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Cathodic Protection

Cathodic Protection Links

Impressed Current CP Rectifier Reading Form

The recordkeeping requirements for a UST system equipped with Impressed Current cathodic protection are different from those systems equipped with sacrificial anodes. Not only does the system need to be tested every three years by a cathodic protection tester, readings from the rectifier need to be visually examined and recorded every sixty (60) days. (A tank owner or operator or a person familiar with the cathodic protection system may make these 60-day readings.) It is not enough to just look at the rectifier and visually verify that the system is operating properly. An inspector will expect to see evidence that this is being done. The Impressed Current Cathodic Protection Rectifier Reading Form (CN-1282) may be used to verify that those readings are being made. The form has space for a lot of information and not all of the data may be available at each location. At a minimum, the date of the reading, the on/off status of the rectifier, the DC output readings and the initials of the person making the reading should be recorded every 60 days. Many tank owners keep rectifier readings in a plastic sleeve attached to the inside of the door of the rectifier box if size permits, so it is always handy and doesn't get mixed up with other paperwork. The person making the readings should be familiar with the initial settings for the system when it was first installed or when it was last tested. Any significant variances from those readings should be noted and a corrosion professional consulted. Readings that deviate from normal readings could mean that some component of the system has been damaged or has ceased to function properly and the desired protection for the UST system is not being provided.

Cathodic Protection (CP) Testing Form

The Division has developed two different testing forms for cathodic protection testing designed to be used to test each method of cathodic protection. These two forms replace the single form that was used to test both passive (galvanic) systems as well as impressed current systems. These are official state forms and test results on forms other than these forms will not be acceptable. The Impressed Current Cathodic Protection Testing Survey (CN-1309) is used to record the test results of impressed current systems and the Galvanic Cathodic Protection Testing Survey (CN-1140) is used to to record the test results of passive (galvanic) systems.

The Division does not currently license or approve individuals as cathodic protection testers. Many individuals with training and experience in this field could be qualified to do cathodic protection testing. Some individuals have completed training courses offered by the National Association of Corrosion Engineers (NACE) and may have certification from that organization. Other individuals may have completed similar training courses and received recognition or certification from other entities. The Division strongly recommends that a tank owner seek out the services of trained and qualified individuals for their required CP testing. The CP testing forms contain a statement that the individual performing such testing has "sufficient education and/or experience to meet the definition of cathodic protection tester in Tennessee and (is) competent to perform the tests indicated". If you hire a tester to do CP testing, be sure he signs the statement and stands behind his test results.

Impressed Current Testing Criteria

The Division recently published guidance to Compliance Inspectors regarding the criteria for testing cathodic protection of impressed current systems. The criteria for passing impressed current systems are slightly different from testing criteria for passing a galvanic system. Cathodic protection testers should be aware of the different criteria. You should be aware that if you have a test performed and the tester uses the wrong criteria to pass the test, it may have to de redone. That could result in additional expense and or inconvenience to you. Click here to read the memo.

Adding Cathodic Protection to a Previously Lined Tank andAdding Additional Anodes to a Cathodically Protected Tank

In 2001 the Division issued a memorandum covering what must be done when a tank owner decides to add additional anodes to a cathodically protected tank. This situation could occur if a protected tank were accidentally shorted to another structure and the factory-installed anode(s) were depleted. It is possible that repairs or modifications to a previously installed tank system could compromise the effectiveness of the cathodic protection systems. This is another reason for the requirement that these systems be checked for proper operation every three years.

The memorandum also described what must be done if a tank owner elects to add cathodic protection to a tank which has been internally lined at an earlier time. A tank owner may elect to do this rather than conduct a periodic internal inspection of the tank lining. The Tennessee Petroleum underground Storage Tank rules require the inspection of the tank lining within 10 years after lining and every five years thereafter. If cathodic protection is added to a lined tank, internal inspections are no longer required if the proper procedures have been followed. This memo describes the procedures and how a tank owner may avoid further mandatory inspections of the internal lining. March 22, 2001 memo.  Addendum to memo.

Use Of A Video Camera to Inspect Lined Tanks

The division allows the use of a video camera to inspect lined tanks. When lined tanks are inspected using a video camera, the evaluation must conform to the procedures described in the KWA Recommended Practice for Inspecting Buried Lined Steel Tanks using a Video Camera, 4.200, dated March (2000) or they will not be acceptable to meet the requirement of the inspection required in Rule 1200-1-15-.02(4)(a)3.(ii). A list of companies that the Division has received an acceptable Third Party evaluation according to the KWA Recommended Practice can be seen here.