JP2013096681A - Reinforcement method and reinforcement structure of boiler tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a simple first aid reinforcement means at a low cost that can maintain the reinforcement strength till the next periodic inspection, as a reinforcement means for an expansion portion having occurred in a boiler tube.SOLUTION: A wire 10 of a heat resistant material that has a linear expansion coefficient equal to a boiler tube t is wound around the expansion portion e of the boiler tube t with a pressing force applied to the boiler tube t. At the same time with winding, spot welding is performed at an appropriate portion from the start end and the wound region. Finally, the terminal end of the wire 10 is spot welded to the boiler tube t. Afterward, a SUS-made foil 12 with the long side directed in the boiler tube axis direction is welded to the wire 10 and the boiler tube surface, favorably performing simultaneous welding over the entire region of the SUS-made foil 12.

Description

  The present invention is applicable to a boiler tube or the like of a boiler provided in a thermal power plant, and relates to a reinforcing method and a reinforcing structure for urgently reinforcing a bulging portion of the boiler tube.

  Boiler tubes installed in a boiler installed in a thermal power plant and placed in a high temperature range are subject to local overheating due to adhesion of carbonized oil, etc., which causes thinning, bulging deformation, or crushing. Cracks occur. When bulging deformation was observed, the bulging part was usually cut and replaced with a new tube. In this case, it is necessary to perform an operation process including cutting, groove processing, welding, and heat treatment (depending on the material).

  That is, as shown in FIG. 5, when the bulging part e generate | occur | produces in the boiler tube t, the boiler tube t is cut | disconnected by the cutting line c set to the upper part and lower part of the bulging part e. After cutting, the upper and lower ends of the new tube tn are welded to the cutting line c. If there is time and there is a stock of new pipes, it is best to perform such repair. However, due to the construction period and the stock situation of new pipes, replacement work may not be performed immediately. For this reason, emergency measures may be required until the next periodic inspection.

  Patent Document 1 discloses a technique for regenerating a portion deteriorated by creep damage using a boiler, a turbine, or the like. In this method, a creep-degraded portion is selectively repaired and welded, and then the deteriorated portion is restrained by a clamp and heated using a high-frequency heating coil to be subjected to regenerative heat treatment.

JP 2003-253337 A

  The repair means disclosed in Patent Document 1 has the advantage that the process of cutting the deteriorated part can be omitted and the work process can be simplified, compared to the conventional replacement work. However, it requires a relatively large device equipped with a clamping device and a high-frequency heating coil. A boiler provided in a thermal power plant is not suitable for working in such a narrow space because a large number of boiler tubes are arranged at narrow intervals.

  In view of the problems of the prior art, the present invention realizes an emergency reinforcing means that is simple and low-cost, and can maintain reinforcing strength until the next periodic inspection, as a reinforcing means for the bulging portion generated in the boiler tube. Objective.

  In order to achieve such an object, the boiler tube reinforcing method of the present invention is a heat-resistant, linear expansion coefficient made of a metal winding member made of the same material as that of the boiler tube. And a second step of welding at least both ends of the winding member wound around the bulging portion to the boiler tube surface or the winding member surface. The bulging portion is reinforced from the outside by a winding member.

  Thus, since it winds so that a bulging part may be pressed from an outer side with a metal winding member, the further bulging of a bulging part can be suppressed. Moreover, since this winding member has a linear expansion coefficient equivalent to a boiler tube, even if the temperature around a boiler tube changes, the pressing force of a winding member is not reduced. Moreover, since at least both ends of the winding member are welded to the boiler tube surface or the winding member surface, the pressing force and the coupling strength of the winding member with respect to the boiler tube can be maintained. The welding operation in the second step can be performed simultaneously in parallel from the wire region where the winding has been completed while performing the wire winding operation in the first step.

