**Number range CHAPTERSection 5 --- Corrosion Protection**

To prevent leaks, all parts of your UST system that are underground and
routinely contain product need to be protected from corrosion. The UST
system includes the tank, piping, and ancillary equipment, such as
flexible connectors, fittings, and pumps. Unprotected metal UST
components can deteriorate and leak when underground electrical currents
act upon them.

![](media/image1.wmf){width="2.816666666666667in"
height="1.961111111111111in"}

One way to protect UST components from corrosion is to **make them with
nonmetallic, noncorrodible materials**, such as USTs made of (or clad or
jacketed with) fiberglass reinforced plastic (FRP) or other
noncorrodible materials --- as illustrated by the FRP tank on the right.
Noncorrodible USTs like these do not require O&M for corrosion
protection.

UST components made from metal, however, that routinely contain product
and are in direct contact with the ground need corrosion protection
provided by cathodic protection or (in some cases) lining the interior
of the tank, as described below. These options require O&M.

**Note: Metal tanks or piping installed after December 22, 1988 must
have a dielectric coating (a coating that does not conduct electricity)
in addition to the cathodic protection described below.**

![](media/image2.png){width="2.7625in" height="1.8527777777777779in"}

**Cathodic Protection Using Sacrificial**

**Anode Systems**

Sacrificial anodes are buried and attached to UST components for
corrosion protection --- as illustrated on the right by an anode
attached to a tank. Anodes are pieces of metal that are more
electrically active than steel, and thus they suffer the destructive
effects of corrosion rather than the steel they are attached to.

![](media/image3.jpeg){width="2.642361111111111in"
height="1.9083333333333334in"}

**Cathodic Protection Using Impressed Current Systems**

An impressed current system --- as shown on the right --- uses a
rectifier to provide direct current through anodes to the tank or piping
to achieve corrosion protection. The steel is protected because the
current going to the steel overcomes the corrosion-causing current
flowing away from it. **The cathodic protection rectifier must always be
on and operating to protect your UST system from corrosion.**

**Corrosion Protection Using Internal Lining**

**Of The Tank**![](media/image4.wmf){width="2.8048611111111112in"
height="1.9527777777777777in"}

This corrosion protection option applies only to tanks installed before
December 22, 1988. These older tanks can be internally lined by trained
professionals to meet the corrosion protection requirements --- as shown
on the right, in which a professional follows industry codes to safely
and effectively line a tank's interior.

It may help you to see your corrosion protection options displayed in
the following table.

+----------------------+-----------------------------------------------+
| **Corrosion          |                                               |
| Protection Choices** |                                               |
+======================+===============================================+
| **Option**           | **Description**                               |
+----------------------+-----------------------------------------------+
| **Noncorrodible      | The tank or piping is constructed of          |
| Material**           | noncorrodible material.                       |
+----------------------+-----------------------------------------------+
| **Steel Tank Clad Or | Examples of cladding or jacket material       |
| Jacketed With A      | include fiberglass and urethane. Does not     |
| Noncorrodible        | apply to piping.                              |
| Material**           |                                               |
+----------------------+-----------------------------------------------+
| **Coated And         | Steel tank and piping is well-coated with a   |
| Cathodically         | dielectric material and cathodically          |
| Protected Steel      | protected.                                    |
| Tanks Or Piping**    |                                               |
+----------------------+-----------------------------------------------+
| **Cathodically       | *This option is only for steel tanks and      |
| Protected**          | piping installed before December 22, 1988.*   |
|                      | Cathodic protection is usually provided by an |
| **Noncoated Steel    | impressed current system.                     |
| Tanks Or Piping**    |                                               |
+----------------------+-----------------------------------------------+
| **Internal Lining Of | *This option is only for steel tanks          |
| Tanks**              | installed before December 22, 1988.* A lining |
|                      | is applied to the inside of the tank. Does    |
|                      | not apply to piping.                          |
+----------------------+-----------------------------------------------+
| **Combination Of     | *This option is only for steel tanks          |
| Cathodically         | installed before December 22, 1988.* Cathodic |
| Protected Steel And  | protection is usually provided by an          |
| Internal Lining Of   | impressed current system. Does not apply to   |
| Tanks**              | piping.                                       |
+----------------------+-----------------------------------------------+
| **Other Methods Used | If you have tanks or piping that do not meet  |
| To Achieve Corrosion | any of the descriptions above, check with     |
| Protection**         | your state UST agency to see if your UST      |
|                      | system meets the requirements for corrosion   |
|                      | protection. You also will need to ask about   |
|                      | the operation, maintenance, and record        |
|                      | keeping requirements applicable to this type  |
|                      | of UST system.                                |
+----------------------+-----------------------------------------------+

Note: In addition to tanks and piping, all other metal components in
direct contact with the ground that routinely hold product --- such as
flexible connectors, swing joints, fittings, and pumps --- must also be
cathodically protected.

