JP2014185805A - Stopper-executed plug for heat exchanger tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of stress corrosion crack.SOLUTION: There is provided a stopper-executed plug 20 for a heat exchanger tube for plugging to close an opening of a heat exchanger tube 5 inserted and fixed into a tube plate 4 in a steam generator, the stopper-executed plug 20 for heat exchanger tube comprises: a plug body 21 that is formed into a cylindrical body 21a having an external diameter which can be inserted into the heat exchanger tube 5, one end of the cylindrical body 21a, which is the tip side to be inserted into the heat exchanger tube 5, being blocked while the other end of the cylindrical body 21a being opened, and the inner diameter of the cylindrical body 21a being formed to become larger from the one end side toward the other end side; and an expansion member 22 that is formed into a bar-shaped body 22a which can be inserted into the interior of the cylindrical body 21a in the plug body 21, the tip side to be inserted into the cylindrical body 21a being formed to have the external diameter larger than the inner diameter brought close to the one end side of the cylindrical body 21a, and expand the external diameter of the cylindrical body 21a when being inserted into the cylindrical body 21a.

Description

  The present invention provides a heat transfer tube plug plug for plugging and closing the heat transfer tube as a heat transfer tube repair, a heat transfer tube plug plug mounting device for mounting the heat transfer tube plug plug on the heat transfer tube, and the The present invention relates to a heat transfer tube plugging method for mounting a heat transfer tube plug on a heat transfer tube and plugging the heat transfer tube.

  For example, a steam generator used in a pressurized water reactor (PWR) is radioactive from the primary side when the side wall of a U-shaped heat transfer tube housed inside it deteriorates beyond the allowable limit. There is a risk of water leaking and entering non-radioactive water on the secondary side. For this reason, it is known that the possibility of the above-mentioned mixing is prevented by closing the end portion of the heat transfer tube which may be deteriorated or deteriorated.

  2. Description of the Related Art Conventionally, for example, a plug (pipe end plug) described in Patent Document 1 has a cylindrical plug body (shell) having a closed end and an open end, and a conical outer surface and is slidably provided in the plug body. And an expansion member. The plug main body is formed of Inconel (registered trademark), and has a conical shape inside. The smaller inner diameter portion is close to the open end, and the larger inner diameter portion is close to the closed end. The expansion member is formed of stainless steel and is captured in the plug body, with a smaller end provided near the open end of the plug body to expand the plug body when moved toward the open end.

JP-A-57-52799

  In the plug plug described in Patent Document 1, the inside of the plug body is conical, and the smaller inner diameter portion is formed close to the open end, and the larger inner diameter portion is formed close to the closed end. An expansion member is disposed. When manufacturing this plug, for example, the inner diameter of the plug body is machined to a constant inner diameter so that the expansion member can be inserted, and the outer diameter on the open end side is gradually increased from the outer diameter on the closed end side. Then, the expansion member is inserted into the plug body, and plastic deformation such as drawing of the open end side of the plug body so that the open end side and the closed end side have the same diameter is performed. An accompanying operation is required. When this plug is attached to the heat transfer tube of the steam generator, the expansion member is moved to the open end side of the plug body with the plug body inserted into the heat transfer tube, and the plug body is plastically deformed to be expanded. Thus, the plug plug described in Patent Document 1 is plastically deformed when the plug body is molded and attached.

  The plastic deformation described above is cold working and has no advantage of temperature change, so that there is an advantage that the working accuracy is high and the strength is increased by work hardening. On the other hand, however, cold working has the disadvantages that residual stress due to plastic deformation is accumulated in the material and stress corrosion cracking susceptibility increases. For this reason, when there is a scratch or the like on the plug body, the development of stress corrosion cracking may occur. In particular, since the inner surface side of the plugging plug is attached to the heat transfer tube in a hollowed form, it is in the environment of the primary system in the steam generator, and therefore, the tendency of stress corrosion cracking tends to occur.

  This invention solves the subject mentioned above, and it aims at providing the plug plug for heat exchanger tubes which can suppress generation | occurrence | production of stress corrosion cracking.

  In order to achieve the above object, the heat transfer tube plug of the first invention is a heat transfer tube plug for plugging and closing the opening of the heat transfer tube inserted and fixed to the tube plate in the steam generator. A cylindrical body having an outer diameter that can be inserted into the heat transfer tube, one end of the cylindrical body on the tip side inserted into the heat transfer tube is closed, and the other end of the cylindrical body is A plug body that is formed open and has an inner diameter that is increased from one end side to the other end side, and a rod-like body that is formed so as to be insertable inside the tubular body in the plug body. The outer diameter of the cylindrical body when the distal end side inserted into the cylindrical body is formed larger than the inner diameter approaching one end side of the cylindrical body and is inserted into the cylindrical body. And an expansion member that expands.

