JP6913489B2 - Piping, water supply system and water supply method - Google Patents

Description

The present invention relates to piping, a water supply system and a water supply method.

Conventionally, when a copper pipe or the like is used as a pipe for supplying hot water or cold water, if the residual chlorine concentration, chloride ion concentration, etc. in the water flowing in the metal pipe are high, pitting corrosion may occur in the pipe such as the copper pipe. There is. At this time, pitting corrosion can be suppressed by adding a rust preventive to water or replacing a pipe such as a copper pipe with a stainless steel pipe.

For example, there are known metal corrosion-preventing polymers that function as effective corrosion inhibitors over a wide range of pH ranges when introduced as fluid additives (see, for example, Patent Document 1).

Patent No. 4167869

Here, the metal corrosion-preventing polymer described in Patent Document 1 or a commonly used rust preventive is added to water used for industrial purposes, and is used for domestic water such as drinking water and bath water. Has the problem that it cannot be applied to. Further, when a metal tube such as a copper tube is replaced with a stainless steel tube that suppresses pitting corrosion, there is a problem that the cost is high. Therefore, it is preferable to suppress the occurrence of pitting corrosion by another method.

An object of the present invention is to provide a pipe in which the occurrence of pitting corrosion is suppressed, a water supply system in which the occurrence of pitting corrosion in the pipe is suppressed, and a water supply method.

The above problem is solved by, for example, the following means.

<1> A first pipe containing the first metal and a second pipe containing a second metal which is arranged upstream of the first pipe in the water flow direction and has a higher ionization tendency than the first metal. Plumbing with parts.

According to the above configuration, the second piping portion containing the second metal having a higher ionization tendency than the first metal, which is a constituent component of the first piping portion, is located upstream of the first piping portion. As a result, the second metal having a higher ionization tendency is ionized preferentially over the first metal, and pitting corrosion of the first piping portion is suppressed.

<2> An outer pipe portion containing a first metal and through which water flows, and an inner pipe portion containing a second metal having a higher ionization tendency than the first metal in at least a part of the inner wall of the outer pipe portion. , With piping.

According to the above configuration, an inner tube portion containing a second metal having a higher ionization tendency than the first metal, which is a component of the outer tube portion, is located at least a part of the inner wall of the outer tube portion. As a result, the second metal having a higher ionization tendency is ionized preferentially over the first metal, and pitting corrosion of the outer tube portion is suppressed.

<3> When the first metal is iron or copper and the first metal is iron, the second metal is at least one of zinc and magnesium, and when the first metal is copper, the first metal. 2 The pipe according to <1> or <2>, wherein the metal is at least one of aluminum and tin.

Since the first metal and the second metal are in the above combination, the above piping can be suitably applied to the supply of domestic water such as drinking water and bath water, and the cost is low.

<4> A water supply system including the pipe according to any one of <1> to <3>, a water supply source for supplying water to the pipe, and a water supply unit to which water is supplied through the pipe.
<5> A water supply method for supplying water from the water supply source to the water supply unit using the water supply system according to <4>.

According to the water supply system and water supply method having the above configuration, the occurrence of pitting corrosion of pipes is suppressed.

<6> A water supply method in which water to which ions of a second metal having a higher ionization tendency than the first metal constituting a pipe is added is supplied from a water supply source to a water-received portion through the pipe.

As in the above configuration, by adding the ions of the second metal, which has a higher ionization tendency than the first metal constituting the pipe, to the water flowing in the pipe, the occurrence of pitting corrosion of the pipe is suppressed.

<7> The water supply method according to <5> or <6>, wherein the temperature of the water to be supplied is 30 ° C. or higher.

When the temperature of the water to be supplied is 30 ° C. or higher, pitting corrosion of pipes such as copper pipes is likely to occur. Even in such a temperature range, pitting corrosion of pipes can be suppressed by the above water supply method.

According to the present invention, it is possible to provide a pipe in which the occurrence of pitting corrosion is suppressed, a water supply system in which the occurrence of pitting corrosion in the pipe is suppressed, and a water supply method.

It is a schematic block diagram which shows the piping which concerns on 1st Embodiment. It is a schematic block diagram which shows the piping which concerns on 2nd Embodiment. It is a figure which shows the result of water supply in Example 1. FIG. It is a figure which shows the result of water supply in the comparative example 1. FIG.

In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. good.

<Piping>
[First Embodiment]
Hereinafter, an embodiment of the piping of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing piping according to the first embodiment. The pipe 10 according to the first embodiment is arranged upstream of the first pipe portion 1 in the water flow direction with the first pipe portion 1 containing the first metal, and has a higher ionization tendency than the first metal. 2 A second piping portion 2 containing a metal is provided.
In FIG. 1, the arrow indicates the water flow direction.

According to the present embodiment, the second piping section 2 containing the second metal having a higher ionization tendency than the first metal, which is a component of the first piping section 1, is located upstream of the first piping section 1. .. As a result, the second metal having a higher ionization tendency is ionized preferentially over the first metal, and pitting corrosion of the first piping portion 1 is suppressed. In addition, the life of the pipe 10 can be extended.

