JPH02235594A - Repairing method for piping for passing through container - Google Patents

Abstract

PURPOSE:To simply repair a defective part by cutting the lower part of a weld zone by leaving a defective part of a piping, bringing the residual part to tube expansion, and also, fitting in a metallic sleeve and welding it, when a defect such as a crack, etc., is generated on a container wall and a piping wall being near the weld zone of the piping for passing through this container wall. CONSTITUTION:A through-hole 2 of a piping 3 is provided on a wall 1 of a metallic container, and by inserting the metallic piping 3 into its hole, the container 1 and the piping 3 are welded and fixed by weld zone 4. In the case when a defect X such as a crack, etc., is generated in the piping 3 in the vicinity of this weld zone 4, a liquid in the container 1 passes through the crack X and leaks out to the lower mirror part 5. In this case, by cutting the piping 3 in a position of the lower part Y-Y' of the defective part X, the lower part is eliminated. Subsequently, by bringing the inside diameter of the upper part which remains behind to enlargement working, an enlarged inner wall 3b is formed, and in the lower cut part, a fitting and supporting part 7 is formed, and also, a metallic sleeve 8 engaged thereto is inserted, a thin diameter part 8a of its tip and the enlarged inner wall part 3b of the residual piping 3 are brought to seal welding 10, and moreover, the lower part is brought to tube expansion 9 up to the inner wall of the through-hole 2, by which it is prevented that a liquid in the container 1 leaks out of the defective part X.

Description

[Detailed Description of the Invention] [Industrial Field of Application J] The present invention relates to a method for repairing a pipe penetrating a container, and in particular, to a method for repairing a pipe penetrating hole when a defect occurs near a welded part.
The present invention relates to a repair method useful when carrying out the repair.

"Conventional technology" Nuclear power generation related plants, various energy related plants,
BACKGROUND OF THE INVENTION In chemical plants, thermal power plants, and the like, piping that penetrates a container, that is, a container penetrating pipe is used.

For example, as shown in Fig. 2, the reactor pressure vessel in a boiling water reactor has a vessel penetration W ( The vessel penetrating pipe 3 is attached by a welding hole 4 between the upper edge of the pipe penetrating hole 2, and various sensors for detecting the state of the reactor are installed. It performs signal transmission, etc.

Since such a container penetrating pipe 3 is attached to a container wall I having excellent mechanical strength, the effect of deformation force due to expansion/contraction or bending of the container penetrating pipe 3 is likely to appear on the piping wall or the welding hole 4. It is required to ensure sufficient reliability, and it is desirable to inspect the condition of the pipe wall at or near the welding hole 4 during periodic inspections.

On the other hand, as shown in Fig. 3, if a defect such as a crack has occurred in the pipe wall near the bottom of the welding hole 4, the fluid in the container will pass through the defective portion X to the lower mirror annulus. In this case, repair methods such as disassembling the welded N4 part and installing new piping by re-welding have been considered.

``Problems to be Solved by the Invention'' However, such a repair method is very large-scale, and if the vessel penetration pipe 3 to be repaired is the reactor pressure vessel mentioned above, it may cause damage to the reactor. After the start of operation, it is necessary to adequately manage the radiation exposure of repair workers.

Therefore, for example, it would be advantageous to be able to carry out defective repair work from inside the container penetrating pipe 3 without dismantling the welded portion 4, but the technique for doing so has not yet been established.

The present invention has been made in view of the above circumstances. (1) To repair a defective part without disassembling the welded part to which the container penetrating pipe is attached.

(11) To suppress the occurrence of new defects after repair work.

The purpose is to

[Means for solving the problem] The present invention proposes two means, and the first means is:
The step of cutting the container penetrating tube at a position spaced toward A direction of the welding hole where the container penetrating tube is attached and removing the cut portion, and removing the remaining tube near the opening including the defective part of the container penetrating tube. a step of enlarging the hole; a step of forming a fitting support on the inner surface of the piping penetration hole spaced outward from the cut portion; and a step of forming a fitting support to be engaged and supported by the fitting support. A step of inserting the tip of the metal sleeve having a section into the enlarged part of the tube hole, a step of bringing the supported part of the metal sleeve into an engaged and supported state with the fitting support part, and a step of inserting the tip of the metal sleeve and the container through the container. This is a method for repairing vessel penetrating piping, which combines the process of welding the inner and outer parts of the pipe.

Further, the second means includes, during the process in the first means, bringing the supported portion of the metal sleeve into an engaged and supported state with the fitting support, and expanding the wall of the metal sleeve to connect the expanded portion to the pipe. This is a method for repairing a container penetrating pipe which additionally includes a step of seal welding between the tip of the metal sleeve and the inner surface of the container penetrating pipe after the metal sleeve is brought into pressure contact with the inner wall of the penetrating hole.

"Operation" In the first means, a new metal sleeve is inserted into the pipe penetration hole, and the supported part is engaged with the fitting support part to be in a supported state, thereby preventing the metal sleeve from coming off. Let it be done. In addition, if the inside of the defective part is covered with a metal sleeve and the tip of the metal sleeve and the inner surface of the container penetrating tube are knoll welded in this state, the space between the inside of the container penetrating tube and the outside thereof will be closed. Repairs can be made without dismantling the original weld.

