JP7060229B2 - Overflow piping of storage tank for wet blast and rectification module for overflow piping - Google Patents

Description

The present invention relates to an overflow pipe of a wet blast storage tank and a rectifying module for the overflow pipe.

In Patent Document 1, as a means for surface-treating a work, a slurry in which abrasive grains and a liquid are mixed is stored in a storage tank, and the slurry in the storage tank is sucked up by a pump and solid-gas liquid is used by high-pressure gas. A wet blasting apparatus is disclosed in which a slurry in a solid-air / liquid three-phase flow state is injected from an injection gun toward a work in a three-phase flow state. The work is placed above the storage tank, and the slurry ejected toward the work returns to the storage tank.

Since the abrasive grains in the slurry scattered by the injection are attached to the wall surface of the work or the processing chamber after the blast injection, the work or the processing chamber is periodically shower-washed with only water. When shower cleaning is performed, the cleaning liquid (water) flows down into the storage tank, so that the liquid level of the slurry in the storage tank rises. The storage tank is provided with an overflow pipe, and the excess liquid is discharged from the drain port at the upper end of the overflow pipe so that the liquid level in the storage tank is kept at a constant height. ..

Japanese Patent No. 5910933

However, since the abrasive grains flow out from the overflow pipe together with the excess liquid, the concentration of the abrasive grains in the slurry in the storage tank decreases. Therefore, there is a problem that the concentration of the abrasive grains of the slurry supplied to the injection gun decreases.

The present invention has been completed based on the above circumstances, and an object of the present invention is to suppress a decrease in the concentration of abrasive grains of the slurry in the storage tank.

The overflow pipe of the storage tank for wet blast of the first invention
A drainage pipe provided in a storage tank for storing wet blast slurry and having a drainage port that opens upward at the upper end, and a drainage pipe.
A rectifying member that surrounds at least the area below the drainage port in the outer periphery of the upper end of the drainage pipe.
It is characterized by having a damping member arranged between the inner circumference of the rectifying member and the outer circumference of the drainage pipe and allowing the slurry to pass while receiving flow resistance .

The overflow piping rectifying module of the second invention
The overflow pipe is configured by attaching it to the upper end of the drainage pipe body provided in the storage tank where the slurry for wet blast is stored.
A drainage tubular member with a drainage port that opens upward at the upper end,
It is characterized by including a rectifying member that surrounds at least a region below the drainage port in the outer periphery of the upper end portion of the drainage tubular member.

According to the first invention, the slurry rises from the lower end of the rectifying member in the rectifying space between the outer periphery of the drain pipe and the inner circumference of the rectifying member toward the drain port. Since the slurry is rectified in the rectified space, the abrasive grains in the slurry settle and the amount of the abrasive grains of the slurry discharged from the drain port is reduced. As a result, a decrease in the abrasive grain concentration of the slurry in the storage tank is suppressed. Further, since the flow force is weakened when the slurry passes through the damping member, the rectifying effect is enhanced.

According to the second invention, the slurry rises from the lower end of the rectifying member in the rectifying space between the outer periphery of the drain pipe main body and the drainage tubular member and the inner circumference of the rectifying member toward the drain port. Since the slurry is rectified in the rectified space, the abrasive grains in the slurry settle and the amount of abrasive grains discharged from the drain port is reduced. As a result, a decrease in the abrasive grain concentration of the slurry in the storage tank is suppressed.

Schematic side sectional view of the wet blasting apparatus of Example 1. Top view of rectifier module Cross section of overflow piping

The first and second inventions may include a wave barrier formed in the rectifying member and arranged at a position higher than the drain port. According to this configuration, even if the liquid level of the storage tank is rippling, it is possible to prevent the slurry from overcoming the rectifying member and reaching the drain port.

The second invention may include a damping member which is arranged between the inner circumference of the rectifying member and the outer circumference of the drainage cylindrical member and allows the slurry to pass while receiving flow resistance. .. According to this configuration, the flow force is weakened when the slurry passes through the damping member, so that the rectifying effect is enhanced.

In the first invention, the damping member may be arranged at substantially the same height as the upper end of the drainage pipe. According to this configuration, a long rectifying space can be secured between the drainage pipe and the rectifying member, so that the rectifying effect is excellent. Further, even if the abrasive grains are temporarily placed on the upper surface of the damping member, the abrasive grains fall out of the flow path of the slurry penetrating the damping member into the rectifying space, so that the abrasive grains are ground on the upper surface of the damping member. There is no risk of grain accumulation.

