JP6386878B2 - Welding method - Google Patents

Description

  The present invention relates to a welding method.

  For example, a nuclear power plant equipped with a pressurized water reactor (PWR) uses light water as a primary cooling water as a reactor coolant and a neutron moderator to produce high-temperature and high-pressure water that does not boil over the entire core. High-temperature high-pressure water is sent to a steam generator to generate steam by heat exchange, and this steam is sent to a turbine generator to generate electricity.

  Such a nuclear power plant has a part which is connected by welding. If tensile stress remains in the vicinity of the weld, it may cause problems such as stress corrosion cracking.

  As a method for suppressing the residual tensile stress in the vicinity of the welded portion, for example, in Patent Document 1, the surface of the reactor internal structure or the surface of the welded portion of the structure is subjected to polishing finish to compressive stress. A method of forming is described.

  Further, as surface processing, Patent Document 2 discloses a pretreatment process for reducing the rigidity of the tip of a buff feather having a plurality of radially provided buff feathers and a buff subjected to the pretreatment process. A polishing method comprising a polishing step for polishing the surface of a workpiece is described.

JP 08-174422 A JP 2012-148377 A

  Here, in Patent Document 1, compressive stress is formed by performing polishing, but tensile stress may be generated by polishing depending on the conditions of the polishing process. If a portion where tensile stress is generated remains, stress corrosion cracking will occur. Moreover, if the range which grind | polishes is wide, a process will take time.

  This invention solves the subject mentioned above, and it aims at providing the welding method which can suppress more reliably the stress corrosion crack of the range including a welding part.

  In order to achieve the above-described object, the welding method of the present invention determines whether or not the welding step for performing welding and the machining around the welded portion are performed, and when machining is performed, Within a range where machining around the welded portion formed in the welding step is performed, and within a range of 20 mm or more from the welded portion, or within a range where machining around the welded portion is performed If there is a curved surface, the range from the welded portion to the curved surface is set as the buffing range, and not the range where the machining around the welded portion formed in the welding step is performed, but in the finishing process other than the welded portion When the range is processed, a buffing range determination step in which the processed range is set as a buffing range, a paint application step for applying paint to the determined buffing range, and buffing until the applied paint can be removed. A buffing step for machining, characterized by having a.

  In order to achieve the above-described object, the welding method of the present invention includes a machining step for machining the vicinity of a welding surface, a welding step for performing welding, and machining around a welded portion formed in the welding step. A paint application step for applying a paint within a range of 20 mm or more from the weld and a buffing step for buffing until the applied paint can be removed. .

  Moreover, it is preferable that the said coating-coating step applies a coating in the range within 30 mm from the said welding part.

  Further, in the paint application step, it is preferable that the paint is applied between the welded portion and the curved surface when the curved surface is within 20 mm of the range where machining around the welded portion is performed.

  Moreover, it is preferable to further have the finishing process step which shape | molds the surface of the said welding part.

  In order to achieve the above object, the welding method of the present invention includes a welding step for performing welding, a finishing step for forming the surface of the welded portion, and a range other than the welded portion is processed in the finishing step. In this case, it is characterized by having a paint application step for applying the paint to the processed area and a buffing step for performing buffing until the applied paint can be removed.

  ADVANTAGE OF THE INVENTION According to this invention, the welding method which can suppress more reliably the stress corrosion crack of the range including a welding part can be provided.

FIG. 1 is a schematic configuration diagram of an example of a nuclear power plant. FIG. 2 is a cross-sectional view showing a weld in a nuclear power plant. FIG. 3 is a block diagram showing a schematic configuration of the welding system according to the embodiment of the present invention. FIG. 4 is a flowchart showing an example of processing operation of the welding system according to the embodiment of the present invention. FIG. 5 is a schematic diagram illustrating an example of a welded portion. FIG. 6 is a schematic diagram illustrating an example of a welded portion. FIG. 7 is a schematic diagram illustrating an example of a welded portion. FIG. 8 is an explanatory diagram for explaining the processing operation of the welding system. FIG. 9 is an explanatory diagram showing an example of the stress distribution. FIG. 10 is a flowchart showing an example of the processing operation of the welding system. FIG. 11 is a flowchart illustrating an example of the processing operation of the welding system.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same. For example, although this embodiment demonstrates as a welding part which connects each part of a nuclear power plant, and the welding method of this welding part, the member of the object to weld is not limited to a nuclear power plant.