In addition, in the second step, when expanding the metal sleeve by plastically deforming the pipe wall of the metal sleeve in the outward radial direction with the supported part of the metal sleeve being engaged and supported by the fitting support ring, the metal The pipe wall of the sleeve and the inner surface of the pipe penetration hole come into pressure contact, creating a seal in this area and preventing the metal sleeve from slipping.

Therefore, in addition to the engagement support between the supported part and the fitting support part, the metal sleeve is also supported in the pipe expansion part, and the metal sleeve is slightly moved in the insertion direction before pipe expansion, and the supported part If the tube is expanded with the engagement and support between the tube and the fitting support loosened, this will reduce the application of external force to the seal weld formed after the tube expansion, and will also reduce thermal displacement in the metal sleeve outside the expanded portion. This allows for minute movement of the parts, thereby suppressing the occurrence of new defects after repair work. Even in this case, movement of the metal sleeve that is larger than thermal displacement or the like is restrained by the supported portion being engaged and supported by the fitting support.

``Example J'' Figures 1(A) to 1(C) illustrate the method for repairing vessel penetrating piping according to the present invention on vessel wall l in the reactor pressure vessel shown in Figures 2 and 3. An example of application to a container penetrating pipe 3 is shown.

The steps will be explained below in order.

[Closing process of existing piping] As shown in Fig. 1 (A), a pipe penetration hole 2 is made in the container wall (mainly made of low-alloy steel, for example).
A closure plug 6 is installed in the tube hole 3a of the container penetrating tube (for example, piping made of SUS304) 3 passing through the container to divide it into upper and lower sections. In this case, reactor cooling water is kept inside the reactor pressure vessel, and after the plug 6 is installed, it is filled with water to reduce the radiation exposure of the workers while working. (The same applies to each of the following tasks).

[Cutting process of container penetrating pipe] As shown in FIG.
A position Y-Y' spaced outward (downward) from the
The container penetrating pipe 3 is cut and the cut outer portion is removed.

[Pipe hole enlargement process] Insert a suitable tool or grinding tool into the pipe hole 3a of the container penetrating pipe 3 left by the above-mentioned cutting to enlarge the pipe wall including the defective part X of the container penetrating pipe 3. For example, the tube hole 3a is cut or ground by about half, and the tube hole 3a is enlarged to form an enlarged hole 3b, as shown in FIG. 1(B).

[Fitting support part formation step J: Cut or grind the inner surface of the pipe penetration hole 2 in the container wall 1 at a position spaced outward (downward) from the prescribed cutting position Y-Y' with an appropriate tool. Then, Figure 1 (B)
As shown in FIG. 2, a fitting support 7 is formed. The fitting support portion 7 is, for example, an annular groove 7 in which the pipe penetration hole 2 is expanded.
a, a spline groove 7b whose maximum diameter matches the bottom of the annular '7rIi7a, and a groove 7c.

``Formation of a new metal sleeve'' As shown in the combined state shown in FIG. The metal sleeve 8 has a thin diameter portion 8a formed at its tip portion to be inserted into the enlarged portion 3b of the through tube 3, and a supported portion on the surface spaced outward from the narrow diameter portion 8a. 8b is formed, and the support part 8b is
The size is such that it can be rotated by the groove engaged with the annular groove 7a, and it has a tooth-shaped spline protrusion so that the spline WII 7b can be moved in the vertical direction. A straight pipe portion is left between the tube 8a and the supported portion 8b for pipe expansion, which will be described later.

Note that SOS316 or the like is selected as the material of the new metal sleeve 8.

[Metal Sleeve Insertion and Engagement Support Step] While aligning the supported portion 8b of the metal sleeve 8 with the spline groove 7b of the fitting support portion 7, the metal sleeve 8 is inserted into the annular groove 7a. Insert the tip of the tube 8a into the enlarged tube 3b of the container penetrating tube 3, and with the supported portion 8b engaged with the annular groove 7a, rotate the metal sleeve 8 slightly to remove the support. The lower surface of the connector 8b is hooked onto the connector 7C of the fitting support connector 7. This supported state prevents the metal sleeve 8 from coming off.

"Pipe expansion process" By inserting appropriate equipment into the metal sleeve 8, etc., the pipe wall is plastically expanded in the radial direction as shown by the arrows in Fig. 1 (C) by the roll method or local internal pressure loading method. The tube is expanded by expanding with deformation.

This pipe expansion range is applied to the straight pipe portion described above, and the wall of the pipe expansion portion 9 is brought into pressure contact with the inner wall of the pipe penetration hole 2.

By forming such an expanded pipe portion 9, the metal sleeve 8 and the inner surface of the pipe penetration hole 2 are brought into pressure contact.
In addition to providing sealing properties in this part, the metal sleeve 8
This prevents it from slipping. Therefore, before carrying out the pipe expansion process, the metal sleeve 8 is slightly moved upward by an amount "r" of the engaging portion between the annular groove 7a and the supported part 8b (for example, a minute gap of Iffia+ or less). If the tube is expanded with the engagement support loosened, it is possible to reduce the application of external force to the seal weld 10 formed in the next step.