  The method of the present invention further includes a third step in which the metal strip is oriented in the axial direction of the boiler tube and welded to both the winding member and the boiler tube surface from the outside of the winding member wound with the strip. It is good to. Thus, by welding the belt-like body to both the winding member and the boiler tube surface from above the winding member, the coupling strength of the winding member to the boiler tube can be increased. The strip is welded to the surface of the winding member and the boiler tube in a partial region or in the entire region.

  If the length of the long side of the belt-like body is equal to or greater than the length of the winding member in the boiler tube axial direction, the belt-like body can be welded to the entire area of the boiler tube axial direction of the winding member. The bond strength can be further increased. Further, if the winding member and the boiler tube are welded over the entire region in the long side direction of the belt-like body rather than partially, the bonding strength can be further improved.

  In the method of the present invention, when reinforcing a bulging portion generated in a boiler tube in a group of boiler tubes arranged in parallel, a semi-cylindrical guide is provided on the back side of the bulging portion, and the inner surface of the guide and the bulging portion are Place the gap where the winding member can be inserted, and then insert the winding member into this gap and wind the winding member around the back of the bulging part along the inner surface of the guide. It is good to turn. As described above, by using the semi-cylindrical guide, it is easy to attach the winding member among the boiler tube groups arranged at a narrow interval.

  The boiler tube reinforcement structure of the present invention that can be directly used for carrying out the method of the present invention comprises a metal winding member made of the same material as that of the boiler tube having heat resistance and linear expansion coefficient. The bulging portion is wound in the circumferential direction so as to press the outer peripheral surface from the outside, and at least both ends of the winding member are welded to the boiler tube surface or the winding member surface. By winding the winding member around the bulging portion and reinforcing the bulging portion from the outside, further bulging of the bulging portion can be suppressed, and even if there is a change in the ambient temperature of the boiler tube, The pressing force can be maintained. In addition, the winding member can be fixed to the boiler tube surface with the required bonding strength by welding at least both ends of the winding member and, if necessary, the intermediate portion.

  In addition to the above configuration, a metal strip is provided from the outside of the wound winding member toward the boiler tube in the axial direction, and the strip is welded to both the winding member and the boiler tube surface. Good. Bonding strength of the winding member to the boiler tube surface can be improved by fixing the belt-like body to the winding member and the boiler tube.

  The winding member is made of a wire, and the wire may be wound in the circumferential direction so as to press the bulging portion from the outside to the outer peripheral surface of the bulging portion. This makes it possible to reinforce the bulge using an easily available wire, and a low-cost reinforcement operation is possible. In addition, you may wind with the space | interval between adjacent wires, or may wind between adjacent wires without a gap. By winding between adjacent wires without a gap, the winding member can be formed in a film shape, and the pressing force against the bulging portion can be increased.

  Alternatively, the winding member is formed of a thin plate-like net formed by crossing the wires in a net shape, and the film-like member is circumferentially pressed against the outer peripheral surface of the bulge portion from the outside. It should be wound. In this manner, by forming the mesh body in advance, winding of the mesh body around the bulging portion becomes easy. Preferably, the wire forming the film-like body may be arranged in the axial direction and the circumferential direction of the boiler tube. Thereby, the strength of the membrane-like body in the circumferential direction of the boiler tube can be improved, and the pressing force against the bulging portion of the membrane-like body can be kept high.

  According to the method of the present invention, a metal winding member made of a material that is heat resistant and has a linear expansion coefficient equivalent to that of a boiler tube is wound around the expanded portion of the boiler tube, and the expanded portion is reinforced from the outside. Therefore, the reinforcement work is easy, and even if the ambient temperature of the boiler tube changes, a high pressing force can be maintained against the bulging portion. Therefore, it is possible to realize an emergency reinforcing means that can maintain strength until the next periodic inspection with a simple and low-cost means. Moreover, the reinforcing structure of this invention can also obtain the effect similar to this invention method by the said structure.

