JPH11106967A - Rust preventing method for opening part in opening work for fluid tube and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely prevent the generation of rust or the like in the opening part bored in a fluid tube. SOLUTION: A water main pipe 2 made of iron and a metallic lump 8 of zinc or the like having an ionization tendency higher than that of the pipe and having a potential lower than that of the pipe are connected by an electric wire 9, and the potential difference is made therebetween, by which a battery of different kinds of metals in which the metallic lump 8 is used as an anode and the opening part 2a is used as a cathode is formed, and the metallic lump 8 is made a sacrificial anode and is consumed to prevent the generation of rust in the opening part 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an existing pipe, for example, a water pipe buried underground, which is subjected to an opening work for connecting a branch pipe or the like, the opening is rusted or corroded. And a method and apparatus for preventing such damage.

[0002]

2. Description of the Related Art In general, when water diversion is performed on a water pipe or the like already laid underground or the like, a water pipe is opened without stopping the flow of water in the water pipe, and then a branch pipe or the like is connected. A continuous water method is used.

[0003] In such a waterless construction method, it is impossible to apply a rust-proofing treatment such as painting to the metal surface of the opening exposed by drilling. It is. As a result, rust may be generated or corroded on the metal surface of the exposed opening, which causes deterioration of water quality.

[0004] In an iron water pipe or the like laid in an electrolyte medium such as soil, the oxygen concentration battery is determined by the difference between the dissolved oxygen concentration in running water in the water pipe and the oxygen concentration of water in soil. By the action, a potential difference is generated between the metal surface of the opening that is being made to flow and the surface of the water pipe that is in contact with the soil, and the metal surface exposed by the perforation is an anode,
A macro cell with the surface of the water pipe as the cathode is formed,
This is because a corrosion current flows from the metal surface.

In order to solve the above problems, in recent years,
There has been provided one in which a sleeve made of a synthetic resin is fitted to the inner surface of the opening after the opening is pierced to perform rustproofing.

[0006]

However, in the rust prevention treatment using the sleeve described above, if the inner surface of the opening is not made smooth, a small gap is formed between the sleeve and the outer peripheral surface. May penetrate and cause rust on the metal surface after drilling.

In addition, the operation of mounting the sleeve in the opening is troublesome and requires a dedicated tool for mounting the sleeve, which increases the cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to prevent rust from being generated in an opening by a simple means without attaching a rust prevention sleeve or the like to the opening. An object of the present invention is to provide a method and a device for preventing rusting of an opening in opening work of a fluid pipe, which can be surely prevented.

[0009]

In order to achieve the above object, a method for preventing rust of an opening according to the present invention comprises opening at least a part of a metal fluid pipe laid in the ground in a flowing water state. In the opening work of branching the fluid from the opening or installing a valve or the like here, the specific metal having a higher ionization tendency than the metal constituting the fluid pipe is electrically connected to the specific metal, It is characterized in that ions are eluted from the specific metal by generating a potential difference between the specific metal and the opening.

[0010] In the above, it is preferable that the fluid in the fluid pipe and the earth and sand in the ground are electrically conducted to have the same potential.

In order to achieve the above object, a rust prevention device according to the present invention is characterized in that at least one of the inside and outside of a fluid near the opening of a metal fluid pipe laid underground is provided by a fluid pipe. Also, a metal lump having a large ionization tendency is provided so as to be electrically connected to the fluid pipe.

In the above-mentioned opening, in which two openings are formed by cutting the fluid pipe, at least one metal block is preferably provided near both openings.

The opening is formed at the center of the pipe axis of the fluid pipe or at an eccentric position in order to branch the fluid through a branch case, a split T-shaped pipe, a saddle, etc., in the vicinity of the opening. Preferably, a metal lump is provided.

It is preferable that the metal lump is zinc or a zinc alloy.