[Seal welding process] With the metal sleeve 8 fixed by the widened W portion 9, weld between the tip of the narrow diameter tube 8a and the inner surface of the container penetrating pipe 3 using, for example, a T■G torch. By performing seal welding in a non-filler state, the seal welded portion 10 is
is formed to close the space between the inside of the container penetrating tube 3 and the lower mirror annulus portion 5 outside thereof.

"Condition after metal sleeve installation" As shown in Figure 1 (C), the defect X near the bottom of the welded part 4 is partially left on the wall of the container penetrating pipe 3 from the beginning. Thin diameter 8 with a new metal sleeve 8 on the inside
Since the seal weld lO performs sealing in the inside and outside directions by being covered with There will be no leakage.

On the other hand, the support for the container penetration pipe 3 installed from the beginning is as follows.
The new metal sleeve 8 is mainly supported by the welding part 4, and the support of the new metal sleeve 8 is mainly performed by the fitting support 7 and the expanded tl part 9. Although a small vertical gap is shown between the supported part 8b and the annular groove 7a, the distance between the welding groove 4 and the fitting support part 7 expands and contracts under the influence of thermal displacement. If vertical movement is allowed and external force is applied, the movement is restrained by the fitting support 7 to avoid affecting the seal welding IO or the thin diameter 8a, etc. Therefore, the generation of new defects is suppressed.

Furthermore, at an appropriate time after seal welding of the new metal sleeve 8, the aforementioned blocking plug 6 is removed.

Other Embodiments> Instead of the embodiments described above, the following configuration can be adopted.

(a) Applicable to repairs of vessel penetration piping other than reactor pressure vessels.

(Portion) Applicable to the repair of parts where flanges are attached by welding around piping.

(c) The spline structure in the fitting support is replaced with a screw mechanism, and a method is adopted in which the metal sleeve is screwed in while rotating. Then, the above-mentioned seal weld is protected by utilizing the axial "side" of the screw-fitting part.

"Effects of the Invention" As explained above, the method for repairing container penetrating piping according to the present invention is as follows: - In order to perform Nlf tlE while leaving the welding hole for attaching the container penetrating pipe as it is, the welded part is dismantled. Compared to the method of replacing the container penetration tube, the effort can be significantly reduced.

■By carrying out repair work while keeping the internal fluid present in the container and isolating it with the remaining container penetration pipe and welded part, it is possible to reduce the influence of the presence of internal fluid on the repair work. can.

■As a result of the above, especially when applied to repair work on vessel penetration pipes in boiling water reactors after the start of operation, repair work can be carried out with reactor cooling water still present in the reactor pressure vessel. By doing so, it is possible to reduce the exposure dose of workers and improve work efficiency.

■By supporting the metal sleeve with the tube expansion tube and the fitting support section, we prevent large forces from thermal displacement and external forces from being applied to the seal weld zone, which protects the seal weld zone and eliminates new defects. can be suppressed from occurring.

It has excellent effects such as:

[Brief explanation of the drawing] Part! Figures (A) to 1 (C) are process explanatory diagrams showing an example in which the method for repairing vessel penetration piping according to the present invention is applied to a vessel penetration pipe of a reactor pressure vessel, and Figure 2 is a boiling water type A front cross-sectional view showing an example of piping that penetrates the lower mirror part in a nuclear reactor,
FIG. 3 is an explanatory diagram of a defective portion in the vicinity of a welded portion of a container penetrating pipe. Container wall (container lower mirror), Piping penetration hole, ... Container penetration pipe (piping), ... Pipe hole, enlarged part, ... Welded part, ... Lower mirror annulus, ... Blocking plug, ... Fitting support part, ... Barb-shaped groove, ... Spline piece, Step part, ... Metal sleeve, 8a ... Narrow diameter part, 8b ... Supported part Part 9...Pipe expansion part, 10...Seal welding part, X...Defect part. New Ishikawajima Harima Heavy Industries Co., Ltd. Figure 1 (A) Figure 1 [Bl Figure 1 (C) Figure 2 - 1π'

Claims (1)

[Claims] 1. A step of cutting the container penetrating tube at a position spaced apart from the welded portion to which the container penetrating tube is attached and removing the cut portion, and a defective portion of the container penetrating tube that remains. forming a fitting support part on the inner surface of the pipe through-hole which is spaced outward from the cut part; a step of inserting a distal end of a metal sleeve having a supported portion to be engaged and supported into the enlarged portion of the pipe hole; a step of bringing the supported portion of the metal sleeve into an engaged and supported state with the fitting support portion; A method for repairing container penetrating piping, comprising the step of seal-welding between the tip of the sleeve and the inner surface of the container penetrating tube. 2. After bringing the supported part of the metal sleeve into an engaged and supported state with the fitting support part, expanding the wall of the metal sleeve and bringing the expanded part into pressure contact with the inner wall of the pipe penetration hole, the tip of the metal sleeve and 2. The method of repairing a container penetrating pipe according to claim 1, further comprising performing seal welding to the inner surface of the container penetrating pipe.