It is a front view of the boiler tube which concerns on 1st Embodiment which constructed the reinforcement structure of this invention. The time of construction of a reinforcement structure is shown in 1st Embodiment, (A) is the top view, (B) is A arrow view in (A). It is a diagram which shows the test result of the reinforcement structure of 1st Embodiment. It concerns on 2nd Embodiment which constructed the reinforcement structure of this invention, (A) is a front view at the time of construction start, (B) is a front view at the time of completion | finish of construction. It is a front view which shows the repair method of the conventional boiler tube bulging part.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS. The present embodiment is an example for a boiler tube of a boiler provided in a thermal power plant. Here, the boiler tube group is connected to the boiler at a narrow interval, and this is an example of reinforcing the bulging portion e generated in one of the boiler tubes t. FIG. 1 shows a state after the reinforcement structure of the present embodiment is constructed. The boiler tube t is made of high Cr steel having an outer diameter of 50 mm, and an Inconel wire 10 having a diameter of 1.2 mm is wound around the bulging portion e of the boiler tube t without a gap. The winding process of the wire 10 will be described with reference to FIG.

  In FIG. 2, the space | interval between the boiler tubes t is about 5 cm, for example. First, a semi-cylindrical guide 14 is disposed on the back side of the boiler tube t. The guide 14 has a semicircular cross section and has small diameter portions 140 at both ends in the longitudinal direction. The small diameter portion 140 is connected to the central large diameter portion 144 via a stepped portion 142. The inner surfaces of the small diameter portions 140 at both ends are in contact with the boiler tube surface above and below the bulging portion e. A gap s is formed between the inside of the large diameter portion 144 and the boiler tube surface. The size of the gap s is set so that the wire 10 can be inserted outside the bulging portion e.

  After the guide 14 is disposed, the wire 10 is inserted into the gap s between the boiler tube surface and the large diameter portion 144. The insertion start position is the upper end region or the lower end region of the large diameter portion 144. The tip of the wire 10 is made to follow the inner surface of the large-diameter portion 144, guided to the inner surface of the large-diameter portion 144, and half-rotated in the circumferential direction to protrude from the gap s on the outlet side. This operation is repeated while applying a tensile force to the wire end protruding from the other gap s. When starting from the upstream side of the large-diameter portion 144, the boiler tube is directed with the wire 10 facing downward and no gap between the boiler tube surface and no gap between the adjacent wires 10. Winding while applying a pressing force to t. When starting from the lower end region of the large-diameter portion 144, it is similarly wound upward. Thus, the wire 10 is wound around the bulging portion e and its upper and lower regions.

  While the wire 10 is being wound, first, the starting end portion of the wire 10 is spot welded, and when further bonding strength is required, spot welding is performed at appropriate locations on the wound region. The linear expansion coefficients of the boiler tube t and the Inconel wire 10 are substantially equal from room temperature to around 650 ° C., which is the upper limit of the heating temperature in the outer region of the boiler tube t. Therefore, even if the temperature of the boiler tube outer side area changes between the temperature ranges, the pressing force of the wire 10 can be maintained. When the winding process of the wire 10 is finished, the terminal portion of the wire 10 is welded to the boiler tube surface.

  Next, a thin plate-like SUS foil 12 having a width of 5 mm and having a long side longer than the winding region of the wire 10 in the boiler tube axial direction is prepared. The SUS foil 12 is directed in the axial direction of the boiler tube t, and is welded simultaneously to both the wire 10 and the boiler tube surface over the entire length of the SUS foil 12 in the long side direction. As for the welding location, the entire long side of the SUS foil 12 is welded. This completes the reinforcement work of the present embodiment.

  According to the present embodiment, the bulging portion e can be prevented from further bulging by winding the wire 10 while applying a pressing force to the bulging portion e. In addition, since spot welding is performed simultaneously with the winding operation of the wire 10 from the start end portion of the wire 10 and the region where the winding has been completed, no special time is required for spot welding. In addition, since the wire 10 is fixed to the boiler tube surface by spot welding for the time being, it becomes easy to perform the next welding operation of the SUS foil 12. Moreover, since the SUS foil 12 is simultaneously welded to both the wire 10 and the boiler tube surface in the entire winding region of the wire 10, the bonding strength of the wire 10 to the boiler tube surface can be improved. Further, since the adjacent wires are wound in a film shape without a gap, the pressing force against the bulging portion e can be increased.

