Environmentally Friendly, Low Maintenance, Corrosion Control

Environmentally Friendly, Low Maintenance, Corrosion Control Method for Fuel Storage Tanks Addressing Common Root Causes of Corrosion in Fuel Storage Tanks

Our retail/commercial fuel delivery industry has spent a lot of time and money researching a problem already addressed in bulk storage and distribution of refined distillates.  Recognizing the same basic systems, the same basic problems, it is sensible to think that the methods that stop or minimize the problem in one is applicable to the other. For damaging corrosion to occur in a fuel storage tank, conditions supporting the corrosion process must exist.

If the conditions that support corrosion are understood it would be prudent to employ methods that have already been proven successful at preventing corrosion rather than just cleaning up and or replacing damaged equipment using temporary methods that will just have to be repeated until an imminent structural failure causes contemplation of lining or replacement of the storage tanks. Treating symptoms of problems while allowing the root cause to continue to reoccur means we allow the continued degradation of equipment, fuel, and infrastructure. After lining or replacement of the tank is performed, what prevents the cycle from repeating?

Treat the Symptoms or Prevent the Root Causes of the Problem

It is disingenuous to suggest that there is only one problem that causes corrosion. Our industry has faced corrosion issues since we began to store products in containers. What is unique is the Aggressive Corrosion that has attacked the infrastructure in our retail fueling systems since 2006. While there more we could learn, what we know is:

There is bacteria that reproduces fast, the bacteria excretes acids as a waste, that acid damages tanks and equipment and sumps.

The bacteria needs food, water, and oxygen (O2) to reproduce and live.

The bacteria is present in the fuels we deliver, in the air and in water. Even if you kill the bacteria in the tank, if water, oxygen and food are present, the bacteria will be reintroduced and grow again. 

The food is present in the tanks, it is the ethanol, the biodiesel, it is even the hydrocarbons now. There is no shortage of available food in the tanks. 

Stop the Water and Oxygen From Entering the Tank -- Stop the Aggressive Corrosion

Methods to control corrosive atmospheres in fuel tanks have been implemented for over 8 years and are currently being used in bulk fuel storage tanks in refineries, terminals and airports worldwide. Methods commonly defined as “Nitrogen (N2) Gas Blanketing” (padding) are used to prevent the formation of corrosion conditions in the ullage (empty space) and to prevent vapor flash conditions. Understand that in typical fuel storage tanks, the ullage has sucked in moist outside air as fuel is sold. Even fuel storage tanks without fuel movement “breath” as the vent and fuel warm and cool. As such, water vapor condenses on the tank top, contributing the water needed. The oxygen is likewise replenished.

 A pressure/vacuum vent is installed on the tank vent. Relatively low cost, dry N2 (nitrogen) is generated or supplied onsite. As the tank pressure falls, the detected drop in pressure is filled with dry N2. No moisture, no O2 enter the tank, therefore with no bacterial growth there is no acidified vapor to corrode equipment or tank components. No corrosive acidified vapor forced into the tank sumps(s). 

Stopping the corrosion in the tank ullage, rust particles no longer form piles called colonies on the tank bottom that contribute to highly acidified fuel and concentrated acid on the tank bottom. 

Quality of Stored Product 

Most refined fuels experience quality degradation when it comes into contact with oxygen, moisture, or other contaminants. Blanketing stored fuel such as generator fuel with a slight pressure (2in.water column) of dry N2 prevents air with oxygen, a known oxidizer and water vapor that condenses on the cool tank interior. Water supports the corrosive environment and O2 supplies the oxidizer to degrade the fuel.