JP2018080774A - Method for repairing v-ball valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for repairing a V-ball valve that efficiently repairs locally generated wear while maintaining valve performance, and allows use over a long term.SOLUTION: A method for repairing a V-ball valve that is a method for repairing wear generated at a valve internal surface in a V-ball valve includes: a measurement step of measuring a wear amount of wear generated at the valve internal surface; and a welding step of applying building-up welding with a hard weld material depending on the measured wear amount in a part where wear is generated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for repairing a V-ball valve, and more particularly to a method capable of efficiently repairing local wear caused by slurry supply control and continuing the use for a long period of time.

  A nickel oxide ore such as limonite or saprolite is charged into a pressurizing apparatus such as an autoclave together with a sulfuric acid solution, and nickel is leached under a high temperature and high pressure of about 240 ° C. to 260 ° C. “High-temperature pressure acid leaching (HPAL: High) A manufacturing process called “Pressure Acid Leach” has been put into practical use.

  In the process using the high-temperature pressure acid leaching method, since free sulfuric acid remains in the leaching slurry obtained by high-pressure acid leaching, neutralization treatment for neutralizing the free sulfuric acid is performed. Specifically, neutralization of free sulfuric acid is performed by adding a general and inexpensive calcium-based neutralizing agent such as limestone or slaked lime. The free sulfuric acid means unreacted sulfuric acid among the sulfuric acid added excessively to perform sufficient leaching in the HPAL process.

  Limestone used as a neutralizing agent is generally made into a slurry of about 8 μm to 10 μm at a particle size D50% using a grinding facility such as a ball mill in order to increase the reaction efficiency with the process liquid. And in the neutralization process, the addition amount of the limestone slurry is adjusted by a control valve corresponding to the pH value of the process liquid.

  Now, the control valve controlled by the continuously changing pH value has a high opening / closing frequency, and depending on the state of the limestone slurry, the casing may be worn in a short period of time. In many cases, a ball-type control valve cut into a V shape (hereinafter, also simply referred to as a “V ball valve”) is used as the control valve from the viewpoint of limestone wear resistance and superior handling. . Even in the V ball valve, depending on the frequency of opening and closing and the state of the limestone slurry, local wear occurs in a part of the casing in a short period (for example, about one month), and as a result, it is scraped from the inside of the casing. Eventually, the limestone slurry is ejected to the outside through the casing.

  Such wear is characterized by being limited to almost the same location because the flow direction of the slurry is constant. Once leakage has occurred outside the casing, the limestone slurry addition line can no longer be used, making it difficult to control the pH of the process liquid.

  Here, the flow rate of the V ball valve is controlled by the degree of opening and closing of a hemispherical valve body incorporated in the valve. More specifically, in this V ball valve, the hemispherical valve body is opened and closed by an actuator using air as a drive source. Moreover, since the opening side of the hemispherical ball is cut into a V shape, it has excellent performance in adjusting the flow rate.

On the other hand, when wear occurs in the V ball valve, there are the following characteristics.
(Abrasion occurs at the same location)
Since the flow direction of the V ball valve is always constant, the wear of the casing is locally promoted in almost the same portion, and finally the limestone slurry is ejected through the casing to the outside of the casing.
(Frequency of malfunctions other than ejection outside the valve body is low)
Almost all of the problems of the V ball valve are ejection of limestone slurry to the outside of the casing due to wear, and the frequency of other problems is low.

  In general, as a method for improving such a problem, as in the case of repairing defects such as corrosion in pipelines such as gas pipes and water pipes, repair methods such as welding overlay, so-called crack padding, A method of covering the outer periphery of the repair portion with a repair band is employed (see, for example, Patent Document 1). However, repairs such as welding overlay and patch padding are effective as emergency measures, but are not suitable as permanent repairs.

JP 2003-97786 A

  The present invention has been proposed in view of such a situation, and while maintaining the performance of the valve, it is possible to efficiently repair locally generated wear and use it over a long period of time. It aims at providing the repair method of a ball valve.

