JPH0815207A - Lining breakage detecting method for surface treated vessel - Google Patents

Abstract

PURPOSE:To provide a lining breakage detecting method for a surface treated vessel, by which a breakage of a plastic lining layer can be detected in its early stage. CONSTITUTION:A metallic can body 1 of a surface treated vessel is made negative, an electrode 4 dipped in a chemical 3 is made positive, and d.c. voltage is applied by a d.c. power supply source 5. If a broken part is found in a plastic lining layer 2, the chemical 3 enters the part and an electric current flows through a circuit. The current is detected by a current detector 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting damage to a lining of a surface treatment tank such as a chromium plating tank and an etching tank using chromic acid.

[0002]

2. Description of the Related Art As a surface treatment tank as described above, one having a structure in which a plastic lining layer such as a hard vinyl chloride resin having excellent corrosion resistance is formed on the surface of a metal can body is widely used. There is. Then, such a plastic lining layer may be damaged due to cracks due to heat cycle or collision with a work.

[0003]

However, such damage is difficult to detect in the initial stage, and in a short time, the steel can body is dissolved by chromic acid, and the chemical liquid containing chromic acid leaks out. There was a risk of being connected. The present invention has been made to solve the above conventional problems and to provide a method for detecting damage to a lining of a surface treatment tank, which enables early detection of damage to the plastic lining layer.

[0004]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, provides a negative electrode for a metal can body of a surface treatment tank whose inner surface is plastic-lined and which is immersed in a chemical solution. Apply DC voltage as a plus,
It is characterized in that the presence or absence of a current flowing through this circuit is used to detect the presence or absence of damage to the plastic lining layer.

[0005]

According to the present invention, if the plastic lining layer is damaged, the chemical liquid penetrates into the part and a current flows through the circuit, so that the damage of the lining layer can be immediately detected. Since the direct current voltage is applied with the can body being negative and the electrode immersed in the chemical liquid being positive, there is also an effect that dissolution of the can body by the chemical liquid can be suppressed.

[0006]

The present invention will be described in more detail below with reference to the illustrated embodiments. In FIG. 1, 1 is a can of a surface treatment tank made of metal such as steel, and 2 is a plastic lining layer such as hard vinyl chloride resin coated on the inner surface. 3 is a chemical solution containing chromic acid filled in the surface treatment tank, and 4 is an electrode immersed in the chemical solution 3. 5 is a DC power source such as a battery,
A direct current voltage is applied with the can 1 being negative and the electrode 4 being positive. Reference numeral 6 is a current detector for detecting the current flowing in this circuit. The current detector 6 may be composed of an ammeter with an alarm contact and a buzzer, or a meter relay and a buzzer.

In the case of the embodiment, the voltage of the DC power supply 5 is
It is 10-12V. If the plastic lining layer 2 has no breakage, no current flows in the circuit due to the insulating effect of the plastic lining layer 2. However, if there is a breakage, the chemical liquid 3 enters the breakage and current flows in the circuit. The detector 6 detects this current and issues an alarm. Since the polarity of the circuit is such that the can body 1 is negative and the electrode 4 is positive as described above, there is also an effect that the dissolution of the can body 1 by the chemical liquid 3 can be suppressed.

In the case of a surface treatment bath for plating,
An anode for electrolysis can be used as the electrode 4. In the case of chromate treatment or pickling, an insoluble electrode, platinum, carbon, lead or the like can be used as the electrode 4.

Most of the can body 1 is grounded, but if a conductive heat exchanger, pump, pipe or the like is attached to the chemical solution 3, these are dissolved by stray current. It is not preferable to apply a voltage because there is a risk of damage. Therefore, in such a case, by floating the surface treatment tank above the ground, the present invention can be carried out without trouble. However, in the case of chromate treatment or pickling in which a conductive device is not installed inside the tank, it is not necessary to float the tank above the ground.

In the above embodiment, the circuit was constructed by installing the independent DC power source 5, but when the object to be treated is the cathode such as plating or cathodic electrolytic degreasing, the power source for that purpose should be used as it is. You can also

[0011]

As described above, according to the present invention, if the plastic lining layer 2 is slightly damaged, a current flows through the circuit, and the current detector 6 detects this current and issues an alarm. Can be issued.
Therefore, unlike the conventional case, there is no possibility that the steel can body 1 is dissolved by the chromic acid and the chemical liquid flows out.
Further, according to the present invention, it is possible to surely detect a damaged portion at any position as long as it is below the liquid surface of the chemical liquid 3, which is effective for early detection of damage. Therefore, the present invention greatly contributes to the industry as a lining damage detection method for a surface treatment tank which solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 can body, 2 plastic lining layer, 3 chemical solution,
4 electrodes, 5 DC power supply, 6 current detector

Claims (1)

[Claims] 1. A plastic lining is applied depending on the presence / absence of a current flowing in this circuit by applying a DC voltage with the metal can body of a surface treatment tank having an inner surface plastic-lined as a minus and an electrode immersed in a chemical solution as a plus. A method for detecting damage to a lining of a surface treatment tank, characterized by detecting whether or not a layer is damaged.