How to Prevent Corrosion in Storage Tanks

One of the most effective ways to prevent storage tank corrosion is by installing an internal barrier lining. These linings create an impermeable shield between the tank wall and its contents, preventing water, oxygen, and chemicals from reaching the metal. Drop-in liners, like those from Perfect Fit Tank Liners, are pre-fabricated membranes often made of flexible PVC that fit inside the tank to physically separate the liquid from the structure.

In addition to corrosion protection, drop-in liners offer significant practical advantages. They can be installed quickly without the need for abrasive blasting or curing time, reducing operational downtime. Their modular design also allows for easier inspection, repair, or full replacement without permanently altering the tank. This makes them an efficient and less disruptive solution for demanding industrial environments.

What is Storage Tank Corrosion?

Storage tank corrosion refers to the gradual degradation of a tank’s construction material due to chemical reactions with its environment. This occurs in tanks made out of carbon steel, and the corrosion manifests as rust. Over time, storage tank corrosion leads to loss of wall thickness, pitting, and structural damage.

Here are several types of corrosion that can affect storage tanks:

• •Uniform Corrosion: This is the even rusting of metal across broad areas. While it reduces metal thickness uniformly, it’s often predictable and can be managed by corrosion allowances or monitored by thickness gauges. Most steel water tanks will exhibit uniform rust if not properly lined.
• •Pitting Corrosion: This is a more dangerous, localized form of corrosion. Small spots penetrate deeply into the metal while the rest of the surface appears intact. Pitting is common at the bottom of tanks where water may settle and concentrate. Pitting can perforate a storage tank’s floor, causing pinhole leaks.
• •Crevice and Weld Corrosion: Seams, gaskets, and weld areas often corrode faster because they can trap liquid or have residual stresses. Welds may have slightly different compositions or microstructures, which can corrode if not fully protected.
• •Microbiologically Influenced Corrosion: Bacterial activity can also cause corrosion in tanks, especially water or fuel tanks. Certain bacteria create corrosive byproducts like hydrogen sulfide acid under deposits, leading to pitting. Diesel storage tanks are known to have this because of water contamination and their ability to foster bacterial growth.

What Causes Corrosion in Storage Tanks?

Storage tank corrosion is driven by a combination of chemical and physical factors. Understanding the major causes of storage tank corrosion is important for prevention. Below are some examples that relate to electroplating baths, electroless plating tanks, water tanks, and secondary containment structures:

• •Exposure to corrosive chemicals: The nature of the liquid being stored is often the biggest factor that can cause corrosion. Many liquid chemicals are inherently corrosive to common tank materials like steel. Strong acids and alkalis will aggressively attack steel surfaces, stripping away protective oxide films and dissolving metal ions.
• •Water and oxygen: Even water can cause corrosion if the tank material is susceptible. Steel water storage tanks will rust due to dissolved oxygen and minerals unless they are lined. Corrosion is essentially an electrochemical reaction requiring moisture and oxygen. Thus, any portion of a tank exposed to water and air together is prone to corrosion.
• •Damaged protective coatings: If a tank’s protective coating or lining is improperly applied, has thin spots, or gets damaged, those exposed areas become sites that corrode rapidly. For example, if an epoxy coating inside a tank was not uniformly applied, a patch might blister and break, exposing steel to the liquid.
• •Microbial activity: In water or fuel tanks, bacterial growth can produce corrosive byproducts such as hydrogen sulfide. Slime-forming bacteria can create differential oxygen cells under their colonies, leading to pitting in the metal beneath.

The Dangers of Storage Tank Corrosion

Unchecked corrosion in storage tanks can lead to serious and costly consequences. As the tank’s metal thins and weakens, the risk of leaks, environmental contamination, structural failure, and safety hazards grows. Below are some of the most serious dangers posed by storage tank corrosion:

• •Leakage and environmental contamination: The most immediate danger is that a corroded tank develops a leak, releasing its contents. Depending on what is stored, this can be an environmental disaster. Corrosion is the leading cause of aboveground storage tank failures, often resulting in spills that contaminate the surroundings.
• •When a tank holding hazardous liquids fails, it endangers workers and the public. One real-world instance occurred in Michigan in 2019, where a plating facility’s storage tank allowed a bright “green ooze” of hexavalent chromium, a carcinogen, to seep through a basement and leak onto a highway. Thus, tank corrosion is not just a maintenance issue; it’s a critical safety concern.
• •Regulatory and legal consequences: Corrosion-related spills often bring regulatory penalties and cleanup liabilities. Environmental laws impose heavy fines for uncontrolled releases of hazardous substances. In an era when regulators penalize spills aggressively, tank owners who delay corrosion prevention face significant costs in fines and cleanup.

Why PVC Tank Liners Are the Best Solution for Corrosion Prevention

Given the challenges and dangers of tank corrosion, many industries turn to PVC drop-in liners as a superior solution for corrosion prevention. PVC tank liners are flexible membranes custom-fabricated to fit inside a tank. They form an inner layer that contains the liquid and completely shields the tank’s structural shell from contact. For electroplating tanks, chemical process tanks, water storage, and secondary containment, PVC liners offer several key advantages:

• •Complete barrier protection
• •Excellent chemical resistance
• •Custom fabrication for a perfect fit
• •Easy installation and minimal downtime
• •Long-term durability and flexibility
• •Cost-effectiveness

Drop-In PVC Tank Liners vs. Epoxy Coating

When choosing a corrosion protection strategy for a storage tank, two prevalent options are installing a drop-in PVC liner or applying an epoxy internal coating. PVC liners like those offered by Perfect Fit Tank Liners offer greater reliability and ease. Epoxy coatings demand more meticulous care and come with more uncertainty.

Drop-in PVC tank liners provide a complete physical barrier between the liquid and the tank structure. In contrast, epoxy coatings rely on strong adhesion, making them vulnerable to pinholes, blistering, and cracking. PVC liners can handle a wide range of chemicals and do not require curing, significantly reducing downtime. Epoxy coatings, on the other hand, require extensive surface preparation—such as sandblasting—and multiple curing stages, which can take a tank out of service for several days.

Flexible PVC liners are not bonded to the tank, allowing them to accommodate wall movement, expansion, contraction, and even small cracks in the substrate. Epoxy is a rigid film with limited flexibility. Any structural movement may lead to coating failure.

Why Storage Tank Owners Partner With Perfect Fit Tank Liners

Perfect Fit Tank Liners is a leading provider of custom PVC drop-in liners, and many tank owners collaborate with them to solve corrosion issues. With over 40 years of experience in manufacturing tank liners, we understand the unique challenges of plating tanks and other tanks that hold harsh chemicals.

Perfect Fit Tank Liners also stand apart with our Express Tank Liner Service—custom liners can be fabricated and ready to ship within 48 hours for urgent needs. Contact our team of experts to learn how Perfect Fit Tank Liners can help you extend tank life, reduce maintenance costs, and prevent corrosion with confidence.