  According to this heat transfer tube plug, the inner diameter of the cylindrical body of the plug body is formed larger from the closed one end to the other open end. For this reason, it is possible to process the inner surface of a cylindrical body by cutting at the time of manufacture of a plug main body, and it does not use the cold work which carries out plastic deformation like the past. The cylindrical body of the plug body is plastically deformed only when the rod-shaped body of the expansion member is press-fitted into the cylindrical body. As a result, since the plastic deformation that causes stress corrosion cracking is not caused in the plug body in a multiple manner, the stress corrosion cracking susceptibility of the plug body can be lowered and the occurrence of stress corrosion cracking can be suppressed.

  In the heat transfer tube plug of the second invention, the plug main body is inclined on the inner surface of the cylindrical body so that the inner diameter increases from one end side to the other end side. The expansion member is formed with an inner taper portion, the proximal end side of the rod-shaped body is formed with an outer diameter larger than the inner diameter of the other end side of the cylindrical body, and the distal end is formed on the outer surface of the rod-shaped body. It is characterized by having an outer taper portion that is inclined so that the outer diameter increases from the side toward the base end side.

  According to the plug for heat transfer tube, when the rod-shaped body is press-fitted into the cylindrical body, the outer tapered portion of the rod-shaped body can be brought into close contact with the inner tapered portion of the tubular body. For this reason, the outer shape of the cylindrical body can be expanded from one end side to the rear end side, and the outer surface of the cylindrical body can be appropriately brought into contact with the inner surface of the heat transfer tube to prevent the plug body from falling off the heat transfer tube. it can. In addition, since the inside of the cylindrical body is closed by bringing the outer tapered portion of the rod-shaped body into close contact with the inner tapered portion of the cylindrical body, the plastically deformed portion is in contact with the primary cooling water in the steam generator. Therefore, it is possible to prevent the plastically deformed portion from being affected by the primary cooling water.

  In the heat transfer tube plug according to the first or second aspect of the present invention, the expansion member is a helical protrusion that protrudes outward from the distal end side to the proximal end side on the outer surface of the rod-shaped body. It is characterized in that a strip is formed.

  According to this heat transfer tube plug, since the expansion member is press-fitted while rotating along the spiral protrusion, the cylindrical body can be expanded uniformly in the circumferential direction, and the outer surface of the cylindrical body Can be appropriately brought into contact with the inner surface of the heat transfer tube to prevent the plug body from falling off the heat transfer tube. Moreover, after the expansion member is press-fitted into the plug body, the spiral protrusion bites into the inner surface of the tubular body, preventing the expansion member from falling off the plug body and preventing the plug body from falling off the heat transfer tube. can do.

  The plug for a heat transfer tube according to a fourth aspect of the present invention is the plug according to any one of the first to third aspects, wherein the plug body is formed on the outer periphery of the other end of the cylindrical body from the outer diameter of the heat transfer tube. Has a flange portion formed to protrude greatly.

  According to the plug for a heat transfer tube, the flange is brought into contact with the opening of the heat transfer tube and the surface of the tube plate. Therefore, when the rod body of the expansion member is press-fitted into the tubular body of the plug body, It is possible to prevent the situation of entering the back of the heat transfer tube and position the plug body.

  The plug for a heat transfer tube according to a fifth aspect of the present invention is the plug according to the fourth aspect, wherein the plug body has an inner diameter equal to or less than an inner diameter of the heat transfer tube on a surface of the flange portion facing the cylindrical body. A groove having a width equal to or larger than the outer diameter is formed.

  According to this heat transfer tube plug, when the flange portion comes into contact with the opening portion of the heat transfer tube and the surface of the tube plate, the contact of the flange portion with the end portion of the heat transfer tube is avoided by the groove. For this reason, when the rod-shaped body of the expansion member is press-fitted into the cylindrical body of the plug main body, it is possible to prevent a situation in which a pressing force is applied to the heat transfer tube and to suppress the influence on the heat transfer tube.

  In the heat transfer tube plug according to a sixth aspect of the present invention, in the first to fifth aspects of the invention, the expansion member projects at a base end of the rod-like body to be larger than an outer diameter of the heat transfer tube. It has the latching | locking part.

