JP5932681B2 - Constraining ring for internal welding of pipe inner surface and usage of constraining ring - Google Patents

Description

  The present invention relates to a restraining ring for pipe inner surface overlay welding and a method of using the restraining ring.

  For stress corrosion cracking (hereinafter referred to as “SCC”) in the vicinity of the welded portion of the stainless steel pipe, an internal overlay welding method (hereinafter referred to as “CRC”) is performed.

  CRC is practically used as a technique for suppressing the occurrence of SCC in the vicinity of a welded portion of a stainless steel pipe. However, when this CRC is applied, the piping is significantly deformed due to the influence of thermal stress accompanying welding. For this reason, it is customary to install a piping restraint for preventing deformation of the piping during the CRC construction.

  Initially, it was customary to install the restraint on the target piping by the welding attachment method. On the other hand, in Japanese Patent Application Laid-Open No. 56-4392 (Patent Document 1), a restraint that can be installed without welding has been developed. Compared with the conventional restraint fastening method by welding, It is described that it is possible to simplify the installation and removal work of the restraining tool.

JP 56-4392 A

  In the above-described technique, since the restraint is a one-ring type restraint, the size and mass of the restraint ring increase in proportion to the diameter of the target pipe. Further, in the work of removing the restraint ring after CRC, it must be removed by hitting with a hammer or the like. Moreover, since the dimension and mass of a restraint ring also increase as the pipe diameter of the object which constructs CRC becomes large, the burden on the operator on the spot will become excessive. In addition, there is a safety risk in swinging large hammers indoors or in narrow areas. For this reason, the constraining ring is often cut and removed and then discarded as it is, and there is a drawback that the manufacturing cost and the burden on the environment are large.

  As described above, Patent Document 1 has a problem in that the mass and size of the restraint ring that increases in proportion to the pipe diameter and the safety risk given to the worker due to the use of a large hammer are large. In addition, when the assembly type is a bolt fastening in order to make the restraining ring easy to handle and have a large size and mass, tightening and removal operations become difficult due to bolting specific to stainless steel. Or, in the case of the assembly type by welding, since the removal is only cutting, it cannot be reused.

  Accordingly, an object of the present invention is to provide a restraint ring for pipe inner surface overlay welding and a method of using the restraint ring that can minimize the influence on the operator and reduce the production cost and the load on the environment. It is in.

In order to solve the above-described problems, the present invention provides a restraint ring for pipe inner surface overlay welding for restraining a thin wall portion formed at the tip of a pipe, and the restraint ring is divided into a plurality of segments. Each segment is formed with a groove into which the thin wall portion is inserted . Each segment is connected by a pin, the top of the pin enters the pin insertion hole of each segment, and the tip of the pin is the tip of the segment The pin protrudes from the opposite side, and the pin has an angle that can be fixed in the pin insertion hole .

  According to the present invention, it is possible to provide a pipe inner surface welding welding ring and a method of using the restraining ring that can minimize the influence on the operator and can reduce the manufacturing cost and the load on the environment.

It is a perspective view explaining the structure of the restraint ring and piping concerning this invention. It is the sectional view on the AA line of FIG. It is a front view of the division | segmentation restraint ring which concerns on the Example of this invention. FIG. 4 is a sectional view taken along line BB in FIG. 3. It is CC sectional view taken on the line of FIG. FIG. 6 is an exploded view of FIG. 5. It is sectional drawing of the division | segmentation restraint ring and piping which attached the welding apparatus which concerns on this invention. It is a perspective view which shows the assembly procedure of the restraint ring which concerns on the Example of this invention. It is a perspective view which shows the assembly procedure of the restraint ring which concerns on the Example of this invention. It is a perspective view which shows the assembly procedure of the restraint ring which concerns on the Example of this invention. It is a perspective view which shows the assembly procedure of the restraint ring which concerns on the Example of this invention. It is a perspective view which shows the assembly procedure of the restraint ring which concerns on the Example of this invention. It is a perspective view which shows the assembly procedure of the restraint ring which concerns on the Example of this invention. It is a flowchart explaining the usage method of the division | segmentation restraint ring by this invention.