  FIG. 1 is a schematic configuration diagram of an example of a nuclear power plant. The nuclear power plant shown in FIG. 1 has a pressurized water reactor (PWR: Pressurized Water Reactor). In this nuclear power plant, in a reactor containment vessel 100, a reactor vessel 101 of a pressurized water reactor, a pressurizer 102, a steam generator 103 and a primary cooling water pump 104 are sequentially connected by a primary cooling water pipe 105, A circulation path of primary cooling water is configured.

  The reactor vessel 101 stores the fuel assembly 120 in a sealed state. The reactor vessel 101 includes a reactor vessel main body 101a and a reactor vessel lid 101b mounted on the upper portion thereof so that the fuel assembly 120 can be inserted and removed. It is configured. The reactor vessel main body 101a is provided with an inlet-side nozzle 101c and an outlet-side nozzle 101d for supplying and discharging light water as primary cooling water in the upper part. A primary cooling water pipe 105 is connected to the outlet side nozzle 101 d so as to communicate with the inlet side water chamber 103 a of the steam generator 103. The inlet side nozzle 101c is connected to the primary cooling water pipe 105 so as to communicate with the outlet side water chamber 103b of the steam generator 103.

  The steam generator 103 is provided with an inlet-side water chamber 103a and an outlet-side water chamber 103b partitioned by a partition plate 103c in a lower part formed in a hemispherical shape. The inlet side water chamber 103a and the outlet side water chamber 103b are separated from the upper side of the steam generator 103 by a tube plate 103d provided on the ceiling portion. On the upper side of the steam generator 103, an inverted U-shaped heat transfer tube 103e is provided. The end portion of the heat transfer tube 103e is supported by the tube plate 103d so as to connect the inlet side water chamber 103a and the outlet side water chamber 103b. The inlet-side nozzle of the inlet-side water chamber 103a is connected to the inlet-side primary cooling water pipe 105, and the outlet-side nozzle of the outlet-side water chamber 103b is connected to the outlet-side primary cooling water pipe 105. In addition, the steam generator 103 is connected to the upper side upper end partitioned by the tube plate 103d, the outlet side secondary cooling water pipe 106a, and the upper side part is connected to the inlet side secondary cooling water pipe 106b. Has been.

  Further, in the nuclear power plant, the steam generator 103 is connected to the steam turbine 107 via the secondary cooling water pipes 106a and 106b outside the reactor containment vessel 100, and the circulation path of the secondary cooling water is configured. .

  The steam turbine 107 includes a high-pressure turbine 108 and a low-pressure turbine 109, and a generator 110 is connected to the steam turbine 107. In addition, the high-pressure turbine 108 and the low-pressure turbine 109 are connected to a moisture separation heater 111 that is branched from the secondary cooling water pipe 106a. The low pressure turbine 109 is connected to the condenser 112. The condenser 112 is connected to the secondary cooling water pipe 106b. The secondary cooling water pipe 106b is connected to the steam generator 103 as described above, and reaches from the condenser 112 to the steam generator 103, and the condensate pump 113, the low-pressure feed water heater 114, the deaerator 115, and the main feed water pump. 116, and a high-pressure feed water heater 117 are provided.

  FIG. 2 is a cross-sectional view showing a weld in a nuclear power plant. In the pressurized water reactor of a nuclear power plant, the steam generator 103 has a primary cooling water pipe 105 connected to an inlet side nozzle of the inlet side water chamber 103a and an outlet side nozzle of the outlet side water chamber 103b. The inlet side nozzle and outlet side nozzle and the primary cooling water pipe 105 are connected by welding. For this reason, a welded portion 30 is formed at a joint portion between the inlet side nozzle and the outlet side nozzle and the primary cooling water pipe 105. Further, buffing ranges 32 and 34 are formed in the vicinity of the welded portion 30. The welded portion 30 and the buffing ranges 32 and 34 will be described later.

