JP2002144074A - Radiographic test method of fillet welded part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily pick up an image of internal defects, etc., of a fillet welded part radiographically even without using any wedge for compensating the wall thickness. SOLUTION: A plurality of X-ray films 16 and 17 are arranged on a back side of a base metal 11 for taking radiographic photos of the fillet welded part 14 of a T-joint 13. When the X-ray films 16 and 17 of different sensitivity are combined with each other, the radiographic photos capable of detecting internal defects of the fillet welded part 14 can be obtained even without using any wedge for compensating the wall thickness. When a pre-packed sheet film is used for the X-ray films 16 and 17, this radiographic test method can be easily applied to even a curved surface of a tube, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a fillet weld used for manufacturing a welded structure such as a chemical plant.
The present invention relates to a radiation transmission test method for a fillet weld for performing flaw detection and the like.

[0002]

2. Description of the Related Art Conventionally, chemical plants and the like,
As a general structure, a welded structure formed by combining materials such as a plate, a pipe, and a rod is widely used. In a welded structure, a welded joint is used for a main part. A butt joint is used in a portion of the welded joint that is important in terms of strength and reliability, but a fillet weld is used in a portion where a butt joint is not used due to its structure.

FIG. 6 is a Japanese Industrial Standard JIS Z 3109.
FIG. 6 shows the imaging arrangement described as FIG. 5 in the radiation test method for aluminum T-welds specified as -1988. FIG. 6A shows a state viewed from the front, and FIG.
(B) shows a state in plan view. Base material 2 on the surface of base material 1
Are butted to form a T-shaped joint 3, and a fillet weld 4 is formed along the boundary of the butted portion. Irradiation such as X-rays 5 is applied to inspect whether or not a defect such as a foreign matter or poor penetration has occurred in such a fillet weld 4. An X-ray film 6 is arranged on the back surface side of the base material 1, and an image by the X-ray transmitted through the fillet weld 4 and the base materials 1 and 2 is taken. Since the penetration thickness of the fillet weld changes discontinuously, the density of the transmission photograph also changes. The wall thickness compensating wedge 7 is used to adjust the radiation transmission thickness.

FIG. 7 shows the relationship between the density of an image photographed with a radiographic film such as the X-ray film 6 in FIG. 6 and the identifiable range of the photographed image. The film density is represented by black 4 to white 0, and is an illuminator for observing a transmission photograph. In a film observer generally called a Schaukasten, the film density is 3.2 to 1.3. If it is within the range, it can be identified. X-ray films have a relatively narrow range of radiation intensities that provide an image that can be identified for a particular film speed. Therefore, when the wedge 7 for thickness compensation is not used in FIG.
By setting the exposure conditions to obtain an appropriate image in the thick part of
The transmitted dose in the thin portion of the fillet weld 4 becomes too large, resulting in a transmission photograph that is very difficult to observe. The thickness compensation wedge 7 has a tip shape adapted to the slope of the fillet weld 4, and the base material 1 and the fillet weld 4 together with the thickness compensation wedge 7 are close to a uniform thickness as a whole. As a result, the change in the transmitted dose in the vicinity of the fillet weld 4 can be reduced.

[0005] A transmissometer 8 and a gradation meter 9 are also arranged in a range where the X-ray film 6 is photographed, so that the resolution of the photographed transmission photograph can be evaluated.

[0006]

In a radiation transmission test of a fillet weld as shown in FIG. 6, it is necessary to prepare a wedge 7 for thickness compensation and to take an image. Wedge 7 for wall thickness compensation
It is necessary to form the tip of the tip into a shape corresponding to the inclination of the surface of the fillet welded portion 4 and to match the material. Further, if the surface shape of the base material 1 is not a flat surface but a curved surface, it must be a curved surface shape conforming to the curved surface. In a welded structure including a pipe, a wedge 7 for thickness compensation is required for each pipe size and material, and in a welded structure in which a variety of pipes and static devices are installed, such as a chemical plant, a realistic structure is required. Application is difficult.

