# Conductivity change of a tank (glass coating on steel)

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• rollingstein
In summary, the conversation discusses the conductivity change in a tank made of steel coated with glass, and whether a small corrosion spot in the glass would result in a significant change in conductivity that could trigger an alarm. The tank has a volume of 10,000 litres and is cylindrical, with an 8 mm steel wall and 2 mm glass coating. The electrical conductivity of steel is 7x106 Siemens/m and glass lining is 10-11 Siemens/m. It is suggested that even a small crack or hole in the glass could show a change in resistance and trigger an alarm. The process of coating steel and copper with glass is called enamelling.
rollingstein
Gold Member
Suppose I have a tank which is made of steel coated with a thin layer of glass on the inside to protect the steel from corrosion (the material stored inside the tank is corrossive; say for arguments sake Water with 10% Hydochloric Acid).

In theory, till the glass is intact there is an electrically insulating barrier between the steel of the tank and the water inside. My question is, how much would be the conductivity change if the glass broke down at some spot. Say, for calculation's sake a 5 mm dia spot in the glass coating got corroded.

Would the resultant contact between the conductive water and steel be enough to give a significant change in conductivity that could be monitored to trigger an alarm?

Or is the idea technically unfeasable because the change would be too small?

To enable quantitative estimates I looked up some numbers:

Tank Volume: 10,000 Litres
Tank Shape: Cylindrical
Steel Thickness of tank wall: 8 mm
Glass Coating Thickness inside Tank: 2 mm

Electrical conductivity:
Steel 7x106 Siemens/m
Glass lining: 10-11 Siemens/m

Certainly ...you wouldn't need a hole that big either , the smallest crack or hole would show a change in resistance and could trigger an alarm , this would work with ordinary domestic tap water too , which is slightly conductive...

Coating steel and copper with a thin coating of glass is called enamelling , enamelled bowls for domestic purposes were very common a 100 years ago , a thin coating of glass dust applied to the surface , and heat to red heat , the glass melts , bonds to the surface in one continuous protective coating , perhaps half a mm thick

anorlunda

## 1. What is conductivity change and why is it important in a tank with glass coating on steel?

Conductivity change refers to the alteration in the ability of a material to conduct electricity. In a tank with glass coating on steel, conductivity change can indicate the effectiveness of the coating in preventing corrosion or leakage of the tank's contents. It is important to monitor conductivity change to ensure the safety and integrity of the tank.

## 2. What factors can cause conductivity change in a tank with glass coating on steel?

Several factors can contribute to conductivity change in a tank with glass coating on steel. These include exposure to corrosive substances, changes in temperature or pressure, and damage to the glass coating. Additionally, the type and quality of the glass coating itself can also affect conductivity change.

## 3. How can conductivity change be measured in a tank with glass coating on steel?

Conductivity change can be measured using a variety of methods, including conductivity meters, electrical resistance probes, and ultrasonic testing. These techniques can provide information on the electrical properties and integrity of the glass coating on the steel tank.

## 4. What are the potential consequences of significant conductivity change in a tank with glass coating on steel?

If conductivity change is not properly monitored and addressed, it can lead to corrosion of the steel tank, which can compromise its structural integrity and potentially result in leaks or rupture. This can have serious environmental, safety, and financial implications for the tank and its contents.

## 5. How can conductivity change in a tank with glass coating on steel be prevented or mitigated?

To prevent or mitigate conductivity change in a tank with glass coating on steel, it is important to regularly inspect and maintain the tank and its coating. This may include implementing corrosion prevention measures, such as applying protective coatings or cathodic protection, and promptly addressing any damage or deterioration to the glass coating. It is also crucial to monitor conductivity change over time to identify any potential issues and take corrective actions as needed.

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