  Further, unlike the conventional repair method, operations such as cutting, welding, and heat treatment do not occur, so the operation can be performed in a short time, and the stock of the new pipe t is unnecessary, so that the operation can be performed at low cost. it can. Moreover, since the flexible wire 10 is wound around the boiler tube surface, it can be applied to any tube diameter and shape of the boiler tube regardless of the straight tube portion or the bent portion. Further, since the semi-cylindrical guide 14 is arranged on the back side of the boiler tube t and the wire 10 is wound, the wire 10 can be smoothly wound even in a narrow space between the boiler tubes. Can do. Note that the thermal effect on the boiler tube due to spot welding of the wire 10 is negligibly small.

  FIG. 3 shows the test results of the reinforcement work actually performed on the boiler tube of the material and shape using the wire of the material and shape. The test conditions were such that the temperature around the boiler tube was 650 ° C., and the internal pressure of the boiler tube was 20.2 MPa. Regarding two boiler tubes of the same material and the same shape, one was wound when the test time was 800 hr, and the other was tested without winding a wire. The boiler tube test body used was a boiler tube having no bulging portion as shown in FIG.

  As a result, the test body without the wire winding led to destruction at 347.5 hr after 800 hr. On the other hand, the specimen wound with the wire did not break even after 775.6 hours after 800 hours. Therefore, it was found that the remaining life until the boiler tube breaks can be extended by more than twice by winding the wire 10.

  When this test condition is converted into actual machine conditions, the remaining life of a boiler tube operated at 603 hours at an operating temperature of 603 ° C. and an operating pressure of 12.1 MPa becomes an operating time of 8,000 hours (approximately 1 year). On the other hand, a boiler tube wound with a wire can extend the life up to an operating time of 17,600 hr (over 2 years). In this way, it is possible to provide emergency reinforcement that is simple and low-cost, with sustainable reinforcement strength until the next periodic inspection. In the first embodiment, only one layer of the wire 10 is wound. However, depending on the temperature around the boiler tube, the state of the bulging portion e, and the internal pressure of the boiler tube, two or more layers may be wound. Good.

(Embodiment 2)
A second embodiment of the method of the present invention will be described with reference to FIG. In the present embodiment, the thin plate-like net body 16 composed of the Inconel wire 10 used in the first embodiment is used as a winding member. The mesh body 16 is configured by connecting a rectangular outer edge 160 formed of the wire 10 and a mesh wire 162 intersecting in the orthogonal direction to the outer edge 160. The mesh wire 162 is configured to face in a direction parallel to or perpendicular to the outer edge 160.

  The mesh body 16 is wound in the circumferential direction while applying a pressing force to the bulging portion e of the boiler tube t and its upper and lower regions. By arranging the outer edge 160 of the mesh body 16 in a direction parallel or orthogonal to the boiler tube axial direction, the mesh wire 162 is arranged to face the axial direction or the circumferential direction of the boiler tube t. Simultaneously with the winding process of the net body 16 of the first embodiment, spot welding is performed on the boiler tube surface at appropriate positions from the start end side outer edge 160 and the region where the winding is finished.

  When the mesh body 16 is wound around the boiler tube by one turn, the end region of the mesh body 16 is overlaid on the start end region, and the SUS foil 12 is overlaid thereon. Similar to the first embodiment, the long side of the SUS foil 12 has a length extending over the entire area of the mesh body 16 in the boiler tube axial direction. And it welds simultaneously to the net body 16 and the boiler tube over the whole region of the SUS foil 12. 4A shows the time of starting the winding process of the net body 16, and FIG. 4B shows the time of the end of the welding process of the SUS foil 12. FIG.