In the second invention, the damping member may be arranged at substantially the same height as the upper end of the drainage tubular member. According to this configuration, a long rectifying space can be secured between the drainage pipe main body and the drainage tubular member and the rectifying member, so that the rectifying effect is excellent. Further, even if the abrasive grains are temporarily placed on the upper surface of the damping member, the abrasive grains fall out of the flow path of the slurry penetrating the damping member into the rectifying space, so that the abrasive grains are ground on the upper surface of the damping member. There is no risk of grain accumulation.

In the first invention, the drainage pipe has a pipe shape with the axis directed in the vertical direction and the outer diameter is constant, and the inner peripheral surface of the rectifying member covers the entire region thereof and is the outer peripheral surface of the drainage pipe. It may be in the opposite direction to. According to this configuration, there is no horizontal region on the inner peripheral surface of the straightening member that allows the abrasive grains to deposit.

<Example 1>
Hereinafter, Example 1 embodying the present invention will be described with reference to FIGS. 1 to 3. In the following description, with respect to the vertical direction, the directions appearing in FIGS. 1 and 3 are defined as upward and downward as they are. The overflow pipe 20 of the first embodiment constitutes the wet blasting device 10. As shown in FIG. 1, an injection gun 12 and a net 13 for mounting the work W are provided in the processing chamber 11 of the wet blasting device 10. The net 13 is arranged below the injection gun 12. The lower end of the processing chamber 11 (the region below the injection gun 12 and the work W) is a storage tank 14 for storing the slurry S.

Slurry S is prepared by using abrasive grains (not shown) selected according to the processing purpose from various powders and granules such as glass, zirconia, WA (white random), resin, baking soda, steel grid, etc., such as tap water. It is a mixture of about 10 to 40% with the liquid of. Since the abrasive grain concentration in the slurry S greatly affects the processing capacity of the work W, it is important to control the abrasive grain concentration of the slurry S in order to perform a good wet blast treatment.

In the first embodiment, the maximum capacity of the slurry S is defined as the state in which the liquid level of the slurry S in the storage tank 14 is at the same height as the upper end surface (drainage port 27) of the overflow pipe 20. Slurry S is prepared by putting abrasive grains having a volume of 10 to 40% into the storage tank 14 and then storing tap water in the storage tank 14 until the liquid level becomes the same as that of the drain port 27. The slurry S in the storage tank 14 is agitated by pumping a part of the slurry S into the storage tank 14 through a bypass flow path 18 described later.

A pump 15 and a compressor 16 constituting the wet blasting device 10 are provided outside the processing chamber 11. The pump 15 is provided in the middle of the slurry pressure feeding path 17 arranged between the storage tank 14 and the injection gun 12, and supplies the slurry S in the storage tank 14 to the injection gun 12. On the downstream side (injection gun 12 side) of the slurry pressure feeding path 17 from the pump 15, the slurry S in the slurry pressure feeding path 17 is returned to the storage tank 14 without passing through the injection gun 12, and the slurry in the storage tank 14 is returned. A bypass flow path 18 for stirring S with a discharge pressure is connected. A gas pressure feeding path 19 is arranged between the compressor 16 and the injection gun 12. The compressor 16 pumps high-pressure gas (for example, air) to the injection gun 12.

When wet blasting is performed on the work W, the slurry S is supplied to the injection gun 12 and high-pressure gas is pumped. Then, the slurry S supplied to the injection gun 12 is accelerated by the pressure of the high-pressure gas, becomes a rectification of the solid-air-liquid three-phase, and is sprayed on the upper surface of the work W. By spraying the slurry S on the work W at a high pressure, a blast treatment such as polishing is performed. The slurry S injected toward the work W returns to the inside of the storage tank 14.

Since the abrasive grains in the slurry S scattered by the injection are attached to the wall surface of the work W and the processing chamber 11 after the blast injection, the inside of the work W and the processing chamber 11 is regularly shower-washed. As the shower cleaning liquid (not shown), only water containing no abrasive grains is used. When shower cleaning is performed, the liquid level of the slurry S in the storage tank 14 rises, so that the storage tank 14 is provided with an overflow pipe 20. By discharging the excess liquid from the drain port 27 at the upper end of the overflow pipe 20, the liquid level in the storage tank 14 is kept at a constant height.

