JP2941611B2 - How to repair structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repair method for restoring soundness of a structure whose soundness has been impaired due to a decrease in structural strength due to a defect generated in a structural member constituting the structure. In particular, the present invention relates to a cutting method for removing (or reducing) the defect of the portion, reinforcing the cut portion, and a repair method suitable for ensuring long-term soundness of the repair portion.

[0002]

2. Description of the Related Art Defects generated in structural members are factors that impair the soundness of structures. The occurrence of such a defect is sensitive to a slight difference in the material composition and the environmental condition of the used environment, and it is extremely difficult to predict the occurrence. Furthermore, cracks, which are the most frequently occurring defects, grow over time, so that leaving the defects in the structural member significantly reduces the soundness of the structure. Therefore, it is very important to detect defects in structural members early by thorough inspection and to repair them as soon as they are found.

It is desirable that such defects be completely removed. This is because if a defect is left, the soundness may be impaired again by the growth of the residual defect. Therefore, repairs that can be performed should be implemented. However, in practice, it is not easy to completely remove defects due to problems such as the material and shape of the member or workability. In particular, it is particularly difficult in a special environment, such as a nuclear reactor, in which a structure having a complicated shape is installed in a narrow space and radiation is applied.

[0004] Surface melting is a technique for removing defects such as cracks. However, in this method, the area from which defects can be removed is limited to the surface portion, and therefore, it is impossible to remove defects that have spread to the inside of the material. Therefore, as a method of removing defects most reliably, cutting of structural members containing defects,
A method has been proposed in which reinforcement is combined with reinforcement for recovering structural strength reduced by cutting.

The basic part of the method described in the known example is disclosed in
The repair under severe operating conditions such as a nuclear reactor is carried out based on the above idea. Its features are: (1) cutting a member with (or possibly having) a material defect together with the defect; (2)
Attach a lid plate to the cutting section to structurally reinforce the cut section, and (3) perform these operations remotely.

[0006]

According to the repair method provided in the above-mentioned known example, in order to reinforce a structural member cut in order to remove a defect from the structural member, in addition to a lid plate, a screw for attaching the lid plate is used. It is necessary to introduce a welding machine and its accessories (welding monitoring camera) etc. to fix parts, tools, screws, etc. to the repair part, screwing the lid plate, and welding to fix the screws Due to the necessity and necessity of performing these operations remotely, it is considered to be extremely difficult to work in a place where the structure is complicated and there is not enough room in the work space. That is, it can be applied only to a part (access hole) having a relatively simple structure in the reactor internal structure and having a sufficient working space.

In the conventional method, a lid plate is attached to reinforce a partially cut structural member in order to remove a defect. However, in such a method, it is necessary to ensure the hermeticity of the inside of a pipe like a pipe. In such a case, there is a high possibility that the seal is broken through the gap between the repaired member and the lid plate. In addition, in the case where the space is usually in water as in the case of a reactor internal structure, such a gap is extremely susceptible to corrosion, and it is also difficult to guarantee the long-term soundness of the repaired part.

In order to overcome such a problem, the present invention has the following objects.

[0009] (1) It can be applied to repair of structural members having a complicated structure in a narrow space, (2) sealing performance of the repaired portion can be ensured, and (3) long-term soundness of the repaired portion. Provide a repair method that can ensure

[0010]

A book which achieves the above object.
A feature of the invention is the structural strength of a structure generated in a structural member.
Defects that reduce or have the potential to reduce
Combine with cutting, surface melting and overlay as needed
Repairs can be carried out from both or one side of the structural member.
And the defects in the structural members
It may interrupt the contact. Specifically, cutting is an example
For example, a part of the defect is removed from the structural member by EDM.
Is Rukoto.

[0011]

[Function] Contact between a defect generated in a structural member and an environmental atmosphere
In order allowed cut off, so good if introduced welder and its accessories (welding surveillance camera) to the auxiliary Osamu unit, can be significantly reduced as compared to the space required to work with the conventional method. Further, since overlay welding only requires scanning the welding machine, control of the apparatus can be greatly simplified. In other words, an object of the present invention is to reduce the contact between a defect generated in a structural member and an environmental atmosphere.
We can apply a welding machine to shut off
Thus, it is possible to reduce the space required for the repair work and simplify the device control. Therefore, in the method of repairing a structure, applicability to a complicated structural member in a narrow space is greatly improved.

Similarly, by applying build-up welding,
It is possible to reinforce the cut structural member without making a gap. Therefore, it is possible to ensure the sealing performance of the repair part.

