Preventing Ethanol Corrosion In Storage Tanks.

With the introduction of Ethanol into the fuels we use, as a method of reducing greenhouse gasses and to lower the use of carbon fuels commonly associated with road transport, there is an increasing need to protect storage tanks from the corrosion caused by these bio-fuels. Adding Ethanol to fuel provides a method of high octane for increased engine performance as well as the environmental and economic advantages that this type of fuel can provide, such as decreasing the harmful emissions from vehicle exhausts. An unfortunate side effect of this is that it increases the corrosion attacks on storage tanks, which causes heavy pitting and scarring, and if left untreated eventually to holes in the tank and leaking product into the surrounding environment. The higher the concentration of Ethanol in the fuel the greater the corrosive attacks on certain metals, plastics and rubbers.

Examples of corrosion

Examples of corrosion found in storage tanks.

Special considerations when storing Ethanol

Tank and terminal owners need to be aware and take special considerations when storing Ethanol blended products. One particular concern is phase separation, where the Ethanol separates from the fuel; Ethanol rich water sinks to the bottom and the fuel rises to the top creating an unbalanced blend, containing water and increasing corrosion risks to the storage tank. Any existing corrosion in steel Storage tanks will be exacerbated by the Ethanol mixture and eventually lead to loss of product and environmental contamination. The use of Ethanol will only increase and is a major concern for oil companies, it is therefore extremely important that tanks and tank components are constructed of the correct materials or suitably protected and regular maintenance and monitoring take place. However even in the best maintained tanks this kind of corrosion can be a problem.

How can we protect our tanks?

One proven method of protecting storage tanks from this aggressive type of corrosion is to internally coat the tank itself with either a single skin solvent free coating resistant to the stored fuel, or alternatively install a double skin system such as Abfad Ltd’s Fuelvac® double skin tank liner, which also provides 24/7 vacuum leak detection monitoring. Once the original steel of the tank has been refurbished and coated with the solvent free resin, the interstice (the space between the original steel wall and the newly installed liner) can be monitored by creating a vacuum which is constantly monitored and if breached alerts the operator immediately; due to the double wall created by the system all stored product remains contained within the tank.

This double layer of protection in storage tanks may seem unnecessary to some, but when considered against the alternative, such as expensive tank replacement, associated major downtime, the loss of product into the environment and the increasing fines that come from breaching strict anti-pollution laws, it pays for companies to be pro-active to these problems rather than reacting only when a breach of the tank has occurred and the issue then becomes serious.

Single skin tank lining

Single skin solvent free lining of an above ground storage tank.

The purpose behind monitoring and lining tanks is good management and enables environmental influence, giving operators the ability to control and contain any potential disaster.

Bio-fuels are here to stay and their use will increase greatly in the foreseeable future, therefore the correct storage tank protection is not only necessary, but vital, to protect our environment and maintain valuable assets.

Double skin tank lining with vacuum monitoring system

Underground storage tank double skin lined and monitored with Abfad’s Fuelvac system.

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