[0007] For this reason, in a chemical plant or the like, as a method of inspecting the fillet welded portion 4, only a visual inspection as a surface inspection, a penetration inspection, and a magnetic particle inspection are employed.
No inspection is performed on the internal flaws in the fillet weld 7. To secure the throat thickness, as shown in FIG.
At the root of the fillet weld 4 that has been beveled and welded,
If penetration failure occurs with a high probability and a repeated stress acts, cracks may develop from there.

SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation transmission test method for a fillet welded part, which can easily photograph an internal flaw or the like of the fillet welded part without using a wedge for thickness compensation by a transmission photograph. It is.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a radiographic method for radiating radiation to a fillet weld formed by performing build-up welding on a fillet of a T-joint. In the test method, a plurality of X-ray films including those having different sensitivities to the radiation are arranged on the back surface side of the base material on which the fillet weld is formed, and the plurality of X-ray films are simultaneously photographed. A radiation transmission test method for a fillet weld, characterized in that:

[0010] According to the present invention, a fillet weld formed by performing build-up welding on a fillet of a T-joint is irradiated with radiation, and an X-ray film is disposed on the back side of the base material to obtain a transmission photograph. Shoot. Since the X-ray films include those having different sensitivities to radiation, even if the exposure conditions fluctuate, any of the X-ray films will have a sensitivity that is more suitable for the fluctuated exposure conditions. . By looking at transmission pictures taken with X-ray films of a plurality of sensitivities, the inside of the fillet weld can be inspected without using a wedge for thickness compensation. Since a wedge for thickness compensation is not used, the test can be performed without restriction on the material and the curved surface shape.

In the present invention, the X-ray film is used by being sealed in a flat and flexible pack.

According to the present invention, since the X-ray film is flat and flexible, a plurality of X-ray films can be easily arranged on the back side of the fillet welded portion.

In the present invention, the surface of the base material on which the fillet weld is formed is a curved surface.

According to the present invention, even if the surface of the base material is a curved surface, it is not necessary to use a wedge for thickness compensation adapted to the curved surface, so that the inspection of the fillet weld formed on the curved surface can be easily performed. Inspection of a chemical plant or the like where it is highly necessary to form a T-shaped joint on a curved surface with piping or the like can be easily performed.

[0015]

FIG. 1 shows the principle of a radiation penetration test method for a fillet weld as one embodiment of the present invention. FIG. 1A shows a state viewed from the front, and FIG. 1B shows a state viewed from the top. Also in the present embodiment, similarly to FIG. 6, a fillet welded portion 14 is formed at a portion of a T-shaped joint 13 formed by two base materials 11 and 12. Inspections such as internal flaws in the fillet weld 14 are inspected based on a transmission photograph taken by irradiating with X-rays 15. In the present embodiment, X-ray films 16 and 17 having different sensitivities are overlapped and a transmission photograph is taken at the same time. If the sensitivity of one X-ray film 16 is higher than the sensitivity of the other X-ray film 17, an image that passes through the fillet welded portion 14 and has a reduced radiation dose can be taken in accordance with the exposure conditions. be able to. On the other hand, with the X-ray film 17 having low sensitivity, an image having a high radiation dose passing through only the base material 11 is taken under the exposure condition. By superimposing and simultaneously exposing the X-ray films 16 and 17 having different sensitivities as described above, it is possible to perform imaging corresponding to a wide range of radiation dose that cannot be achieved by a single film.

In the vicinity of the fillet weld 14, the imaging range of the X-ray films 16 and 17 includes a transmittance meter 18 and a gradation meter 19.
Is placed. As the transmittance meter 18 and the gradation meter 19, those defined in JIS Z 3109 can be used. Four types of transmittance meters 18 using wires are defined as A02, A04, A08, and A16. As for the tone meter 19, four types, that is, A type, B type, C type, and D type using a plate material are defined.