However, since the abrasive grains flow out from the overflow pipe 20 together with the excess liquid, the concentration of the abrasive grains in the slurry S in the storage tank 14 decreases, and as a result, the slurry S supplied to the injection gun 12 There is a concern that the abrasive grain concentration will decrease. The overflow pipe 20 of the first embodiment realizes that the decrease in the abrasive grain concentration of the slurry S in the storage tank 14 is suppressed.

As shown in FIG. 3, the overflow pipe 20 includes a drainage pipe main body 21 and a rectifying module 23 attached to the upper end portion of the drainage pipe main body 21. The rectifying module 23 is removable from the drain pipe main body 21. The drainage pipe main body 21 has a constant outer diameter dimension over the entire length, and has a circular pipe shape cut at a right angle to the axis. The drainage pipe main body 21 is installed with its axis directed in the vertical direction (vertical direction). The lower end portion of the drainage pipe main body 21 is fixed so as to penetrate vertically with respect to the bottom wall portion of the storage tank 14. A male screw portion 22 for attaching the rectifying module 23 is formed on the outer periphery of the upper end portion of the drain pipe main body 21.

The rectifying module 23 is a member in which a metal drainage tubular member 24, a metal rectifying member 28, and a metal damping member 30 are integrated. The drainage tubular member 24 has a cylindrical shape having an outer diameter substantially the same as that of the drainage pipe main body 21, and is arranged with its axis directed in the vertical direction. The outer diameter of the drainage tubular member 24 is constant from the upper end to the lower end, and the outer peripheral surface of the drainage tubular member 24 is a circumferential curved surface having no unevenness or step in the vertical direction.

A female screw portion 25 that can be screwed into the male screw portion 22 of the drain pipe main body 21 is formed on the inner circumference of the drainage tubular member 24. By screwing the female screw portion 25 into the male screw portion 22, the drainage tubular member 24 is coaxially attached to the upper end portion of the drainage pipe main body 21 to form the drainage pipe 26. The upper end of the drainage tubular member 24 (that is, the upper end of the drainage pipe 26) is opened upward as a circular drainage port 27.

The rectifying member 28 has a cylindrical shape having a larger diameter than the drain pipe 26, and is arranged with its axis directed in the vertical direction. Both the inner diameter dimension and the outer diameter dimension of the rectifying member 28 are constant dimensions from the upper end to the lower end thereof. The inner peripheral surface of the rectifying member 28 is a circumferential curved surface having no irregularities or steps in the vertical direction. The rectifying member 28 is integrated with the drainage cylindrical member 24 via the damping member 30, and coaxially surrounds the drainage tubular member 24.

The damping member 30 is a component called a punching metal having a plurality of through holes 31 formed in a disk having an outer diameter the same as the inner diameter of the rectifying member 28. The damping member 30 is housed inside the rectifying member 28, and the outer peripheral edge of the damping member 30 and the inner peripheral surface of the rectifying member 28 are fixed by welding. The damping member 30 is arranged so as to cover the drainage port 27 from above, and the lower surface of the damping member 30 is fixed to the opening edge of the drainage port 27 (the upper end edge of the drainage tubular member 24) by welding. The drainage port 27 communicates the inside of the drainage tubular member 24 (drainage pipe 26) with the space above the drainage port 27 through a plurality of through holes 31. In a plan view, the damping member 30 is arranged in an annular region between the inner circumference of the rectifying member 28 and the outer circumference of the drain pipe 26, and a circular opening region of the drain port 27.

The damping member 30 is arranged at a position lower than the upper end of the rectifying member 28, that is, at substantially the same height as the liquid level of the slurry S in the storage tank 14. Therefore, the upper end of the rectifying member 28 is arranged at a position higher than the drainage tubular member 24 (drainage port 27). The region of the rectifying member 28 above the drainage port 27 or the damping member 30 functions as a wave blocking portion 29. The lower end of the rectifying member 28 is arranged at substantially the same height as the lower end of the drainage tubular member 24. The position of the lower end of the rectifying member 28 is preferably arranged sufficiently lower than the lower end of the drainage tubular member 24. The lower the position of the lower end of the rectifying member 28, the longer the vertical dimension of the rectifying space 32 can be secured, so that the rectifying effect is improved.

