JP2011194302A - Corroded part removing method for cast iron pipe outer surface, and corroded part removing apparatus used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time required for removing operation of deposits and graphitized corroded part on cast iron pipe outer surfaces.SOLUTION: An excavation pit 7 is dug toward a ductile cast iron pipe 25 buried underground, a blast agent and high pressure water supplied from a high pressure pump are jetted together from a nozzle gun 4, toward the deposits which are stuck to the cast iron pipe outer surfaces 26 of the ductile cast iron pipe 25 exposed in the excavation pit 7 and toward the graphitized corroded part in which iron of the cast iron pipe outer surfaces 26 is corroded and a graphite layer remains on the cast iron pipe outer surfaces 26, and thus, the deposits and the graphitized corroded part are removed from the cast iron pipe outer surfaces 26. Consequently, only with a series of operations of jetting the blast agent and the high pressure water together from the nozzle gun 4, both the deposits and the graphitized corroded part can be scraped off from the cast iron pipe outer surfaces 26 with the blast agent jetted from the nozzle gun 4, and time required for the removing operation of the deposits and the graphitized corroded part on the cast iron pipe outer surfaces 26 can be shortened.

Description

  This invention is designed to inject deposits and graphitized corrosion parts from the outer surface by spraying blasting agent on the adhered substances adhering to the outer surface of the ductile cast iron pipe excavated in the excavation mine and the graphitized corrosion parts. The present invention relates to a method for removing a corroded portion on the outer surface of a cast iron pipe and a corroded portion removing apparatus used for the method for removing a corroded portion on the outer surface of the cast iron pipe.

  Ductile cast iron pipes buried in the ground have anticorrosion coating on the outer surface to prevent corrosion of the outer surface due to the surrounding soil environment. However, in such a ductile cast iron pipe, when the anticorrosion coating is deteriorated and peeling occurs, graphitization corrosion in which the iron on the outer surface of the cast iron pipe corrodes may occur from the peeled portion. When graphitization corrosion occurs, the proportion of the graphitization corrosion portion where a large amount of graphite remains on the outer surface of the cast iron pipe increases, which causes water leakage and damage. Therefore, in order to perform pipe maintenance such as preventing leakage and breakage of the water and determining the priority of the renewal timing of the ductile cast iron pipe, the corrosion amount of the cast iron pipe outer surface is appropriately investigated.

  To investigate the amount of corrosion of the outer surface of the cast iron pipe, first, the ductile cast iron pipe is dug from the ground, and deposits such as soil adhering to the outer surface of the cast iron pipe are scraped off with a scraper, and then knocked off with a keren hammer. When the deposits are almost removed, the remaining deposits are completely scraped with a wire brush. Thereafter, all the graphitized corrosion portions on the outer surface of the cast iron pipe are peeled off with the sharp edge of the test hammer, and the graphitized corrosion portions are completely removed from the outer surface of the cast iron tube. Next, the depth of the graphitized corrosion portion is measured with a depth gauge, the resin is filled into the graphitized corrosion portion having a corrosion depth of 2.0 mm or more, and then the anticorrosion coating is applied to the outer surface of the cast iron pipe within the investigation range. Is done.

  However, since the amount of corrosion on the outer surface of the cast iron pipe must be removed in order using various tools such as scrapers, keren hammers, wire brushes, test hammers, etc., the removal work Was spending a lot of time. In particular, if there is a ductile cast iron joint within the investigation range, it is necessary to investigate the amount of corrosion down to the small parts such as bolts and nuts of the joint, so that the corrosion is done manually using a tool as described above. It was hard to conduct a quantity survey.

  Therefore, an object of the present invention is to shorten the time required for the operation of removing the deposits on the outer surface of the cast iron pipe and the graphitized corrosion portion.

  In order to solve the above-mentioned problems, a method for removing a corroded portion of an outer surface of a cast iron pipe according to the present invention includes digging a digging mine toward a ductile cast iron pipe buried in the ground and exposing the ductile cast iron pipe exposed in the digging mine. The blast agent and the high-pressure water supplied from the high-pressure pump are jetted from the nozzle gun together with the adhering matter adhering to the outer surface and the graphitized corrosion portion of the outer surface of the cast iron pipe, thereby The graphitized corrosion portion was removed from the outer surface of the cast iron pipe.