  This inventor repeated earnest examination in order to solve the subject mentioned above. As a result, the wear amount of the wear generated on the inner surface of the valve is measured, and in the portion where the wear occurs, the performance of the valve is improved by performing build-up welding with a hard welding material according to the measured wear amount. While maintaining, it discovered that it could be used for a long time after repair, and came to complete this invention.

  (1) A first invention of the present invention is a method for collecting wear generated on the inner surface of a valve in a V-ball valve, and measuring a wear amount of wear generated on the inner surface of the valve; And a welding process in which build-up welding is performed with a hard welding material in accordance with the measured amount of wear at a portion where the wear occurs.

  (2) The second invention of the present invention is the V ball valve repair method according to the first invention, wherein in the measurement step, a wear depth or a wear volume is measured as the wear amount.

  (3) According to a third aspect of the present invention, in the first or second aspect, the V ball valve is made of SUS316, and in the welding step, the hard welding capable of welding to the SUS616. This is a method of repairing a V ball valve using a material.

  (4) According to a fourth aspect of the present invention, in the third aspect of the invention, in the welding process, the welding process includes overlay welding using an austenitic hard chromium / niobium carbide material as the hard welding material. It is.

  (5) In the first invention according to any one of the first to fourth inventions, in the welding process, build-up welding is performed with the hard welding material only on a locally worn portion on the inner surface of the valve. This is a method for repairing a V ball valve.

  (6) A sixth invention of the present invention is the method of repairing a V ball valve according to any one of the first to fifth inventions, wherein the V ball valve is used for adjusting a flow rate of limestone slurry as a neutralizing agent. It is.

  According to the present invention, it is possible to efficiently repair locally generated wear while maintaining the performance of the valve, and to provide a V ball valve repair method that can be used for a long period of time. it can.

It is a longitudinal cross-sectional view which shows the structure of the principal part of V ball valve. It is a photograph figure which shows a mode when abrasion has arisen in the valve | bulb inner surface. It is the photograph which observed the mode of the valve | bulb inner surface after performing build-up welding with the hard welding material with respect to the abrasion which arose on the valve | bulb inner surface of the V ball valve.

  Hereinafter, a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention.

<< 1. Configuration of V Ball Valve >>
The repair method of the V ball valve according to the present embodiment is a method of collecting wear generated on the inner surface of the V ball valve. The V ball valve is a ball valve in which the opening side of the ball is cut into a V shape. Hereinafter, prior to detailed description of the repairing method, the configuration of the V ball valve will be briefly described.

  FIG. 1 is a longitudinal sectional view showing a configuration of a main part of the V ball valve. The V ball valve 1 includes a valve portion 2 and an actuator portion 3 that controls opening and closing of the ball valve body 22. In FIG. 1, only the main components are denoted by reference numerals and the outline will be described.

  The valve unit 2 has a flow path 21 through which a fluid such as slurry flows. A ball valve body 22 having a spherical outer shape (hemispherical shape) is disposed in the middle of the flow path 21. In FIG. 1, an arrow F clearly indicated along the flow path 21 indicates the flow of fluid such as slurry. Hereinafter, “slurry” will be described as a specific example of the fluid.

  A spherical ball valve body 22 constituting the valve portion 2 is provided with a through hole 23 having substantially the same diameter as the flow path 21. When the ball valve body 22 is rotated and opened, the valve seat constituting the ball valve body 22 moves at an angle of about 90 degrees, so that the slurry flows through the flow path 21 through the through hole 23 ( Arrow F direction). Further, the ball valve body 22 has a hemispherical ball opening side cut into a V-shape (see, for example, FIG. 2). As described above, the ball valve body 22 having the opening cut into a V shape allows the slurry flow rate to be adjusted more accurately by the rotation of the ball valve body 22.

  In the valve portion 2, reference numeral 24 indicates the configuration of the valve body (valve casing), and reference numeral 25 indicates the configuration of the valve cap.

