JP5778395B2 - Pickling equipment and processing method when pickling equipment is stopped - Google Patents

Description

  The present invention relates to a pickling facility and a processing method when the pickling facility is stopped.

  As equipment for removing scale formed on the surface of the steel strip, continuous pickling equipment in which an acidic chemical solution is stored is used. For example, hydrochloric acid or sulfuric acid is used as the acidic chemical solution, and the acidic chemical solution has a high temperature of about 90 ° C. suitable for scale removal.

  Conventional pickling tanks that store acidic chemicals are laid on the inner surface of the iron-skin tank that forms the outer shape of the pickling tank, the lining material with heat resistance and acid resistance that covers the inner surface of the iron-skin tank, and the inner surface of the lining material And bricks with heat resistance and acid resistance. The lining material prevents corrosion of the iron skin tank due to acidic chemicals. The brick blocks the heat transmitted from the acidic chemical to the lining material and the iron skin tank, and prevents the lining material and the iron tank from being deformed or damaged by the heat (for example, Patent Document 1).

Japanese Utility Model Publication No. 5-45071

  However, when the continuous pickling equipment is suddenly stopped, the steel strip in the pickling tank, for example, locally generates a portion that is per-acid pickled, and this causes the steel strip to break. There is. Although it is possible to clean the steel strip by opening the lid of the pickling tank, if the lid of the pickling tank is opened, the acid fume diffuses and corrodes the surrounding equipment. However, there is a problem that the work in the vicinity of the pickling tank is difficult, which is not realistic.

  An object of the present invention is to provide a continuous pickling facility capable of preventing the steel strip from breaking even when the continuous pickling facility is stopped suddenly, and a processing method at the time of stopping in the pickling facility. And

The first pickling equipment of the present invention is a pickling equipment that removes the scale formed on the surface of the steel strip by pickling with an acidic chemical solution, and is about 90 ° C. suitable for removing the scale. An acid-resistant resin pickling tank having an open lid that can store an acid chemical solution and having an openable lid, and a fluid in the pickling tank can be discharged from the pickling tank by gravity. The discharge port provided on the downstream side of the inclined portion and the acid chemical solution stored in the pickling tank are arranged so that the cleaning liquid can be discharged toward the steel strip in the pickling tank. A cleaning nozzle configured to be able to clean the surface of the steel strip after being discharged from the discharge port, and a pipe that passes through the pickling tank and supplies cleaning liquid to the cleaning nozzle from the outside of the pickling tank If the provided not only acidic chemical liquid stored in the pickling tanks the steel Also to be discharged from the discharge port, including cleaning liquid surface was washed in, in which occupies if possible to make the cleaning of the steel strip of the pickling bath without opening the open lid.

  According to the first pickling equipment of the present invention, since the steel strip cleaning nozzle that discharges the cleaning liquid toward the steel strip is provided, the acidic chemical solution is washed away from the surface of the steel strip without opening the lid portion of the pickling tank. It becomes possible. Thereby, even if it is a case where a pickling facility stops suddenly, the over pickling of a steel strip can be prevented and by extension, the fracture of a steel strip can be prevented. And since the steel strip in a pickling tank can be wash | cleaned, without opening a cover part, it becomes possible to respond rapidly toward the restoration of a pickling installation.

  In addition, in pickling tanks that have been laid with bricks as in the past and pickling tanks having a laminated structure other than bricks, if pipes for cleaning liquid are inserted through the pickling tank, the bricks and linings that constitute the pickling tank It must be processed so as to penetrate all the material and the iron skin tank, and the processing is difficult. Furthermore, since it is not easy to firmly install the pipe for the cleaning liquid on the brick in the pickling tank or a laminated portion other than the brick, the pipe for the cleaning liquid may be damaged during use. Also, since it is not easy to firmly install the pipe for the cleaning liquid on the brick in the pickling tank or a laminated structure other than the brick, the pipe for the cleaning liquid cannot be fixed at the optimum position, and the cleaning performance is lowered. there is a possibility.

  In this regard, by making the pickling tank made of acid-resistant resin, the pickling tank can be formed in a single layer, and since it becomes easier to process the pickling tank than before, the pickling tank is penetrated. In addition to facilitating the insertion of the cleaning pipe, it is easy to install the cleaning pipe in the optimum position. An example of the acid-resistant resin pickling tank is a polypropylene pickling tank.