  In this way, the blasting agent sprayed from the nozzle gun causes the deposit and the graphitization only by a series of operations in which the blasting agent and high-pressure water are sprayed together from the nozzle gun toward the deposits and graphitized corrosion parts on the outer surface of the cast iron pipe. Since both of the corroded parts can be scraped off the outer surface of the cast iron pipe, the deposits and the graphitized corroded parts are removed in order using various tools such as a scraper, keren hammer, wire brush, and test hammer as in the past. Compared to the case, deposits and graphitized corrosion portions can be easily removed from the outer surface of the cast iron pipe. Therefore, it is possible to shorten the time required to remove the deposits on the outer surface of the cast iron pipe and the graphitized corrosion portion.

  The blasting agent is stored in a blast tank, a blast hose connected to the nozzle gun is inserted into the blast tank, and the blast hose is generated by the flow of high-pressure water supplied to the nozzle gun from the high-pressure pump through the high-pressure hose. Due to the negative pressure, the blasting agent can be sucked into the nozzle gun through the blast hose, and the blasting agent can be injected from the nozzle gun together with the high-pressure water.

  When alumina having a particle size in the range of 46 mesh to 80 mesh is used as the blasting agent stored in the blast tank, it is preferable because both the deposit and the graphitized corrosion portion are easily removed. When the particle size of alumina is larger than 46 mesh, it becomes difficult for alumina to collide with the deep part of the graphitized corrosion part, and the removability of the graphitized corrosion part is deteriorated. On the other hand, the smaller the particle size of alumina, the easier it is for alumina to collide with the deep part of the graphitized corrosion part, and it is possible to scrape off to the deep part of the graphitized corrosion part. Although it is preferable, when the particle size of alumina is smaller than 80 mesh, the scraping action of the deposit by alumina becomes too weak, and the deposit removability deteriorates.

  As the blasting agent to be stored in the blast tank, it is preferable to use mixed alumina in which a mixing volume ratio of alumina having an average particle size of 20 mesh and alumina having an average particle size of 60 mesh is mixed in a ratio of 2: 1 to 1: 2. .

  As the average particle size of alumina is smaller, the suction of alumina to the blast hose is interrupted in the middle, or the suction of alumina is discontinuous, and the blast hose is pulsated and the suction of alumina tends to become unstable. By mixing 20 mesh alumina, which has a relatively large particle size, and 60 mesh alumina, which has the best removability of both the deposit and the graphitized corrosion portion, the removability of both the deposit and the graphitized corrosion portion is improved. This is because the suction of alumina into the blast hose can be stabilized while securing the above.

  When silica sand having a particle size in the range of 0.7 to 1.2 mm is used as the blasting agent stored in the blast tank, removal of both deposits and graphitized corrosion parts and suction stability of the silica sand to the blast hose are achieved. Can do well. For this reason, silica sand having a particle size in the range of 0.7 to 1.2 mm has both removability and suction stability of deposits and graphitized corrosion parts without mixing particles having different particle sizes such as alumina. Is most preferable.

  In order to solve the above problems, the corroded part removing apparatus of the present invention is connected to a high pressure washer, a nozzle gun to which high pressure water is supplied from a high pressure pump of the high pressure washer through a high pressure hose, and the nozzle gun. The blast hose is inserted from above, and has a blast tank that stores a blasting agent inside, and a carriage is provided at the bottom of the blast tank so that it can be used for the method for removing the corroded portion of the outer surface of each cast iron pipe. It was.

  Thus, if a cart is provided at the lower part of the blast tank, the blast tank can be moved by the cart, so that the heavy blast tank can be easily moved, and the installation of the blast tank on the site can be simplified. it can. Also, in a narrow excavation pit, the nozzle gun is routed toward the outer surface of the cast iron pipe and the graphitized corrosion part, so the blast hose is twisted or bent, and the suction of the blast agent to the blast hose is unstable. However, by moving the blast tank with the carriage according to the handling of the nozzle gun, it is possible to quickly eliminate twisting and bending of the blast hose and to stabilize the suction of the blast agent to the blast hose.