  According to the plug for heat transfer tube, the expansion member is press-fitted until the locking portion comes into contact with the flange portion of the plug body and stops. For this reason, it can be confirmed that the rod-like body of the expansion member is press-fitted into the tubular body of the plug main body and the tubular body is reliably expanded.

  According to a seventh aspect of the present invention, in the plug plug for heat transfer tubes according to the sixth aspect, the expansion member has a fitting portion formed in the locking portion.

  According to this plug for heat transfer tubes, the plug body can be removed from the heat transfer tube by forming the fitting portion in the locking portion and pulling out the expansion member from the plug body with a tool attached by the fitting portion. it can.

  The plug for a heat transfer tube according to an eighth aspect of the present invention is the plug according to any one of the first to seventh aspects, wherein the plug body has an uneven portion from one end side to the other end side on the outer surface of the cylindrical body. It is formed.

  According to this plug for heat transfer tubes, when the rod-shaped body is press-fitted into the cylindrical body, the rod-shaped body is expanded outwardly by the rod-shaped body and is pressed against the inner surface of the heat transfer tube. The convex part of the concavo-convex part is crushed by the elastic force of the tube sheet. For this reason, the outer surface of the tubular body of the plug body can be more closely attached to the inner surface of the heat transfer tube, and the opening of the heat transfer tube can be more reliably plugged.

  According to the present invention, the occurrence of stress corrosion cracking can be suppressed.

FIG. 1 is a schematic side sectional view of a steam generator according to an embodiment of the present invention. FIG. 2 is a side sectional view of the plug for heat transfer tubes according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of the expansion member of the plug for a heat transfer tube according to the embodiment of the present invention. FIG. 4 is a cross-sectional view of the expansion member of the plug for a heat transfer tube according to the embodiment of the present invention. FIG. 5 is a side sectional view showing a procedure for attaching the plug for a heat transfer tube according to the embodiment of the present invention. FIG. 6 is a side cross-sectional view showing a procedure for attaching the plug for a heat transfer tube according to the embodiment of the present invention. FIG. 7 is a schematic view showing a manufacturing process of the plug for a heat transfer tube according to the embodiment of the present invention. FIG. 8 is a side sectional view showing another example of the plug for heat transfer tube according to the embodiment of the present invention. FIG. 9 is a side sectional view showing another example of the plug for heat transfer tube according to the embodiment of the present invention. FIG. 10 is a side cross-sectional view showing another example of the plug for a heat transfer tube according to the embodiment of the present invention.

  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.

  FIG. 1 is a schematic side sectional view of a steam generator according to this embodiment. The steam generator 1 is used, for example, in a pressurized water reactor (PWR: Pressurized Water Reactor). The pressurized water reactor uses light water as a reactor coolant and neutron moderator. The pressurized water reactor sends primary cooling water to the steam generator 1 as high-temperature and high-pressure water that does not boil light water over the entire core. In the steam generator 1, the heat of the primary cooling water at high temperature and high pressure is transmitted to the secondary cooling water, and water vapor is generated in the secondary cooling water. Then, the steam generator is rotated by this steam to generate electricity.

  The steam generator 1 has a hollow cylindrical shape that extends in the up-down direction and is hermetically sealed, and has a trunk portion 2 in which the lower half is slightly smaller in diameter than the upper half. The trunk portion 2 is provided with a tube group outer cylinder 3 having a cylindrical shape disposed at a predetermined distance from the inner wall surface of the trunk portion 2 in the lower half portion thereof. The lower end portion of the tube group outer tube 3 extends to the vicinity of the tube plate 4 disposed below in the lower half of the body portion 2. A heat transfer tube group 5A is provided in the tube group outer tube 3. The heat transfer tube group 5A includes a plurality of heat transfer tubes 5 having an inverted U shape. Each heat transfer tube 5 is arranged with the U-shaped arc portion facing upward, the lower end portion is inserted and fixed in the tube hole 4 a of the tube plate 4, and the intermediate portion is interposed through a plurality of tube support plates 6. It is supported by the tube group outer tube 3. A large number of heat transfer tube insertion holes (not shown) are formed in the tube support plate 6, and each heat transfer tube 5 is inserted into the heat transfer tube insertion hole to support each heat transfer tube 5.