Second pickling of the present invention, a measuring tank for temporarily storing the diverted fluid from a portion of the fluid discharged from the pre-Symbol outlet, the measuring tank temporarily storing fluid a ph meter for measuring a ph value, and when the measurement result by the ph meter enters a predetermined range, information indicating that the opening lid may be opened is output. .

  When pickling equipment is regularly inspected or repaired, or when inspected or repaired irregularly in an emergency, the lid of the pickling tank is opened and the operator inspects the inside. There is. However, when bricks are laid inside the pickling tank as in the past, even if the acidic chemical liquid is extracted from the pickling tank, the acidic chemical liquid has permeated into the bubbles of the brick. In the case of having a structure in which a lining material and an iron skin tank are laminated as described above, an acidic chemical solution remains between the layers. That is, the conventional pickling equipment cannot prevent the generation of acid fumes from the remaining acidic chemical when the lid is opened. That is, it is substantially impossible to open the lid portion of the pickling tank while suppressing acid fume.

In this regard, according to the second pickling facility of the present invention, it is possible to suppress the diffusion of acid fume .

The first pickling equipment stop processing method of the present invention stores an acid chemical solution at about 90 ° C. suitable for removing scale formed on the surface of a steel strip, and has an open lid that can be opened. A steel pickling tank, a discharge port provided on the downstream side of the inclined portion so that the fluid in the pickling tank can be discharged from the pickling tank by gravity, and a steel strip in the pickling tank And a cleaning nozzle configured to be able to clean the surface of the steel strip after the acidic chemical stored in the pickling tank is discharged from the discharge port. A pickling facility stop-time treatment method that is performed in a pickling facility comprising a pipe that passes through the pickling bath and supplies a cleaning liquid to the cleaning nozzle from the outside of the pickling bath, When the steel strip pickled by the acidic chemical stops in the pickling tank, A discharge start step of discharging the acidic chemical stored in the pickling tank from the discharge port, a steel strip cleaning step of discharging the cleaning liquid toward the steel strip and cleaning the surface of the surface of the steel strip; The steel strip in the pickling tank can be cleaned without opening the open lid .

  According to the first stop processing method of the pickling equipment of the present invention, since the steel strip cleaning step for discharging the cleaning liquid toward the steel strip is included, before the lid portion of the pickling tank is opened, It becomes possible to wash away the acidic chemical solution that generates fume from the surface of the steel strip. Thereby, the acidic chemical | medical solution which can become a generation source of an acid fume can be removed rapidly, and the spreading | diffusion of the acid fume by opening of a pickling tank is suppressed. As a result, even if the lid is opened, corrosion of the peripheral equipment of the pickling tank can be suppressed.

  Further, according to the first treatment method of the pickling facility of the present invention, the steel strip can be broken after the acidic chemical is discharged by washing away the acidic chemical remaining locally on the surface of the steel strip. It becomes possible to extremely reduce the property.

Second stop processing method pickling of the present invention, in the stop processing method of the first pickling, before Symbol fluid that is diverted from a part of the discharged fluid from the discharge port temporarily A storage tank, and a ph meter for measuring a ph value of the fluid temporarily stored in the measurement tank, and when the measurement result by the ph meter enters a predetermined range, The method further includes a step of outputting information indicating that it may be opened.

According to the stop processing method of the second pickling facility of the present invention, it is possible to suppress the diffusion of acid fume.

  According to the present invention, it is possible to prevent the steel strip from breaking even when the pickling facility is suddenly stopped.

FIG. 1 is a schematic configuration diagram of a continuous pickling facility according to an embodiment. FIG. 2 is a flowchart showing a stop time processing method executed in the continuous pickling facility of FIG. 1. FIG. 3 is a cross-sectional view of a conventional pickling tank.

  Drawing 1 is a schematic structure figure of continuous pickling equipment 1 concerning one embodiment. As shown in FIG. 1, the continuous pickling facility 1 includes a pickling tank 10, a waste liquid duct 11, a waste liquid pit 12, a cleaning unit 13, a remaining amount detection unit 14, and a control device 15.

  The pickling tank 10 of this embodiment is formed in a substantially rectangular parallelepiped shape using polypropylene (PP) as a material. The pickling tank 10 is not formed by laminating bricks, lining materials, and iron skin tanks as in the prior art, but is formed by a single layer of polypropylene. The bottom portion 20 of the substantially rectangular plate shape of the pickling tank 10 is disposed so as to be slightly inclined with respect to the horizontal plane. Four wall portions 21 are erected substantially vertically from the four straight edge portions of the bottom portion 20 of the pickling tank 10. An opening 22 in the upper part of the pickling tank 10 surrounded by a rectangular shape by all upper ends of the four wall portions 21 is covered with a lid portion 23 so as to be opened and closed.