  The blast hose is preferably inserted vertically into the blast tank. In this way, compared to the case where the blast hose is inserted obliquely into the blast tank, the suction of the blast agent is less likely to be interrupted or pulsated to the blast hose. Can be done.

  According to the method for removing a corroded portion of the outer surface of the cast iron pipe of the present invention, the blasting agent and the high-pressure water supplied from the high-pressure pump are jetted together from the nozzle gun toward the deposit and the graphitized corroded portion of the outer surface of the cast iron tube. As a result, the deposits and graphitized corroded parts are removed from the outer surface of the cast iron pipe, so that the blast agent sprayed from the nozzle gun and the deposits and graphite are only ejected from the nozzle gun by a series of operations. Both of the corrosion corrosion parts can be scraped off the outer surface of the cast iron pipe. Therefore, it is easier to remove deposits and graphitized corrosion parts from the outer surface of the cast iron pipe by using various tools such as a scraper, keren hammer, wire brush, and test hammer as in the past. And the graphitized and corroded portion can be removed, and the time required to remove the deposit on the outer surface of the cast iron pipe and the graphitized and corroded portion can be shortened.

The side view which shows the corrosion part removal apparatus of embodiment of this invention Fig. 1 is an enlarged side view of the vicinity of the nozzle gun of the corroded portion removing device FIG. 1 is an exploded exploded perspective view of a blast tank of the corroded part removing apparatus of FIG. (A) is an enlarged perspective view which shows the state which inserted the blast suction pipe diagonally in the blast tank of the corroded part removal apparatus of FIG. 1, (b) is an enlarged perspective view of the oblique insertion jig vicinity of (a).

  A corroded part removing apparatus according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the corroded part removing apparatus 1 includes a high-pressure washing machine 2, a nozzle gun 4 having a nozzle 3 at the tip, and a blast tank 5 in which a blasting agent such as alumina or silica sand is stored.

The high-pressure washing machine 2 is connected to a water supply tank 6 in which the high-pressure pump (not shown) stores water and a water supply hose, and the discharge water pressure of the high-pressure pump can be set to 140 kg / cm ² or more. Is used. For example, model number: SEC-1520 (made by Super Kogyo Co., Ltd.) can be mentioned.

  As shown in FIG. 2, a nozzle gun 4 having a barrel length L of 800 mm, 230 mm, or 120 mm can be used. However, if the barrel length L is too long, Since it is difficult to handle, it is possible to use a short barrel having a barrel length L of about 8 mm.

As shown in FIGS. 1 and 2, a high pressure hose 9 connected to the high pressure pump of the high pressure washer 2 is connected to the nozzle gun 4 and is discharged from the high pressure pump via the high pressure hose 9. High pressure water having a water pressure of 140 kg / cm ² or more is supplied. A blast hose 10 for sucking the blasting agent in the blast tank 5 is connected to the tip of the nozzle gun 4. The high pressure hose 9 and the blast hose 10 are preferably about 10 m long in consideration of the workability in the excavation pit 7 and the workability of the withdrawal operation.

  As shown in FIG. 3, the blast tank 5 has a side surface portion 11 formed in a rectangular parallelepiped shape and a bottom surface portion 12 formed in a quadrangular pyramid shape so that its volume decreases downward. A pedestal 13 is provided at each lower end. The inner and outer surfaces of the side surface portion 11 and the inner and outer surfaces of the bottom surface portion 12 are thermally sprayed with silicon for rust prevention. Thereby, the sliding of the blasting agent in the blast tank 5 is improved, and the suction effect of the blasting agent is increased.

  The blast tank 5 is placed on a transport carriage 15 provided with wheels 14 at four corners of the loading platform in which the pedestal 13 is formed in a square shape, as indicated by the arrows in FIG. Thereby, since the blast tank 5 can be moved by the transporting carriage 15, the heavy blast tank 5 can be easily moved, and the installation of the blast tank 5 at the site can be simplified.

  A lid 17 that closes the upper end opening 16 is attached to the upper end portion of the blast tank 5 so that the internal blast agent does not get wet even in rainy weather so that a part of the lid 17 can see the internal blast agent. It is formed of an acrylic plate 18.