  The body 2 is provided with a water chamber 7 at its lower end. The interior of the water chamber 7 is divided into an entrance chamber 7A and an exit chamber 7B by a partition wall 8. One end of each heat transfer tube 5 communicates with the entrance chamber 7A, and the other end of each heat transfer tube 5 communicates with the exit chamber 7B. Further, the entrance chamber 7A is formed with an inlet nozzle 7Aa that communicates with the outside of the body portion 2, and the exit chamber 7B is formed with an exit nozzle 7Ba that communicates with the outside of the body portion 2. The inlet nozzle 7Aa is connected to a cooling water pipe (not shown) through which primary cooling water is sent from the pressurized water reactor, and the outlet nozzle 7Ba sends the primary cooling water after heat exchange to the pressurized water reactor. The cooling water piping (not shown) to send is connected.

  In the upper half of the body portion 2, an air-water separator 9 that separates feed water into steam and hot water, and a moisture separator that removes the moisture of the separated steam and makes it close to dry steam. 10 is provided. Between the steam / water separator 9 and the heat transfer tube group 5A, a water supply pipe 11 for supplying secondary cooling water from the outside into the body 2 is inserted. Furthermore, the trunk | drum 2 has the vapor | steam exhaust port 12 formed in the upper end part. Further, the body 2 has a tube plate in the lower half of which the secondary cooling water supplied from the water supply pipe 11 into the body 2 flows down between the body 2 and the tube group outer tube 3. 4, a water supply passage 13 is formed that is folded back and raised along the heat transfer tube group 5A. The steam outlet 12 is connected to a cooling water pipe (not shown) for sending steam to the turbine, and the water supply pipe 11 has two steams used in the turbine cooled by a condenser (not shown). A cooling water pipe (not shown) for supplying the next cooling water is connected.

  In such a steam generator 1, the primary cooling water heated in the pressurized water reactor is sent to the entrance chamber 7 </ b> A, circulates through the numerous heat transfer tubes 5, and reaches the exit chamber 7 </ b> B. On the other hand, the secondary cooling water cooled by the condenser is sent to the water supply pipe 11 and rises along the heat transfer pipe group 5 </ b> A through the water supply path 13 in the trunk portion 2. At this time, heat exchange is performed between the high-temperature and high-pressure primary cooling water and the secondary cooling water in the body 2. Then, the cooled primary cooling water is returned from the exit chamber 7B to the pressurized water reactor. On the other hand, the secondary cooling water that has exchanged heat with the high-temperature and high-pressure primary cooling water rises in the body 2 and is separated into steam and hot water by the steam / water separator 9. The separated steam is sent to the turbine after moisture is removed by the moisture separator 10.

  In the steam generator 1 described above, when the side wall of the heat transfer tube 5 accommodated therein deteriorates beyond the allowable limit, radioactive water leaks from the primary side and is mixed into the non-radioactive water on the secondary side. There is a fear. For this reason, the possibility of the above-mentioned mixing is prevented by closing the end portion of the heat transfer tube 5 that may be deteriorated or deteriorated. Further, when the steam generator 1 described above is replaced and the used steam generator 1 is stored or dismantled, the end of the heat transfer tube 5 is closed so that the radiation from the heat transfer tube 5 during storage or dismantling is blocked. Prevent the risk of leakage. Such a heat transfer tube plug for closing the end of the heat transfer tube 5 will be described below.

  FIG. 2 is a side sectional view of the plug for a heat transfer tube according to the present embodiment, FIGS. 3 and 4 are sectional views of an expansion member of the plug for a heat transfer tube according to the present embodiment, and FIGS. It is a sectional side view which shows the attachment procedure of the plug for heat exchanger tubes which concerns on embodiment of this invention.

  As shown in FIG. 2, the heat transfer tube plug 20 includes a plug body 21 and an expansion member 22.

  As shown in FIG. 2, the plug body 21 has an outer diameter smaller than the inner diameter of the heat transfer tube 5 so that the plug body 21 can be inserted into the heat transfer tube 5 that is opened and provided on the water chamber 7 side of the tube plate 4. (See FIG. 5). Further, the plug body 21 is formed by closing one end of a cylindrical body 21a which is the distal end side inserted into the heat transfer tube 5 and opening the other end of the cylindrical body 21a. That is, the plug body 21 has a hole in which the tubular body 21a is opened at the other end and closed at one end. The plug body 21 is formed such that the inner diameter of the hole of the cylindrical body 21a is increased from one end side to the other end side. For this reason, the plug main body 21 is formed on the inner surface of the hole of the cylindrical body 21a with an inner tapered portion 21b that is inclined so as to increase from one end side toward the other end side.