  The steel strip 2 with the scale formed on the surface is transported in the pickling tank 10 in which the acidic chemical solution is stored in order to remove the scale formed on the surface. For example, hydrochloric acid, sulfuric acid, nitric acid, or hydrofluoric acid (hydrofluoric acid) is used as the acidic chemical solution, and the acidic chemical solution has a high temperature of about 90 ° C. suitable for scale removal.

  A waste liquid port 24 connected to the waste liquid duct 11 is provided at a lower portion of the wall portion 21 of the pickling tank 10. The bottom portion 20 of the pickling tank 10 is inclined as described above, and the surface of the bottom portion 20 having the lowest position level is flush with the lowermost surface of the waste liquid port 24 or the surface of the bottom portion 20 having the lowest position level. Also, the waste liquid port 24 is provided so that the position level of the lowermost surface of the waste liquid port 24 is lower.

Moreover, each inner surface of the bottom part 20 and the wall part 21 of the pickling tank 10 is formed smoothly so that the fluid in the pickling tank 10 may be naturally guided to the waste liquid port 24 by gravity. The waste liquid duct 11 is disposed so as to guide the fluid from the pickling tank 10 to the waste liquid pit 12. A discharge valve 25 is disposed between the waste liquid port 24 and the waste liquid duct 11. When the discharge valve 25 is closed, no fluid flows from the pickling tank 10 to the waste liquid duct 11. When the discharge valve 25 is open, the fluid is discharged from the pickling tank 10 to the waste liquid duct 11. The step of extracting the acidic chemical solution from the pickling tank 10 is performed regularly and irregularly at the time of an emergency stop of the production line.

  The conventional pickling tank 50 illustrated in the schematic cross-sectional view of FIG. 3 is an iron skin tank 51 that forms the outer shape of the pickling tank 50, and is made of rubber having heat resistance and acid resistance covering the inner surface of the iron skin tank 51. The lining material 52 includes a heat-resistant and acid-resistant brick 53 spread on the inner surface of the lining material 52 and a suction duct 54. In such a conventional pickling tank 50, when the hole 56 as shown with a broken line is formed in the vicinity of the bottom face 55 located in the lowest position inside the pickling tank 50, the brick 53, the lining material 52, and the iron skin tank 51 are formed. The holes 56 must be formed so as to penetrate all of the plurality of layers, and processing is difficult. Furthermore, since the strength around the processed hole 56 may be weakened, it is not realistic to pass the hole 56. Therefore, conventionally, a suction duct 54 is provided from the upper opening of the pickling tank 50 to the bottom surface 55 inside the pickling tank 50 in order to suck the acidic chemical solution by a pump or the like. However, according to such a conventional configuration, even if the suction port 57 of the suction duct 54 is disposed low to the vicinity of the bottom surface 55 of the pickling tank 50, the acidic chemical solution remains between the bottom surface 55 and the suction port 57. Unavoidable.

  In this regard, in the continuous pickling facility 1 of the present embodiment, the bottom 20 of the pickling tank 10 is inclined, and a waste liquid port 24 is provided at the lower end of the wall 21 of the pickling tank 10 (position level). The bottom surface of the bottom 20 and the bottom surface of the waste liquid port 24 are flush with each other, or the position of the bottom surface of the waste liquid port 24 is lower than the surface of the bottom 20 with the lowest position level. 24). Furthermore, since each inner surface of the bottom part 20 and the wall part 21 of the pickling tank 10 is formed smoothly so that the fluid in the pickling tank 10 is naturally guided to the waste liquid port 24 by gravity, the pickling tank 10 It is possible to make the acidic chemical solution attached to the inner surface less likely to remain than before.

  However, the acidic chemical solution remains on the inner surface of the pickling tank 10 including the inner surfaces of the bottom portion 20, the wall portion 21 and the lid portion 23, and the surface of the steel strip 2 only by guiding the acidic chemical solution to the waste liquid port 24 by gravity. As a countermeasure, the continuous pickling facility 1 of the present embodiment includes a cleaning unit 13 for cleaning the inner surface of the pickling tank 10 and the surface of the steel strip 2 after extracting the acidic chemical solution.