According to the method and apparatus of the present invention, a metal fluid pipe is electrically connected to a low-potential metal mass having a higher ionization tendency so that a potential difference is generated between them. As a result, a dissimilar metal battery in which the metal lump is used as an anode and the opening of the fluid tube is used as a cathode is formed, and the metal lump serves as a sacrificial anode and is consumed, thereby preventing the opening from being rusted. You.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the method and the apparatus of the present invention, and shows an example in which the present invention is applied to an insertion method in which a gate valve device is installed in a water main.

In this insertion method, a water main 2 made of ductile cast iron or the like, which is rust-proof coated on the inner and outer peripheral surfaces and is buried in the soil 1, is cut to a required length and removed.
The gate valve device 3 is installed in a water-free state.

That is, first, the soil 1 at the portion where the gate valve device 3 is installed is excavated to expose the water main 2, and a working pit is formed.

Next, a case 4 is attached to the outer peripheral surface of the water main 2.
Is mounted while maintaining watertightness by a packing 5 and a special pressing wheel 6 with a detachment prevention metal fitting.

Next, a working valve and a drilling machine (both not shown) are attached to the upper end opening of the case 4,
Is cut to a required size, and the cut piece is held by a cutter and removed from above.

Then, after removing the boring machine and inserting the gate valve device 3 to the bottom of the tube of the case 4 by the inserting machine, the inserting machine and the working valve are removed to complete the operation.

FIG. 1 shows the gate valve device 3 after the operation is completed.
The installation state of is shown. Note that the reference numeral 7 indicates that the reduction gear 8
This is a butterfly valve that is rotated together with a valve stem associated with the butterfly valve.

After the gate valve device 3 is installed, the excavated work pit is backfilled, but before the work is performed, the method and the apparatus of the present invention are used to open both pits 2a, 2a of the water main 2. That is, the metal surface exposed by cutting is subjected to rust prevention treatment.

In this rust prevention work, first, the ionization tendency is higher than that of ductile cast iron (or steel pipe), which is the material of the water main 2, on the soil 1 in the vicinity of both the openings 2a, that is, in the excavated work pit. A large and low-potential metal lump 8 made of zinc or a zinc alloy is provided.

Next, the electric wires 9 led out from each metal block 8
The case in which the metal directly contacting the water main 2, that is, the rust preventive coating applied to the outer peripheral surface of the water main 2 is peeled off, and the metal is directly in contact with the metal surface. 4 is connected to the iron cap 10 of the fixing bolt, or is connected to the special pressing ring 6 with the metal fittings for preventing detachment as indicated by the imaginary line.

Thus, the water main 2 and the metal lump 8 are
The metal block 8 is electrically connected to the anode and the water main 2.
A dissimilar metal battery having the opening 2a as a cathode is formed.
In addition, the electric wire 9 is preferably a copper wire or the like having an ionization tendency equal to or lower than that of iron so that the electric wire 9 itself is not consumed.

After the metal block 8 and the water main 2 have been connected in this way, when the pits are backfilled, a potential difference occurs between the water main 2 and the metal block 8, and the metal block 8 on the anode side is removed. It becomes zinc ions and flows out into the soil 1, which is an electrolyte.

Therefore, only the metal block 8 is consumed as a sacrificial anode and is prevented from flowing through the opening 2a.
Even if the oxygen concentration cell action occurs between the flowing water in the water main 2 and the water in the soil, the opening 2
The phenomenon that rust is generated or corrodes on the metal surface of a can be suppressed. This rust prevention effect is continued until the metal block 8 is completely consumed. Therefore, the size of the metal block 8 may be appropriately set according to the service life of the water main 2.

In the first embodiment, in order to eliminate the potential difference between the running water near the opening 2a in the water main 2 and the soil 1, they are electrically connected to each other by the conductive wire 11 to maintain the same potential. You may make it.

In this way, the effect of the oxygen concentration cell function between the running water and the soil 1 is eliminated, and the rust prevention effect of the metal block 8 is further enhanced. Further, the conductive wire 11 is formed in the opening 2a.
, The effect is further improved.

FIG. 2 shows a second embodiment of the present invention.