  Further, in the nuclear power plant, a safe end pipe is provided between the inlet side nozzle and the outlet side nozzle, and the primary cooling water pipe 105, and the inlet side nozzle, the outlet side nozzle, and the safe end pipe are welded. The primary cooling water pipe 105 and the safe end pipe may be welded.

  In the nuclear reactor plant 101, a primary cooling water pipe 105 is connected to an inlet side nozzle 101c and an outlet side nozzle 101d. The inlet side nozzle 101c and outlet side nozzle 101d are connected to the primary cooling water pipe 105 by welding. For this reason, welds are also formed at the joints between the inlet-side nozzle 101 c and the outlet-side nozzle 101 d and the primary cooling water pipe 105. Further, the inlet-side nozzle 101c, the outlet-side nozzle 101d, and the primary cooling water pipe 105 are provided with a safe-end pipe therebetween, and the inlet-side nozzle 101c, the outlet-side nozzle 101d, and the safe-end pipe are welded. Then, the primary cooling water pipe 105 and the safe end pipe may be welded. Thus, in the nuclear power plant, various members are joined together by welding, and a welded portion is formed.

  Next, a method for forming a welded portion, that is, a welding method will be described with reference to FIGS. FIG. 3 is a block diagram showing a schematic configuration of the welding system according to the embodiment of the present invention.

  As shown in FIG. 3, the welding system 10 includes a machining device 12, a welding device 14, a finishing device 16, a paint application device 18, and a buffing device 20. In addition, the welding system 10 is an example, what is necessary is just to have the welding apparatus 14, the coating material coating apparatus 18, and the buff processing apparatus 20, and has the machining apparatus 12 and the finishing apparatus 16. It does not have to be. Each unit may be operated by an operator or may operate automatically.

  The machining apparatus 12 is an apparatus that cuts and polishes the vicinity of a welding end surface of a member to be welded (a surface facing the other member to be welded). The machining device 12 performs a process of forming a groove near the weld end face and a process of adjusting the thickness of the weld end face. As the machining device 12, various machining devices can be used.

  The welding device 14 is a device for welding the weld end face. As the welding device 14, an arc welding device that melts a filler metal and performs welding can be used. The arc welding equipment includes various equipment with different welding methods and heating sources, such as TIG (Tungsten Inert Gas) welding, plasma welding, etc., covered arc welding, submerged arc welding, MIG welding, carbon dioxide arc welding, self Various apparatuses of a welding method in which a filler material such as shield arc welding and a heating source are integrated can be used. Further, as the welding apparatus 14, a high-density energy welding apparatus that irradiates a high-density energy beam and melts and joins the objects to be welded can be used without using a filler material. As the high-density energy welding apparatus, an apparatus that performs welding by spraying a high-energy beam such as electron beam welding (EBW) or laser beam welding (LBW) can be used.

  The finishing device 16 is a device that forms the welded portion by processing the surface of the welded portion. As the finishing device 16, a grinder can be used.

  The paint coating device 18 is a device that applies paint to a range including the periphery of the welded portion. As the paint, various paints that can be applied to a member to be welded, such as a paint used for scoring, can be used. Various coating mechanisms such as sprays and brushes can be used as the paint coating device 18.

  The buffing device 20 is a device that performs buffing around the welded portion. The buff processing device 20 has a plurality of radially provided buff wings, and is a device that processes the target range by contacting the target range while rotating the buff wings. Here, as the buff feather, for example, a buff feather of # 60, Φ150 × 30 can be used. Here, the hub processing apparatus 20 performs polishing along the extending direction of the welded portion (longitudinal direction of the bead). That is, the buff processing apparatus 20 moves the buff feather in the extending direction of the welded portion. The buffing device 20 can relieve the tensile stress around the welded part by moving the buffing blade in the extending direction of the welded part.