The cylindrical space between the outer circumference of the upper end of the drain pipe 26 and the inner circumference of the rectifying member 28 is the rectifying space 32. The rectifying space 32 is opened to a space above the drainage pipe 26 (a space surrounded by the wave breaker 29) through a plurality of through holes 31. The lower end of the rectifying space 32 is open to the space below the rectifying module 23. Of the inner peripheral surface of the rectifying member 28, the entire region constituting the rectifying space 32 is in the horizontal direction (front-back direction or front-back direction or) with a certain interval from the outer peripheral surface of the drainage tubular member 24 (upper end portion of the drainage pipe 26). Facing in the left-right direction).

In the wet blasting apparatus 10 provided with the overflow pipe 20 and the rectifying module 23 of the first embodiment, the work W and the work W and the abrasive grains in the slurry S adhering to the wall surface of the processing chamber 11 after the blast injection are removed. The inside of the processing chamber 11 is regularly shower-washed with only water. An amount of slurry S corresponding to the cleaning liquid (water) flowing down into the storage tank 14 during shower cleaning is discharged from the drain pipe 26.

During this time, the slurry S does not reach the drainage port 27 directly, but once flows into the rectifying space 32 from the lower end of the rectifying member 28, rises in the rectifying space 32, and then flows from the drainage port 27 to the drainage pipe 26. Is discharged to. Since the slurry S is in a turbulent flow state due to the stirring action outside the rectifying member 28 (rectifying space 32), the abrasive grain concentration of the slurry S is kept substantially constant. On the other hand, in the rectifying space 32, since the slurry S is rectified while rising, the abrasive grains in the slurry S settle due to their own weight.

Moreover, since the damping member 30 is arranged at the upper end of the rectifying space 32 and the slurry S receives flow resistance when passing through the through hole 31 of the damping member 30, the ascending speed of the slurry S is slow. The sedimentation of the abrasive grains also progresses due to the decrease in the ascending speed of the slurry S. Due to the sedimentation of the abrasive grains, the abrasive grain concentration of the slurry S becomes lower toward the upper end side in the rectifying space 32, and the content of the abrasive grains in the slurry S becomes smaller at the time of being discharged from the drain port 27.

The inventor of the present application does not include the overflow pipe 20 including the rectifying member 28 and the damping member 30 of the first embodiment, and the rectifying member 28 and the damping member 30 with respect to the amount of abrasive grains discharged from the overflow pipe 20. An experiment was conducted to verify the difference from the overflow pipe (not shown). The amount of slurry S in the storage tank 14 was 30 L, and the concentration of abrasive grains in the slurry S was 30%. The aperture ratio of the through hole 31 in the damping member 30 (the ratio of the total opening area of the through hole 31 to the total area of the damping member 30) was set to 58%.

Two types of abrasive grains mixed in the slurry S were prepared: resin abrasive grains 180 to 230 μm (# 80, true specific density 1.5) and WA abrasive grains 250 to 350 μm (# 60, true specific density 3.5). By starting the pump 15 and injecting the slurry S supplied to the injection gun 12 through the slurry pressure feeding path 17 to the work W for 30 minutes, the slurry S is pumped to the bottom of the storage tank 14 through the bypass flow path 18. , The slurry S in the storage tank 14 was stirred and dispersed. During this period, a total of 20 L of tap water as washing water was continuously flowed into the storage tank 14.

Finally, the total amount of abrasive grains discharged from the overflow pipe 20 to the outside of the storage tank 14 was measured with a measuring cup, and the fluctuation of the abrasive grain concentration of the slurry S in the storage tank 14 was confirmed. At the time of measurement, the discharged slurry S was placed in a measuring cup and left for 5 minutes, and the amount of settled abrasive grains was visually confirmed. As a result of the experiment, in the case of the overflow pipe not provided with the rectifying member 28 and the damping member 30, the discharge amount of the resin abrasive grains was 1.6 L, and the discharge amount of the WA abrasive grains was 0.2 L. On the other hand, in the case of the overflow pipe 20 of the first embodiment provided with the rectifying member 28 and the damping member 30, the discharge amount of the resin abrasive grains is suppressed to 0.5 L, and the discharge amount of the WA abrasive grains is 0.025 L. It was suppressed.

From the above experimental results, it was confirmed that the amount of abrasive grains discharged was reduced by providing the rectifying member 28 and the damping member 30. Further, it can be seen that the WA abrasive grains having a large specific gravity have a more remarkable effect of reducing the discharge amount than the resin abrasive grains having a small specific gravity. It is presumed that this is because the WA abrasive grains having a large specific density are less likely to rise in the rectifying space 32.

