the adhesive strength of the inner surface vinyl chloride lining steel pipe of the present invention, the adhesive strength of all inner surface vinyl chloride lining steel tubes in one batch can be inspected nondestructively.

It is a mimetic diagram showing the composition of inspection system 100 by one embodiment of the present invention. It is a mimetic diagram explaining a part of production line of an inner surface vinyl chloride lining steel pipe containing inspection system 100 by one embodiment of the present invention. It is a schematic diagram which shows the induction heating process in the manufacturing line of an inner surface vinyl chloride lining steel pipe. It is a mimetic diagram of a protection mechanism of thermal image measuring device 20 in inspection system 100 by one embodiment of the present invention. It is a flowchart of the inspection method by one Embodiment of this invention. It is a figure explaining the maximum temperature of the steel pipe surface. It is a graph which shows the relationship between the maximum temperature of various site | parts, and the adhesive force of the sample cut into length 20mm containing the said site | part in 1 batch of inner surface vinyl chloride lining steel pipes.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, with reference to FIG.2 and FIG.3, an example of the manufacturing line of an inner surface vinyl chloride lining steel pipe is demonstrated.

  One batch (usually about 10 to 50) of the steel pipes 82 is conveyed on the line in a state of being arranged substantially parallel to each other, and dust and dirt on the inner surface of the steel pipe are blown off by the inner surface blast shot. Subsequently, as shown in FIG. 2, a vinyl chloride pipe 80 having an outer surface coated with an adhesive is sequentially inserted into the steel pipe 82. In this way, a batch of steel pipe groups is formed in which a plurality of steel pipes 82 into which the vinyl chloride pipes 80 are inserted are arranged substantially in parallel with each other.

  One batch of steel pipe group is conveyed to the induction heating area with the two induction heating coils 20 retracted. The induction heating coil 20 has a band-like ring shape and can move in the extending direction of the steel pipe 82. After one batch of the steel pipe group is conveyed to the induction heating area, the induction heating coil 20 moves and the steel pipe group is passed through the internal space of the induction heating coil 20, and the induction heating coil 20 is a steel pipe 82 shown in FIG. Stop at the center position.

  Thereafter, one batch of the steel pipe group is heated by the induction heating coil 20 as follows. As shown in FIG. 3, the two induction heating coils 20 move at a constant speed from the center position of the steel pipe 82 to both ends while being applied with an AC voltage having a predetermined frequency and voltage. In this process, after the steel pipe 82 is heated to a temperature of 130 to 230 ° C, the vinyl chloride pipe 82 receives the heat and is heated to 80 to 180 ° C. The polyvinyl chloride tube 82 thus heated starts to expand sequentially from the central portion in the extending direction toward both ends. Then, the adhesive applied to the outer surface of the vinyl chloride pipe 82 and the inner surface of the steel pipe 80 come into contact with each other, whereby an adhesive force is developed between the steel pipe 80 and the vinyl chloride pipe 82. In this way, a plurality of inner surface vinyl chloride lined steel pipes 84 are obtained.

  Next, since the end portion of the steel pipe 80 is difficult to heat, as shown in FIG. The part is further heated. Although the subsequent steps are not shown in the drawings, the inner surface vinyl chloride lining steel pipe 84 may be subjected to soaking treatment and further subjected to outer surface coating. Thereafter, the vinyl chloride tube protruding from both ends is cut to finish the end face. Thereafter, the product is visually inspected by the operator, and rejected products are removed. Only some of the finished products are tested for adhesion as defined in the above-mentioned standard, and the rest are shipped in a bundle.

  In one embodiment of the present invention, the surface temperature of a plurality of steel pipes 82 in one batch is measured in a non-contact manner in the induction heating process. Here, the “inner surface vinyl chloride lining steel pipe” to which the present invention is applied is not limited as long as the vinyl chloride pipe is bonded to the inner surface of the steel pipe, but the following are exemplified. First, there is a JIS G3442 galvanized steel pipe for water piping with hard vinyl chloride (JIS K6742) bonded to it (VB pipe). Alternatively, a hard vinyl chloride (JIS K6742) may be bonded to the inner surface of a carbon steel pipe (black pipe) for JIS G3452 piping. The outer surface of this inner surface vinyl chloride lined steel pipe may be given a primary anti-corrosion coating (VA pipe) or hard vinyl chloride (JIS K6742) may be bonded (VD pipe).

(Adhesion test system)
With reference to FIG.1 and FIG.2, the test | inspection system 100 of this embodiment is demonstrated. The induction heating coil 10 is as described above with reference to FIG.