  The cleaning unit 13 includes a plurality of pickling tank cleaning nozzles 30 a disposed inside the pickling tank 10, a plurality of steel strip cleaning nozzles 30 b disposed inside the pickling tank 10, and the outside of the pickling tank 10. A pump 31 for feeding the cleaning liquid, a plurality of pipes 32 for supplying the cleaning liquid sent from the pump 31 to the pickling tank cleaning nozzle 30a and the steel strip cleaning nozzle 30b, and a supply valve 33 for adjusting the flow rate of each pipe 32 It is comprised by. The pickling tank cleaning nozzle 30a, the steel strip cleaning nozzle 30b, and the pipe 32 are all formed from a resin having acid resistance. The pickling tank cleaning nozzle 30a, the steel strip cleaning nozzle 30b, and the pipe 32 are connected to each other by bonding or screwing. It is preferable not to use a metal inferior in acid resistance as compared with the resin for the member disposed inside the pickling tank 10. The plurality of pickling tank cleaning nozzles 30 a are appropriately disposed so that the cleaning liquid can be applied as uniformly as possible to the inner surfaces of the bottom portion 20, the wall portion 21, and the lid portion 23. The plurality of steel strip cleaning nozzles 30b are appropriately disposed so that the cleaning liquid can be applied as evenly as possible to the surface of the steel strip 2 conveyed inside the pickling tank 10. The pump 31 and the supply valve 33 can be operated from the control device 15. The cleaning liquid may be water or a fluid containing various chemicals.

  While the pickling tank cleaning nozzle 30 a and the steel strip cleaning nozzle 30 b are disposed inside the pickling tank 10, the pump 31 is disposed outside the pickling tank 10. Therefore, the pipe 32 is disposed so as to penetrate the wall portion 21 of the pickling tank 10. If a hole is simply formed in the pickling tank 10, there is a possibility that the acidic chemical solution and the acid fume leak from the inside of the pickling tank 10 to the outside of the pickling tank 10. Therefore, in the pickling tank 10 of this embodiment, the piping 32 and the wall part 21 are couple | bonded so that there may be no clearance gap. As a method of coupling the pipe 32 and the wall portion 21, a method of welding the pipe 32 and the wall portion 21, a method of filling other members between the pipe 32 and the wall portion 21, a pipe 32 and the wall portion 21, Examples of the method include a method of closely adhering them without gaps.

  The waste liquid obtained by mixing the acidic chemical liquid washed away by the cleaning liquid and the cleaning liquid is discharged to the waste liquid pit 12 through the waste liquid duct 11.

  A remaining amount detection unit 14 is disposed in the middle of the waste liquid duct 11. The remaining amount detection unit 14 includes a branch pipe 40 for diverting a part of waste liquid from the pickling tank 10 toward the waste liquid pit 12, a measurement tank 41 for temporarily storing the waste liquid diverted by the branch pipe 40, and a measurement tank. The PH meter 42 measures the ph value of the waste liquid stored in 41. The ph value measured by the PH meter 42 is transmitted to the control device 15. The fluid that has flowed into the measurement tank 41 is finally discharged to the waste liquid pit 12.

  On the inner surface of the pickling tank 10 formed smoothly, there is almost no portion where the acidic chemical solution remains unlike the inner surface of the conventional pickling tank. Therefore, if the cleaning time increases, it remains in the pickling tank 10. The acidic chemical solution that is being gradually decreased. When the acidic chemical solution remaining in the pickling tank 10 decreases, the amount of acidic chemical solution contained in the waste liquid decreases. When the amount of the acidic chemical liquid contained in the waste liquid decreases, the ph value of the waste liquid approaches the ph value of the cleaning liquid. That is, as the cleaning time increases, the ph value of the waste liquid gradually approaches the ph value of the cleaning liquid from the ph value of the acidic chemical liquid. Therefore, the remaining amount detection unit 14 can indirectly detect the remaining amount of the acidic chemical remaining in the pickling tank 10 by measuring the ph value of the waste liquid.

  The control device 15 controls the discharge valve 25, the pump 31, the supply valve 33 and the PH meter 42. Furthermore, the control device 15 controls the conveyance of the steel strip 2 by controlling a conveyance device (not shown) and detects the conveyance stop of the steel strip 2. Further, the control device 15 controls the operation of the entire continuous pickling facility 1. The control device 15 is configured by a general-purpose computer, for example.

