JP4029229B2 - Clevis equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a clevis device used when artificially introducing stress corrosion cracking into a heat-affected zone on the inner peripheral surface of a welded joint between pipes.
[0002]
[Prior art]
In general, in welded joints of pipes made of stainless steel, etc., when heat input during welding is large, the heat-affected zone on the pipe side adjacent to the welded joints is deficient in chromium and carbon precipitates at the grain boundaries. When the sensitized heat-affected zone has residual stress due to the heat effect of welding, stress corrosion cracking may occur along the grain boundary.
[0003]
For this reason, in nuclear power plants, etc., nondestructive inspections such as ultrasonic flaw inspection are performed on welded joints of various pipes, but it is considered difficult to detect defects near welded joints. The technology is not established yet.
[0004]
Therefore, it is aimed to improve the inspection technology in the future, but for that purpose, a test body in which stress corrosion cracking is artificially introduced into the heat-affected zone on the inner peripheral surface of the welded joint is created, It is necessary to improve the inspection technique by repeating the nondestructive inspection test using the specimen.
[0005]
When artificially introducing stress corrosion cracking into the heat-affected zone on the inner peripheral surface of the welded joint between pipes, a pair of pipes, which are test pipes for manufacturing a test specimen, are joined together by welding. A method in which a clevis device is placed inside, a graphite fiber wool pad is brought into contact with the inner peripheral surface of the welded joint by the clevis device, and both pipes are stored in an autoclave (pressure cooker) and boiled in high-pressure high-temperature water. In this way, high-temperature and high-temperature water stays in the contact area of the pad on the inner peripheral surface of the welded joint and gives environmental conditions that are likely to corrode due to the potential difference generated between the inner peripheral surface of the welded joint and the pad. As a result, the generation of stress corrosion cracking is promoted, so that stress corrosion cracking can be generated at the contact portion of the pad.
[0006]
FIGS. 4 and 5 show an example of a clevis device used in the prior art. The pipes 2 and 2 joined through the welded joint 1 are approximately in the pipe axis direction (vertical direction in FIG. 5). A disk-shaped base plate 3 is arranged so as to be orthogonal, and the base plate 3 is arranged at a position slightly lower than the weld joint 1 by, for example, support legs (not shown) mounted at a plurality of locations as indicated by A in FIG. It is supposed to be.
[0007]
Bolts 5 having nuts 4 screwed to both ends thereof are penetrated in the center of the base plate 3 in the tube axis direction, and the diameter of the bolts 5 is gradually reduced downward in FIG. A tapered sleeve 6 having such a tapered shape is externally fitted so as to be slidable in the tube axis direction and is held by an upper nut 4 so as not to be pulled out.
[0008]
Further, a plurality of tension pieces 7 are arranged on the base plate 3 so as to surround the taper sleeve 6, and each tension piece 7 has a protrusion 8 projecting downward at the lower end thereof. A pressing plate 11 which is slidably inserted into a slit 9 extending in the radial direction opened at 3 and has an inclined surface 10 formed on the inner side so as to match the outer peripheral surface of the taper sleeve 6, and the tip of the pressing plate 11 The planar shape is configured to be substantially T-shaped by the arc plate 12 along the inner peripheral surface of the pipes 2 and 2 which are welded and fixed to the part. The outer surface of the arc plate 12 is made of graphite fiber wool. Pad 13 is mounted.
[0009]
In the figure, reference numeral 14 denotes a water passage hole for circulating the high-pressure high-temperature water when boiled with high-pressure high-temperature water in the autoclave.
[0010]
Thus, when the upper bolt 5 is tightened and the taper sleeve 6 is lowered, the tension pieces 7 are projected outward in the radial direction of the base plate 3 through the push plate 11 due to the taper shape of the taper sleeve 6. The pad 13 attached to the outer surface of the arc plate 12 of the tension piece 7 is pressed against the inner peripheral surface of the welded joint portion 1.
[0011]
[Problems to be solved by the invention]
However, in the conventional clevis device as described above, each tension piece 7 is configured to have a substantially T-shaped planar shape by the push plate 11 and the circular arc plate 12, and is thus applied by the push plate 11. There is a problem that the pressing force acts only near the center of the arc plate 12 and the pressing force on the inner peripheral surface side of the welded joint portion 1 becomes weak near both ends of the arc plate 12. The entire region of the attached pad 13 could not be pressed evenly against the inner peripheral surface of the weld joint 1.
[0012]
Further, weld distortion as shown in FIG. 5 protrudes inward on the inner peripheral surface of the welded joint portion 1 of the pipes 2 and 2, and the arc plate 12 is arranged so as to avoid interference with the protruding end portion of the weld distortion. Forming the groove portion 12a on the outer side surface has been performed, but ingenuity to make the pad 13 adhere well to the inner peripheral surface of the welded joint portion 1 in consideration of such welding distortion is not made, There is a possibility that a gap may be formed between the pad 13 and the inner peripheral surface of the weld joint 1.