  In the present invention, in the induction heating area, the thermal image measuring device is installed on at least one of the upper side and the lower side of the steel pipe group. In the example shown in FIG. 1, six thermal image measurement devices 20 are arranged above the steel pipe group. The thermal image measuring device 20 measures the surface temperature of the steel pipe group during the induction heating. In the present embodiment, the entire temperature distribution of the upper surface of the steel pipe group can be measured over time by the six thermal image measuring devices 20. Although details will be described later, according to this measurement result, the adhesive force on the upper side of the steel pipe group can be evaluated. From the viewpoint of evaluating the adhesive strength on the lower side of the steel pipe group and conducting a more accurate inspection, a thermal image measuring device is also provided below the steel pipe group, and the overall temperature distribution on the lower surface of the steel pipe group is also determined. It is preferable to measure. The number of thermal image measuring devices 20 is not particularly limited. When trying to observe the entire surface of a steel pipe group with a single thermal image measurement device, it is necessary to install a thermal image measurement device above the steel pipe group, and there is a risk that sufficient resolution will not be obtained to capture the shape of the pipe There is also. Therefore, as shown in FIG. 1, it is preferable to measure the temperature by dividing the observation region on the surface of the steel pipe group with a plurality of thermal image measurement devices.

  As shown in FIG. 4, the inspection system 100 preferably has a protection mechanism that protects the thermal image measurement device 20 from at least one of heat, steam, and magnetic flux generated from the steel pipe group. In FIG. 4, the protection mechanism includes a magnetic shield plate 70 and an air injection unit 72. The magnetic shield plate 70 is made of an alloy such as iron, cobalt, or nickel, and is a housing that covers the thermal image measurement device 20. However, the portion of the thermal image measuring device 20 that faces the lens 22 is open. The thermal image measuring device 20 can be protected from heat and magnetic flux by the magnetic shield plate 70. In addition, when vapor adheres to the lens 22, accurate air temperature measurement is hindered, so that air is jetted near the opening of the magnetic shield plate 70 by the air jetting unit 72.

  The protection mechanism is not limited to that shown in FIG. For example, it is also preferable to install a glass plate in the opening portion of the magnetic shield plate. Further, instead of the air injection unit 72 or in addition to the air injection unit 72, a separate air supply unit for circulating air inside the housing of the magnetic shield plate may be provided.

  Next, referring to FIG. 1, the control unit 30 applies an AC voltage to the induction heating coil 20, moves the induction heating coil 20, and measures a temperature (starts and stops measurement) by the thermal image measurement device 20. Control. In addition, the spray 60 described later is also controlled.

  The memory 40 records the measurement result by the thermal image measurement device 20, that is, the time-dependent measurement data of the temperature distribution on the surface of the steel pipe group. In addition, the memory 40 has recorded in advance data on suitable temperatures used when determining the success or failure of the adhesive force described later.

  The evaluation unit 50 evaluates the adhesive force between the steel pipe 82 and the vinyl chloride pipe 80 of the obtained individual inner surface vinyl chloride lining steel pipe 84 based on the measurement result by the thermal image measurement device 20 read from the memory 40. . A specific example of the evaluation method will be described later. Then, the evaluation result is output to the memory 40 and recorded.

  The control unit 30 and the evaluation unit 50 can be realized by a central processing unit (CPU) inside the computer. The memory 40 can be realized using a hard disk, ROM, or RAM.

  The inspection system of the present invention preferably includes a marking device that performs marking on the inner surface vinyl chloride lining steel pipe that is determined to be rejected by the evaluation unit. The inspection system 100 of this embodiment has the spray 60 as a marking device with reference to FIG.1 and FIG.2. The control unit 30 reads the measurement result from the memory 40, controls the spray 60, and sprays only the rejected inner surface vinyl chloride lining steel pipe (failed material). Thereby, since the operator can identify the rejected material in the above-described inspection process, the operator removes this. 1 and 2, the spray 60 is arranged immediately after the tube end heating process in the production line, but the position is not limited as long as it is before the inspection process. Moreover, it is good also as an inkjet etc. instead of a spray.

(Adhesion test method)
Next, an example of an inspection method that can be performed by the inspection system 100 will be described with reference to FIG. First, the control unit 30 applies an AC voltage to the induction heating coil 20 and starts moving the induction heating coil 20 to start induction heating of a batch of steel pipe groups (step S1). At the same time or after a predetermined time has elapsed, the thermal image measurement device 20 starts measuring the surface temperature of the steel pipe group (step S2). The measurement result is recorded in the memory 40 as needed.

  Then, based on the measurement result by the thermal image measuring device 20, the adhesive force of each obtained inner surface vinyl chloride lining steel pipe 84 is evaluated. A specific example will be described with reference to steps S3 to S5 in FIG. 5 and FIG.