  Further, as shown in FIG. 2, the plug body 21 has an outer surface of the cylindrical body 21a formed with a uniform outer diameter from one end side to the other end side, and is continuous with the outer surface in the circumferential direction and in the longitudinal direction. A plurality of concavo-convex portions 21c are provided in parallel. As for the uneven | corrugated | grooved part 21c, the outer surface of a convex part is made the same diameter as the outer surface of the cylindrical body 21a. Moreover, the plug main body 21 has a flange portion 21d formed on the outer periphery of the other end of the cylindrical body 21a so as to protrude outwardly from the outer diameter of the heat transfer tube 5 to be inserted (FIGS. 5 and 6). reference). The flange portion 21d has a flat inner surface facing the opening of the heat transfer tube 5 and an outer surface on the opposite side.

  The plug body 21 configured as described above is made of a super heat resistant material (for example, Inconel (registered trademark) TT690 alloy or MA690 alloy) so that it can be used in the steam generator 1 in use.

  As shown in FIG. 2, the expansion member 22 forms a rod-like body 22 a that can be inserted into a cylindrical body 21 a in the plug main body 21 (see FIG. 6). The rod-like body 22a is formed such that the distal end side inserted into the tubular body 21a has an outer diameter smaller than the inner diameter of the opening at the other end of the tubular body 21a, and the distal end side extends from the middle of the tubular body 21a to one end side. The outer diameter is formed larger than the approaching inner diameter. Moreover, the rod-shaped body 22a is formed in the external shape where the base end side is larger than the internal diameter of the opening part of the other end of the cylindrical body 21a. Further, the outer diameter of the tip of the rod-shaped body 22a is formed larger than the inner diameter of the cylindrical body 21a at the position where the concave and convex portion 21c of the cylindrical body 21a is formed. For this reason, the expansion member 22 is formed on the outer surface of the rod-shaped body 22a with an outer tapered portion 22b that is inclined so as to increase from the distal end side toward the proximal end side. In other words, the rod-like body 22a of the expansion member 22 expands the outer diameter of the tubular body 21a by pushing the tubular body 21a from the inside when inserted into the tubular body 21a of the plug body 21 (FIG. 6). Note that the inclination angle θ2 of the outer taper portion 22b of the rod-like body 22a is formed smaller than the inclination angle θ1 of the inner taper portion 21b of the cylindrical body 21a.

  Further, as shown in FIG. 2, the expansion member 22 has a protrusion 22c that protrudes outward from the distal end side to the proximal end side and extends in a spiral shape in the longitudinal direction of the rod-like body 22a on the outer surface of the rod-like body 22a. Has been. As shown in FIGS. 3 and 4, the protrusion 22c is formed so that the outer surface of the rod-shaped body 22a is cut between the protrusions 22c and protrudes outside the rod-shaped body 22a. FIG. 3 shows an example in which the space between the protrusions 22c is cut flat, and FIG. 4 shows an example in which the space between the protrusions 22c is cut into a concave curve. 3 and 4, the top of the ridge 22c is shown as being sharp, but the top of the ridge 22c may be formed in a flat shape or an arc shape. In addition, when it has the protrusion 22c, the outer taper part 22b mentioned above is formed based on the top part of the protrusion 22c.

  Moreover, the expansion member 22 has the latching | locking part 22d which protruded largely outside the outer diameter of the heat exchanger tube 5 in the base end of the rod-shaped body 22a, as shown in FIG. 2 (refer FIG. 6). The locking portion 22d has a flat inner surface facing the opening of the heat transfer tube 5. When the expansion member 22 is inserted into the cylindrical body 21a of the plug body 21, the flat inner surface of the locking portion 22d faces the flat outer surface of the flange portion 21d of the plug body 21 (see FIG. 6). ).

  The expansion member 22 configured in this manner is formed of a high-strength corrosion-resistant material (for example, precipitation hardening stainless steel) so that it can be used in the steam generator 1 in use.

  As shown in FIG. 5, such a heat transfer tube plug 20 has a plug body 21 inserted into the heat transfer tube 5, and a flange portion 21 d is connected to the opening of the heat transfer tube 5 and the water chamber 7 side of the tube plate 4. It supports in the state contact | abutted to the surface of. Although the method of supporting the plug body 21 is not clearly shown in the drawing, for example, a mechanism for pressing the flange portion 21d against the tube plate 4 is used as appropriate. Thereafter, as shown in FIG. 6, the rod-like body 22 a of the expansion member 22 is press-fitted into the cylindrical body 21 a of the plug body 21. Although the method of press-fitting the expansion member 22 into the plug body 21 is not clearly shown in the drawing, for example, a hydraulic mechanism that presses the locking portion 22d toward the plug body 21 is used as appropriate. Then, the rod-shaped body 22a of the expansion member 22 is press-fitted into the cylindrical body 21a of the plug body 21, so that the rod-shaped body 22a has a tubular shape due to the relationship between the outer diameter of the rod-shaped body 22a and the inner diameter of the tubular body 21a. The body 21a is pushed outward and the outer shape of the cylindrical body 21a is expanded. For this reason, the outer surface of the cylindrical body 21 a is pressed against the inner surface of the heat transfer tube 5, and the convex portion of the concavo-convex portion 21 c is crushed by the elastic force of the tube plate 4 through the heat transfer tube 5, and the heat transfer tube 5 is plugged by the plug body 21. The opening is plugged and closed. Moreover, the cylindrical body 21 a of the plug body 21 is closed by the rod-shaped body 22 a of the expansion member 22.

