JPH10221241A - Sensing method and device for intra-pipe surface defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sense a minute surface defect at the inner surface of a pipe which contains a composite material of metal, resin, etc., and is embodied long stretching, in a small diameter, and having a bend, wherein sensing of such defect has not been possible according to the conventional test techniques. SOLUTION: A fluid adjusted to a contact rate of flow or a constant pressure is supplied to the inner surface of a pipe 6 to become a test sample, and the values at this time about the rate of flow and pressure are measured and compared with the corresponding values of the standard sample, and on the basis of the obtained difference, an intra-pipe surface defect including minute projections and recesses or involving flow-path section area is found. This surface defect sensing device is arranged so that one end of the pipe 6 as test sample is connected to a water supply pipe 2 put in communication with a water storage chamber 1 and equipped with a pressure gauge 3 and flow meter 4, a return water chamber 8 is furnished to garther the water drained through the pipe 6, and that a level adjusting water returning pipe 9 and supply water pipe 10 are installed between the return water chamber 8 and water storage chamber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for evaluating and testing the properties of the inner surface of a pipe, and more particularly to a method and an apparatus for detecting a defect on the inner surface of a pipe.

[0002]

2. Description of the Related Art An optical observation device is a typical device for evaluating and testing the inner surface of a long tube. Specifically, there is an endoscope type using a fiber scope or a prism.

[0003] Electromagnetically, there are defect detection devices such as eddy current deep wound devices and ultrasonic deep wound devices.

[0004]

The above-mentioned prior art has the following problems. Optical observation device: In this device, it is necessary to combine the light source and the observation device, and it is difficult to insert the light source and the observation device simultaneously with a small-diameter tube. It is said that it is difficult to manufacture glass fibers and the like having a certain length or more. In a tube material having a large number of bent portions, the curvature of the glass fiber is limited, making observation difficult.

[0005] Ultrasonic deep scratch test: This test method makes it difficult to detect a defect accompanied by a gradual surface change near the extreme surface.
Also, in the case of a multilayer structure such as a coating film, it is difficult to separate the coating film from the tube material main body, and inspection cannot be performed.

Eddy current deep wound test: This test method has good sensitivity and can be applied to metal tubing, but for nonmetallic materials and composites of nonmetallic materials, the nonmetallic material portion is inspected. Is difficult.

Therefore, the problems to be solved by the present invention (objects)
It is possible to detect fine irregularities on the inner surface of a tube material such as a long, small-diameter metal, resin, or other composite material that could not be detected by conventional test techniques.
An object of the present invention is to provide a method and an apparatus for detecting a surface defect in a pipe.

[0008]

SUMMARY OF THE INVENTION The present invention utilizes the fact that a fluid having a constant pressure or a constant flow rate flows through the inner surface of a complicated tube to change the pressure loss of the fluid due to irregularities on the inner surface of the tube. The basic concept was to determine the defect on the inner surface of the tube by measuring the pressure.

The method of detecting a defect on the inner surface of a pipe provided on the basis of the basic concept described above supplies a fluid adjusted to a constant flow rate or a constant pressure to the inner surface of a pipe to be a test sample, and measures the flow rate and pressure value at this time. Then, by measuring the difference between these values in the standard sample, a defect with minute irregularities on the inner surface of the tube material and a defect with a flow path cross-sectional area are detected.

[0010] The pipe inner surface defect detecting device provided based on the above-described basic concept is characterized in that one end of a pipe as a test sample is connected to a water supply pipe connected to a water storage tank and provided with a pressure gauge and a flow meter. There is provided a return water tank for communicating and collecting water drained through the pipe material, and a water level adjusting water return pipe and a supply water pipe are arranged between the return water tank and the water storage tank.

The pressure of the fluid in the tube is determined by the cross-sectional area of the inner surface of the tube, the amount of change in the cross-sectional area, the roughness of the inner surface of the tube, etc. if the type of fluid, the temperature, and the length of the tube are constant. .

For this reason, a pipe having the same shape without defects is used as a standard sample, a fluid having a constant pressure or flow rate is caused to flow on the inner surface of the pipe, and the pressure and flow rate at that time are measured, so that the difference in pressure loss from the standard sample is determined. By inspecting, it is possible to inspect more than the inner surface of the pipe.