  Next, an example of the welding process will be described with reference to FIGS. FIG. 4 is a flowchart showing an example of processing operation of the welding system according to the embodiment of the present invention. FIG. 5 to FIG. 7 are schematic diagrams each showing an example of a welded portion. FIG. 8 is an explanatory diagram for explaining the processing operation of the welding system. FIG. 9 is an explanatory diagram showing an example of the stress distribution.

  First, an example of processing will be described with reference to FIG. In the process shown in FIG. 4, each process 14 is executed by the welding system 10. In the welding method, first, a welded portion is formed (step S11). That is, welding is performed by a welding apparatus. Further, the welding method may be a case where machining is performed before welding or a case where finishing is performed after welding.

  In the welding method, when welding is performed, it is determined whether there is a machined portion (step S12). The machined part is a part processed (for example, polished or cut) by the machining device 12. In the welding method, it is determined whether the machined portion is in a range including a weld end including a range exposed on the surface even after the weld is formed.

  When it is determined that there is a machined portion (Yes in step S12), the welding method determines whether there is a curved surface within 20 mm from the weld line (step S14). When it is determined that the welding method has no curved surface within 20 mm from the weld line (No in step S14), that is, the flat surface continues from the welded portion by 20 mm or more, the range of 20 mm or more from the weld end surface is set as the buffing range. (Step S16). That is, as shown in FIG. 5, when the machined portion 46 is on the end surface of the welded portion 44 side of the first member 40 and the second member 42 that are members to be welded, the distance D from the end portion of the welded portion 44. Is set as the buffing range. Here, the distance D is in a range of 20 mm or more. The distance D is preferably 20 mm or more and 30 mm or less. Here, the range of the distance D corresponds to the buffing ranges 32 and 34.

  When it is determined that the welding method has a curved surface within 20 mm from the weld line (Yes in step S14), the range from the welding end surface to the curved surface is set as the buffing range (step S18). That is, the range from the weld end surface to the start point of the curved surface is set as the buffing range. That is, as shown in FIG. 6, the first member 40a and the second member 42a, which are members to be welded, are joined by the welded portion 44a, and the vicinity of the welded portion 44a of the first member 40a (within 20 mm from the welded portion 44a). ), The range of the distance Da is set as the buffing range. The range of the distance Da is a range from the weld end surface to the start point of the curved surface. In the above embodiment, the vicinity of the welded portion 44a is taken as an example within a range of 20 mm from the welded portion 44a. However, the present invention is not limited to this. It is good also considering the vicinity of the welding part 44a as the range within 30 mm from the welding part 44a.

  Moreover, when it determines with a welding method not having a machining part (it is No at step S12), it is determined whether there exists the range which the processing tool contacted (step S20). That is, it is determined whether the finishing process is performed by the finishing apparatus 16 and the processing tool has come into contact with a place other than the weld. Here, you may make it determine whether the welding method contacted within 30 mm from the welding line. In other words, the welding method may set a range for determining whether or not the processing tool has come into contact.

  When it is determined that the processing tool is in contact with the welding method (Yes in step S20), the contact range is set to the buffing range (step S22). That is, as shown in FIG. 7, the first member 40b and the second member 42b, which are members to be welded, are joined at the welded portion 44b, and the machining tool comes into contact in the vicinity of the welded portion 44a of the first member 40b. When the ranges 60 and 62 are present, the range of the distances Db and Dc where the ranges 60 and 62 are formed is set as the buffing range.

  When it is determined that the processing tool is not in contact (No in step S20), the welding method determines that there is no buffing (step S24). That is, it is determined that machining is not performed by the buffing apparatus 20.

  In the welding method, after setting the buffing range in step S16, step S18 or step S22, the paint is applied to the set buffing range (step S26). That is, the paint is applied to the range where the buffing is performed using the paint application device 18. Further, in the welding method, when it is determined in step S24 that there is no buffing, the paint is not applied.