The first metal is not particularly limited as long as it is usually used as a material constituting a pipe, and for example, iron, copper and the like are preferable from the viewpoint of cost.

The second metal is not particularly limited as long as it has a higher ionization tendency than the first metal. Further, the second metal is preferably one that dissolves as ions in water flowing in the pipe and then adheres to the first pipe portion 1 containing the first metal. As a result, pitting corrosion of the first piping portion 1 can be suitably suppressed.

As the second metal, for example, zinc, magnesium, aluminum, tin and the like are preferable because the ions easily adhere to the first piping portion 1, the reactivity with water is poor, and the influence on the human body is small. Further, when the ions of the second metal are likely to adhere to the first piping portion 1, the ion concentration of the second metal in the water downstream of the piping 10 is reduced, and the water flowing in the piping 10 can be used as drinking water, bath water, or the like. It can be suitably used as domestic water.

When the first metal is iron, the second metal is preferably at least one of zinc and magnesium. When the first metal is copper, the second metal is preferably at least one of aluminum and tin, and the second metal is more preferably aluminum. Since the first metal and the second metal are in the above combination, the above piping can be suitably applied to the supply of domestic water such as drinking water and bath water, and the cost is low. Further, the ions of the second metal are likely to adhere to the first piping portion 1, and pitting corrosion of the first piping portion 1 can be suitably suppressed.

Further, a two-layer pipe having an outer layer portion covering the outer peripheral portion of the second piping portion 2 or a second piping portion 2 having an outer pipe arranged on the outer peripheral portion of the second piping portion 2 and being an inner pipe, and an outer pipe. It may be a double pipe with a pipe. The outer layer portion and the outer pipe are not particularly limited as long as the constituent materials are less soluble in water than the second metal constituting the second piping portion 2. With these configurations, water leakage in the piping can be suppressed.

In the pipe 10 of the present embodiment, for example, an existing pipe (for example, a copper pipe) is used as the first pipe part 1, and the second pipe part 2 (for example, an aluminum pipe) is connected to the existing pipe. May be good.

[Second Embodiment]
Next, another embodiment of the piping of the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram showing the piping according to the second embodiment. The pipe 20 according to the second embodiment contains the first metal, and has a second outer pipe portion 3 through which water flows and at least a part of the inner wall of the outer pipe portion 3 has a higher ionization tendency than the first metal. It includes an inner pipe portion 4 containing a metal.
Since the first metal and the second metal are the same as the first metal and the second metal used in the above-described first embodiment, the description thereof will be omitted.
In FIG. 2, the arrows indicate the water flow direction.

According to the present embodiment, the inner tube portion 4 containing a second metal having a higher ionization tendency than the first metal, which is a component of the outer tube portion 3, is located at least a part of the inner wall of the outer tube portion 3. .. As a result, the second metal having a higher ionization tendency is ionized preferentially over the first metal, and pitting corrosion of the outer tube portion 3 is suppressed. In addition, the life of the pipe 20 can be extended.

The pipe 20 may be a pipe (for example, a two-layer pipe) in which the inner pipe portion 4 is arranged so as to cover at least a part of the inner wall of the outer pipe portion 3, preferably the inner wall of the outer pipe portion 3. ..

The material constituting the outer pipe portion 3 is the same as that of the first piping portion 1, and the material constituting the inner pipe portion 4 is the same as that of the second piping portion 2.

<Water supply system>
The water supply system according to the first embodiment of the present invention includes the pipes according to the first and second embodiments described above, a water supply source for supplying water to the pipes, and a water supply unit to which water is supplied through the pipes. According to such a water supply system, the occurrence of pitting corrosion of pipes is suppressed.

The water supply source is not particularly limited as long as it has a configuration in which water is supplied to the water-received portion through the above-mentioned piping. For example, it may be a water source that supplies domestic water such as drinking water and bath water to the water supply unit.

The water-received portion is not particularly limited as long as the water is supplied from the water supply source through the above-mentioned piping. For example, it may be around the kitchen, bathroom, washroom, toilet, etc. of a detached house, an apartment house, a commercial facility, a public facility, or the like.

<Water supply method>
In the water supply method according to the embodiment of the present invention, water is supplied from the water supply source to the water supply unit by using the water supply system described above. According to such a water supply method, the occurrence of pitting corrosion of the pipe is suppressed.

The water supplied from the water supply source is preferably domestic water such as drinking water and bath water. For example, hypochlorous acid (HClO) and hypochlorite ion (ClO ^{−) that contribute to sterilization, oxidation reaction, etc.} ) And other residual chlorine components may be contained. The concentration of the residual chlorine component in water may be 1.0 ppm or less, or 0.1 ppm to 1.0 ppm. The concentration of chloride ions in water may be 200 ppm or less.

The temperature of the water to be supplied may be 30 ° C. or higher, 50 ° C. or higher, 60 ° C. or higher, or 80 ° C. or higher. When the temperature of the water to be supplied is 30 ° C. or higher, pitting corrosion of pipes such as copper pipes is likely to occur, but even in such a temperature range, pitting corrosion of pipes can be suppressed.