  It is considered that the adhesive force varies for each steel pipe or for each part within one steel pipe because the induction heating accuracy is not high. In places where the heating of the vinyl chloride pipe is insufficient, a gap is formed between the steel pipe and the vinyl chloride pipe, resulting in insufficient adhesion. Therefore, in one embodiment, the maximum temperature of the steel pipe in the heating process can be suitably used as an index for evaluating the adhesive strength. As shown in FIG. 6, while the induction heating coil 20 moves from the central position of the steel pipe to both ends, the surface temperature of the steel pipe gradually increases from the central portion toward both ends, and sequentially reaches the maximum temperature.

  Therefore, in step S3, the evaluation unit 50 determines the maximum temperature of the surface of each steel pipe 82 in the heating process from the measurement data recorded in the memory 40 at a predetermined interval in the extending direction of the steel pipe 82, for example, about 5 to 20 mm. Extracted at intervals (see each measurement point in FIG. 6).

  In step S <b> 4, the evaluation unit 50 reads out optimum data according to the pipe diameter and type from the data of the suitable temperature recorded in advance in the memory 40. In other words, the emissivity changes because the material of the steel pipe surface differs depending on the type (VA pipe, VB pipe, VD pipe). Moreover, since the curvature of the steel pipe surface also changes depending on the pipe diameter, the emissivity changes. When the emissivity changes, the temperature displayed on the thermal image measurement device also changes. Therefore, it is necessary to change the suitable temperature (threshold value) for each type and tube diameter. For example, in the case of a tube diameter φ21.7 mm and a VA type, since a suitable temperature is 200 ° C. or higher, data of “determination temperature: 200 ° C.” is read out.

  In step S <b> 5, the evaluation unit 50 compares all the extracted maximum temperatures with the determination temperature read from the memory 40. And the evaluation part 50 determines that all the maximum temperatures extracted in the extending direction among the plurality of inner surface vinyl chloride lining steel pipes are equal to or higher than the determination temperature, and other than that, that is, 1 Even if there is a part that does not meet the judgment temperature even at a place, it is judged as rejected. In this way, the adhesive strength of individual inner surface vinyl chloride lined steel pipes is evaluated based on the extracted maximum temperature.

  When it is determined that all the inner surface vinyl chloride lining steel pipes are acceptable, the heating is finished (step S8). The evaluation result may be recorded in the memory 40. In addition, although the example which performs a pass / fail determination before completion | finish of a heating process was shown in FIG. 5, you may perform a pass / fail determination after a heating process.

  If there is even one rejected material, the process proceeds to step S6, and the evaluation result is recorded in the memory 40. The evaluation result is information on the position of the rejected material (how many inner surface vinyl chloride lining steel pipes are rejected from the top of the line). Thereafter, in step S7, the control unit 30 reads the measurement result from the memory 40, controls the spray 60, sprays only the rejected inner surface vinyl chloride lining steel pipe (failed material), and heats it. The process ends (step S8). Since subsequent tube end heating is as shown in FIG. In the inspection process, the operator can identify the rejected material and remove it.

  If even one rejected material is produced in one batch, the heating conditions (specifically, heating temperature and coil moving speed) are changed so that the steel pipe can be heated to a slightly high temperature in the next batch. can do.

  As described above, according to the inspection method of the present embodiment, the adhesive strength can be inspected nondestructively based on the surface temperature of the steel pipe for all the portions of all the inner surface vinyl chloride lining steel pipes in one batch.

  In addition, in the location where a vinyl chloride pipe is heated too much (location where the surface temperature of a steel pipe is too high), the shape failure of an inner surface vinyl chloride lining steel pipe tends to occur due to excessive expansion of the vinyl chloride pipe. However, since such an end product can be easily discriminated by an operator in the inspection process, it is not necessary to apply the pass / fail judgment of the present embodiment. Therefore, in the above pass / fail determination, it is not necessary to set an upper limit of the maximum temperature.

  In the process of induction heating a batch (42 pieces) of steel pipe group using the inspection system 100 shown in FIGS. 1 and 2, the surface temperature of the steel pipe group is measured by six thermal image measuring devices installed above the steel pipe group. Measured over time. From the measurement results, the maximum temperature at various sites was extracted from 42 inner surface vinyl chloride lined steel pipes (tube diameter φ21.7 mm, VA type). Then, cut the inner surface vinyl chloride lined steel pipe, prepare a sample with a length of 20 mm including the extraction site, and attach the sample to the JWWA standard hard vinyl chloride lined steel pipe for water supply (JWWA K116) using the specified inspection method. The power was tested. The relationship between the maximum temperature of each part and the adhesive force obtained in this way is shown in FIG.