Further, as the position of the lower end of the rectifying member 28 is closer to the bottom wall portion of the storage tank 14, the vertical dimension of the rectifying space 32 becomes longer, the rectification of the slurry S can be promoted, and the time required for the sedimentation of the abrasive grains becomes longer. Since it can be secured, the discharge of abrasive grains can be suppressed more effectively. When the opening ratio of the through hole 31 of the damping member 30 is 75% or more, the damping effect (flow resistance) becomes small and the discharge rate of the slurry S hardly decreases, so that the amount of abrasive grains discharged is reduced. The effect is reduced.

As described above, the overflow pipe 20 of the first embodiment is provided in the storage tank 14 in which the slurry S for wet blast is stored, and the drain pipe 26 having a drain port 27 that opens upward at the upper end thereof. It is configured to include a tubular rectifying member 28 that surrounds at least a region below the drainage port 27 in the outer periphery of the upper end portion of the drainage pipe 26.

Further, the rectifying module 23 constitutes an overflow pipe 20 by being attached to the upper end portion of the drainage pipe main body 21 provided in the storage tank 14, and is for drainage having a drainage port 27 having an upward opening at the upper end portion. A tubular member 24 and a tubular rectifying member 28 that surrounds at least a region below the drain port 27 in the outer periphery of the upper end portion of the drainage tubular member 24 are provided.

The slurry S stirred in the storage tank 14 flows into the rectifying space 32 between the outer periphery of the drain pipe 26 and the inner circumference of the rectifying member 28 from the lower end of the rectifying member 28, and rises in the rectifying space 32. And head toward the drainage port 27. Since the slurry S is rectified in the rectifying space 32, the abrasive grains in the slurry S settle and the amount of abrasive grains discharged from the drain port 27 is reduced. As a result, a decrease in the abrasive grain concentration of the slurry S in the storage tank 14 is suppressed.

Further, the abrasive grains are crushed or worn by the blasting process and become smaller, but it is desirable to discharge the smaller abrasive grains because the blasting ability is reduced. Since the reduced abrasive grains are unlikely to settle in the rectifying space 32, they are discharged from the drain port 27 together with the excess liquid. Therefore, the overflow pipe 20 also exhibits a function of removing unnecessary particles (smaller abrasive particles) to the outside of the storage tank 14.

Further, in a plan view, a damping member 30 that allows the slurry S to pass while receiving flow resistance is arranged between the inner circumference of the rectifying member 28 and the outer circumference of the drain pipe 26. Therefore, the slurry S is arranged. The flow of the slurry S weakens as it passes through the through hole 31 of the damping member 30. As a result, the speed of the slurry S rising in the rectifying space 32 decreases, so that the rectifying effect is enhanced. Moreover, the damping member 30 is arranged at substantially the same height as the upper end (drainage port 27) of the drainage pipe 26, and the rectifying space 32 between the drainage pipe 26 and the rectifying member 28 is in the vertical direction (slurry S). Since it is secured for a long time in the ascending direction), it has an excellent rectifying effect.

Further, since the rectifying member 28 is formed with a wave-proof portion 29 arranged at a position higher than the drain port 27, the slurry S is a rectifying member even if the liquid level of the slurry S of the storage tank 14 is rippling. It is possible to prevent the drainage port 27 from getting over the 28. Therefore, the slurry S can always reach the drain port 27 after being rectified via the rectifying space 32.

Further, the drainage pipe 26 has a pipe shape with the axis directed in the vertical direction and a constant outer diameter, and the region constituting the rectifying space 32 in the inner peripheral surface of the rectifying member 28 covers the entire region of the drainage pipe 26. It is oriented so as to face the outer peripheral surface of the. According to this configuration, there is no horizontal region on the inner peripheral surface of the straightening member 28 that allows the abrasive grains to be deposited. As a result, it is possible to prevent the concentration of the abrasive grains of the slurry S in the storage tank 14 from decreasing.