This embodiment is the same as the above-described first embodiment except that the installation position of the metal block 8 is different.

That is, the two metal blocks 8, 8 are fixed on the bottom surface immediately below both openings 2a in the case 4 by conductive bolts 12 of copper or the like, and a conducting wire 30 extending from the inside thereof is connected to a water main. It is fixed to 2. In this case, before drilling the opening, the tip of the conducting wire 30 extending from the metal block 8 fixed to the case 4 is screwed and fixed to the water main pipe 2 by means such as a screw, and then the hole is drilled in the case 4. Just start.

In this embodiment, the metal lump 8
, And the metal block 8 is consumed as a sacrificial anode, so that rust occurs in the opening 2a as in the first embodiment. Is prevented.

In the second embodiment, since zinc ions flow out into flowing water, it is preferable to apply the present invention not to drinking water but to the main water main 2 for sewage or industrial water. In addition,
Obviously, any metal that does not harm humans can be applied to drinking water.

FIG. 3 shows a third embodiment of the present invention.

In this embodiment, a branch case 14 having a branch pipe portion 13 is attached to the outer peripheral surface of an iron water main pipe 2 buried in the soil 1 while maintaining watertightness, and the drill case is drilled by a drilling machine (not shown). An opening 2a having a C-shaped cross section was formed on the side wall of the water main 2 at a position eccentric from the center of the pipe axis, and applied to a construction in which running water of the water main 2 was branched to the branch pipe 13 side without interruption. Things. Reference numeral 15 denotes a gate valve device for temporarily blocking the flow of water to the branch pipe section 15 side.

In the same manner as in the above embodiment, after the construction is completed and before the work pit is backfilled, a metal lump 8 of the same material, such as zinc, is placed on the soil in the pit near the opening 2a. The lead-out wire 9 is brought into contact with the water main 2 directly by metal, and is connected to the conductive member 40 exposed outside the branch case 14.

When the working pits are backfilled in this state, a dissimilar metal battery having the metal lump 8 as the anode and the opening 2a as the cathode is formed, and the metal lump 8 As a result, rust does not occur on the metal surface of the opening 2a exposed by the perforation.

Although not shown, also in this embodiment, the flowing water and the soil 1 may be electrically connected to each other by a conductive wire, and the metal block 8 may be provided in the branch case 14.

FIG. 4 shows a fourth embodiment of the present invention.

In this embodiment, after a split T-shaped pipe 16 is attached to the outer peripheral surface of an iron water main pipe 2 buried in soil (not shown), a water pipe is inserted from a branch pipe section 17 side. A circular opening 2a is formed in the side wall of the main pipe 2 at the center of the pipe axis,
This is applied to a construction for branching the running water in the water main 2 to the branch pipe 17 side. Reference numeral 18 denotes a gate valve device.

Also in this embodiment, after the construction is completed and before the pits are backfilled, a metal block 8 made of zinc or the like is installed.
The wire 9 derived from this is divided into a split T close to the opening 2a.
It is connected to the flange of the pipe 16 so as to be electrically conductive. As a result, a dissimilar metal battery having the metal lump 8 as an anode and the opening 2a as a cathode is formed, and the metal lump 8 becomes a sacrificial anode and is consumed. It is prevented from occurring.

The present invention is not limited to the above embodiment.

When the metal block 8 is provided outside the water main 2, not only the soil 1 as in the embodiment, but also the outer walls of the cases 4, 16 and the branch case 14, the saddle and the like near the opening 2a. Alternatively, they may be integrally fixed in a conductive manner. At this time, the shape of the metal block 8 may be any shape suitable for the mounting portion.

Even if two openings 2a are formed as in the first and second embodiments, one metal block 8 is used, and two electric wires derived therefrom are connected to the vicinity of each opening 2a. May be connected to an appropriate member.

The material of the metal block 8 is, in addition to the above zinc,
Aluminum or an alloy thereof, magnesium or an alloy thereof, or an alloy of a combination of the three can also be used.

