Corrosion Control Alternatives for Aboveground Storage Tanks

Underground and aboveground tanks are important parts of all farms and industrial facilities. These are used for the collection and storage of petroleum and food products, wastewater, chemicals, and water, among other materials. The most common material option for these tanks is steel. This is because of its durability and strength that are essential to withstand the rigors typical of large scale storage. Unfortunately, steel is prone to corrosion resulting from various electrochemical, chemical, and environmental reactions with it.

PVC tank liners are among the commonly used options for the barrier protection of steel tanks from corrosion. These provide a protective layer between the steel and destructive elements that contribute to its corrosion. The liners are resistant to most alkalis and acids stored in the tanks and come in different temperature and chemical resistance limits to meet the needs of all industries.

Here are the other control options of corrosion in steel tanks:

Galvanic Cathodic Protection

This corrosion protection alternative relies on the difference in energy levels between various materials for the provision of a driving potential. Steel will be used as the cathode since it has a high energy level. The anode in the reaction is generally zinc or magnesium. This is sacrificed to protect the steel from various reactions that would corrode it.

The galvanic protection systems are primarily maintenance-free, though the anodes are periodically replaced. The corrosion protection potential of this option is unfortunately limited. It can only be used on small surface areas on your tank or its coated portions.

Impressed Current Protection Systems

rust on oil barrels

Here, electric local AC power is converted into a direct current (DC) using a rectifier. This current will then be distributed from anodes in the soil around your tank and disrupt reactions with the steel. The anode materials, in this case, are those with a low consumption rate to guarantee their prolonged life even in high current. Impressed current protection systems protect large areas of the tank. They are, however, mostly used in underground tanks.

Corrosion Inhibitors

These are compounds comprising chemicals that prevent corrosion. The inhibitors are applied to the inner or outer layer of your tank in various forms. They generally avert corrosion through the removal of dissolved oxygen from your stored electrolyte. This way, reduction and oxidation reactions will not occur between the tank’s steel and its contents.

Tank Isolation

If you have a small aboveground tank, you can minimize its risk of corrosion by isolating it from the soil. This is because the ground contains conductive electrolytes that will react with the steel and lead to its corrosion. You can separate your small tank by placing it on saddles if it is horizontal and adding structural members for vertical tanks. After this, you can protect the tank from atmospheric corrosive elements using a good-quality coating material.

The above control options go a long way in prolonging the service life of your tank by protecting it against corrosion. They are, however, not enough. You will need an expert to conduct thorough inspections of the tank regularly. This helps in early identification of corrosion and the employment of remedial measures before the tank fails or is completely corroded.

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