JPS592113Y2 - Corrosion-proof structure for piping - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a corrosion protection structure for metal piping in an environment where current flows.

Specifically, it is a corrosion-proof structure for piping intended to prevent corrosion of the metal piping connected to the insulating pipe in an environment where electric current flows out of the metal piping connected to the insulating pipe.

In metal piping constructed with insulating pipes interposed to prevent current from leaking through the piping, if the inner wall of the piping leaks with electrolyte solution, the metal piping located on both sides of the insulating pipes. A phenomenon occurs in which a minute current flows from the side where the potential is higher to the side where the potential is lower, corroding the tip of the metal piping on the side where the potential is higher.

In order to prevent the above phenomenon, a sacrificial electrode is installed between the insulating pipe and the metal pipe on the higher potential side of the metal pipe connected to the above insulating pipe through an insulating gasket. A structure in which the electrodes are electrically connected is known.

For example, in an electrolyzer in which multiple electrolytic cells are electrically connected in series and the gas outlet of each electrolytic cell is connected to one gas collection metal header with metal piping, the header is connected as shown in Figure 1. 2 and the gas outlet of the electrolytic cell 1 are constructed with an insulating pipe 4 interposed therebetween, and an insulating packing 5 is provided between the metal pipe 3 on the side with a higher potential and the insulating pipe 4. A sacrificial electrode 6 is attached through it.

By electrically connecting the metal pipe and the sacrificial electrode, corrosion of the metal pipe, which occurs when the inner wall of the pipe gets wet with the electrolyte mist entrained in the gas taken out from the gas outlet, is prevented. There is.

In the structure of the piping to which the sacrificial electrode is attached as described above, the sacrificial electrode is generally made of the same material as the metal piping, but a sufficient corrosion prevention effect is not obtained.

That is, by attaching the sacrificial electrode, current flows out from the sacrificial electrode, and corrosion of the metal pipe can be prevented to some extent, but since both are made of the same material, current also flows out from the metal pipe through the liquid film on the inner wall. Corrodes piping.

It is also conceivable to use a material that is electrically less noble than the metal pipe as the sacrificial electrode, but this results in a problem that the amount of elution is large, shortening the replacement period, and complicating maintenance management of the device.

As a result of repeated studies to solve the above problem, the inventors of the present invention found that
By providing the sacrificial electrode in an insulating pipe and spacing it from the metal piping for the purpose of corrosion prevention, the liquid film resistance on the inner wall of the piping between the metal piping and the sacrificial electrode is increased. He discovered that it was possible to cause current to flow out, and completed the present invention.

That is, the present invention provides a method for installing a sacrificial electrode in a metal pipe connected to an insulating pipe in an environment where current flows, and connecting the metal pipe and the sacrificial electrode. It has an anti-corrosion structure.

In other words, in the present invention, even if the electrolyte solution is completely filled in the pipe, the electrolyte solution will continue to flow through the pipe and the electrolyte solution as a condensate even if it adheres to the pipe wall. This structure prevents electrolytic corrosion of metal piping (including the device's discharge nozzle, etc.) through which current flows.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

FIG. 2 is a sectional view of a typical embodiment of the present invention.

In the present invention, the piping is constructed by connecting an insulating pipe 4 to a metal pipe 3-1 in an environment where current flows.

The structure of the present invention is suitably applied when the material of the metal pipe 3-1 is a metal that is easily corroded by current flow, such as iron, copper, or stainless steel.

In particular, when the material is iron, the above-mentioned corrosion is severe and it is particularly preferably applied.

Further, the insulating pipe 4 may be made of an insulating material and having the necessary strength without any particular limitation.

For example, rubber, polypropylene. Polyvinyl chloride, Teflon, etc. are commonly used.

For the connection between the metal pipe 3 and the insulating pipe 4, any known pipe connection method may be used without any particular restriction.

For example, a method in which the connection portion between the metal pipe 3 and the insulating pipe 4 is tightened with bolts as a flange structure, a method in which the insulating pipe 4 is inserted into the metal pipe 3, etc. are common.

Further, in the present invention, the length of the insulating pipe may be such that it can sufficiently secure the mounting position of the sacrificial electrode, which is determined by the conductivity of the electrolyte solution that wets the inside of the pipe during use, as will be described later.