Further, the water supply method of the present invention is not limited to the method using the water supply system described above. For example, in the water supply method according to the embodiment of the present invention, water to which ions of a second metal having a higher ionization tendency than the first metal constituting the pipe is added is supplied from the water supply source to the water supply portion through the pipe. You may.

By adding the ions of the second metal, which has a higher ionization tendency than the first metal constituting the pipe, to the water flowing through the pipe, the occurrence of pitting corrosion of the pipe is suppressed.

The concentration of the ions of various secondary metals in water is preferably equal to or lower than the upper limit of the water quality standard based on the Waterworks Law from the viewpoint of preferably suppressing the occurrence of pitting corrosion of pipes and reducing the influence on the human body.

In addition, a compound containing a second metal which becomes an ion of the second metal in water may be added to water. Further, the ion of the second metal is not limited to the ion of the second metal alone, and the second metal may form an ion together with other elements.

The compound containing the second metal may be any compound containing zinc, magnesium, aluminum, tin and the like, and examples thereof include polyaluminum chloride, sodium succinate, potassium succinate, zinc chloride and magnesium chloride.

In the water supply system and the water supply method in the present embodiment, a mechanism for removing the ions of the second metal in the water flowing in the pipe on the downstream side of the pipe in the water flow direction, for example, adsorbing and removing the ions of the second metal in the water. , A filter for separating may be used. Thereby, the ion concentration of the second metal in water can be suitably reduced.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
In this example, aluminum ions were added to highly corrosive water, and the water to which aluminum ions were added was used as a copper pipe (inner diameter 1.0 cm, length 10 cm, and in this example, a half-divided copper pipe was used). The effect of preventing pitting when it was poured into the aluminum was examined. The details are as follows.

First, in water (80 ° C., pH 7.0) containing 1.0 ppm of residual chlorine and 100 ppm of chloride ions, polyaluminum chloride ([Al ₂ (OH) _n Cl _6-n ] _m 1 ≦ n ≦ 5) was used as an aluminum ion source. , M ≦ 10) 10 ppm was added, and water to which polyaluminum chloride was added was prepared. Next, water added with polyaluminum chloride was supplied to a beaker having a water supply section and a drainage section on the left and right wall surfaces at a flow rate of 4 L / hour, and the above-mentioned copper pipe was immersed in the water stored in the beaker.
The concentration of polyaluminum chloride in the water in the beaker was 10 ppm. The temperature of the water in the beaker was adjusted to 80 ° C. by a thermocouple, a temperature controller and a mantle heater. Furthermore, the copper pipe and the reference electrode (SSE: saturated silver / silver chloride electrode) were connected by a lead wire so that the potential of the copper pipe could be measured.

Water containing polyaluminum chloride was continuously allowed to flow in a beaker in which the copper pipe was immersed for one month, and then the inside of the copper pipe was confirmed. The results are shown in FIG.
As shown in FIG. 3, no pitting corrosion was observed inside the copper pipe. In addition, a white film derived from aluminum ions in water was observed on the inner surface of the copper pipe.

Further, the potential of the copper pipe after continuing to flow water containing polyaluminum chloride into a beaker for one month was measured using a reference electrode (SSE: saturated silver / silver chloride electrode) and found to be 100 mV.

[Comparative Example 1]
Next, when highly corrosive water to which aluminum ions were not added was passed through a copper pipe (inner diameter 1.0 cm, length 10 cm, in this comparative example, a half-divided copper pipe was used), pitting The outbreak was examined. The details are as follows.

First, water (80 ° C., pH 7.0) containing 1.0 ppm of residual chlorine and 100 ppm of chloride ions was prepared. Next, in the same manner as in Example 1, water without adding aluminum ions was supplied to the beaker at a flow rate of 4 L / hour, and the above-mentioned copper pipe was immersed in the water stored in the beaker.

After continuing to flow water without adding aluminum ions into a beaker in which the copper pipe was immersed for one month, the inside of the copper pipe was confirmed. The results are shown in FIG.
As shown in FIG. 4, pitting corrosion was observed inside the copper pipe.

Further, the potential of the copper pipe after continuing to flow water without adding aluminum ions into the beaker for one month was measured using a reference electrode (SSE: saturated silver / silver chloride electrode) and found to be 180 mV.
In Comparative Example 1, a higher potential was measured than in Example 1, but considering that pitting corrosion occurred in Comparative Example 1, the potential measured in Comparative Example 1 was higher than the pitting potential. It is presumed to be a noble potential.

From the results of Example 1 and Comparative Example 1, it was shown that the occurrence of pitting corrosion of copper pipes can be suppressed by adding aluminum ions to water.

1 1st piping part 2 2nd piping part 3 Outer pipe part 4 Inner pipe part 10, 20 Piping

Claims (2)

Comprising compounds der Ru polyaluminum chloride containing aluminum is larger ionization tendency second metal than copper is a first metal constituting the pipe is added water (provided that the corrosion inhibitor other than polyaluminum chloride A water supply method for supplying water (excluding water) from a water supply source to a water supply section through the pipe. The water supply method according to claim 1 , wherein the temperature of the water to be supplied is 30 ° C. or higher.

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