  A drain 19 for discharging the blasting agent is provided at the center of the bottom surface portion 12 of the blast tank 5, and as shown in FIGS. 1 and 3, an upper portion of the blast tank 5 contains the blast tank 5. A blast suction pipe 20 that sucks the blasting agent and an air intake pipe 21 that takes external air into the blast tank 5 are provided.

  The blast suction pipe 20 is inserted vertically from the upper end opening 16 of the blast tank 5 to the vicinity of the drain 19 and is inserted and fixed in the center of the column 22 provided on the lid 17. The blast suction pipe 20 is connected to the blast hose 10 connected to the nozzle gun 4 at the upper end thereof. Thereby, the blast hose 10 is inserted into the blast tank 5 via the blast suction pipe 20. Further, a spring 24 is attached to the guide portion 23 of the blast hose 10 to the blast suction pipe 20 to prevent the guide portion 23 of the blast hose 10 from being bent.

  The air intake pipe 21 is inserted vertically from the upper end opening 16 of the blast tank 5, and is inserted and fixed to the column 22 so that its discharge port is adjacent to the position of the suction port of the blast suction pipe 20. As a result, the air taken into the blast tank 5 from the air intake pipe 21 is easily sucked into the blast suction pipe 20, and the pulsation of the blast hose 10 due to discontinuous suction of the blast agent is reduced.

  The blasting agent stored in the blast tank 5 is cast iron because the iron on the outer surface 26 of the cast iron pipe corrodes and the removability of the outer surface 26 of the duct iron cast pipe 25 embedded in the ground to the deposits such as soil. In consideration of the removability of the graphitized corrosion portion where a large amount of graphite remains on the outer surface 26 of the tube and the suction stability of the blasting agent to the blast hose 10 and the blast suction tube 20, the optimum size is used.

  From the test results to be described later, in alumina, the mixing volume ratio of alumina (# 20) having an average particle size of 20 mesh and alumina (# 60) having an average particle size of 60 mesh is mixed at a ratio of 2: 1 to 1: 2. It was found that it is preferable to use the mixed alumina (# 20 + # 60) and the silica sand having a particle size of 0.7 to 1.2 mm (New Special No. 5A).

  Next, a method for removing a corroded portion of the outer surface 26 of the cast iron pipe using the corroded portion removing apparatus 1 configured as described above will be described.

  First, as shown in FIG. 1, a dug pit 7 having a U-shaped cross section is dug so that a space of about 50 cm is secured beside the pipe and under the pipe toward the ductile cast iron pipe 25 buried in the ground, The ductile cast iron pipe 25 is exposed in the excavation pit 7.

Next, the discharge water pressure from the high pressure pump of the high pressure washer 2 is set to 140 kg / cm ² or more, and the high pressure water is supplied to the nozzle gun 4 via the high pressure hose 9. At this time, a negative pressure is generated in the blast hose 10 and the blast suction pipe 20 by the flow of the high-pressure water supplied to the nozzle gun 4, and this negative pressure causes the blast agent to pass through the blast suction pipe 20 and the blast hose 10 to the nozzle gun 4. The blast agent is sucked from the nozzle 3 together with high-pressure water.

  Then, as shown in FIG. 2, the nozzle gun 4 is routed toward the deposit and the graphitized corrosion portion with the nozzle 3 and the cast iron pipe outer surface 26 separated by about 50 to 100 mm. As a result, the blasting agent sprayed from the nozzle 3 collides with the deposit and the graphitized corrosion portion, scrapes both the deposit and the graphitized corrosion portion from the outer surface 26 of the cast iron pipe, and simultaneously the high-pressure water sprayed from the nozzle 3 Prevent dust from being generated by blasting agent. In this way, deposits and graphitized corrosion portions are removed from the outer surface 26 of the cast iron pipe.

  Here, as described above, since the nozzle gun 4 is routed toward the deposit on the outer surface 26 of the cast iron pipe or the graphitized corrosion portion in the narrow excavation pit 7, the blast hose 10 is twisted or bent to cause blasting. Although the suction of the agent to the blast hose 10 and the blast suction pipe 20 is likely to be unstable, the blast hose 10 is twisted or bent by moving the blast tank 5 with the transport carriage 15 according to the handling of the nozzle gun 4. It can be eliminated quickly and the suction of the blasting agent to the blast hose 10 can be stabilized.

