Preventing MIC Corrosion: Essential Steps for Storage Tank Longevity

Microbiologically Influenced Corrosion (MIC) is a persistent and damaging form of corrosion that affects storage tanks in various industries. MIC occurs when microorganisms colonize the internal surfaces of tanks, leading to corrosion and potential structural failures. Preventing MIC corrosion is crucial for ensuring the longevity and integrity of storage tanks. In this blog post, we will discuss essential steps for preventing MIC corrosion, including proactive measures, regular inspections, and the use of appropriate coatings and treatments.

Corrosion that is influenced by microorganisms like bacteria, fungi, and microalgae is known as microbiologically influenced corrosion, or MIC. While microorganisms do not specifically cause any particular types of corrosion, they can speed up corrosion reactions or change the way that corrosion works. Rapid corrosion of metals and alloys exposed to soils, seas, distilled water, freshwater, crude oil, hydrocarbon fuels, process chemicals, and sewage has been linked to microbial action. MIC has an impact on a wide range of infrastructure and sectors, including those that produce oil, power, transport, water, and wastewater.

Understanding MIC Corrosion 

MIC corrosion is a complex process influenced by the presence of microorganisms, which can include bacteria, fungi, or archaea. These microorganisms form biofilms on the internal surfaces of storage tanks, creating an environment that promotes localized corrosion. The biofilms produce corrosive byproducts that attack the tank’s structural material, leading to material degradation and potential failure.

Understanding the factors contributing to MIC corrosion is essential. These factors include the presence of specific microorganisms, the availability of nutrients, temperature, pH levels, and the presence of oxygen or other electrochemical conditions favorable for corrosion.

MIC corrosion can lead to various consequences, such as reduced tank capacity, compromised structural integrity, increased maintenance costs, and potential leaks or environmental contamination. Preventing MIC corrosion is crucial for maintaining the longevity and reliability of storage tanks.

Proactive Measures to Prevent MIC Corrosion 

Taking proactive measures is key to preventing MIC corrosion in storage tanks. By addressing the factors that contribute to MIC, industries can significantly reduce the risk of corrosion. Here are some essential steps to consider:

Material Selection: Choose materials that are resistant to MIC corrosion when constructing storage tanks. Consider using stainless steel, corrosion-resistant alloys, or linings that can withstand the corrosive environment created by microorganisms.

Environmental Control: Control the tank’s environment to minimize conditions favorable for MIC corrosion. This includes maintaining proper ventilation, controlling temperature and humidity levels, and removing stagnant water or organic matter that can serve as nutrient sources for microorganisms.

Nutrient Management: Limit the availability of nutrients necessary for microorganism growth. Control the levels of nitrogen and phosphorous, as excessive amounts can promote microbial proliferation. Implement proper water treatment processes to remove excess nutrients.

Biocide Treatments: Consider the use of biocide treatments to control microbial populations and inhibit biofilm formation. Biocides can be applied periodically or continuously, depending on the specific needs and conditions of the storage tank.

Coatings and Linings: Apply protective coatings or linings to the internal surfaces of storage tanks. These coatings create a physical barrier that inhibits the attachment and growth of microorganisms, protecting the tank’s structural material from corrosion.

By implementing these proactive measures, industries can significantly reduce the risk of MIC corrosion and ensure the longevity of their storage tanks.

Regular Inspections and Monitoring 

Regular inspections and monitoring are vital for detecting early signs of MIC corrosion and taking prompt action. Here are some essential steps to include in the inspection and monitoring process:

Visual Inspection: Conduct regular visual inspections of the internal surfaces of storage tanks to identify signs of biofilm formation, corrosion, or other indicators of MIC corrosion. Pay close attention to areas prone to microbial growth, such as corners, crevices, or areas with stagnant water.

Non-Destructive Testing (NDT): Utilize non-destructive testing techniques, such as ultrasonic thickness measurements or electrochemical testing, to assess the thickness and integrity of the tank’s structural material. NDT can identify localized corrosion or thinning caused by MIC.

Microbiological Testing: Collect samples from the tank’s surfaces and conduct microbiological testing to identify the presence of microorganisms associated with MIC corrosion. These tests can help determine the specific types of microorganisms present and their potential for corrosive activity.

Corrosion Monitoring: Implement corrosion monitoring systems that continuously measure and analyze corrosion rates within the storage tank. These systems provide real-time data on the corrosion processes and can help identify any abnormal corrosion activity associated with MIC.

Regular inspections and monitoring allow for early detection of MIC corrosion, enabling prompt intervention and preventive measures to be taken to mitigate the damage.

Coating and Treatment Options

The use of appropriate coatings and treatments can help prevent MIC corrosion in storage tanks. Consider the following options:

Corrosion-Resistant Coatings: Apply coatings specifically designed to resist MIC corrosion. These coatings form a protective barrier that inhibits microorganism attachment and provides long-term protection against corrosion.

Biocide Treatments: Implement biocide treatments to control microbial populations and prevent biofilm formation. Biocides can be applied periodically or continuously to inhibit the growth of microorganisms responsible for MIC corrosion.

Passivation Treatments: Utilize passivation treatments to create a protective layer on the tank’s surfaces, making them more resistant to corrosion. Passivation treatments involve applying chemicals or inhibitors that enhance the natural corrosion resistance of the tank’s material.

Consult with corrosion experts and coating manufacturers to select the most suitable coatings and treatments based on the specific requirements and conditions of the storage tank.

Preventing MIC corrosion in storage tanks is crucial for maintaining their longevity and reliability. By implementing proactive measures, conducting regular inspections and monitoring, and utilizing appropriate coatings and treatments, industries can significantly reduce the risk of MIC corrosion. Taking these essential steps ensures the integrity of storage tanks, minimizes maintenance costs, and preserves the safety and reliability of stored substances.

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