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. Microbiologically influenced corrosion (MIC), which affects a wide range of infrastructure and sectors, has an impact on the production of oil, electricity, transportation, and water and wastewater.
Microbiologically Influenced Corrosion (MIC) is a persistent threat to the integrity of storage tanks in various industries. This form of corrosion occurs when microorganisms, such as bacteria or fungi, colonize the internal surfaces of the tanks and produce corrosive byproducts. In this blog post, we will explore the identification, prevention, and control of MIC corrosion in storage tanks. Understanding these key aspects is crucial for mitigating the damage caused by MIC and ensuring the longevity of storage tank assets.
Metals and alloys exposed to corrosive environments, such as soils, water, and industrial chemicals, are subject to accelerated corrosion due to MIC. The cost of corrosion, which includes diminished material strength and/or loss of containment, has been estimated to be 20% higher when some microbes’ corrosive organic secretions (such acetate) are involved.
Identifying MIC Corrosion in Storage Tanks:
Detecting MIC corrosion in storage tanks can be challenging, as it often remains unseen until significant damage has occurred. However, early identification is essential to prevent further deterioration and mitigate potential risks. Here are some methods for identifying MIC corrosion:
Visual Inspection: Regular visual inspections can reveal signs of corrosion, such as localized pitting, discoloration, or unusual deposits on the tank surfaces. Pay attention to areas where stagnant water or biofilms are likely to form.
Microbiological Testing: Collecting samples from the tank surfaces and conducting microbiological tests can confirm the presence of microorganisms associated with MIC. These tests can identify the specific types of bacteria or fungi present and their potential for corrosive activity.
Corrosion Monitoring: Monitoring the corrosion rate of the tank’s surfaces using techniques like electrochemical testing or weight loss analysis can provide insights into the presence of MIC corrosion. An increased corrosion rate compared to expected values can indicate the influence of microorganisms.
Non-Destructive Testing: Employing non-destructive testing methods, such as ultrasonic thickness measurements or X-ray imaging, can assess the thickness of the tank walls and detect localized corrosion or thinning caused by MIC.
Early identification of MIC corrosion allows for timely intervention and preventive measures, reducing the potential for severe damage and costly repairs.
Prevention of MIC Corrosion in Storage Tanks:
Preventing MIC corrosion in storage tanks requires a comprehensive approach that addresses both the environmental conditions conducive to microbial growth and the corrosion mechanisms associated with microorganisms. Here are some preventive measures to consider:
Material Selection: Choosing materials resistant to MIC, such as stainless steel or corrosion-resistant alloys, for constructing storage tanks can minimize the risk of corrosion caused by microorganisms.
Protective Coatings: Applying protective coatings or linings to the internal surfaces of storage tanks creates a physical barrier that inhibits the attachment and growth of microorganisms. These coatings should be compatible with the stored liquids and provide long-term protection against corrosion.
Biocides and Antimicrobial Treatments: Implementing biocides or antimicrobial treatments can control microbial populations and prevent their corrosive activity. However, careful consideration must be given to the selection and application of these treatments to avoid adverse effects on the stored liquids or the environment.
Environmental Control: Creating an environment unfavorable for microbial growth is crucial in preventing MIC corrosion. Measures such as maintaining proper tank ventilation, controlling temperature and humidity levels, and reducing the availability of nutrients can help inhibit the proliferation of microorganisms.
Controlling MIC Corrosion in Storage Tanks:
When MIC corrosion is already present in storage tanks, controlling its progression becomes essential to limit further damage. Here are some strategies for controlling MIC corrosion:
Cleaning and Biofilm Removal: Regular cleaning and removal of biofilms from the tank surfaces can disrupt the colonization of microorganisms and prevent the formation of localized corrosion sites.
Biocide Treatment: Implementing targeted biocide treatments can control and eliminate microbial populations responsible for MIC corrosion. However, it is crucial to follow appropriate guidelines for biocide selection, concentration, and application to ensure effectiveness while minimizing potential risks.
Cathodic Protection: Installing cathodic protection systems, such as sacrificial anodes or impressed current systems, can mitigate MIC corrosion by redirecting the flow of electrons away from vulnerable areas of the tank’s structure.
Monitoring and Maintenance: Implementing a comprehensive monitoring and maintenance program allows for regular assessment of the tank’s condition. This includes inspections, corrosion monitoring, and microbiological testing to detect any signs of MIC corrosion and take appropriate actions promptly.
MIC corrosion poses a significant threat to the integrity of storage tanks, but identification, prevention, and control strategies can help minimize its impact. Through proactive measures such as visual inspections, material selection, protective coatings, and targeted treatments, industries can safeguard their storage tanks and prolong their lifespan, ensuring the safe containment of valuable liquids.
To discuss any of the concepts described here in more detail, our friendly and experienced customer service team can help. We offer tried and tested services around Houston, Texas, and Longbeach, California.
Call us at +1 800 656 0167
Or email us at info@storagetankinspections.com