  Thus, the heat transfer tube plug 20 of the present embodiment is a heat transfer tube plug 20 for plugging and closing the opening of the heat transfer tube 5 inserted and fixed to the tube plate 4 in the steam generator 1. Thus, a cylindrical body 21a formed to have an outer diameter that can be inserted into the heat transfer tube 5 is formed, one end of the cylindrical body 21a on the distal end side inserted into the heat transfer tube 5 is closed, and the other end of the cylindrical body 21a is closed. A plug body 21 formed open and having an inner diameter of the cylindrical body 21a that is increased from one end side to the other end side, and a rod-like shape that can be inserted into the cylindrical body 21a of the plug body 21. When the body 22a is inserted into the cylindrical body 21a so that the distal end side inserted into the cylindrical body 21a has an outer diameter larger than the inner diameter approaching one end side of the cylindrical body 21a, the cylindrical body 21a And an expansion member 22 that expands the outer shape.

  According to the heat transfer tube plug 20, the inner diameter of the tubular body 21 a of the plug body 21 is increased from the closed one end to the other open end. For this reason, it is possible to process the inner surface of the cylindrical body 21a by cutting at the time of manufacturing the plug main body 21, and it is not necessary to use the conventional cold working for plastic deformation. The cylindrical body 21a of the plug body 21 is plastically deformed only when the rod-shaped body 22a of the expansion member 22 is press-fitted into the cylindrical body 21a. As a result, the plastic deformation that causes stress corrosion cracking is not caused in the plug body 21 in a multiple manner, so that the stress corrosion cracking susceptibility of the plug body 21 can be lowered and the occurrence of stress corrosion cracking can be suppressed. .

  Here, the manufacturing process of the plug for heat transfer tubes according to the present embodiment is shown in FIG. As shown in FIG. 7, the plug for a heat transfer tube 20 of the present embodiment includes a columnar member shown in FIG. 7 (a), an inner surface (inner taper portion) of the cylindrical body 21a as shown in FIG. 7 (b). 21b) is processed by cutting. Then, as shown in FIG.7 (c), the uneven | corrugated | grooved part 21c and the flange part 21d are processed by cutting. On the other hand, a conventional plug for a heat transfer tube (see, for example, Patent Document 1) is not clearly shown in the figure. For example, a hole having a uniform inner diameter is machined into a columnar member by cutting and is closed from one end side. Is also processed by cutting so that the outer diameter (thickness) of the other open end is increased. Thereafter, the expansion member is put into the processed hole. Thereafter, the other end closed so as to narrow the inner diameter on the open side of the hole is squeezed inward to be plastically deformed. Thereafter, a part of the outer shape and inner shape of the plug body is processed by cutting. This conventional plug for a heat transfer tube expands the plug body by pulling the expansion member toward the open side of the plug body, and at this time, the plug body is plastically deformed. Thus, the heat transfer tube plug 20 of the present embodiment does not cause plastic deformation during manufacture, and the conventional heat transfer tube plug plug causes plastic deformation during manufacture. For this reason, the plug for plugs for heat transfer tubes 20 of the present embodiment does not cause multiple plastic deformations that cause stress corrosion cracking on the plug body 21 as compared with the plug for plugs for heat transfer tubes of the related art. Thus, the stress corrosion cracking susceptibility of the plug body 21 can be lowered and the occurrence of stress corrosion cracking can be suppressed.

  In the heat transfer tube plug 20 of the present embodiment, the plug body 21 has an inner taper portion 21b that is inclined so that the inner diameter increases from one end to the other end on the inner surface of the cylindrical body 21a. The expansion member 22 is formed on the outer surface of the rod-shaped body 22a with a large outer diameter from the distal end side toward the proximal end side, and is formed on the outer surface of the rod-shaped body 22a from the distal end side toward the proximal end side. It is preferable that the outer tapered portion 22b be inclined so that the outer diameter is increased.