  The method for removing the corroded portion of the outer surface 26 of the cast iron pipe is merely a series of operations in which the blast agent and the high-pressure water are jetted from the nozzle 3 toward the deposit and the graphitized corroded portion of the outer surface 26 of the cast iron tube. Both the deposit and the graphitized corrosion portion can be scraped off from the outer surface 26 of the cast iron pipe by the blasting agent sprayed from. For this reason, it is easier to remove deposits and graphitized corrosion using conventional tools such as scrapers, keren hammers, wire brushes, and test hammers. The portion can be removed from the outer surface 26 of the cast iron pipe, and the time required for removing the deposit and the graphitized corrosion portion can be shortened.

  In the said embodiment, although silica sand and alumina were used as a blasting agent, you may use blasting agents other than silica sand and an alumina. In this case, the blasting agent is mixed in the water supply tank 6 together with water, the discharge water pressure of the high pressure pump of the high pressure washer 2 is increased, and the liquid mixture of the blasting agent and water is supplied to the nozzle gun 4 by the high pressure pump. Then, the mixed liquid may be ejected from the nozzle 3.

  In the above embodiment, as the alumina stored in the blast tank 5, the mixing volume ratio of alumina (# 20) having an average particle size of 20 mesh and alumina (# 60) having an average particle size of 60 mesh is 2: 1 to 1. : Mixed alumina (# 20 + # 60) mixed at a ratio of 2 was used, but the alumina stored in the blast tank 5 may have a particle size in the range of 46 mesh to 80 mesh.

  Moreover, in the said embodiment, although the blast suction pipe | tube 20 and the air intake pipe 21 were inserted perpendicularly | vertically from the upper end opening 16 of the blast tank 5 to the drain 19 vicinity, as shown to Fig.4 (a), the blast tank 5 You may insert diagonally from the side part 11 to the drain 19 vicinity. In this case, the blast suction pipe 20 and the air intake pipe 21 are inserted into the blast tank 5 through a cylindrical oblique insertion jig 27 as shown in FIG. Specifically, the oblique insertion jig 27 is fixed so as to be inserted obliquely into a rectangular fixing member 29 fixed to the side surface portion 11 of the blast tank 5 with a bolt 28.

  Here, as described above, blasting is performed by injecting the blasting agent and high-pressure water together from the nozzle 3 of the nozzle gun 4 toward the deposit and the graphitized corrosion part, and the blasting agent removes the deposit and the graphitized corrosion part. And a test for confirming the suction stability of the blasting agent to the blast hose 10 and the blast suction pipe 20 will be described. The test conditions are shown in Table 1.

  The test results are shown in Table 2. As shown in Table 2, in any of alumina having an average particle size of 46 mesh (# 46), alumina having an average particle size of 60 mesh (# 60), and alumina having an average particle size of 80 mesh (# 80), Both of the graphitized corrosion portions could be removed almost completely from the outer surface 26 of the cast iron pipe. The removal performance was best for # 60, followed by # 46 and # 80.

  With alumina (# 20) having an average particle size of 20 mesh, deposits could be almost completely removed from the outer surface 26 of the cast iron pipe, but some graphitized corrosion portions remained. This is because when the alumina particle size becomes 20 mesh, the alumina particle size becomes too large, and the alumina (# 20) sprayed from the nozzle 3 is less likely to collide with the deep part of the graphitized corrosion part. This is because it becomes difficult to remove the portion. Further, alumina (# 100) having an average particle size of 100 mesh has a small particle size, so that it easily collides with the deep portion of the graphitized corrosion portion, and the removability of the deep portion becomes the best. Therefore, although the graphitized corrosion portion can be removed almost completely, the scraping action of the deposit by alumina becomes too weak, and it becomes difficult to remove the deposit from the outer surface 26 of the cast iron pipe.