  FIG. 2 is a flowchart of the stop processing method executed by the control device 15 of the continuous pickling facility 1.

  First, the control device 15 detects the stop of the continuous pickling facility 1 and the stop of the steel strip 2 (step S100). The stop of the steel strip 2 includes various stops such as a stop by an instruction from the control device 15, a stop by an operator's operation, and an emergency stop.

  When detecting the stop of the steel strip 2, the control device 15 starts discharging the acidic chemical by opening the discharge valve 25 (step S101). When the discharge valve 25 is opened, the acidic chemical liquid flows out from the pickling tank 10 to the waste liquid duct 11 by gravity.

  Next, the control device 15 starts cleaning the pickling tank 10 by discharging the cleaning liquid from the pickling tank cleaning nozzle 30a (step S102). Washing of the pickling tank 10 may be started while the acidic chemical solution is being discharged from the pickling tank 10, or may be started after the acidic chemical solution is sufficiently discharged from the pickling tank 10. When the cleaning liquid is discharged from the pickling tank cleaning nozzle 30a to the inner surface of the pickling tank 10, the acidic chemical remaining on the inner surface of the pickling tank 10 is gradually removed.

  Next, the control device 15 starts cleaning the steel strip 2 by discharging the cleaning liquid from the steel strip cleaning nozzle 30b (step S103). The cleaning of the steel strip 2 may be started while the acidic chemical liquid is being discharged from the pickling tank 10 or may be started after the acidic chemical liquid is sufficiently discharged from the pickling tank 10. The steel strip 2 may be cleaned after the pickling tank 10 is cleaned, may be executed before the pickling tank 10 is cleaned, or may be executed while the pickling tank 10 is being cleaned. May be. When the cleaning liquid is discharged to the steel strip 2 from the steel strip cleaning nozzle 30b, the acidic chemical remaining on the surface of the steel strip 2 is gradually removed.

  Next, the control apparatus 15 detects whether the acidic chemical | medical solution remains in the pickling tank 10 (step S104). The control device 15 determines that the acidic chemical solution does not remain in the pickling tank 10 when the ph value detected by the PH meter 42 enters a predetermined range. Note that the relationship between the remaining amount of the acidic chemical solution in the pickling tank 10 and the ph value is stored in advance in the storage device of the control device 15 as data based on simulation, experiment, prior verification, and the like. The ph value that is the criterion for determining the completion of cleaning may be fixed in advance, or may be formed so that it can be input as appropriate.

  When it determines with the acidic chemical | medical solution not remaining in the pickling tank 10, the control apparatus 15 complete | finishes washing | cleaning by stopping supply of the washing | cleaning liquid to the pickling tank washing nozzle 30a and the steel strip washing nozzle 30b ( Step S105).

  Next, the control device 15 notifies that the lid can be opened using a notification means such as a lamp or a speaker (step S106), and the continuous pickling facility 1 processing method is terminated. The operator may confirm the ph value and allow the lid portion 23 to be opened and closed.

  If the steel strip 2 is left with the acidic chemical liquid remaining on the surface of the steel strip 2, a portion of the steel strip 2 in the pickling tank that is locally pickled is generated. The band may break. In addition, when the lid portion 23 of the pickling tank 10 is opened, the acid fume diffuses from the steel strip 2 and the peripheral devices are likely to corrode, and the work near the pickling tank is difficult. In this regard, according to the present embodiment, the acid chemical solution remaining in the steel strip 2 is reduced to a very small amount by washing the steel strip 2 together with the pickling bath 10 without opening the lid portion 23 of the pickling bath 10. It can be removed. In particular, when the continuous pickling equipment 1 is suddenly stopped, there is a great merit in that the steel strip 2 can be cleaned without opening the lid portion 23 of the pickling tank 10.

  While washing the pickling tank 10 and the steel strip 2 using the washing unit 13, the remaining amount of the acidic chemical solution in the pickling tank 10 is grasped using the remaining amount detection unit 14, thereby It is possible to predict the amount of acid fume diffusion before opening. Accordingly, it is possible to open the lid 23 of the pickling tank 10 after confirming that the acidic chemical solution has been sufficiently washed away, and further, the influence on the peripheral equipment due to the diffusion of the acid fume is compared with the conventional continuous pickling. It can be significantly reduced from the equipment.