As the fluid, air, water or the like is generally used, but in order to clarify the pressure loss, a highly viscous liquid is desirable. If it is impossible to contaminate the inside of the tube with a fluid, it is preferable to use gas or air.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an apparatus for carrying out a method for detecting an inner surface defect of a pipe according to the present invention. The pipe 6 to be a test sample or a defect-free pipe made of the same shape as this is used. It is a device for the tube material.

The apparatus includes a water storage tank 1, a water supply pipe 2 connected to the water storage tank 1, a return water tank 8 provided below and opposite to the water storage tank 1, a water storage tank 1 and the return water tank. 8, a water level adjusting water return pipe 9 having an upper end connected to a water level upper limit side wall of the water storage tank 1 and a lower end directed to the return water tank 8, and a lower end to the return water tank 8 via the water supply pump 11. It is provided with a supply water pipe 10 which is communicated and whose upper end is communicated with the upper part of the water storage tank 1.

The water supply pipe 8 is provided with a pressure gauge 3, a flow meter 4 and a water supply regulating valve 5, and is provided with a pipe with a drain valve 7 directed to the return water tank 8.

A pipe 6 serving as a test sample is connected between the water supply pipe 2 and the pipe with the drain valve 7, and is supplied from the water tank 1, which maintains a constant water level by overflow from the water level adjustment water return pipe 9. Water having a constant water pressure is supplied, and the water is poured into the tube 6 of the test sample. At this time, the water pressure is adjusted by the water supply adjusting valve 5. The water pressure value is checked with a water pressure gauge 3.

As described above, water is supplied to the test tube 6 at a constant pressure. A similar test is also performed on a standard sample of a defect-free tube. Then, a defect in the tube is determined from the flow rate difference between the test tube 6 and the standard sample.

[Experimental Example] In order to confirm the method of detecting a defect on the inner surface of a pipe material using the above apparatus, a copper pipe having a length of 10.0 m, an outer diameter of 12.7 φ, and a wall thickness of 0.9 t was flattened to a minor diameter of 8 mm. Then, it was installed at the site of the test tube 6 in FIG. 1 and subjected to the test.
At this time, adjust the flow rate of the standard sample to 5 liter / min. Next, as a test tube, the height of 0.2 m
m, an artificial defect having a protrusion having a width of 5 mm and a protrusion of 1 mm parallel to the flow path was attached, and the same test as above was performed. As a result, in the case of population defect, the flow rate is 5.6 liter / mi
n and the effects of population deficiencies are evident.

In the above embodiment, water is used as the fluid. However, in principle, any fluid may be used as long as it does not deteriorate the test tube. For example, oil,
Solvents, gases, etc.

As a method of applying a constant pressure, a water tank was used. However, if a constant pressure can be confirmed as a pressure source,
A pressure pump with a fixed discharge amount, a large-sized pressure tank, or the like may be used.

[0022]

According to the present invention as described above, a test can be performed nondestructively irrespective of the length and shape of the tube by catching minute defects on the inner surface of the tube as changes in pressure loss of the fluid. became. Therefore, it is possible to detect minute irregularity defects on the inner surface of a tube material including a composite material such as a metal, a resin, etc. having a long, small diameter and bend, which cannot be detected by the conventional test technology. The intended problem (object) of providing a defect detection method and apparatus can be achieved.

Further, since the method of the present invention is a non-destructive inspection, it can be applied to a 100% inspection of products.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a state of detecting a surface defect inside a pipe according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 water storage tank 2 water supply pipe 3 pressure gauge 4 flow meter 5 water supply adjustment valve 6 tube material; sample 7 drain valve 8 return water tank 9 water level adjustment water return pipe 10 supply water pipe 11 water supply pump

Claims (2)

[Claims] 1. A fluid adjusted to a constant flow rate or a constant pressure is supplied to the inner surface of a tube as a test sample.
By measuring the pressure value and measuring the difference from those values in the standard sample, defects with minute irregularities on the inner surface of the tube and defects with a channel cross-sectional area are detected. Detection method. 2. A return tank for connecting one end of a pipe to be a test sample to a water supply pipe connected to a water storage tank and provided with a pressure gauge and a flow meter, and for collecting water discharged through the pipe. A water level adjusting water return pipe and a supply water pipe are provided between the return water tank and the water storage tank.