FIG. 2 shows that, as shown in FIG. 1, a total of four X-ray films 16, 17 having different sensitivities are used.
The schematic configuration of the simulation test body 20 whose effect has been confirmed is shown.
FIG. 2A shows a configuration viewed from the front, and FIG. 2B shows a configuration viewed from the top. In the simulation test body 20, the plate-shaped base material 2
A lap joint 23 is formed by arranging a plate-shaped base material 22 on the surface of the base material 1. Welding of the lap joint 23 is performed by the fillet weld 24, and the X-ray 25
And X-ray films 16 and 17 are arranged on the back surface.
Such a configuration is considered to be equivalent to irradiating the X-ray 15 from the direction inclined to the T-shaped joint 13 in FIG.

On the surface of the base material 21, a transmittance meter 28 in which wires having different linear shapes are arranged and a transmittance meter 29 in which a plurality of through holes having different diameters are arranged in a plate material are arranged. As the transmittance meter 29 using a plate material, two plates having different plate thicknesses are arranged.

FIG. 3 shows an X film 1 obtained by photographing a transmission photograph.
6 and 17 show the positions at which the concentration is measured. X1 to X14
Of the 14 positions to, 9 from X4 to X12
The portion extends over the fillet weld 24. In particular, X1
Since 0 to X12 is the thin portion of the fillet weld 24, the transmitted radiation dose increases. X13 and X14 are
This corresponds to the position of the transmittance meter 29.

FIG. 4 shows a schematic shape of the X-ray films 16 and 17 used in the present embodiment. The pre-pack type sheet film 30 is sold, for example, by Fuji Photo Film Co., Ltd. under the trade name of “Industrial X-Ray Sheet Pack Film”. Such a pre-pack type sheet film 30 is thin and light, so that it is easy to handle. X-ray film 31 is made of aluminum foil and plastic
Since it is sealed in a vacuum pack 32 having a layer structure and has excellent water resistance and oil resistance, it can be used even in an environment under bad conditions. Some products also include lead foil intensifying screens.

Generally, an X-ray film is used in a state of being housed in a robust cassette. However, since the cassette is thick, it is difficult to use a plurality of cassettes as in this embodiment. Since the pre-pack type sheet film 30 as shown in FIG. 4 is flat and easy to handle, it is also easy to stack a plurality of sheets as in this embodiment. In addition, even when X-ray films having different sensitivities are used side by side, they can be easily cut with a cutter knife or the like in a dark room, and after arranging, it is easy to apply black tape for light shielding.

Table 1 below shows combinations of X-ray films 16 and 17. The high-sensitivity X-ray film 16 uses a sensitivity called “# 80”, and the low-sensitivity and high-resolution X-ray film 17 uses a sensitivity called “# 50”. The order in which two images are combined so that a total of four images are arranged from left to right corresponding to the X-ray 25 irradiation side, that is, from the upper side to the lower side. The shooting conditions are the same.

[0023]

[Table 1]

Table 2 below shows the film density at each position for the combination No. 1 in Table 1.

[0025]

[Table 2]

Table 3 below shows the film density at each position for the combination No. 2 in Table 1.

[0027]

[Table 3]

Table 4 below shows the film density at each position for the combination No. 3 in Table 1.

[0029]

[Table 4]

Table 5 below shows the film density at each position for the combination No. 4 in Table 1.

[0031]

[Table 5]

Referring to the results of Tables 2 to 5, when about four pre-packed sheet films 30 as shown in FIG. 4 are used as the X-ray films 16 and 17, there is no difference depending on the overlapping position. I understand. Of the positions X4 to X12 related to the fillet weld 24, # 80 is set at the positions X4 to X6 on the thick side, and the positions X10 to X12 at the thin side.
In # 50, the density of each of the photographable ranges is 1.3 to 3.
It can be seen that it falls within the range of 2.

When two types of X-ray films 16 and 17 having different sensitivities are used, that is, a total of four X-ray films 16 and 17 as in this embodiment, two sets of the same transmission photograph can be taken simultaneously. For example, one set may be attached as a test result to a report or the like, and the other set may be stored as a record. In addition, it is possible to shoot with a larger number of images and efficiently shoot images for a plurality of distribution destinations.