In the above embodiment, the water main pipe 2 has been described as being buried in the soil 1. However, the present invention is also applicable to fluid pipes laid in contact with concrete, seawater, groundwater, etc., in addition to soil. Can. That is, the opening 2a
May be laid in an electrolyte medium in which a potential difference is generated when the metal lump 8 is on the cathode side and the metal lump 8 is on the anode side.

The present invention can be applied not only to the above-mentioned opening work used in the watertight construction method, but also to other opening works of existing pipes in which rust prevention cannot be performed on the opening after drilling.

[0052]

According to the present invention, the following effects can be obtained.

(A) According to the first aspect of the present invention, the fluid pipe and the ionization tendency more easily than the fluid pipe can be used without performing the troublesome work of mounting a rust prevention sleep in the opening as in the conventional case. By using the potential difference between a large low-potential metal and consuming at the expense of only the metal, it is possible to reliably prevent rust and the like from being generated in the opening.

(B) According to the second aspect of the present invention, the effect of the potential difference between the fluid and the earth and sand is eliminated, and the potential difference between the fluid pipe and the metal alone is obtained.

(C) According to the apparatus of the third to fifth aspects, it can be easily provided irrespective of the number and shape of the openings, the positions of the openings, and the shape of the split T-tube, etc., and the structure is extremely high. Because it is simple, it can be implemented at low cost.

(D) According to the invention of claim 6, when applied to an iron-based fluid pipe, the potential difference is large and long-term use is possible.

[0057]

[Brief description of the drawings]

FIG. 1 is a central longitudinal side view showing a first embodiment applied when a gate valve device is installed by an insertion method according to the present invention.

FIG. 2 is a central vertical sectional side view showing a second embodiment in which a metal lump is provided in a case of a gate valve device.

FIG. 3 is a central vertical sectional front view showing a third embodiment applied to a non-water cutting method in which a fluid is branched from an opening eccentrically formed in a water main pipe by using a branch case.

FIG. 4 is a central vertical sectional front view showing a fourth embodiment applied to an uninterrupted water method in which a fluid is branched from an opening formed in the center of a water main pipe using a split T-shaped pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Soil 2 Water main pipe (fluid pipe) 2a Opening 3 Gate valve device 4 Case 5 Packing 6 Special press ring 7 Butterfly valve 8 Metal block 9 Electric wire 10 Cap 11 Conductive wire 12 Conductive bolt 13 Branch pipe section 14 Branch case 15 Partition Valve device 16 split T-tube 17 branch pipe portion 18 gate valve device 40 conductive member

Claims (6)

[Claims] 1. An opening construction in which at least a part of a metal fluid pipe laid underground is opened in a flowing water state, a fluid is branched from the opening, or a valve or the like is installed here. The specific metal having a higher ionization tendency than the metal constituting the fluid pipe is electrically conducted, and by causing a potential difference between the specific metal and the opening, ions are eluted from the specific metal. A rust prevention method for an opening in fluid pipe opening construction. 2. The electric potential of the fluid in the fluid pipe and the earth and sand underground is set to the same electric potential.
Rust prevention method for an opening in fluid pipe opening construction described in 1 above. 3. A metal block having a larger ionization tendency than the fluid pipe is electrically connected to the fluid pipe in at least one of the inside and outside of the fluid near the opening of the metal fluid pipe laid underground. An anticorrosion device for an opening in a fluid pipe opening construction, which is provided so as to conduct. 4. The opening according to claim 3, wherein at least one metal lump is provided in the vicinity of both openings in the case where two openings are formed by cutting the fluid pipe. Rust prevention device for openings in fluid pipe opening work. 5. An opening formed at the center of a pipe axis of a fluid pipe or at an eccentric position in order to diverge a fluid through a branch case, a split T-tube, a saddle, or the like. The rust prevention device for an opening in a fluid pipe opening construction according to claim 3, wherein a metal lump is provided in the vicinity. 6. The rust prevention device for an opening in a fluid pipe opening construction according to claim 3, wherein the metal lump is zinc or a zinc alloy.