Similarly, by applying build-up welding,
It is possible to reinforce the cut structural member without making a gap. Therefore, long-term soundness of the repaired portion can be ensured without occurrence of crevice corrosion or the like.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Defects usually occur at the surface and grow towards the inside of the material. Although the tip of the defect has a unique notch shape, growth of the defect can be prevented if the shape is improved. For this reason, attempts have been made to improve the tip shape of the defect or to erase the defect itself by irradiating the surface with, for example, a laser or the like. However, in the approach from the material surface, there is a limit to the depth at which the effect reaches, and at present, it is not a very effective method when the defect grows deep inside the material.

Although it is possible to find a defect by carefully observing the surface, it is difficult to grasp the growth direction and length of the defect. Therefore, the most reliable method of removing the defect including the defect grown to a deep position is cutting a structural member including the defect. FIG. 1A shows a defect 2 penetrating the structural member 1 (hereinafter referred to as a penetrating defect) and a defect 3 not penetrating (hereinafter referred to as a non-penetrating defect). Also in this case, it is desirable to cut a thickness 4 (hereinafter, referred to as a thickness) corresponding to the thickness of the structural member similarly to the penetration defect. As a means for cutting, as is known in the art, electric discharge machining capable of arbitrarily controlling the shape and amount of a portion to be cut is desirable.

FIG. 2 shows the procedure of this embodiment. First, a part of a structural member including a defect to be removed is cut. in this case,
Although the thickness of the structural member may be cut, in order to perform the overlay welding performed later, it is necessary to cut to a certain depth, suspend once, and overlay the cut portion. The same work is performed from the side opposite to the side where the repair was performed earlier. From the opposite side, cutting is performed until the welded portion already performed is reached, and the cut portion is welded. Thereby, as shown in FIG. 1b, the defect can be completely removed, and the shape of the structural member can be restored.

In this embodiment, unlike the conventional example, the front and back surfaces of the repair surface can be completely sealed. Further, since there is no gap, there is no possibility of corrosion due to the gap. Therefore, the soundness of the repaired part can be maintained for a long time.

In the case of a non-penetrating defect, if the length 5 of the non-penetrating defect can be grasped, only the repair from the surface where the defect occurs (cutting of the structural member and overlay welding) is sufficient. If the defect penetrates but repair from both sides is difficult, the thickness of the member may be cut from one side and then welded by overlay welding to close the through hole.

A second embodiment will be described. There are several types of defects in the material, some of which can prevent growth by blocking contact with the environmental atmosphere in which the structural member is located. That is, in this embodiment, although a part of the defect remains, the purpose is to shut off the defect from the environmental atmosphere. Of course, it is the best repair to completely remove such a defect, but it is an effective repair when it is difficult due to operational restrictions or the like.

FIG. 3 is a diagram schematically showing a cross section of a member repaired according to this embodiment. FIG. 4 is an example of a repair procedure according to the present embodiment. In this embodiment, the defect generating surface 6 of the structural member including the defect is melted, and the defect is erased near the surface. In the case of a penetration defect, the surface is melted from both surfaces of the member. The surface melting can be performed by using non-filler welding, laser beam irradiation, or other heat sources in addition to overlay welding.
Further, in order to reduce the length of the remaining defect 10 (hereinafter referred to as a residual defect), it is also possible to perform cutting and overlay welding of the structural member instead of the surface melting. Furthermore, if there is no problem in the structural strength, after cutting, the surface can be melted instead of the overlay welding to cut off the defect and the environment. If the contact between the defect and the environment atmosphere can be cut off by the above repair, the growth of the defect can be prevented.

The third embodiment is a method of repairing a penetration defect from only one side. FIG. 5 schematically shows a cross section of a member repaired by the present embodiment. As can be seen from FIG. 5, when a defect penetrates, it is not possible to not only remove the defect but also completely block the contact between the defect and the environmental atmosphere. However, when the environment atmosphere in which the members are in contact is different between the front and the back, for example, if one side is an environment atmosphere that promotes the growth of defects, and the back side is an environment that is not so, the environment between the defects and the environment atmosphere that promotes the growth of the defects is Defect growth can be prevented only by interrupting the contact.

A procedure for performing repair according to this embodiment will be described. In the repair according to this embodiment, the surface of the structural member containing the defect is melted from the environment side that promotes the growth of the defect, and the contact between the defect and the environmental atmosphere (the side that promotes the growth of the defect) is prevented. As a means of surface melting, non-filler welding, laser beam irradiation, and other heat sources can be used in addition to overlay welding.

In order to reduce the length of the remaining defects, it is also possible to carry out cutting and overlay welding of the structural members.
In this case, if the thickness of the structural member is cut, the defect can be completely removed, but this case corresponds to the repair according to the first embodiment. If there is no problem in the structural strength, it is also possible to cut off the surface of the structural member instead of the overlay welding after cutting the structural member to cut off the contact between the defect and the environmental atmosphere. These repairs can prevent the growth of defects.