  Examples of the present invention will be described below.

  FIG. 1 is a perspective view for explaining the configuration of a restraining ring and piping according to the present invention.

  2 is a cross-sectional view taken along line AA in FIG.

  In FIG. 1, a part of the restraining ring is cut to show the groove.

  1 and 2, the restraining ring 1 is an integral donut-shaped metal ring. A ring-shaped groove 1 a is provided on the inner side surface of the restraining ring 1. The thin portion 2a of the pipe 2 is inserted into the groove 1a. Overlay welding 3 is applied to the thin-walled portion 2a while the thin-walled portion 2a is inserted into the groove 1a. The restraint ring 1 is also a fixing member of the welding apparatus and is a member for preventing deformation of the pipe 2 by the overlay welding 3. Therefore, when the overlay welding 3 is finished, the restraining ring 1 is removed.

  Overlay welding 3 is not welding for connecting metals, but is performed for imparting desired characteristics to the surface of the metal. The overlay welding according to the present embodiment is for covering the wetted part of the inner surface of the pipe with a weld metal that is not sensitized in advance, and improves the sensitivity to stress corrosion cracking. Therefore, it is necessary to process the portion to be built into a thin wall beforehand. This is because if the thickness is not reduced, the build-up weld portion becomes a thick portion, and the thick portion becomes a resistance to the liquid flowing in the pipe.

  Now, the build-up welding 3 is performed by inserting a welding head for build-up welding into the inside of the pipe 2 from the opening 1b of the restraining ring 1 and applying the build-up welding 3 to the thin-walled portion 2a. At this time, overlay welding 3 is performed over the entire inner peripheral surface of the pipe 2 by rotating a welding device (details will be described with reference to FIG. 7).

  However, the melted portion of the overlay welding 3 rises to around 1500 ° C., and this melting temperature is applied to the pipe 2. Furthermore, as the melting part gradually moves, the temperature rapidly decreases and reaches 50 ° C. to 200 ° C. on the outer surface of the pipe 2. Due to this intense temperature difference, heat shrinkage occurs in the pipe 2 and deformation occurs. In particular, since the build-up welding 3 is performed on the thin-walled portion 2a of the pipe 2, if the deformation occurs in the groove 1a of the restraining ring 1, the pipe 2 is firmly fixed in the groove 1a.

  For this reason, the worker has had a safety problem because the worker has to remove the restraining ring 1 from the tip 2a of the pipe 2 by hitting the restraining ring 1 with a hammer as described above. In some cases, the constraining ring 1 may be cut and removed. In this case, the constraining ring cannot be reused, resulting in a problem that the manufacturing cost and the load on the environment are large.

  Accordingly, the inventors of the present invention have studied various kinds of restraint rings that can be easily removed and can be reused repeatedly. As a result, the following embodiments were obtained.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 3 is a front view of the restraining ring according to the first embodiment of the present invention.

  4 is a cross-sectional view taken along line BB in FIG.

  5 is a cross-sectional view taken along the line CC of FIG.

  FIG. 6 is an exploded view of FIG.

  In FIG. 3, the constraining ring of this embodiment is a divided constraining ring 4 divided into a plurality of parts. This split type constraining ring 4 is divided into segments 5, 6, and 7. Each segment 5, 6, and 7 has a pin 8 inserted into a pin insertion hole 5c (shown in FIG. 4), 6c, and 7c. It is configured to be connected in a ring shape. As shown in FIG. 3, grooves 5a, 6a, and 7a for attaching the pipe 2 are formed on the inner wall surfaces of the segments 5, 6, and 7 constituting the split-type restraining ring 4 by machining. In the grooves 5a, 6a, and 7a, a thin portion 2a (shown in FIG. 4) of the pipe 2 that has been thinned in advance by machining is fitted into the grooves 5a, 6a, and 7a.