<Other Examples>
The present invention is not limited to the examples described in the above description and drawings, and for example, the following examples are also included in the technical scope of the present invention.
(1) In the above embodiment, the rectifying member is provided with a wave-proof portion higher than the drainage port, but the height of the upper end of the rectifying member may be the same as the drainage port.
(2) In the above embodiment, the damping member is arranged between the inner circumference of the rectifying member and the outer circumference of the drain pipe in a plan view, but the damping member is provided between the inner circumference of the rectifying member and the outer circumference of the drain pipe. It may be in a non-existent form.
(3) In the above embodiment, the damping member is arranged at the upper end of the drain pipe, but the damping member may be arranged at a height lower than the upper end of the drain pipe.
(4) In the above embodiment, the drainage pipe has the axis directed in the vertical direction, but the drainage pipe may have the axis directed in the diagonal direction with respect to the vertical direction.
(5) In the above embodiment, the drainage pipe has a pipe shape having a constant outer diameter, but the drainage pipe may have a pipe shape whose outer diameter dimension changes in the axial direction.
(6) In the above embodiment, the entire region constituting the rectifying space in the inner peripheral surface of the rectifying member is oriented so as to face the outer peripheral surface of the drain pipe, but the rectifying space in the inner peripheral surface of the rectifying member. It is not necessary that a part of the region constituting the drainage pipe faces the outer peripheral surface of the drainage pipe.
(7) In the above embodiment, a part of the damping member covers the drainage port, but the damping member may be in a form that does not cover the drainage port.
(8) In the above embodiment, the drainage pipe is composed of a drainage pipe main body and a drainage tubular member, but the drainage pipe may be a single member.
(9) In the above embodiment, the rectifying module is attached to and detached from the drain pipe main body, but the drain pipe main body and the rectifying module may be integrated.
(10) In the above embodiment, the drainage pipe is cylindrical, but the drainage pipe may be a square cylinder, an elliptical cylinder, or the like.
(11) In the above embodiment, the rectifying member is cylindrical, but the rectifying member may be a square cylinder, an elliptical cylinder, or the like.
(12) In the above embodiment, the opening at the upper end of the wave breaker may be closed with a lid plate. By doing so, when the liquid level of the slurry is rippling, it is possible to surely prevent the slurry from overcoming the rectifying member (wave-proof portion) and reaching the drain port. Further, a through hole may be formed in the lid plate. The lid plate may be fixed to the wave-proof portion by welding or the like, or may be detachable from the wave-proof portion.
(13) In the above embodiment, the entire rectifying member is a member separate from the storage tank, but the rectifying member may be integrally formed with the storage tank. Specifically, a part of the rectifying member in the circumferential direction is composed of a part of the wall portion constituting the storage tank, and the surrounding area of the rectifying member not composed of the storage tank is separated from the storage tank. The drainage pipe may be surrounded by the entire circumference of the drainage pipe as a whole.
(14) In the above embodiment, the rectifying member has a tubular shape that surrounds the drainage pipe over the entire circumference, but the rectifying member may be in a form that covers only a part of the drainage pipe in the circumferential direction. ..

14 ... Storage tank 20 ... Overflow pipe 21 ... Drainage pipe body 23 ... Rectification module 24 ... Drainage tubular member 26 ... Drainage pipe 27 ... Drainage port 28 ... Rectification member 29 ... Waveproof part 30 ... Damping member S ... Slurry

Claims (5)

A drainage pipe provided in a storage tank for storing wet blast slurry and having a drainage port that opens upward at the upper end, and a drainage pipe.
A rectifying member that surrounds at least the area below the drainage port in the outer periphery of the upper end of the drainage pipe.
A storage tank for wet blasting, which is arranged between the inner circumference of the rectifying member and the outer periphery of the drainage pipe and is provided with a damping member that allows the slurry to pass while receiving flow resistance . Overflow piping. The overflow pipe for a wet blast storage tank according to claim 1, further comprising a wave barrier formed in the rectifying member and arranged at a position higher than the drain port. The overflow pipe for a wet blast storage tank according to claim 1 or 2 , wherein the damping member is arranged at substantially the same height as the upper end of the drain pipe. The drainage pipe has a pipe shape with the axis directed in the vertical direction and a constant outer diameter.
The wet blast according to any one of claims 1 to 3, wherein the inner peripheral surface of the rectifying member faces the outer peripheral surface of the drainage pipe over the entire area thereof. Overflow piping for storage tanks. The overflow pipe is configured by attaching it to the upper end of the drainage pipe body provided in the storage tank where the slurry for wet blast is stored.
A drainage tubular member with a drainage port that opens upward at the upper end,
A rectifying module for an overflow pipe, comprising a rectifying member that surrounds at least a region below the drain port of the outer periphery of the upper end portion of the drainage tubular member .

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