**Use the O&M checklist on the next page. Following the checklist look
for record keeping forms and discussions of special corrosion protection
situations.**

+----------+-----------------------------------------------------------+
| **      |                                                           |
| Basic    |                                                           |
| O&M      |                                                           |
| C        |                                                           |
| hecklist |                                                           |
| For      |                                                           |
| C        |                                                           |
| orrosion |                                                           |
| Prot     |                                                           |
| ection** |                                                           |
+==========+===========================================================+
| **Sac    | **You need to have a periodic test conducted by a         |
| rificial | qualified corrosion tester to make sure your cathodic     |
| Anode**  | protection system is adequately protecting your UST       |
|          | system. This test needs to be conducted:**                |
| **       |                                                           |
| Cathodic | 1.  Within 6 months of installation.                      |
| Pr       |                                                           |
| otection | ```{=html}                                                |
| S        | <!-- -->                                                  |
| ystems** | ```                                                       |
|          | 1.  At least every 3 years after the previous test.       |
|          |                                                           |
|          | ```{=html}                                                |
|          | <!-- -->                                                  |
|          | ```                                                       |
|          | 1.  Within 6 months after any repairs to your UST system. |
|          |                                                           |
|          | >  Make sure the professional tester is qualified to     |
|          | > perform the test and follows a standard code of         |
|          | > practice to determine that test criteria are adequate.  |
|          | >                                                         |
|          | >  If any test indicates your tanks are not adequately   |
|          | > protected, you need to have a corrosion expert examine  |
|          | > and fix your system.                                    |
|          | >                                                         |
|          | >  Testing more frequently can catch problems before     |
|          | > they become big problems.                               |
|          |                                                           |
|          | -   **You need to keep the results of at least the last   |
|          |     two tests on file.** See the next page for a cathodic |
|          |     protection test record keeping form.                  |
+----------+-----------------------------------------------------------+
| **I      | **You need to have a periodic test conducted by a         |
| mpressed | qualified corrosion tester to make sure your cathodic     |
| Current  | protection system is adequately protecting your UST       |
| Cathodic | system. This test needs to be conducted:**                |
| Pr       |                                                           |
| otection | 1.  Within 6 months of installation.                      |
| S        |                                                           |
| ystems** | ```{=html}                                                |
|          | <!-- -->                                                  |
|          | ```                                                       |
|          | 1.  At least every 3 years after the previous test.       |
|          |                                                           |
|          | ```{=html}                                                |
|          | <!-- -->                                                  |
|          | ```                                                       |
|          | 1.  Within 6 months after any repairs to your UST system. |
|          |                                                           |
|          | >  Make sure the professional tester is qualified to     |
|          | > perform the test and follows a standard code of         |
|          | > practice to determine that test criteria are adequate.  |
|          | >                                                         |
|          | >  If any test indicates your tanks are not adequately   |
|          | > protected, you need to have a corrosion expert examine  |
|          | > and fix your system.                                    |
|          | >                                                         |
|          | >  Testing more frequently can catch problems before     |
|          | > they become big problems.                               |
|          |                                                           |
|          | -   You need to keep the results of at least the last two |
|          |     tests on file. See next page for a cathodic           |
|          |     protection test record keeping form.                  |
|          |                                                           |
|          | ```{=html}                                                |
|          | <!-- -->                                                  |
|          | ```                                                       |
|          | -   **You need to inspect your rectifier at least every   |
|          |     60 days to make sure that it is operating within      |
|          |     normal limits.**                                      |
|          |                                                           |
|          | >  This inspection involves reading and recording the    |
|          | > voltage and amperage readouts on the rectifier. You or  |
|          | > your employees can perform this periodic inspection.    |
|          | >                                                         |
|          | >  Make sure your cathodic protection professional       |
|          | > provides you with the rectifier's acceptable operating  |
|          | > levels so you can compare the readings you take with an |
|          | > acceptable operating level. If your readings are not    |
|          | > within acceptable levels, you must contact a cathodic   |
|          | > protection professional to address the problem.         |
|          |                                                           |
|          | -   You need to keep records of at least the last 3       |
|          |     rectifier readings. See page 39 for a 60-Day          |
|          |     Inspection Results record keeping form.               |
|          |                                                           |
|          | -   You should have a trained professional periodically   |
|          |     service your impressed current system.                |
|          |                                                           |
|          | -   Never turn off your rectifier!                        |
+----------+-----------------------------------------------------------+
| **Inte   | -   Within 10 years after lining and at least every 5     |
| rnally** |     years thereafter, the lined tank must be inspected by |
|          |     a trained professional and found to be structurally   |
| *        |     sound with the lining still performing according to   |
| *Lined** |     original design specifications. Make sure the         |
|          |     professional performing the inspection follows a      |
| *        |     standard code of practice.                            |
| *Tanks** |                                                           |
|          | -   Keep records of the inspection (as specified in       |
|          |     industry standards for lining inspections).           |
+----------+-----------------------------------------------------------+