  According to the plug 20 for heat transfer tubes, when the rod-shaped body 22a is press-fitted into the tubular body 21a, the outer tapered portion 22b of the rod-shaped body 22a can be brought into close contact with the inner tapered portion 21b of the tubular body 21a. Therefore, the outer shape of the cylindrical body 21a can be expanded from one end side to the rear end side, the outer surface of the cylindrical body 21a is appropriately brought into contact with the inner surface of the heat transfer tube 5, and the plug body 21 is detached from the heat transfer tube 5. Can be prevented. In addition, since the inside of the cylindrical body 21a is closed by bringing the outer tapered portion 22b of the rod-shaped body 22a into close contact with the inner tapered portion 21b of the cylindrical body 21a, the plastically deformed portion is the primary in the steam generator 1. Without contacting the cooling water, it is possible to prevent the plastically deformed part from being affected by the primary cooling water.

  Further, in the heat transfer tube plug 20 of the present embodiment, the expansion member 22 is formed with a spiral protrusion 22c protruding outward from the distal end side to the proximal end side on the outer surface of the rod-shaped body 22a. preferable.

  According to the heat transfer tube plug 20, the expansion member 22 is press-fitted while rotating along the spiral protrusion 22 c, so that the cylindrical body 21 a can be expanded uniformly in the circumferential direction. It is possible to prevent the plug body 21 from falling off the heat transfer tube 5 by appropriately bringing the outer surface of the cylindrical body 21 a into contact with the inner surface of the heat transfer tube 5. In addition, after the expansion member 22 is press-fitted into the plug body 21, the spiral protrusion 22c bites into the inner surface of the cylindrical body 21a, so that the expansion member 22 is prevented from falling off the plug body 21, and the heat transfer tube 5 The plug body 21 can be prevented from falling off.

  Further, in the heat transfer tube plug 20 of the present embodiment, the plug body 21 has a flange portion 21d formed to protrude larger than the outer diameter of the heat transfer tube 5 on the outer periphery of the other end of the cylindrical body 21a. Is preferred.

  According to the heat transfer tube plug 20, the flange portion 21 d is brought into contact with the opening of the heat transfer tube 5 and the surface of the tube plate 4 on the water chamber 7 side, so that the rod-shaped body 22 a of the expansion member 22 is connected to the plug body 21. The plug body 21 can be prevented from entering the back of the heat transfer tube 5 when being pressed into the cylindrical body 21a, and the plug body 21 can be positioned.

  Further, in the heat transfer tube plug plug 20 of the present embodiment, as shown in a side sectional view showing another example of the heat transfer tube plug plug according to the present embodiment of FIG. It is preferable that a groove 21e having a width equal to or smaller than the inner diameter of the heat transfer tube 5 and equal to or larger than the outer diameter of the heat transfer tube 5 is formed on the inner surface facing the tubular body 21a.

  According to this heat transfer tube plug 20, when the flange portion 21 d comes into contact with the opening of the heat transfer tube 5 and the surface of the tube plate 4 on the water chamber 7 side, the flange portion is connected to the end of the heat transfer tube 5 by the groove 21 e. Avoid 21d abutment. For this reason, when the rod-shaped body 22a of the expansion member 22 is press-fitted into the cylindrical body 21a of the plug main body 21, a situation in which a pressing force is applied to the heat transfer tube 5 can be prevented, and the influence on the heat transfer tube 5 can be suppressed. The groove 21e is formed so as not to come into contact with the heat transfer tube 5 in the state before the expansion when the plug body 21 is inserted into the heat transfer tube 5 as shown in FIG. 5, and as shown in FIG. Even after the main body 21 is expanded, the heat transfer tube 5 is not contacted. Therefore, it is preferable that the groove 21e has a width that extends from the outer surface of the other end opened of the cylindrical body 21a to the outer diameter of the heat transfer tube 5 after expansion.

  Further, in the heat transfer tube plug 20 of the present embodiment, the expansion member 22 preferably has a locking portion 22d that protrudes larger than the outer diameter of the heat transfer tube 5 at the proximal end of the rod-shaped body 22a.

  According to the heat transfer tube plug 20, the expansion member 22 is press-fitted until the inner surface of the locking portion 22 d faces the outer surface of the flange portion 21 d of the plug body 21 and the inner surface contacts the outer surface and stops. Is done. For this reason, it can be confirmed that the rod-like body 22a of the expansion member 22 is press-fitted into the tubular body 21a of the plug body 21 and the tubular body 21a is reliably expanded.