  In FIG. 4, the tip of the pipe 2 is a thin portion 2a by machining. The thin portion 2 a is inserted into a groove 7 a provided on the inner surface of the segment 7. Both end portions of the segment 7 are stepped portions 7b, and the stepped portion 5b of the segment 5 and the stepped portion 6b of the segment 6 overlap each other. Pin insertion holes 5c, 6c, 7c are provided in the respective step portions 5b, 6b, 7b, and the pin insertion holes 5c, 6c, 7c are formed by overlapping the step portions 5b, 6b, 7b. The integral split restraint ring 4 is formed by inserting the pin 8 into the pin insertion holes 5c, 6c, 7c. An opening 4a is provided at the center of the split restraint ring 4, and a welding apparatus (described with reference to FIG. 7) enters the pipe 2 from the opening 4a to perform overlay welding.

  In FIG. 5, step portions 5b and 6b are formed at both ends of each segment 5 and 6, respectively. Each of the step portions 5b and 6b is provided with two pin insertion holes 5c and 6c in the radial direction. In addition, since this figure is sectional drawing of the connection part of the segments 5 and 6, the connection part of the segment 7 does not appear. However, the structure is exactly the same as that of the segments 5 and 6 (the same applies to FIG. 6).

  As shown in FIG. 5, the stepped portions 5b and 6b at both ends of each segment 5 and 6 are overlapped, and the pin 8 is inserted when the pin insertion holes 5c and 6c are aligned, so that one restraining ring 4 is formed. It will be assembled.

  In FIG. 6, the pin 8 is a pin having a predetermined angle that is wedge-shaped with respect to the pin insertion holes 5c and 6c of the segments 5 and 6. As shown in FIG. 6, the predetermined angle of the pin 8 satisfies φa> φb ≧ φc> φd, φe> φf, and φa> φe> φb> φd> φf.

  By setting φa> φe, which is a characteristic feature of the present embodiment, the pin 8 in the assembled state surely enters and is fixed into the pin insertion holes 5c, 6c, and 7c of the segments 5, 6, and 7. become. Therefore, when φd> φf, a part of the tip of the pin 8 in the assembled state protrudes from the opposite side of the segments 5, 6, 7, and the mechanism can be easily pushed out when the restraining ring 4 is removed. It has become. That is, the pin 8 can be easily removed by hitting the tip of the pin 8 partially protruding from the opposite side of the segments 5, 6, and 7.

  The overlay welding by the welding apparatus attached to the division | segmentation restraint ring is demonstrated using FIG.

  FIG. 7 is a cross-sectional view of the split restraint ring and piping to which the welding device is attached.

  In FIG. 7, a weld rail mounting hole 4 b for supporting the weld rail 10 is provided on the opposite side of the split restraint ring 4. A welding device 9 is rotatably supported on the welding rail 10.

  In the welding device 9, the welding head 9 a enters the pipe 2 through the opening 4 a provided in the split restraining ring 4. The welding apparatus 9 is configured to perform overlay welding 3 on the thin portion 2a of the pipe 2 while the welding head 9a rotates by rotating on the welding rail 10.

  Next, a specific use procedure will be described with reference to FIG.

FIG. 8 is a perspective view showing a procedure for using the restraining ring according to the embodiment of the present invention.
(1) In FIG. 8A, first, the thin portion 2a of the pipe 2 is fitted into the groove 5a processed into the segment 5.
(2) In FIG. 8B, segment 6 similarly fits thin portion 2a of pipe 2 into groove 6a. At that time, the stepped portion 5b of the segment 5 and the stepped portion 6b of the segment 6 are overlapped, and the pin insertion holes 5c and 6c are overlapped and arranged.
(3) In FIG. 8C, the pin 8 is inserted into the overlapping pin insertion holes 5c and 6c. At this point, the pin 8 is kept in a temporarily fixed state so as to be lightly pressed.
(4) In FIG. 8D, the segment 7 similarly fits the thin portion 2c of the pipe 2 into the groove 7a (not shown). At this time, the stepped portion 5b of the segment 5 and the stepped portion 6b of the segment 6 are overlapped with the stepped portion 7b of the segment 7, and the pin insertion holes 5c and 7c and 6c and 7c are overlapped.
(5) In FIG. 8E, all the remaining pins 8 are inserted into the pin insertion holes 5c, 7c and 6c, 7c as shown in FIG. After insertion, tap the pin 8 with a plastic hammer or the like until the product is no longer loosened, and perform final tightening.
(6) In FIG. 8F, the installation of the restraining ring 4 used for the CRC method is completed.