**Record For Periodic Testing Of Cathodic Protection Systems**

**(for use by a qualified cathodic protection tester)**

Test Date:\_\_\_\_/\_\_\_\_/\_\_\_\_ Facility
Name/ID:\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Note: Provide site sketch as directed on the back of this page.

**Cathodic Protection (CP) Tester Information:**

Name: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Phone Number:\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Address:
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Testing must be conducted by a qualified CP tester. Indicate your
qualifications as a CP tester:

Identify which of the following testing situations applies:

1.  Test required within 6 months of installation of CP system
    (installation date was \_\_/\_\_/\_\_)

2.  Test required at least every 3 years after installation test noted
    above

3.  Test required within 6 months of any repair activity -- note repair
    activity and date below:

Indicate which industry standard you used to determine that the cathodic
protection test criteria are adequate:
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

+---+------------------------------------------------------------------+
| * |                                                                  |
| * |                                                                  |
| C |                                                                  |
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| o |                                                                  |
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| P |                                                                  |
| r |                                                                  |
| o |                                                                  |
| t |                                                                  |
| e |                                                                  |
| c |                                                                  |
| t |                                                                  |
| i |                                                                  |
| o |                                                                  |
| n |                                                                  |
| T |                                                                  |
| e |                                                                  |
| s |                                                                  |
| t |                                                                  |
| M |                                                                  |
| e |                                                                  |
| t |                                                                  |
| h |                                                                  |
| o |                                                                  |
| d |                                                                  |
| U |                                                                  |
| s |                                                                  |
| e |                                                                  |
| d |                                                                  |
| ( |                                                                  |
| c |                                                                  |
| h |                                                                  |
| e |                                                                  |
| c |                                                                  |
| k |                                                                  |
| o |                                                                  |
| n |                                                                  |
| e |                                                                  |
| ) |                                                                  |
| * |                                                                  |
| * |                                                                  |
+---+------------------------------------------------------------------+
|   | > 100 mV Cathodic Polarization Test                              |
+---+------------------------------------------------------------------+
|   | > -850 mV Test (Circle 1 or 2 below)                             |
|   | >                                                                |
|   | > 1\) Polarized Potential (instant off) 2) Potential with CP     |
|   | > Applied , IR Drop Considered                                   |
|   | >                                                                |
|   | > **Note:** **All readings taken must** **meet the -850 mV       |
|   | > criteria to pass**                                             |
+---+------------------------------------------------------------------+
|   | > Other Accepted Method (please describe):                       |
+---+------------------------------------------------------------------+

**Is the cathodic protection system working properly?** **Yes** **No**

**(circle one)**

**If answer is no, go to the directions at the bottom on the back of
this page.**

My signature below affirms that I have sufficient education and
experience to be a cathodic protection tester; I am competent to perform
the tests indicated above; and that the results on this form are a
complete and truthful record of all testing at this location on the date
shown.

CP Tester Signature**:
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**
Date:\_\_\_\_\_\_\_\_\_\_\_\_\_

**Keep This Paper On File For At Least Six Years**

**Site Sketch:** Provide a rough sketch of the tanks and piping, the
location of each CP test, and each voltage value obtained (use space
below or attach separate drawing). Voltage readings through concrete or
asphalt do not provide accurate readings and are not acceptable. Perform
sufficient testing to evaluate the entire UST system.

