How to Conduct a Cathodic Protection Inspection of Water Storage Tanks

A galvanic cathodic protection system for underground storage tanks consists of sacrificial anodes attached to the Underground Storage Tank during manufacturing and specifies wiring for an inspection station installed near the ground’s surface. Galvanic systems have limited life spans during which the sacrificial anode degrades and protects the tank or piping. When the sacrificial anodes can no longer protect the tank or piping, they lose their effectiveness and begin to corrode.

Impressed Current Cathodic Systems

The impressed current cathodic protection system usually provides electrodes with a much longer life span than a galvanic anode. These systems include a rectifier that converts the alternating current power source to a direct current that is properly calibrated to provide the required protection. Since the power source is delivered to the electrode and is not generated by the degradation of the electrode, the power supply to the electrode may be recalibrated to provide additional power, when needed, as long as the electrodes are still functional.

Checklist for Impressed Current Cathodic Protection Systems

You need to have a periodic test conducted by a third-party inspector to make sure your cathodic protection system is adequately protecting your UST system. This test needs to be conducted:

  • At least every 1 year after the previous test.
  • Within 60 days after any repairs to your UST system.
  • Keep the results of at least the last two tests on file.
  • Inspect your rectifier and record the readings at least every 60 days to make sure that it is operating within normal limits. 
  • Keep records of the operating life of the facility.
  • Never turn off your rectifier!

What Cathodic Protection Does

Cathodic protection is an electrical technique for preventing corrosion. Cathodic protection prevents underground tanks and lines from corroding by utilizing the natural energy found in all metallic substances. In layman’s terms, anodes are metal substances buried in the ground near the tank and lines. The anodes are interconnected by a wire and contain a high level of natural energy. Natural energy causes electricity to flow through the soil, wire, and buried metal. The buried anodes completely dissolve into the soil over time, preventing corrosion of the steel tank or lines. Cathodic protection systems are classified into two types: impressed current and sacrificial anode. Impressed current systems necessitate the use of an external power source, whereas sacrificial anode systems do not.

Three Tips for Maintaining Your Cathodic Protection System and Extending its Working Life

1. Are you having regular inspections?

Regular testing and inspection are advised to ensure that your system is in good working order. Establishing a monitoring and logging system can also aid in corrosion prevention efforts.

Inspections and a planned maintenance schedule can also ensure that you are in accordance with the most recent Federal regulations. The regulations also require that your system be tested by a qualified cathodic protection tester within six months of installation and every three years after that.

However, if you wait three years to test the system, the amount of damage to steel tanks and lines that can occur if your cathodic protection system hasn’t been working is enormous.

2. Is your cathodic protection system providing the correct amount of protection against corrosion?

A rectifier control box is usually located near the tank monitor in impressed current protection systems. A volt meter is always present in the rectifier box, and an amp meter with a red/green indicator light is optional. These meters and indicator lights only indicate that power is present, not whether it is sufficient. Corrosion protection is disabled if the system’s indicator light is red. Contact a cathodic protection specialist right away.

3. Is wiring exposed to the system?

Look for any broken or disconnected wires around the tanks. These wires are most likely part of the cathodic protection system. A broken wire could cause a part of the system to malfunction, indicating that the system is not providing corrosion protection. Contact your cathodic protection professional to determine if these wires are part of the cathodic protection system. If the exposed wires are part of the cathodic protection system, repairs will be required to ensure there are no exposed wires. It should always be kept in mind that any digging in the area of the tank field could very easily disable the cathodic protection system. If you have any concerns you should contact your cathodic protection specialist.

Does your underground tank need a cathodic protection inspection?

We offer tried and tested services in Crockett, Grapeland, Kennard, Latexo, Lovelady, Ratcliff, HOUSTON, TEXAS. 

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