[0013]
Therefore, in the conventional clevis apparatus, when the pipes 2 and 2 are boiled with high-pressure and high-temperature water in the autoclave, the inner peripheral surface of the welded joint portion 1 cannot be easily given corrosive environmental conditions, and stress corrosion There was a problem that the incidence of cracking was poor.
[0014]
The present invention has been made in view of the above circumstances, and by providing a clevis device in which the entire area of the pad can be uniformly pressed against the inner peripheral surface of the welded joint portion and can be satisfactorily adhered without gaps, The purpose is to improve the incidence.
[0015]
[Means for Solving the Problems]
In the present invention, a pad made of a fibrous material of a conductor is brought into contact with the inner peripheral surface of the welded joint portion in high-pressure high-temperature water so as to induce the generation of stress corrosion cracking in the heat-affected zone of the inner peripheral surface of the welded joint portion between pipes. A clevis device that is maintained in a state, a disc-shaped base plate disposed in a pipe so as to be substantially orthogonal to the pipe axis direction, a bolt attached to a center portion of the base plate in the pipe axis direction, A taper sleeve that is externally slidably fitted to the bolt in the tube axis direction, is held so as not to be removed by a nut, and has a taper shape so that the diameter gradually decreases toward one side of the tube axis direction; The fan-shaped planar shape is formed at a plurality of locations on the outer periphery, is slidably engaged with the base plate in a radial direction, and has an inclined concave surface on the inside so as to match the outer peripheral surface of the tapered sleeve. And a gap shaping material that is mounted to hold the pad on the outside of the tension piece and is formed corresponding to welding distortion so that the pad is in close contact with the inner peripheral surface of the weld joint. It is what.
[0016]
Therefore, in the present invention, when the clevis device is arranged inside both pipes, the position is adjusted to the weld joint, the nut is tightened, and the taper sleeve is slid toward one side in the tube axis direction, the taper of the taper sleeve is reduced. Depending on the shape, each tension piece is projected to the outside in the radial direction of the base plate, and the pad held on the outside of each tension piece via a gap shaping material is pressed against the inner peripheral surface of the weld joint. Since the flat shape is a fan shape, the pressing force by the taper sleeve is evenly applied to the outer surface of each tension piece, and the entire area of the pad is evenly pressed against the inner peripheral surface of the welded joint. The pad is closely adhered to the inner peripheral surface of the welded joint portion with no gap by the gap shaping material.
[0017]
Further, with respect to the gap shaping material, a plurality of ultra-thin gap shaping metal foils laminated in the advancing and retreating direction of the tensioning piece by sequentially shifting the end portions along the welding distortion of the inner peripheral surface of the weld joint, It is possible to form the stepped portion of the gap shaping metal foil with a base metal foil that covers the outermost gap shaping metal foil together.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
1 to 3 show an example of an embodiment for carrying out the present invention, and portions denoted by the same reference numerals as those in FIGS. 4 and 5 represent the same items.
[0020]
In this embodiment, the basic configuration is configured in substantially the same manner as the conventional clevis device, but the tension piece that is configured to have a substantially T-shaped planar shape by the push plate and the arc plate is used. The pad 13 is changed to a single piece tension piece 15 whose planar shape is a fan shape, and a gap shaping material 16 formed corresponding to welding distortion is interposed outside the tension piece 15. Is characterized in that is closely attached to the inner peripheral surface of the welded joint portion 1.
[0021]
More specifically, each of the tension pieces 15 having a fan-shaped planar shape is disposed at a plurality of locations on the outer periphery of the taper sleeve 6, and a radius at which a protrusion 17 projecting downward at the lower end of the taper sleeve 6 is opened in the base plate 3. A slanting concave surface 19 is formed on the inner side so as to be slidably fitted in a slit 18 extending in the direction and to coincide with the outer peripheral surface of the tapered sleeve 6.
[0022]
Further, the gap shaping material 16 is mounted on the outer side of each tension piece 15 so as to hold the pad 13 made of graphite fiber wool, and the end portions are sequentially shifted so as to follow the welding distortion of the inner peripheral surface of the welded joint portion 1. A plurality of ultra-thin gap shaping metal foils 20 stacked in the advancing and retreating direction of the tension piece 15, and a base metal foil 21 covering the stepped portion of each gap shaping metal foil 20 together with the outermost gap shaping metal foil 20. And fixed by spot welding.
[0023]
Here, when forming the gap shaping material 16 in correspondence with the welding distortion, for example, the welding distortion of the welded joint portion 1 is molded with a fast-hardening dent silicon or the like, and the distortion amount of the molded mold is accurately measured. Based on the amount of distortion, the gap shaping material 16 is accurately formed by appropriately combining gap shaping metal foils 20 having a plurality of thicknesses, for example, 0.05 microns, 0.1 microns, and 0.2 microns. Is preferred.