The acceptance criteria of the standard is 20 N / cm ² or more, but in this example, 80 N / cm ² or more was used as a reference. From FIG. 7, an adhesive force of 80 N / cm ² or more was obtained in any part where the maximum temperature was 200 ° C. or higher, but in some parts where the maximum temperature was less than 200 ° C., the adhesive force was insufficient. . If any part of one product has insufficient adhesion, it is ineligible as a product. Therefore, it is an example of reliable product inspection that it is determined that a product having a maximum temperature of 200 ° C. or higher for all the extracted parts is an acceptable material, and that other products are unacceptable materials. In this way, it has been found that a defective material with insufficient adhesive strength can be determined based on the maximum temperature of the steel pipe.

  According to the inspection method and inspection system for the adhesive strength of the inner surface vinyl chloride lining steel pipe of the present invention, the adhesive strength of all inner surface vinyl chloride lining steel tubes in one batch can be inspected nondestructively.

DESCRIPTION OF SYMBOLS 100 Inspection system 10 Induction heating coil 20 Thermal image measuring device 22 Lens of thermal image measuring device 30 Control part 40 Memory 50 Evaluation part 60 Spray 70 Magnetic shield board 72 Air injection part 80 Vinyl chloride pipe 82 Steel pipe 84 Inner surface vinyl chloride lining steel pipe 86 Electric furnace

Claims (9)

A batch of steel pipe groups in which a plurality of steel pipes having vinyl chloride pipes inserted therein are arranged substantially in parallel with each other are heated by an induction heating coil to expand the vinyl chloride pipe, whereby the inner surface of the steel pipe is A step of measuring a surface temperature of the steel pipe group by a thermal image measuring device installed on at least one of an upper side and a lower side of the steel pipe group in a process of bonding a vinyl chloride pipe to obtain a plurality of inner surface vinyl chloride lined steel pipes; ,
Based on the measurement result by the thermal image measurement device, the step of evaluating the adhesive force between the steel pipe and the vinyl chloride pipe of the obtained individual inner surface vinyl chloride lining steel pipe,
A method for inspecting the adhesive strength of an inner surface vinyl chloride-lined steel pipe.   In the evaluation step, the maximum temperature of the surface of each steel pipe in the heating process is extracted at predetermined intervals in the extending direction of the steel pipe, and the individual inner surface vinyl chloride lining is extracted based on the extracted maximum temperature. The method for inspecting the adhesive strength of an inner surface vinyl chloride lined steel pipe according to claim 1, wherein the adhesive strength of the steel pipe is evaluated.   In the evaluation step, among the plurality of inner surface vinyl chloride lined steel pipes, all the maximum temperatures extracted in the extending direction are determined to be acceptable, and the others are rejected. The method for inspecting the adhesive strength of an inner surface vinyl chloride-lined steel pipe according to claim 2, wherein   The inner surface vinyl chloride lining steel pipe according to any one of claims 1 to 3, further comprising a step of marking with a marking device on the inner surface vinyl chloride lining steel pipe determined to be rejected after the evaluation step. Inspection method for adhesion. An induction heating coil for heating a batch of steel pipe groups in which a plurality of steel pipes each having a vinyl chloride pipe inserted therein are arranged substantially in parallel;
Measuring the surface temperature of the steel pipe group in the process of expanding the vinyl chloride pipe by the heating to adhere the vinyl chloride pipe to the inner surface of the steel pipe and obtaining a plurality of inner surface vinyl chloride lined steel pipes, A thermal image measuring device installed on at least one of the upper and lower sides of the steel pipe group;
Based on the measurement result by the thermal image measuring device, the evaluation unit for evaluating the adhesive force between the steel pipe and the vinyl chloride pipe of the obtained individual inner surface vinyl chloride lining steel pipe,
A system for inspecting the adhesive strength of an inner surface vinyl chloride lined steel pipe, comprising: A memory for recording measurement results obtained by the thermal image measurement device;
The evaluation unit extracts, from the memory, the maximum temperature of the surface of each steel pipe in the heating process at predetermined intervals in the extending direction of the steel pipe, and based on the extracted maximum temperature, The inspection system for the adhesive strength of an inner surface vinyl chloride lining steel pipe according to claim 5, wherein the adhesive strength of the inner surface vinyl chloride lining steel tube is evaluated.   The evaluation unit determines that all the maximum temperatures extracted in the extending direction are equal to or higher than a predetermined temperature among the plurality of inner surface vinyl chloride lining steel pipes, and rejects other than that. The inspection system for the adhesive strength of an inner surface vinyl chloride lined steel pipe according to claim 6.   The inspection of the adhesive strength of the inner surface vinyl chloride lining steel pipe according to any one of claims 5 to 7, further comprising a marking device that performs marking on the inner surface vinyl chloride lining steel pipe determined to be rejected by the evaluation unit. system. The adhesion of the inner surface vinyl chloride lined steel pipe according to any one of claims 5 to 8, further comprising a protection mechanism that protects the thermal image measurement device from at least one of heat, steam, and magnetic flux generated from the steel pipe group. Power inspection system.

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