  According to this embodiment, the further bulging of the bulging part e can be suppressed by winding the net | network body 16 applying a pressing force to the bulging part e. Moreover, since the SUS foil 12 is simultaneously welded to both the wire 10 and the boiler tube surface in the entire winding region of the wire 10, the bonding strength to the wire 10 boiler tube surface can be improved. Moreover, since processes such as cutting, welding, and heat treatment are not required as in the prior art, it can be performed in a short time and at low cost.

  Further, as compared with the winding of the wire 10 of the first embodiment, the mesh body 16 can be wound by one turn. Therefore, while being able to perform a winding process in a short time, it can construct to arbitrary pipe diameters. However, the construction for the bend portion is not as easy as the straight pipe portion, and is suitable for application to the straight pipe portion. In this way, it is possible to provide emergency reinforcement that is simple and low-cost, with sustainable reinforcement strength until the next periodic inspection.

  Note that the wire 10 of the first embodiment and the net 16 of the second embodiment may be combined for construction. For example, the net 16 may be wound on the first layer and the wire 10 may be wound on the second layer. As a result, it is possible to provide a reinforcing structure in which the pressing force is large with respect to the bulging portion e and the reinforcing strength is further sustainable for a long time.

  According to the present invention, a bulging portion generated in a boiler tube can be used as a life extension measure until the next periodic inspection, and a simple and low-cost emergency reinforcing means can be realized, and a boiler tube of a boiler provided in a thermal power plant or the like Applicable to.

10 wire 12 SUS foil 14 guide 140 small diameter portion 142 stepped portion 144 large diameter portion 16 mesh body 160 outer edge 162 mesh wire c cutting line e bulging portion s gap t boiler tube tn new tube

Claims (8)

In the reinforcing method for reinforcing the bulging portion generated in the boiler tube,
A first step of winding a metal winding member made of a material having the same heat resistance and linear expansion coefficient as that of the boiler tube in the circumferential direction so as to press the bulging portion on the outer peripheral surface of the bulging portion from the outside. When,
A second step of welding at least both ends of the winding member wound around the bulging portion to the boiler tube surface or the surface of the winding member;
A method of reinforcing a boiler tube, wherein the bulging portion is reinforced from the outside by the winding member.   The method further includes a third step of directing the metal strip in the axial direction of the boiler tube and welding the strip from the outside of the winding member wound around the strip to both the winding member and the boiler tube surface. The method for reinforcing a boiler tube according to claim 1. The bulging portion generated in the boiler tube in the boiler tube group in which the bulging portion is arranged in parallel,
The first step includes
A first step of disposing a semi-cylindrical guide on the back side of the bulging portion with a gap into which the winding member can be inserted between the inner surface of the guide and the bulging portion;
3. The method according to claim 1, further comprising a second step of inserting the winding member into the gap and winding the winding member around the back surface of the bulging portion along the inner surface of the guide. The boiler tube reinforcing method described. In the reinforcement structure that reinforces the bulging part generated in the boiler tube,
A metal winding member made of a material that is heat resistant and has a linear expansion coefficient equivalent to that of the boiler tube is wound in the circumferential direction so as to press the bulging portion from the outside to the outer peripheral surface of the bulging portion. A boiler tube reinforcement structure, wherein at least both ends of a member are welded to the boiler tube surface or the surface of the wound member.   A metal strip is provided from the outside of the wound winding member toward the axial direction of the boiler tube, and the strip is welded to both the winding member and the boiler tube surface. The boiler tube reinforcement structure according to claim 4.   The said winding member consists of a wire, and this wire is wound by the circumferential direction so that the bulging part may be pressed on the outer peripheral surface of the said bulging part from the outside. Boiler tube reinforcement structure.   The winding member is a thin plate-like net formed by crossing wires in a net shape, and is wound in the circumferential direction so that the net presses the bulging portion from the outside to the outer peripheral surface of the bulging portion. The boiler tube reinforcing structure according to claim 4 or 5, wherein the boiler tube is reinforced.   The boiler tube reinforcing structure according to claim 7, wherein the wire forming the mesh body is arranged in an axial direction and a circumferential direction of the boiler tube.

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