Wisconsin Administrative Code
Department of Agriculture, Trade and Consumer Protection
ATCP 90-139 - Trade and Consumer Protection
Chapter ATCP 93 - Flammable, Combustible, And Hazardous Liquids
Subchapter V - General UST Storage and Underground Piping
Section ATCP 93.520 - Corrosion protection

Universal Citation: WI Admin Code ยง ATCP 93.520

Current through August 26, 2024

(1) GENERAL.

(a) Where required. Vent lines, vapor lines and any portion of a single or double-wall tank system, whether new or existing, that routinely contains product and is in contact with the ground or with water shall be protected from corrosion by one of the following methods:
1. The tank and piping are constructed of an inherently corrosion-resistant material.

2.
a. The tank and piping are installed at a site that is determined by a certified corrosion expert to be non-corrosive during the operational life of the system.

b. A certified corrosion expert retained for the purpose of determining a non-corrosive site shall make at least one personal visit to each tank site during the design stage.

Note: See ATCP Table 93.200-5 for information on contacting NACE.

3. The tank is a listed composite or jacketed tank designated as complying with UL 1746, and the piping is protected by one of the methods in this subsection.

Note: In addition to composite and jacketed tanks, the UL 1746 standard also includes requirements for coated tanks and tanks with pre-engineered cathodic protection systems. These last 2 types of cathodic protection are not included in the blanket approval under this section.

4. The tank and piping are protected with a sacrificial anode system in accordance with a standard developed by a nationally recognized association or independent testing laboratory that is acceptable to the department.

5.
a. The tank and piping are protected with a corrosion protection system designed by a certified corrosion expert and comply with either sub. (2) or (3).

b. A corrosion expert retained for the purpose of designing an impressed current corrosion protections system shall make at least one personal visit to each tank site during the design stage.

(b) Design and construction.
1. To allow for periodic testing, new and replacement factory- or field-installed corrosion protection systems shall have appropriate connections, insulated lead wires and accessible test stations, including as specified in subds. 2. and 3.

2. All lead wires connected to a tank, anode, reference electrode, or other component associated with the corrosion protection system shall terminate at a test station.

3. The termination of each lead wire at a test station shall be clearly labeled or coded to identify the specific component to which it is connected.

4. Impressed current systems shall be designed to prevent stray current conditions that may negatively impact other underground structures, utility lines, or cable anchors, or any impressed current systems protecting those items.

5. Local utilities shall be notified by the contractor when impressed current systems are installed, repaired, or adjusted, including where an increase in rectifier amperage or voltage output occurs.

(c) Operation and maintenance.
1. Operation and maintenance of corrosion protection systems shall be in accordance with national standards acceptable to the department.

2. All new and existing corrosion protection systems shall be operated and maintained to continuously provide corrosion protection for the life of the tank system.

3. For impressed current systems, operation and maintenance practices and procedures shall be evaluated, and conducted in a manner that minimizes direct current interference to or from any underground structure, utility line, or cable anchors in the area.

(d) Periodic testing requirements.
1.
a. All new and existing corrosion protection for UST systems shall be tested within 6 months of installation or repair and at least annually, except as provided in subd. 3.

b. For sacrificial anode systems, structure-to-soil potential readings shall be conducted with a minimum of one local potential measurement near the UST center and away from the anodes and one remote potential measurement. Alternatively, a minimum of three potential measurements, one at each of the UST ends and one near the center of the UST, may be taken.

Note: This requirement is from NACE standard TM-0101.

bm. For impressed current systems, structure-to-soil potential readings shall be conducted with a minimum of three potential measurements, one at each of the UST ends and one near the center of the UST.

Note: This requirement is from NACE standard TM-0101.

c. For each product line, structure-to-soil potentials shall be taken above the piping, at the ends and middle, away from the anode locations. Piping runs over 50 feet shall have additional readings taken every 25 feet.

d. For impressed current systems, the annual test shall include instant-off potentials.

2. In addition to the requirements in subd. 1., impressed current corrosion protection systems shall be inspected and evaluated by the site operator at least every 60 days to ensure the equipment is providing adequate current in accordance with its design.

3. Tanks designated as sti-P3® equipped with a preinstalled sacrificial anode system and test station shall be tested in accordance with all of the following:
a. Testing shall occur within 6 months of installation and at least every 3 years thereafter until the tank is 10 years old.

b. Testing shall occur annually in accordance with subd. 1. after the tank is 10 years old.

4. The results of the inspections, evaluations and testing under this paragraph shall be summarized on the department's form, TR-WM-141, and retained at the site in accordance with s. ATCP 93.500(9).

Note: Form TR-WM-141, UST Corrosion Protection Test/Survey Report, is available from the Bureau of Weights and Measures, PO Box 8911, Madison, WI 53708-8911, or at telephone (608) 224-4942, or from the Bureau's Web site at https://datcp.wi.gov/Pages/Programs_Services/PetroleumHazStorageTanks.aspx.

Note: Section ATCP 93.500(9) specifies retention requirements for testing and repair records of corrosion protection systems.

(e) Certifications for corrosion protection.
1. A certified cathodic protection tester shall be on the site to supervise and monitor the initial post-installation start-up of impressed current corrosion protection systems.