  After that, the CRC method will be installed.

  On the other hand, the removal of the restraining ring is performed in the reverse order described above after the CRC method is completed.

  Since the pin that has been tightened is protruding from the back side of the restraining ring, the pin is removed from the back side with a plastic hammer or the like. At this time, since the pin and the through hole are tapered, they can be removed with a light force.

  That is, at the beginning of removal, all the pins 8 are first extracted, and then the segment 7 is pulled in a direction parallel to the axis of the pipe 2 and removed. Thereafter, the segments 6 and 5 are removed one by one in the same procedure.

  Here, the difference from the conventional restraint ring is demonstrated.

  In the conventional method, for example, when performing installation, several operators and a lifting machine such as a chain block are used depending on the size and mass. In this method, the difficulty of work increases in a narrow place, and it is necessary to take measures such as limiting other work. On the other hand, the split type constraining ring of the embodiment can be handled by only one or two workers, so that it is not necessary to limit other operations.

  Since the restriction of other work is not required, the work for attaching and removing the restraint ring is not a critical work in the regular inspection process, and as a result, the regular inspection period can be shortened. Moreover, the planned dose can be set low by reducing the work man-hours.

  Also, there is a significant difference in removal from the conventional restraining ring. In the conventional method, since it is an integral ring shape, it is necessary to remove the restraining ring by moving it in a parallel direction while maintaining a posture perpendicular to the axis of the pipe, but the straight diameter of the pipe after CRC construction contracts. In many cases, the pipe bites into the groove of the restraining ring and cannot move. In that case, since the restraint ring is cut and removed, the cut restraint ring becomes a waste product, which affects the environmental load and the cost of manufacturing the new restraint ring.

  On the other hand, in the split type constraining ring according to the embodiment of the present invention, by removing the fixing pins, each becomes a single product state. Therefore, the contraction force of the pipe is dispersed and can be moved with a light force, and the shape is damaged. Can be removed without

  FIG. 9 is a flowchart for explaining a method of using the restraining ring according to the present invention.

In FIG. 9, a method for attaching the split restraint ring to the pipe will be described.
(1) Thinning the pipe tip by machining (step 101)
(2) Insert the tip of the thinned pipe into the groove of the first segment (step 102)
(3) Insert the end of the pipe into the groove of the second segment (step 103)
(4) The step portions provided at both ends of the first and second segments are overlapped (step 104).
(5) A pin insertion hole is formed by the overlapped stepped portion (step 105).
(6) Insert a pin into the formed pin insertion hole (step 106).
(7) The third segment is combined with the first and second segments, and a pin is inserted to complete the constraining ring (step 107).
(8) A welding apparatus is installed on the completed restraining ring (step 108).
(9) Overlay welding is performed on the thin portion of the pipe (step 109).
(10) Remove the welding device from the restraining ring (step 110).
Next, a method for removing the split constraint ring will be described.
(11) Remove pins from all segments (step 111)
(12) Remove the third segment from the piping and the first and second segments (step 110).
(13) Remove the second segment from the pipe and the first segment (step 113).
(14) Remove the first segment from the pipe (step 114)

  As shown in FIG. 3, in this embodiment, two pin insertion holes are provided in the radial direction of the pipe. This is to obtain an effect of reinforcing the torsion of the split constraint ring 4.

  That is, in the overlay welding, as described above, the pipe is exposed to a temperature difference between the high temperature and the low temperature, so that the pipe 2 is deformed. Since this deformation is transmitted from the grooves 5a, 6a and 7a to the segments 5, 6 and 7, twisting occurs there.

  However, in this embodiment, since two pin insertion holes 5c, 6c, 7c are provided in the radial direction of the pipe 2, there is an effect of restraining torsion.

  In this embodiment, the order of the segments is determined by attaching and removing the three segments.