  On the other hand, with respect to the suction stability of the alumina blast hose 10 and the blast suction pipe 20, the larger the particle size, the easier the suction is stabilized, and # 20 was the best, but # 46, # 60, # 80 In both of # 100 and # 100, the suction to the blast hose 10 and the blast suction pipe 20 was interrupted, or the blast hose 10 pulsated and the suction became unstable. However, when using a mixed alumina (# 20 + # 60) in which a mixing volume ratio of alumina having an average particle size of 20 mesh and alumina having an average particle size of 60 mesh is mixed in a ratio of 2: 1 to 1: 2, It was found that both the removability of the deposit and the removability of the graphitized corrosion portion and the suction stability were good and excellent in all respects. This is because # 20 where the suction is most stable and # 60 which has the best removability of the deposit and the graphitized corrosion portion are mixed to ensure the removability of the deposit and the removability of the graphitized corrosion portion. This is because the suction to the blast hose 10 and the blast suction tube 20 of alumina can be stabilized.

  In the case of silica sand, when the particle size is 0.7 to 1.2 mm (New Special No. 5A), the removal and suction stability of both deposits and graphitized corrosion parts are good. It turned out that it is excellent in the point.

  Further, the suction stability of the blasting agent to the blast hose 10 and the blast suction tube 20 is as follows: when the blast suction tube 20 is inserted vertically into the blast tank 5 as shown in FIG. 3, and when blast suction is performed as shown in FIG. Comparing with the case where the tube 20 is inserted into the blast tank 5 obliquely, the blast agent is more stably sucked into the blast hose 10 and the blast suction tube 20 when the blast suction tube 20 is inserted vertically into the blast tank 5. I understood that.

2 High pressure washer 4 Nozzle gun 5 Blast tank 7 Excavation pit 9 High pressure hose 10 Blast hose 15 Carriage truck 25 Ductile cast iron pipe 26 Cast iron pipe outer surface

Claims (7)

  The excavation pit (7) is dug toward the ductile cast iron pipe (25) buried in the ground, and adheres to the cast iron pipe outer surface (26) of the ductile cast iron pipe (25) exposed in the excavation pit (7). The blast agent and the high-pressure water supplied from the high-pressure pump are jetted together from the nozzle gun (4) toward the graphitized corrosion portion of the outer surface (26) of the cast iron pipe and A method for removing a corroded portion on an outer surface of a cast iron pipe, wherein the graphitized corroded portion is removed from the outer surface (26) of the cast iron tube.   The blast agent is stored in a blast tank (5), a blast hose (10) connected to the nozzle gun (4) is inserted into the blast tank (5), and the blast hose (9) is inserted into the blast tank (5) via the high pressure hose (9). The blast agent is sucked into the nozzle gun (4) through the blast hose (10) by the negative pressure generated in the blast hose (10) by the flow of high-pressure water supplied to the nozzle gun (4), and the blast The method for removing a corroded portion on the outer surface of a cast iron pipe according to claim 1, wherein an agent is sprayed together with the high-pressure water from the nozzle gun (4).   The method for removing a corroded portion on the outer surface of a cast iron pipe according to claim 2, wherein the blasting agent stored in the blast tank (5) is alumina having a particle size in the range of 46 mesh to 80 mesh.   The blasting agent stored in the blast tank (5) is a mixed alumina in which a mixing volume ratio of alumina having an average particle size of 20 mesh and alumina having an average particle size of 60 mesh is mixed at a ratio of 2: 1 to 1: 2. The method for removing a corroded portion of an outer surface of a cast iron pipe according to claim 2, wherein   The method for removing a corroded portion on the outer surface of a cast iron pipe according to claim 2, wherein the blasting agent stored in the blast tank (5) is silica sand having a particle size in the range of 0.7 to 1.2 mm.   A high pressure washer (2), a nozzle gun (4) to which high pressure water is supplied from a high pressure pump of the high pressure washer (2) via a high pressure hose (9), and a blast hose connected to the nozzle gun (4) (10) is inserted from the upper part, has a blast tank (5) which stored the blasting agent inside, and provided the cart (15) in the lower part of the blast tank (5). The corrosion part removal apparatus used for the corrosion part removal method of the cast iron pipe outer surface as described in any one.   The said blast hose (10) is inserted in the said blast tank (5) perpendicularly | vertically, The corrosion part removal apparatus of Claim 6 characterized by the above-mentioned.

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