Note: NACE requires a person with Senior Corrosion Technologist certification or higher for corrosion protection system commissioning.

2. A certified cathodic protection tester shall perform or supervise the performance of reinstallation or replacement of anodes.

Note: NACE requires a person with Level 1 Cathodic Protection Tester certification or higher for reinstallation or replacement of anodes.

3.
a. All new and existing corrosion protection for UST systems shall be tested by a certified cathodic protection tester, except as provided in subd. 3. b.

Note: NACE requires a person with corrosion technologist certification or higher or a person with corrosion technician certification who is directly supervised by a certified corrosion technologist or higher to perform work as a state-certified cathodic protection tester.

b. Tanks designated as sti-P3® shall be tested by a person holding a certification from the Steel Tank Institute or one of the certifications in subd. 3. a.

Note: Additional information on corrosion protection certifications is available from the department's Web site at https://datcp.wi.gov/Pages/Programs_Services/PetroleumHazStorageTanks.aspx.

(2) SACRIFICIAL ANODE SYSTEMS.

(a) General. All new and existing sacrificial anode systems shall maintain the standard protection threshold reading of at least negative 850 millivolts or shall comply with the requirements of par. (b).

(b) Failing sacrificial anode systems.
1. Unless arrangements are made with the authorized agent or the department to conduct follow-up testing, the cause of the failure shall be investigated and repaired within 90 days of the failed reading; or the entire tank system shall be emptied within 90 days of the failed reading and shall remain empty until the repair is completed.

2. If more than 2 years have elapsed since the previous corrosion protection test, or if the corrosion protection system has been inoperative for 2 years or more, an internal inspection shall be performed by a third party in accordance with one of the following standards:
a. For lined tanks, the internal inspection shall be in accordance with API 1631 or KWA.

b. For unlined tanks, the internal inspection shall be in accordance with ASTM G158 Method B.

3. If the tank fails the internal inspection, one of the following shall occur:
a. The tank system shall be permanently closed.

b. The tank system shall be lined or any present lining shall be repaired in accordance with API 1631, and an impressed current corrosion protection system shall be installed.

4. After an inspection under this paragraph, if the tank is not closed under subd. 3. a., a precision tightness test shall be performed on the tank system in accordance with s. ATCP 93.515(4). In addition, a tightness test shall be performed on the ullage portion of the tank in accordance with s. ATCP 93.515(10).

(3) IMPRESSED CURRENT SYSTEMS.

(a) General.
1. Equipment for impressed current systems shall be served by a dedicated and clearly marked electrical circuit that remains energized at all times.

2. All new and existing impressed current systems shall maintain either of the following standard protection levels:
a. An instant-off reading of at least negative 850 millivolts.

b. A 100 millivolt or greater negative shift in polarization between the instant-off reading and the native soil reading or a 100 millivolt or greater positive shift in the depolarized structure potential from the instant-off reading.

3. When a new impressed current system is installed or an existing system is replaced in whole or in part, an ammeter shall be installed, along with an hour meter that totals the number of hours during which electric current flows through the system.

(b) Failing impressed current systems. If impressed current corrosion protection readings taken in accordance with sub. (1) (d) 2. indicate the system is not maintaining adequate continuous protection, the system shall be analyzed by a certified corrosion expert for site corrosion potential and qualification of system functionality.

(c) Inoperative impressed current systems.
1. Impressed current systems that have been inoperative for 120 days or less shall comply with all of the following requirements:
a. Power shall be restored and the system shall be tested by a certified cathodic protection tester for system functionality.

b. If the impressed current system is damaged or inoperable, a certified corrosion expert shall repair, survey, and recommission the system.

2. Impressed current systems that have been inoperative for 121 to 180 days shall comply with all of the following requirements:
a. A precision tightness test shall be performed on the tank system in accordance with s. ATCP 93.515(4) within 15 days of discovery.

b. Power shall be restored and the system shall be tested for system functionality by a certified cathodic protection tester.

c. If the impressed current system is damaged or inoperable, a certified corrosion expert shall repair, survey, and recommission the system.

3. Impressed current systems that have been inoperative for 181 to 365 days shall comply with all of the following requirements:
a. A precision tightness test shall be performed on the tank system in accordance with s. ATCP 93.515(4) within 15 days of discovery.

b. A certified corrosion expert shall assess, survey, and recommission the impressed current system and perform any necessary repairs.

4. Impressed current systems that have been either inoperative or not tested for more than 365 days shall comply with all of the following requirements:
a. An internal inspection of the tank shall be performed in accordance with sub. (2) (b) 2.

b. If the tank fails the internal inspection, the tank owner shall either have the tank repaired and lined, or have the lining repaired in accordance with s. ATCP 93.530, or have the tank permanently closed and removed in accordance with s. ATCP 93.560.

c. If the tank is not closed under subd. 4. b., a certified corrosion expert shall assess, survey, and re-commission the impressed current system and perform any necessary repairs.

d. If the tank is not closed under subd. 4. b., a precision tightness test shall be performed on the tank system in accordance with s. ATCP 93.515(4). In addition, a tightness test shall be performed on the ullage portion of the tank in accordance with s. ATCP 93.515(10).

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