  The actuator unit 3 is provided with a pneumatic cylinder 31. A rotatable shaft 32 is connected to the pneumatic cylinder 31. When the shaft 32 is rotated by the reciprocating motion of the piston in the pneumatic cylinder 31, the shaft 32 serves as a rotation axis, and the opening / closing control of the ball valve body 22 in the valve unit 2 is performed. In the actuator unit 3, the aspect in which the pneumatic cylinder 31 is configured has been described. However, the actuator unit 3 is not limited to a cylinder mechanism such as a pneumatic cylinder, and is configured by an electric motor or the like. A mode of rotating may be used.

  Here, the constituent material of the V ball valve 1 is not particularly limited. For example, it can be configured using austenitic stainless steel. Among austenitic stainless steels, SUS316 is particularly excellent in corrosion resistance, has high strength, and is more suitable as a constituent material for control valves.

≪2. V Ball Valve Repair Method >>
Now, the V ball valve 1 having the above-described configuration is suitably used as a control valve in a slurry addition line of a neutralizing agent such as limestone or slaked lime. In general, in the neutralization treatment, the pH state of the solution continuously changes, and therefore the frequency of opening and closing the V ball valve 1 is very high. The flow rate of the slurry such as limestone slurry added and supplied using the V ball valve 1 is no longer high, and depending on the state of the slurry itself, wear of the valve casing 24 occurs in a short period of time.

  Specifically, in the V ball valve 1, for example, wear is locally generated on the inner surface (valve inner surface) of the valve casing 24 such as the dotted circled portions X1 and X2 in FIG. FIG. 2 is a photographic view showing a state when wear occurs on the inner surface of the valve (X portion in FIG. 2). Thus, it is considered that the reason why the local wear occurs is due to an operational characteristic that the valve seat constituting the ball valve body 22 moves at an angle of about 90 degrees when the V ball valve 1 is opened and closed.

  Conventionally, it has been known that when local wear occurs on the inner surface of the V ball valve 1, it is effective to repair the worn portion by build-up welding or patching. However, although repair by build-up welding or the like has a temporary improvement effect, new wear gradually occurs and it is necessary to repeat the repair, and measures such as stopping the operation each time are required.

  Moreover, even if it only says build-up welding, in order to maintain the repair effect over a long period of time, if build-up welding was performed such that the inner diameter of the valve casing 24 of the V ball valve 1 was reduced, The volume (volume space) in the valve casing 24 is significantly reduced, resulting in a decrease in the flow rate of the slurry to be controlled. Furthermore, in such a repair, an excessive build-up welding location may become a physical obstacle, resulting in a failure of the effective opening / closing operation of the ball valve body 22. Effective flow control by the body 22 cannot be performed.

  Therefore, in the present embodiment, the measurement process for measuring the wear amount of the wear generated on the inner surface of the V ball valve 1 and the wear amount measured in the measurement process in the portion where the wear occurs. And a welding process for performing build-up welding with a hard welding material. Hereinafter, each step will be described.

[Measurement process]
In the measurement process, the amount of wear generated on the inner surface of the V ball valve 1 is measured. The amount of wear that has occurred on the inner surface of the valve means the degree of wear that has occurred in the target part to be welded in the next welding process. It can be determined by indirectly measuring the volume or wear volume. Note that the measurement of the wear amount is not limited to the measurement based on the wear depth and the wear volume, and may be based on another measure capable of quantitatively measuring the degree of wear.

  In the measurement step, the degree of wear that has occurred is estimated by measuring the amount of wear such as the depth of wear and the wear volume on the inner surface of the valve. And based on the measurement result, the tolerance of build-up welding in the next welding process can be determined. According to such a method, it is possible to suppress the reduction of the inner diameter of the valve casing 24, the reduction of the volume based on the reduction, and the reduction of the slurry flow rate, compared with the case where the overlay welding is simply performed as in the prior art. As a result, the performance of the V ball valve 1 having an excellent flow rate control function can be maintained, and the slurry supply control can be executed stably over a long period of time.

  The method for measuring the wear depth and the wear volume is not particularly limited and can be performed by a known method. Specifically, it can be measured using a laser displacement meter or the like, and can be performed by measuring a change in the distance between the lower surface of the displacement meter and the upper surface of the sensing plate of the measuring element. For example, in the V ball valve 1, the thickness of the valve casing 24 in the dotted line circled portions X <b> 1 and X <b> 2 in FIG. 1 is about 10 mm to 15 mm. Therefore, when compared with the thickness (thickness at the time of a new article), the wear amount can be measured by measuring the depth of the recess (wear depth) caused by the wear.