  That is, as shown in FIG. 8A, the stepped portion 5b of the segment 5 is bilaterally symmetric (both stepped portions are upward), and therefore, it is necessary to first attach the segment 5 to the pipe. Subsequently, as shown in FIG. 8B, the stepped portion 6b of the segment 6 is asymmetrical (the stepped portion 6b facing the segment 5 faces downward and the stepped portion 6b facing the segment 7 faces upward). Therefore, after the segment 5, the segment 6 is attached to the pipe. Next, as shown in FIG. 8D, since the stepped portion 7b of the segment 7 is the left and right object (both stepped portions are downward), the segment 7 is finally attached to the pipe.

  When detaching, segment 7 is sequentially removed in the order of segment 6 and segment 5.

  As described above, according to the present invention, a split type constraining ring can be reused from the viewpoint that it can be removed without damaging its shape. Therefore, there is an advantage that the preparation cost of spare parts and additional parts can be reduced. Further, since there is no waste due to cutting and discarding when it cannot be removed, there is an advantage that the burden on the environment is reduced.

  Moreover, since the division | segmentation restraint ring by this invention is lightweight and small-sized, there exists an advantage that a handleability can be improved, the work man-hour can be reduced, and the exposure dose can be reduced. Further, since it can be reused, there is an advantage that the manufacturing cost can be reduced and the load on the environment can be reduced.

  Moreover, SCC countermeasures for stainless steel piping are an essential item in recent years, and the CRC method, which is one of them, is a method with a lot of application results. This is a great advantage for safety risk management, exposure dose management, and process security.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1 ... restraint ring,
1a ... groove,
2 ... Piping,
2a ... Thin part,
3 ... overlay welding,
4 ... Split restraint ring,
4a ... opening,
4b ... weld rail mounting holes,
5 ... segment,
5a ... groove,
5b ... the step,
6 ... segment,
6a ... groove,
6b ... the step,
7 ... segment,
7a ... groove,
7b: a step,
8 ... pin,
9 ... Welding device,
9a ... welding head,
10: Welding rail.

Claims (5)

A restraining ring for pipe inner surface overlay welding for restraining a thin part formed at the tip of the pipe,
The constraining ring is divided into a plurality of segments, each of which has a groove into which the thin portion is inserted ,
Each segment is connected by a pin,
The top of the pin enters the pin insertion hole of each segment, the tip of the pin protrudes from the opposite side of the segment,
A restraining ring for building up an inner surface of a pipe, wherein the pin has an angle capable of being fixed in the pin insertion hole. Before SL stepped portions provided at both ends of each segment, the pipe internal surface cladding for constraining ring according to claim 1 provided with the pin insertion hole of the pin in the stepped portion. Before Symbol pin insertion hole pipe inner surface cladding for restraint ring of claim 2 it is provided two in the radial direction of the pipe. A process of thinning the tip of the pipe by machining;
Inserting the thinned tip of the pipe into the groove of the first segment;
A step of inserting the distal end portion of the pipe into the groove of the second segment,
A step of overlapping step portions provided at both ends of each of the first segment and the second segment;
Forming a pin insertion hole by said step portion superimposed,
A pin having a fixed can angle to the pin insertion hole, and the pin insertion hole at one end a pin inserted into the pin insertion holes from, Ru protrudes the tip of the pin from the other end of the pin insertion hole step ,
Combining the third segment in each of said first segment and said second segment, said first segment and the third segment, the stepped portion superimposed, and the second segment and the third segment, Into each pin insertion hole formed in each of the stacked stepped portions, another pin having an angle that can be fixed in the pin insertion hole is inserted from one end of each of the pin insertion holes, and the other pin tip portion Projecting from the other end of each pin insertion hole to complete the split restraint ring,
Performing overlay welding on the thin-walled portion of the pipe;
A method of using a constraining ring comprising : Tapping the tip of the pin to remove the pin from all the segments;
Removing the third segment from the piping and the first and second segments;
Removing the second segment from the pipe and the first segment;
Removing the first segment from the pipe;
The use method of the constraining ring of Claim 4 containing these .

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