JPS6017734Y2 - Film holder for radiographic testing - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a film holder for radiographic testing of a welded portion between a heat exchanger tube and a tube sheet.

Conventionally, to inspect seal welds on thin plates of heat exchanger tubes in steam generators, etc., magnetic particle testing or liquid penetrant testing was often used to target the surface of the weld, and gas or liquid was also used. Its soundness is confirmed through leakage tests, etc.

Additionally, radiographic testing is rarely performed as a method of inspecting for defects within seal welds.

In this case, for a seal welded portion having a shape as illustrated in FIGS. 1 and 2, a radiographic test is carried out in the manner shown in FIGS. 3 and 4 (A' arrow view). .

In Figures 1 and 2, 1'a and l'b are heat exchanger tubes 2'
a, 2'b are tube plates, 3'a.

3'b is a seal weld.

Figures 3 and 4 show the state of the radiographic test of the seal weld 3'a shown in Figure 1, where 4' is the radiation source or
ray (or gamma ray 0 generator, 5' is a radiation film, 6
' is a line indicating the direction of radiation.

That is, the usual method is to irradiate the seal welded portion 3'a obliquely with radiation as shown by 6' and set a radiation film 5' on the inner surface of the heat exchanger tube 1'a as shown in the figure. With this method, if the diameter of the heat transfer tube is small, it may be difficult to set the film 5' in the specified position inside the tube 1'a. 1'a is extremely different in the longitudinal direction and the circumferential direction, making it difficult to obtain appropriate exposure conditions.Therefore, there was a drawback that the range that could be inspected in one photographing was extremely small.

In addition, when the wall thickness is thin, a low energy radiation source or a low tube voltage X-ray generator is required.

The purpose of this invention is to eliminate the drawbacks of the conventional methods described above, by making it easier to set the radiation film on the inner surface of the heat exchanger tube, and by improving the image quality chamber of the film and increasing the range that can be inspected with a single film. It is designed to be wide and is used for non-destructive inspection of welded parts of heat exchanger tube seals in various types of heat exchangers, such as nuclear power, thermal power, and chemical equipment.

Hereinafter, the present invention will be described as shown in Fig. 6 (a sectional view for explaining the film holder for radiographic testing of welded parts according to the present invention) and Fig. 7.
(B-B cross-sectional plan view in Figure 6) and Figure 8 ((A) is the film holder of the present invention corresponding to Figure 6, (B) is the inspection result) .

1 is a heat exchanger tube, 2 is a tube plate, 31 is a seal weld between both 1 and 2, 4 is a radiation source or an X-ray (γ-ray) generator,
5 is a radiation (X-ray, γ-ray) film, 6 is a line indicating the direction of radiation, 7 is a block for loading the film 5 and for preventing halation and fogging, and 8 is a scattering radiation prevention plate.

The block 7 is made of a defect-free material with a radiation transparency equal to that of the seal weld 3, and its dimensions are such that the diameter of the upper protrusion 7a is approximately the same as the outer diameter of the heat exchanger tube 1; The diameter of the lower insertion part 7b with a step is approximately equal to the inner diameter of the heat exchanger tube 1, and the radiation film 5 and scattering prevention plate 8 are inserted into the predetermined positions up to the position below the seal welding part 3. A slit 7C is provided.

It is possible to attach the anti-scattered radiation plate 8 to the slit 7C of the block in advance, so that the radiation film 5 can be easily loaded.

The block 7 is the heat exchanger tube 1 with the seal weld 3 to be inspected.
Then, the radiation film 5 is set in the slit 7C adjacent to the anti-scattered radiation plate 8 as shown in the figure.

The actual implementation state in that case is shown in FIG.

In (A) of FIG. 8, the same parts as those in FIG. 6 indicate the same parts, and in (B), a is the testable range,
b indicates the appropriate density range, C indicates the film density change line, and compared to the case of the conventional apparatus shown in Fig. 5, the values of a and b above are larger than the aI and b/ of the opening in Fig. 5, and the film density change line As shown by the line C (c' in Figure 5), the film density is within the testable range a1, and the value of the suitability range is the fifth.
Figure opening aI.

b', and the film density has many uniform parts as shown by the change line C.

Although FIG. 8 shows an example in the longitudinal direction of the film, the same can be said for the circumferential direction of the heat exchanger tube.

The present invention includes a block having a protrusion having a diameter approximately equal to the outer diameter of the heat exchanger tube welded to a tube plate, and an insertion portion having a step between the protrusion and the same and having a diameter approximately equal to the inner diameter of the heat exchanger tube. This is a film holder for radiographic testing of welded parts, characterized by forming a film loading slit extending from the insertion part to the insertion part.

That is, in accordance with the present invention, as described in the embodiments above, the block (the seal welded portion is made of a material having a radiation transparency equal to S) is inserted into the heat transfer tube, and the heat transfer is carried out. The radiation transmission thickness is averaged in both the longitudinal and circumferential directions of the heating tube, and the photographed film has a uniform density of S, and the image quality is much better than that of the conventional method that does not use the block of the present invention. It will be done.

In addition, the area that can be inspected at one time is wide, and the number of films required to inspect the entire circumference of the seal weld is small, so inspection can be carried out in a short time.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views showing the seal weld, respectively.
The figure is a vertical cross-sectional view for explaining the outline of the radiographic test state of a conventional seal weld, FIG. 4 is a plan view looking inward in the direction of arrow A' in FIG. 3, and FIG. Fig. 6 is a longitudinal cross-sectional view of a radiographic test state of a seal weld corresponding to A, and Figs. One embodiment of the invention is shown, FIG. 6 is a longitudinal cross-sectional view of a film holder for radiographic testing of seal welds according to the invention, and FIG. 7 is a cross-sectional view taken along line B-B in FIG. 8(A) is a vertical cross-sectional view of the film holder according to the present invention corresponding to FIG. 6, and (B) is a cross-sectional plan view seen in the viewing direction. FIG. 3 is a diagram showing density range and film density change. In the figure, 1... heat exchanger tube, 2... tube sheet, 3... seal welded part, 4... radiation source or X-ray generator, 5... ...Radiation film, 6...Line indicating the direction of radiation, 7...
...Block, 7a is the protruding part, 7b is the insertion part, 7C
is slit, 8... scattering: line prevention plate, a...
...Testable range, b...Appropriate concentration range, C
...Film density change line.

Claims (1)

[Scope of utility model registration request] A block consisting of a protruding portion having a diameter approximately equal to the outer diameter of the heat transfer tube welded to the tube sheet, an insertion portion having a step with the protruding portion and having a diameter approximately equal to the inner diameter of the heat transfer tube, and inserting from the protruding portion. 1. A film holder for radiographic testing, characterized in that a film loading slit is formed that extends over the entire length of the film holder.