  In the welding method, when a paint is applied, buffing is performed until the paint is removed (step S28). For example, as shown in FIG. 8, the paint 80 applied to the surface of the second member 42 is processed (polished) by the buffing apparatus 20.

  In the welding method, a range where buffing is performed is set, a coating is applied to the range, and buffing is performed with the buffing apparatus 20 until the coating can be removed, so that compression stress remains in the target range. It can be.

  Here, in FIG. 9, the vertical axis represents stress, and the horizontal axis represents the distance with the center of the welded portion 44 as the origin. The stress is a positive value for tensile stress and a negative value for compressive stress. FIG. 9 shows an example in which buffing ranges 32 and 34 are formed at both ends of the welded portion 44 as shown in FIG. As shown in FIG. 9, the range of the distance D <b> 1 is a range corresponding to the welded portion 44. The range of the distance D is a range corresponding to the buffing ranges 32 and 34. As shown in FIG. 9, in the range of the distance D, a tensile stress is applied before the buffing is performed, but a compression stress is applied by performing the buffing.

  As described above, the welding method is performed by machining and finishing the vicinity of the welded portions 44, 44a, and 44b, and selectively buffing the region where the tensile stress remains, so that the welded portion 44, It can suppress that a tensile stress remains in the vicinity of 44a and 44b. Moreover, the welding method can buff the target region without omission by performing buffing after applying the paint. Thereby, it can suppress that a tensile stress remains. In addition, since it can be determined whether the buffing process has been completed in the area because the paint has disappeared, it is possible to suppress an excessive increase in the force acting on the target area in the buffing process. Thereby, it can suppress that a tensile stress remains by buffing.

  As described above, the welding method can accurately perform buffing on a region where tensile stress remains, and can suppress the remaining tensile stress due to buffing. Thereby, the stress corrosion cracking of the range including a weld part can be suppressed more reliably.

  Here, the welding method performs polishing by the hub processing device 20 along the extending direction of the welded portion (longitudinal direction of the bead). That is, the buffing blade of the buffing device 20 is moved in the extending direction of the weld. The processing apparatus 20 can relieve the tensile stress around the welded portion by moving the buff feather in the extending direction of the welded portion.

  Next, an example of welding processing when machining is performed will be described with reference to FIG. FIG. 10 is a flowchart showing an example of the processing operation of the welding system. The process shown in FIG. 10 is performed using each part of the welding system 10.

  In the welding method, a range including the weld end is machined (step S42). In the welding method, after machining, a weld is formed (step S44). That is, welding is performed by the welding device 14. In the welding method, when welding is performed, the finishing process of the welded portion is performed (step S46). That is, the surface of the welded portion is processed and molded using the finishing device 16. The processing in FIG. 10 may not be finished.

  In the welding method, after finishing, it is determined whether there is a curved surface within 20 mm from the weld line (step S48). That is, the range of buffing is determined based on the shape of the member to be welded.

  In the welding method, when it is determined that there is no curved surface within 20 mm from the weld line (No in step S48), that is, the flat surface continues from the welded portion by 20 mm or more, the paint is applied to a range of 20 mm or more from the weld end surface (step) S50). That is, the coating material is applied in a range of 20 mm or more from the weld end surface using the coating material application device 18.

  In the welding method, when it is determined that there is a curved surface within 20 mm from the weld line (Yes in step S48), the paint is applied in a range from the weld end surface to the curved surface (step S52). That is, the paint is applied to the range from the weld end surface to the start point of the curved surface using the paint application device 18.

  In the welding method, when the paint is applied in step S50 or step S52, buffing is performed until the paint is removed (step S54).

  In this way, when machining is performed, the paint is applied to a range of 20 mm or more from the welded portion, and buffing is performed until the applied paint can be removed, so that the region where tensile stress remains is applied. Thus, buffing can be performed accurately, and the residual tensile stress due to the buffing can be suppressed. Thereby, the stress corrosion cracking of the range including a weld part can be suppressed more reliably.