  Furthermore, since the temperature of the pickling tank 10 can be quickly lowered by washing the pickling tank 10 with a washing liquid having a temperature lower than that of the acidic chemical solution, the work inside the pickling tank 10 becomes relatively easy. In particular, since the pickling tank 10 made of polypropylene expands and contracts more flexibly than a conventional pickling tank, there is less risk of breakage than conventional even if the temperature is rapidly lowered.

  According to the stop time processing method executed by the continuous pickling facility 1 and the continuous pickling facility 1 of the present embodiment, the lid 23 is opened even when the continuous pickling facility 1 is suddenly stopped. Since the steel strip 2 can be cleaned without being broken, the steel strip 2 can be prevented from being broken by peracid washing. In addition, even when the lid portion 23 is opened, the pickling tank 10 can be quickly opened while reducing the corrosion of the pickling tank peripheral device due to the acid fume and the difficulty of work in the vicinity of the pickling tank. Is possible.

  The present invention can be applied to various continuous pickling facilities without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Continuous pickling equipment 2 Steel strip 10 Pickling tank 11 Waste liquid duct 12 Waste liquid pit 13 Cleaning unit 14 Residual amount detection unit 15 Control device 20 Bottom part 21 Wall part 22 Opening 23 Lid part 24 Waste liquid port 25 Discharge valve 30a Pickling tank washing Nozzle 30b Steel band cleaning nozzle 31 Pump 32 Pipe 33 Supply valve 40 Branch pipe 41 Measuring tank 42 PH meter 50 Pickling tank 51 Iron tank 52 Lining material 53 Brick 54 Suction duct 55 Bottom face 56 Hole 57 Suction port

Claims (4)

Pickling equipment for removing the scale formed on the surface of the steel strip by pickling with an acidic chemical solution,
The acid chemical solution of about 90 ° C. suitable for removing the scale is stored, and has an open lid that can be opened and an acid-resistant resin pickling tank having an inclined portion formed at the bottom,
A discharge port provided on the downstream side of the inclined portion so that the fluid in the pickling tank can be discharged from the pickling tank by gravity;
By being arranged so that the cleaning liquid can be discharged toward the steel strip in the pickling tank, the surface of the steel strip is removed after the acidic chemical stored in the pickling tank is discharged from the discharge port. A cleaning nozzle configured for cleaning;
A pipe that passes through the pickling tank and supplies the cleaning liquid from the outside of the pickling tank to the cleaning nozzle;
The provided, so as to be discharged from the discharge port, including the washing liquid washing the pooled acidic chemical liquid not only the surface of the steel strip in the pickling tank, the acid pickling without opening the open lid A pickling facility characterized by the fact that it is possible to wash the steel strip in the tank. A measuring tank for temporarily storing the diverted fluid from a portion of the fluid discharged from the pre-Symbol outlet,
A ph meter for measuring the ph value of the fluid temporarily stored in the measurement tank,
The pickling equipment according to claim 1, wherein information indicating that the opening lid may be opened is output when a measurement result by the ph meter enters a predetermined range. A pickling tank made of acid-resistant resin that stores an acid chemical solution of about 90 ° C. suitable for removing scale formed on the surface of the steel strip and has an openable lid,
A discharge port provided on the downstream side of the inclined portion so that the fluid in the pickling tank can be discharged from the pickling tank by gravity;
By being arranged so that the cleaning liquid can be discharged toward the steel strip in the pickling tank, the surface of the steel strip is removed after the acidic chemical stored in the pickling tank is discharged from the discharge port. A cleaning nozzle configured for cleaning;
It is a processing method at the time of stoppage of the pickling equipment, executed in the pickling equipment comprising a pipe that passes through the pickling tank and supplies the cleaning liquid to the washing nozzle from the outside of the pickling tank,
When the steel strip pickled by the acidic chemical solution is stopped in the pickling tank, a discharge start step for discharging the acidic chemical solution stored in the pickling tank from the discharge port;
A steel strip cleaning step for discharging the cleaning liquid toward the steel strip and cleaning the surface of the surface of the steel strip, and
It is possible to wash the steel strip in the pickling tank without opening the open lid. A measuring tank for temporarily storing the diverted fluid from a portion of the fluid discharged from the pre-Symbol outlet,
A ph meter for measuring the ph value of the fluid temporarily stored in the measurement tank,
The processing method at the time of the stop of the pickling facility according to claim 3, further comprising a step of outputting information indicating that the opening lid may be opened when a measurement result by the ph meter enters a predetermined range.