  Note that the processing in this measurement step may be automated by a computer. Specifically, when the V ball valve 1 is continuously used, the occurrence of wear and the degree of wear (amount of wear) are periodically measured by a laser or the like after a predetermined time has elapsed, For example, the measurement result is displayed by display means such as a display.

[Welding process]
In the welding process, build-up welding is performed with a hard welding material in accordance with the amount of wear measured in the measurement process in a portion where wear has occurred. This welding process is a process of performing build-up welding and repairing. At this time, in the present embodiment, based on the wear amount measured in the measurement process, the welding amount allowed from the wear amount ( Weld welding based on the welding tolerance).

  The allowable welding amount refers to an allowable welding amount within a range in which the inner diameter of the valve casing 24 of the V ball valve 1 is not reduced and the internal volume does not decrease. As described above, in the repair method according to the present embodiment, welding is performed to the extent that build-up welding is possible in accordance with the measured amount of wear. Therefore, after repair is performed, the valve casing of the valve portion 2 is used. It is possible to prevent a decrease in the volume in 24, a decrease in the slurry flow rate due to this, and a defective rotation of the ball valve body 22.

  Here, the build-up welding is performed using a hard welding material. In this way, by applying build-up welding with a hard welding material according to the measured amount of wear, it is possible to take measures to give wear resistance to the inner surface of the valve, and after the repair, it is stable over a long period of time. In addition, the slurry can be additionally supplied using the V ball valve 1.

  Conventionally, for example, in perforated repair, a V-ball valve composed of SUS316 or the like is patched from the outside using a SUS316 plate (for example, about 3 mm to 5 mm) of the same material, and the SUS316 from the inside. We were repairing with welding materials. However, repair by welding with the same material cannot always withstand wear for the same period as a new article because of the effect of changing the structure of the material. In addition, as described above, it is difficult to extend the life by increasing the wear allowance because it is not possible to perform excessive welding that greatly changes the inner diameter of the valve casing.

  On the other hand, according to the aspect in which build-up welding is performed using a hard welding material, even in welding within a range of allowable welding amount according to the amount of generated wear, the repair frequency is not increased and thereafter for a long period of time. The slurry can be added and supplied stably using the V ball valve 1.

  As the hard welding material, if the V ball valve 1 is made of, for example, SUS316, a hard welding material made of a dissimilar metal that can be welded to the SUS316 is used. Specifically, for example, an austenitic hard chromium / niobium carbide material can be suitably used as the hard welding material. An austenitic hard chromium / niobium carbide material has a very hard property compared to a material such as SUS316. The use of other hard welding materials is not limited.

  Moreover, it does not specifically limit as a method of build-up welding, It can carry out by a well-known method. Specifically, methods such as TIG welding and plasma welding are known, and other methods such as gas welding, plasma welding, and laser welding can also be used. Further, build-up welding is performed according to the amount of wear, and at that time, it may be a single layer or a multilayer layer as long as it is within the allowable welding range. In addition, after performing the build-up welding process, it is hardened by performing a supercooling process or the like.

  FIG. 3 is a photograph showing the state of the inner surface of the V-ball valve 1 after the build-up welding is performed on the inner surface of the valve with a hard welding material.

  As described above in detail, according to the repair method of the V ball valve according to the present embodiment, it is possible to effectively extend the period up to the perforation, and to reduce the environmental risk due to leakage of the slurry to the outside. Can be reduced. Moreover, since it can be used stably over a long period of time after the repair, the repair frequency can be reduced, the operation stop period can be shortened, and the risk of process change can be reduced.

  Specific examples to which the present invention is applied will be described below, but the present invention is not limited to these examples.