[0024]
When the welding distortion of the welded joint portion 1 is significant, a groove 15a is formed on the outer surface of each tension piece 15 so as to avoid interference with the protruding end portion of the welding distortion, as in the case of the conventional clevis device. Then, as shown by a two-dot chain line in FIG. 2, the edge portion of the groove 15a is shaved by a grinder so as to follow the welding distortion so that the number of the gap shaping metal foils 20 forming the gap shaping material 16 does not increase extremely. It is better to
[0025]
Thus, when a clevis device is arranged inside the pipes 2 and 2 and the welded joint portion 1 is aligned, one nut 4 is tightened and the taper sleeve 6 is slid toward one side in the tube axis direction. Each of the tension pieces 15 projects outward in the radial direction of the base plate 3 due to the taper shape of the taper sleeve 6, and the pad 13 held on the outer side of each tension piece 15 via a gap shaping material 16 is provided in the weld joint 1. At this time, each tension piece 15 has a fan-shaped planar shape, so that the pressing force by the taper sleeve 6 is evenly applied to the outer surface of each tension piece 15 and the entire area of the pad 13 is evenly distributed. Further, the pad 13 is pressed against the inner peripheral surface of the welded joint portion 1 and is closely adhered to the inner peripheral surface of the welded joint portion 1 without a gap by the gap shaping material 16 formed corresponding to the welding distortion.
[0026]
Therefore, according to the above-described embodiment, the entire area of the pad 13 can be evenly pressed against the inner peripheral surface of the welded joint portion 1 so as to adhere well without gaps. Therefore, when the pipes 2 and 2 are boiled with high-pressure high-temperature water in the autoclave Moreover, it is possible to satisfactorily impart an environmental condition that is easy to corrode to the inner peripheral surface of the welded joint portion 1 and to significantly improve the rate of occurrence of stress corrosion cracking.
[0027]
In addition, the clevis device of the present invention is not limited to the above-described embodiment, and the pad may be made of a conductive fiber material, and may not necessarily be made of graphite fiber wool. In the illustration, the case where stress corrosion cracking is introduced into the heat affected zone on both sides in the tube axis direction across the welded joint is illustrated, but the stress is applied only to one heat affected zone adjacent to the welded joint. If it is desired to introduce corrosion cracking, the thickness of each tension piece in the tube axis direction should be about half that shown in the figure so that the pad is pressed only on one heat-affected zone. Of course, various modifications can be made within the range not to be performed.
[0028]
【The invention's effect】
According to the clevis device of the present invention described above, the entire area of the pad can be pressed evenly against the inner peripheral surface of the welded joint portion so as to adhere well without gaps. It is possible to satisfactorily impart environmental conditions that are easily corroded to the surface, and to obtain an excellent effect that the rate of occurrence of stress corrosion cracking can be significantly improved.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of an embodiment of the present invention.
FIG. 2 is a view taken in the direction of arrows II-II in FIG.
FIG. 3 is a perspective view showing details of the gap shaping material of FIG. 2;
FIG. 4 is a plan view showing a conventional example.
FIG. 5 is a view taken in the direction of arrows VV in FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Welded joint part 2 Piping 3 Base plate 4 Nut 5 Bolt 6 Tapered sleeve 13 Pad 15 Tension piece 16 Gap shaping material 19 Inclined concave surface 20 Gap shaping metal foil 21 Base metal foil

Claims (2)

Hold the pad made of fiber material of the conductor in contact with the inner peripheral surface of the welded joint in high-pressure and high-temperature water so that stress corrosion cracking can be induced in the heat-affected zone on the inner peripheral surface of the welded joint between pipes A clevis device, a disk-shaped base plate disposed in a pipe so as to be substantially orthogonal to a pipe axis direction, a bolt attached to a central portion of the base plate in a pipe axis direction, and a pipe with respect to the bolt A taper sleeve that is externally slidably fitted in the axial direction, is held so as not to be pulled out by a nut, and has a tapered shape so that the diameter gradually decreases toward one side in the tube axis direction, and a plurality of locations around the outer circumference of the taper sleeve The fan-shaped tension piece is formed in a flat shape in which an inclined concave surface is formed on the inside so as to be slidably engaged with the base plate in the radial direction and to coincide with the outer peripheral surface of the tapered sleeve. A clevis device comprising: a gap shaping member mounted to hold the pad on the outside of the tension piece and formed to correspond to welding distortion so that the pad is brought into close contact with the inner peripheral surface of the weld joint. . A plurality of ultra-thin gap shaping metal foils, in which the gap shaping material is laminated in the advancing and retreating direction of the tensioning pieces by sequentially shifting the ends so as to follow the welding distortion of the inner peripheral surface of the weld joint, and each gap shaping metal foil 2. The clevis device according to claim 1, wherein the stepped portion is formed of a base metal foil that covers the outermost gap shaping metal foil together.

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