Next, a fourth embodiment will be described. The present embodiment relates to the cutting of a part of a structural member performed to remove a defect in the first embodiment, and in the case where a decrease in the structural strength does not impair the soundness of the structure, the subsequent reinforcement. This is a method of finishing the repair without taking any measures.
As a result, defects can be reduced or eliminated.

The fifth embodiment is different from the first to third embodiments in that the long-term soundness of the repaired portion is compared with that before the repair by performing overlay welding using a repair material having high deterioration resistance. This is a repair method characterized by improvement.

The sixth embodiment is different from the first to fifth embodiments in that before or after the repair, the repaired portion is provided with a surface treatment for relaxing the internal stress of the structural member or improving the corrosion resistance. This is a repair method characterized by improving the long-term soundness of the repair part compared to before repair.

A seventh embodiment is different from the first to sixth embodiments in that the long-term soundness of the repaired part is improved by improving the environmental atmosphere with which the repaired part comes into contact, as compared with before the repaired part. This is a characteristic repair method.

The eighth embodiment is a method of repairing material deformation characterized by applying the first to seventh embodiments to the shaping of a deformed structural member.

[0029]

As described in detail above, according to the present invention,
Defects occurred structural member has been difficult conventionally, even while remaining particularly narrow defects generated in the structural member of the installed complex shape in space part, and the defect that left the structural member
The contact with the environmental atmosphere can be cut off. others
Because repair unit odor Te, repair can be secured tightly sealed and long-term health, there is Shimuru effect if possible.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a structural member schematically showing a target portion of a repair method according to a first embodiment of the present invention, and FIG.
FIG. 1 is a cross-sectional view of a structural member schematically showing a portion to be subjected to a repair work method according to a first embodiment of the present invention after build-up welding.

FIG. 2 is a flowchart showing a construction procedure of a repair method according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a structural member schematically showing a construction portion of a repair method according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing a construction procedure of a repair method according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a structural member schematically showing a construction part of a repair method according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Structural member, 2 ... Penetration defect, 3 ... Non-penetration defect, 4 ... Thickness equivalent to the thickness of a structural member, 5 ... Length of non-penetration defect, 6 ... Defect generation surface, 7 ... Cutting Thereafter, a welded portion, 8: a defect removed by repair, 9: a defect erased portion near the surface, 10: a residual defect, and 11: a molten surface portion.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yasukata Tamai 3-1-1 Sachimachi, Hitachi-City, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Meijisuke Naruse 3-1-1 Sachimachi, Hitachi-City, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (72) Inventor Hideyasu Furukawa 3-1-1 Kochicho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi Plant (72) Inventor Koichi Kurosawa Koichisan, Hitachi City, Ibaraki Prefecture Hitachi 1-1, Hitachi, Ltd. (72) Inventor Eisaku Hayashi 3-1-1, Saimachi, Hitachi, Hitachi, Ibaraki Pref. Hitachi, Ltd. Hitachi, Ltd. (72) Inventor Shigeo Hattori Hitachi, Ibaraki, Japan 3-1-1, Sachimachi Hitachi, Ltd. Hitachi Plant (72) Inventor Takenori Shindo 6-9 Takaracho, Kure City, Hiroshima Pref. The company Kure Plant (56) Reference Patent flat 1-48695 (JP, A) (58 ) investigated the field (Int.Cl. ^6, DB name) E04G 23/02 B23K 9/04 B23K 31/00 B23P 6 / 04 G21C 19/02

Claims (6)

(57) [Claims] 1. The structural strength of a structure generated in a structural member is reduced.
Deterioration or potential defect
Combine with cutting, surface melting and overlay as needed
Repairs can be carried out from both or one side of the structural member.
And the defects in the structural members
Repairing method of Structures characterized Rukoto shim not block contact. 2. The structural strength of a structure generated in a structural member is determined.
Deterioration or potential defect
By cutting from one or both sides of the structural member
Te, repairing method of Structures characterized that you reduce or eliminate the defects generated in the structural member. 3. The method according to claim 1, wherein
To use repair materials with high resistance to deterioration.
Therefore, the generation of new defects or the growth of defects is prevented.
Repair method of the structure, which was characterized by non-Rukoto. 4. The method according to any one of claims 1, 2 and 3,
There are, repairing method of Structures characterized that you applying a surface treatment to the repaired portion. 5. A method according to claim 1, wherein the first, second, third, and fourth aspects of the present invention are arranged in the same manner as in the first aspect.
In repair method of Structures characterized that you improve environmental atmosphere repaired portion are in contact. 6. The method of claim 1, 2, 3, 4, or 5
In one paragraph, repair how structures characterized that you applied to shaping of the deformed member.