FIG. 5 shows another embodiment of the present invention.
This shows a state in which a test is performed to inspect a fillet welded portion 44 in which a base material 42 is joined to a curved base material 41 by forming a T-shaped joint 43 for flaws inside the welded portion. X-ray film 1 for irradiating X-rays 45 and taking transmission pictures
6 and 17 use the prepacked sheet film 30 as shown in FIG.
1 can be easily bent in accordance with the curved shape on the back side.

Although the X-ray film 31 is enclosed in the vacuum pack 32 one by one in the pre-pack type sheet film 30 shown in FIG. 4, when a plurality of sheets are used in combination, they are stacked in advance or arranged side by side. It is also possible to prepare a prepacked sheet film that has been combined. When a flat base material 21 is to be inspected as shown in FIG. 1, a cassette in which a plurality of X-ray films are stored in combination may be used. Further, in each of the embodiments, although transmission imaging is performed using X-rays, γ
Of course, the present invention can be similarly applied to other radiations such as a line.

[0036]

As described above, according to the present invention, with respect to a fillet weld formed by performing build-up welding on a fillet of a T-joint, a plurality of sensitivities are applied to the back side of the base material by irradiating radiation. The transmitted X-ray films are stacked or arranged side by side to take a transmission photograph. Since X-ray films include those with different sensitivities to radiation, even if the exposure conditions fluctuate, any of the X-ray films will be more favorable exposure conditions, and as a whole, inspection for internal flaws etc. It can be done reliably. The exposure condition does not need to be uniform near the fillet weld, and the inside of the fillet weld can be inspected without using a wedge for thickness compensation. Since a wedge for thickness compensation is not used, the test can be performed without restriction on the material and the curved surface shape.

Further, according to the present invention, since the X-ray film is flat and flexible, a plurality of the X-ray films can be easily stacked or arranged on the back side of the fillet welded portion.

Further, according to the present invention, it is not necessary to use a wedge for thickness compensation adapted to a curved surface. Inspection of a chemical plant or the like can be easily performed to improve reliability.

[Brief description of the drawings]

FIG. 1 is a simplified front view and a plan view showing a radiation transmission test method for a fillet weld as one embodiment of the present invention.

FIGS. 2A and 2B are a front view and a plan view showing a schematic configuration of a simulation test body 20 for confirming the effect of the radiation transmission test method of FIG.

FIG. 3 is a view showing a position where the density of a transmission photograph is measured by the simulation test piece 20 of FIG. 2;

FIG. 4 is a perspective view showing a schematic structure of a prepacked sheet film 30 used as the X-ray films 16 and 17 in FIGS.

FIG. 5 is a simplified front view showing a radiation transmission test method of a fillet weld as another embodiment of the present invention.

FIG. 6 is a simplified front view and a plan view showing a radiation transmission test method for a fillet weld specified by JIS.

FIG. 7 is a diagram showing a relationship between the density of a transmitted image of an X-ray film and a density range in which defects can be identified.

[Explanation of symbols]

 11, 12, 21, 22, 41, 42 Base material 13, 43 T-shaped joint 14, 24, 44 Fillet welded part 15, 25, 45 X-ray 16, 17, 31 X-ray film 20 Simulated test specimen 30 Prepack type Sheet film 32 Vacuum pack

Claims (3)

[Claims] 1. A method for radiating radiation to a fillet weld formed by performing build-up welding on a fillet of a T-joint and taking a transmission photograph, the method comprising: A plurality of X-ray films including those having different sensitivities to the radiation are arranged on the back side of a base material on which a portion is formed, and photographing is performed simultaneously with the plurality of X-ray films. Radiation transmission test method for part. 2. The method according to claim 1, wherein the X-ray film is used by being sealed in a flat and flexible pack. 3. The radiation transmission test method for a fillet weld according to claim 2, wherein the surface of the base material on which the fillet weld is formed is a curved surface.