Generally, it is sufficient that the length is 199 mm or more.

The connection of the other insulating pipe 4 is not particularly limited.

For example, when applied to the electrolytic cell, it may be a gas outlet of the electrolytic cell.

The feature of the present invention is that in the above-mentioned piping, the insulating pipe 4
The sacrificial electrode 6 is provided on a part of the inner wall, and the sacrificial electrode is connected to the metal pipe 3-1 connected to both sides of the insulating pipe 4.

By providing the sacrificial electrode on the insulating pipe 4 as described above, it is possible to create a space between the metal pipe and the sacrificial electrode, and even if the inner wall of the pipe is wet with the electrolyte solution, current can be selectively passed from the sacrificial electrode. It can be made to flow out.

The sacrificial electrode increases the resistance of the electrical path formed by the liquid film of the electrolyte solution existing between the metal piping on the higher potential side and the sacrificial electrode, and increases the resistance between the sacrificial electrode and the metal piping on the higher potential side. It is preferable to install the metal pipe as far away from the metal pipe as possible so that the current flows preferentially from the part to which the metal pipe is electrically connected.

The above distance varies somewhat depending on the conductivity of the electrolyte solution that wets the inner wall of the pipe, but is generally 10 mm or more, preferably 59 mm or more.
It may be set to mm or more.

Note that the above-mentioned interval refers to the distance from the connection between the metal pipe and the sacrificial electrode to the tip of the sacrificial electrode.

Furthermore, if the mounting position of the sacrificial electrode 6 is too far away from the metal pipe 3-1, current may flow to the other metal pipe 3-1.
2, the distance from the metal pipe 3-2 may be shortened, leading to an increase in leakage current.

Therefore, it is preferable that the mounting position be spaced a certain distance from the metal pipe.

The interval may be approximately 20 mm or more.

In the present invention, the sacrificial electrode is attached to an insulating pipe 4.
There is no particular restriction as long as it comes into contact with the electrolyte solution present within.

For example, it is common to attach a sacrificial electrode to the inner wall of an insulating pipe, or as shown in the figure, a sacrificial electrode 6 is interposed in the middle of the insulating pipe as a flange structure to form the insulating pipe 4. .

Further, in order to uniformly protect the metal pipe from corrosion, the sacrificial electrode is preferably exposed on the inner periphery of the insulating pipe.

Further, as a means for electrically connecting the sacrificial electrode 6 and the metal pipe 3, any known method may be used without particular limitation.

Generally, it is preferable to make the above connection using an electric conductor from outside or inside the piping.

As understood from the above description, the structure of the present invention allows current to selectively flow out from the sacrificial electrode even when the inner wall of the pipe in an environment where current flows is wetted with an electrolyte solution.

Therefore, the sacrificial electrode can be made of the same material as the metal pipe, and the sacrificial electrode replacement synchronization can be extended.

The present invention is suitably applied to piping that connects a gas outlet of a cathode chamber of a diaphragm electrolyzer using the ion exchange membrane, asbestos diaphragm, or the like as a diaphragm and a gas collection header.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional structure for attaching a sacrificial electrode to a pipe. FIG. 2 is a sectional view showing a typical aspect of the piping of the present invention. In addition, in the figure, 1 is an electrolytic tank, 2 is a gas collection header, 3.3-1.3-2 is metal piping, 4 is an insulating pipe,
5 indicates an insulating packing, and 6 indicates a sacrificial electrode.

Claims (5)

[Scope of utility model registration request] (1) In a pipe in which an insulating pipe is connected to a metal pipe in an environment where current flows, a sacrificial electrode is provided in the insulating pipe, and a corrosion-proof structure for the pipe is formed by connecting the metal pipe and the sacrificial electrode. . (2) Scope of claim for utility model registration (1) where the piping is iron piping connecting the diaphragm electrolyzer cathode chamber and the gas collection header
Structure described. (3) The structure according to claim (1) for utility model registration, wherein the length of the insulating pipe is 100 mm or more. (4) The structure according to claim (1), in which the sacrificial electrode is attached to the metal pipe at a distance of 10 mm or more. (5) The structure according to claim (1), wherein the sacrificial electrode is made of the same material as the metal pipe.