Storage Tanks External Bottom Cathodic Protection

حفاظت کاتدی کف خارجی مخازن

One of the problems in the oil and gas industry is the corrosion of the aboveground tanks external bottom, which causes a lot of damage to these industries annually. Tanks external bottom cathodic protection is used as a complementary coating method to prevent this type of corrosion. The Tanks external bottom cathodic protection is accomplished in two ways: sacrificial anode and impressed current and can be temporary (short-term) or permanent (long-term). In the sacrificial anode cathodic protection method, usually is used magnesium or zinc anodes with the backfill, depending on the electrical resistivity of the soil. The impressed current cathodic protection method is used cast iron (HSCI) or mixed metal oxide (MMO) anodes depending on the required current rate and design life.


Impressed current anodes are positioned to protect the tanks external bottom can be in three general forms: shallow and deep well or anode lattice. In shallow case, the anodes are placed around the tank bottom at a designated distance.

Schematic of tanks bottom cathodic protection by impressed current method using MMO or HSCI anodes as shallow anode bed

Schematic of tanks bottom cathodic protection by impressed current method using MMO or HSCI anodes as shallow anode bed

 

In the tanks bottom cathodic protection with the deep well anode bed, wells are drilled at a designated distance from the tank and the anodes are inserted.

Schematic of tanks bottom cathodic protection by impressed current method using MMO or HSCI anodes as deep well anode bed

Schematic of tanks bottom cathodic protection by impressed current method using MMO or HSCI anodes as deep well anode bed

 

In the case of anode lattice usage, the ribbon MMO anodes and the conductor bars are placed as the lattice with the appropriate infrastructure before the tank is installed.

Schematic of tanks bottom cathodic protection by impressed current method using MMO anodes as anode lattice

Schematic of tanks bottom cathodic protection by impressed current method using MMO anodes as anode lattice

Since it is not possible to access the anodes beneath the tank after the tank is installed, it is important to pay attention to the quality of the anodes and their connections before installing the tank.

Installing ribbon MMO anodes in tanks bottom cathodic protection by impressed current method Installing ribbon MMO anodes in tanks bottom cathodic protection by impressed current method

Installing ribbon MMO anodes in tanks bottom cathodic protection by impressed current method

Borna Electronics Co. with over 30 years of experience in cathodic protection, declares its readiness to design, procurement, consultation and construction of cathodic protection systems for aboveground tanks external bottom and implement cathodic protection monitoring systems for them.