[Example]
In the V ball valve (material: SUS316) used for the limestone slurry addition line, a treatment for repairing wear on the inner surface of the valve caused by continuous use was performed. As a countermeasure against wear, overlaying repair of dissimilar metals that were excellent in wear resistance and capable of welding overlaying with SUS316, which is a valve base material, was performed. FIG. 2 is a photograph showing the state of wear occurring on the inner surface of the V ball valve before repair, and shows the portion where the X portion is worn. The place where abrasion occurred was in a range of approximately 10 cm × 10 cm.

  First, the amount of wear generated on the inner surface of the valve was measured. Specifically, the wear depth was measured with a laser displacement meter. As a result, it was found that wear of about 1 mm to 2 mm occurred on the inner surface of the valve casing having a thickness of 10 mm (whole range (10 cm × 10 cm)).

  Next, on the basis of the measured amount of wear, build-up welding using a hard welding material was applied to the entire range where wear occurred. Specifically, on the basis of the measured amount of wear, build-up welding of about 1 mm to 2 mm was performed on the entire worn portion of the inner surface of the valve. As the hard welding material, an austenitic hard chromium / niobium carbide material (manufactured by Weldwell, ABRASOCORD 43) was used. It should be noted that wear occurred on the inner surface of the valve in a part of the region, and no welding treatment was naturally applied to a portion where no wear occurred.

  After such a repair, the V ball valve after collection was attached again to the limestone slurry addition line, and the slurry was added and supplied. As a result, it took about two months until local wear occurred again and perforation occurred, and the use could be continued for a long time. During this time, the ball valve body was also effectively rotated, the flow rate of the slurry was accurately adjusted, and the performance of the V ball valve was fully demonstrated.

DESCRIPTION OF SYMBOLS 1 V ball valve 2 Valve part 3 Actuator part 21 Flow path 22 Ball valve body 23 Through-hole 24 Valve body main body (valve casing)
25 Valve cap 31 Motor 32 Shaft

(1) A first invention of the present invention is a method for repairing wear generated on an inner surface of a V ball valve, the measuring step for measuring the wear amount of the wear generated on the inner surface of the valve, A method of repairing a V-ball valve, comprising: a welding step of performing build-up welding with a hard welding material in accordance with the measured amount of wear in a portion where wear has occurred.

(3) A third invention of the present invention, in the first or second invention, the V ball valve is constituted by SUS316, in the welding process, which can be welded to the SUS 3 16 This is a method for repairing a V ball valve using a hard welding material.

<< 1. Configuration of V Ball Valve >>
The repair method of the V ball valve according to the present embodiment is a method of repairing wear generated on the inner surface of the V ball valve. The V ball valve is a ball valve in which the opening side of the ball is cut into a V shape. Hereinafter, prior to detailed description of the repairing method, the configuration of the V ball valve will be briefly described.

After such repair, the repaired V-ball valve was reattached to the limestone slurry addition line, and the slurry was added and supplied. As a result, it took about two months until local wear occurred again and perforation occurred, and the use could be continued for a long time. During this time, the ball valve body was also effectively rotated, the flow rate of the slurry was accurately adjusted, and the performance of the V ball valve was fully demonstrated.

Claims (6)

A method of collecting wear generated on the inner surface of a V ball valve,
A measuring step for measuring the wear amount of wear generated on the inner surface of the valve;
And a welding step of performing build-up welding with a hard welding material in accordance with the measured amount of wear in the portion where the wear has occurred. The method of repairing a V ball valve according to claim 1, wherein in the measurement step, a wear depth or a wear volume is measured as the wear amount. The V ball valve is made of SUS316,
The method for repairing a V ball valve according to claim 1, wherein the welding process uses a hard welding material capable of being welded to the SUS616. The method for repairing a V-ball valve according to claim 3, wherein in the welding step, build-up welding is performed using an austenitic hard chromium / niobium carbide material as the hard welding material. The method for repairing a V-ball valve according to any one of claims 1 to 4, wherein, in the welding step, build-up welding is performed with the hard welding material only on a locally worn portion on the inner surface of the valve. The method of repairing a V ball valve according to claim 1, wherein the V ball valve is used for adjusting a flow rate of a limestone slurry as a neutralizing agent.