**If CP system fails test, you must have a corrosion expert fix the
system.**

> If the answer was no, indicating that your CP system is not working,
> you must have a ***corrosion expert*** investigate and fix the
> problem. A corrosion expert has additional training, skills, and
> certification beyond the corrosion tester who filled out the bulk of
> this form. A corrosion expert must be:

-   Accredited/certified by NACE International (The Corrosion Society)
    as a corrosion specialist or cathodic protection specialist, or

-   Be a registered professional engineer with certification or
    licensing in corrosion control.

As long as you have the UST, be sure you keep a record that clearly
documents what the corrosion expert did to fix your CP system.

**Keep This Paper On File For At Least Six Years**

**60-Day Inspection Results For**

**Impressed Current Cathodic Protection Systems**

Facility
Name:\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Amp Range
Recommended:\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Voltage Range
Recommended:\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

+----------+---------------+----------+-----------+------------------+
| **Date** | **Your Name** | *        | **Amp**   | **Is Your System |
|          |               | *Voltage |           | Running          |
|          |               | R        | **        | Properly?        |
|          |               | eading** | Reading** | (Yes/No)**       |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+
|          |               |          |           |                  |
+----------+---------------+----------+-----------+------------------+

1.  **If the rectifier voltage and/or amperage output(s) are outside the
    recommended operating levels, contact a cathodic protection expert
    to address the problem.**

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```
1.  **Never turn off your rectifier.**

2.  **Keep this record for at least 6 months after the date of the last
    reading.**

**Some Special Corrosion Protection Situations**

**What If You Have An STI-P3 Tank With A PP4 Test Station?**

If you have a PP4 test station installed with an STI-P3 tank, you may
perform the periodic testing of your cathodic protection system by using
the meter provided to you with the PP4 test station.

1.  Don't forget to record the result of the reading and keep at least
    the last two results.

```{=html}
<!-- -->
```
1.  If your test readings do not pass, you must take action to correct
    the problem. Call your installer and ask that the corrosion expert
    who designed the system examine it and correct the problem.

**What If You Combine Internal Lining And Cathodic Protection?**

If you chose the combination of internal lining and cathodic protection
for meeting corrosion protection requirements on your UST, you may not
have to meet the periodic inspection requirement for the lined tank.
However, you must always meet the requirements for checking and testing
your cathodic protection system as described in the basic O&M checklist
for corrosion protection on page 36. The 10-year and subsequent 5-year
inspections of the lined tank are not required if the integrity of the
tank was ensured when cathodic protection was added. You should be able
to show an inspector documentation of the passed integrity assessment.

Example 1:

If you have cathodic protection and internal lining applied to your tank
at the same time, periodic inspections of the lined tank **are not**
required because an integrity assessment of the tank is required prior
to adding the cathodic protection and internal lining.

Example 2:

If you had cathodic protection added to a tank in 1997 that was
internally lined in 1994 and the contractor did not perform an integrity
assessment of the tank at the time cathodic protection was added (or you
cannot show an inspector documentation of the passed integrity
assessment), then periodic inspections of the lined tank **are**
required because you cannot prove that the tank was structurally sound
and free of corrosion holes when the cathodic protection was added. The
lined tank needs to be periodically inspected because the lining may be
the only barrier between your gasoline and the surrounding environment.

**What If You Have A Double Walled Steel UST With Interstitial
Monitoring And Cathodic Protection?**

If you have a cathodically protected double walled steel tank and you
use interstitial monitoring capable of detecting a breach in both the
inner and outer wall or ingress of product and water as your method of
leak detection, then you should monitor your cathodic protection system
within six months of installation and following any activity that could
affect the CP system.

If you are using impressed current cathodic protection, you still need
to perform the 60-day checks of your rectifier to make sure it is
operating within normal limits.

3.  Testing the cathodic protection system more frequently may help
    catch problems quicker.

4.  If your test readings do not pass, you must take action to correct
    the problem. Call your installer and ask that the corrosion expert
    who designed the system examine it and correct the problem.

5.  Don't forget to keep at least the last two results of your cathodic
    protection testing.

**Do All UST Sites Need Corrosion Protection?**

A corrosion expert may be able to determine the soil at an UST site is
not conducive to corrosion and will not cause the tank or piping to have
a release during its operating life. If so, you must keep a record of
that corrosion expert's analysis for the life of the tank or piping to
demonstrate why your UST has no corrosion protection.