  Further, in the heat transfer tube plug plug 20 of the present embodiment, as shown in the side sectional views showing other examples of the heat transfer tube plug plug according to the present embodiment of FIGS. It is preferable that fitting portions 22e and 22f are formed on the stop portion 22d.

  The fitting part 22e shown in FIG. 9 is configured as a male screw. The fitting portion 22e can be attached with a tool (not shown) having a female screw that is screwed into the male screw. Moreover, the fitting part 22f shown in FIG. 10 is comprised as a ditch | groove formed in the circumferential shape. The fitting portion 22f can be attached with a tool (not shown) having a claw member that fits into the groove. Therefore, by forming the fitting portions 22e and 22f in the locking portion 22d, the plug body 21 can be removed from the heat transfer tube 5 by pulling out the expansion member 22 from the plug body 21 with the attached tool.

  Moreover, in the heat transfer tube plug plug 20 of the present embodiment, the plug body 21 preferably has an uneven portion 21c formed on the outer surface of the cylindrical body 21a from one end side to the other end side.

  According to this heat transfer tube plug 20, when the rod-shaped body 22 a is press-fitted into the tubular body 21 a, the rod-shaped body 22 a is expanded outwardly by the rod-shaped body 22 a and pressed against the inner surface of the heat transfer tube 5. Then, the convex portion of the concave and convex portion 21 c is crushed by the elastic force of the tube plate 4 through the heat transfer tube 5. For this reason, the outer surface of the cylindrical body 21a of the plug body 21 can be more closely attached to the inner surface of the heat transfer tube 5, and the opening of the heat transfer tube 5 can be more reliably plugged.

DESCRIPTION OF SYMBOLS 1 Steam generator 4 Tube plate 5 Heat transfer tube 20 Plug plug for heat transfer tubes 21 Plug main body 21a Cylindrical body 21b Inner taper part 21c Uneven part 21d Flange part 21e Groove 22 Expansion member 22a Rod-like body 22b Outer taper part 22c Projection 22d Engagement Stop part 22e, 22f Fitting part

Claims (8)

A heat transfer tube plug for plugging and closing an opening of a heat transfer tube inserted and fixed to a tube plate in a steam generator,
A cylindrical body having an outer diameter that can be inserted into the heat transfer tube is formed, and one end of the cylindrical body on the tip side inserted into the heat transfer tube is closed and the other end of the cylindrical body is opened. A plug main body that is formed and has an inner diameter that is increased from one end to the other end; and
The plug body has a rod-like body formed so as to be insertable inside the cylindrical body, and has an outer diameter larger than an inner diameter in which a distal end side inserted into the cylindrical body approaches one end side of the cylindrical body. An expansion member that expands the outer diameter of the cylindrical body when inserted into the cylindrical body,
A plug for heat transfer tubes, comprising:   The plug body is formed on the inner surface of the cylindrical body with an inner taper portion that is inclined so that the inner diameter increases from one end side to the other end side, and the expansion member is a base of the rod-shaped body. An outer taper portion whose end side is formed to have an outer diameter larger than the inner diameter of the other end side of the cylindrical body and is inclined so that the outer diameter increases from the distal end side toward the proximal end side on the outer surface of the rod-shaped body The plug for a heat transfer tube according to claim 1, wherein the plug is provided with a plug.   3. The plug for a heat transfer tube according to claim 1, wherein the expansion member is formed with a spiral protrusion protruding outward from a distal end side to a proximal end side on an outer surface of the rod-shaped body. plug.   The plug body according to any one of claims 1 to 3, wherein the plug body has a flange portion formed on the outer periphery of the other end of the cylindrical body so as to protrude larger than the outer diameter of the heat transfer tube. The plug for a heat transfer tube as described.   The plug body is characterized in that a groove having a width not more than the inner diameter of the heat transfer tube and not less than the outer diameter of the heat transfer tube is formed on a surface of the flange portion facing the cylindrical body. Item 5. A plug for a heat transfer tube according to Item 4.   The said expansion member has the latching | locking part which protruded larger than the outer diameter of the said heat exchanger tube in the base end of the said rod-shaped body, The heat transfer tube use as described in any one of Claims 1-5 characterized by the above-mentioned. Plug plug.   The plug for a heat transfer tube according to claim 6, wherein the expansion member has a fitting portion formed in the locking portion.   The plug main body plug according to any one of claims 1 to 7, wherein the plug body has an uneven portion formed on an outer surface of the cylindrical body from one end side to the other end side. .

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