  Also, as shown in FIG. 10, when the curved surface is in the vicinity, by applying the paint from the weld to the starting point of the curved surface and buffing until the applied paint can be removed, the tensile stress remains. It is possible to accurately perform buffing on a certain region, and to suppress a residual tensile stress due to buffing. Moreover, the area | region which performs buffing can be reduced by not buffing a curved surface. Here, the curved surface is less susceptible to stress corrosion cracking due to tensile stress. Thereby, the stress corrosion cracking of the range including a weld part can be suppressed more reliably.

  Next, an example of a welding process when machining is not performed will be described with reference to FIG. FIG. 11 is a flowchart illustrating an example of the processing operation of the welding system. The process shown in FIG. 11 is performed using each part of the welding system 10.

  A welding method forms a welding part (step S60). As for the welding method, when welding is performed, finishing of the welded portion is performed (step S62). In the welding method, after finishing, it is determined whether or not there is a range in which the processing tool is in contact (step S64). That is, it is determined whether the processing tool of the finishing device 16 has come into contact with a place other than the welded portion.

  When it is determined that the processing tool is not in contact with the welding method (No in step S64), the present process is terminated. That is, no processing is performed by the buff processing apparatus 20.

  In the welding method, when it is determined that the processing tool is in contact (Yes in step S64), the paint is applied to the contact range (step S66). That is, the paint is applied to the area where the tool is in contact with the paint application device 18.

  In the welding method, when the paint is applied in step S66, buffing is performed until the paint is removed (step S68).

  In this way, when machining is not performed and finishing is performed, paint is applied to the area where the tool contacts in finishing, and buffing is performed until the applied paint can be removed. It is possible to accurately perform the buffing on the region where the tensile stress remains, and to suppress the tensile stress from remaining due to the buffing. Moreover, it can suppress performing a buff process on the unnecessary part. Thereby, the stress corrosion cracking of the range including a weld part can be suppressed more reliably.

  Moreover, the welding method may determine the range determined to perform the above-described buffing based on a plurality of criteria. For example, when there is a range where machining is performed around one weld and a range where machining is not performed but a finishing tool is in contact, it is preferable to buff both ranges. Thereby, it can suppress more reliably that tensile stress remains in the vicinity of a welding part.

DESCRIPTION OF SYMBOLS 10 Welding system 12 Machining device 14 Welding device 16 Finishing device 18 Paint coating device 20 Buffing device 30 Welding part 32, 34 Buffing range

Claims (6)

A welding step for performing welding;
It is determined whether the machining around the welded portion is performed, and when machining is performed, the machining is performed around the welded portion formed in the welding step, and When there is a curved surface within a range of 20 mm or more from the welded portion, or 20 mm of the range where machining around the welded portion is performed, a range between the welded portion and the curved surface is defined as a buffing range, Buffing range determination step in which, when the range other than the welded portion is processed by finishing, not the range where machining around the welded portion formed in the welding step is performed, the processed range is set as the buffing range When,
A paint application step for applying paint to the determined buffing range;
And a buffing step of buffing until the applied paint can be removed. Machining steps for machining the vicinity of the welding surface;
A welding step for performing welding;
A paint application step for applying a paint to a range of 20 mm or more from the welded part, in a range where machining around the welded part formed in the welding step is performed;
And a buffing step of buffing until the applied paint can be removed.   The welding method according to claim 2, wherein in the paint application step, the paint is applied in a range within 30 mm from the welded portion.   3. The paint application step, in the case where there is a curved surface within 20 mm of a range where machining around the welded portion is performed, the paint is applied between the welded portion and the curved surface. 3. The welding method according to 3.   The welding method according to any one of claims 2 to 4, further comprising a finishing step of forming a surface of the welded portion. A welding step for performing welding;
A finishing step for shaping the surface of the weld,
When a range other than the welded portion is processed in the finishing step, a paint application step of applying a paint to the processed range;
And a buffing step of buffing until the applied paint can be removed.

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