JANUARY 31 2003
Review all potential readings. Annotate the low potential measurements, the
high potential measurements, and other significant potential measurements to re-evaluate
those locations when performing the corrosion survey.
If the data taken show that the current output is not sufficient to satisfy the
criteria in Chapter 6, adjust or supplement the system as necessary. After 30 days,
perform a corrosion survey for those locations identified in paragraph 4-3.
CORROSION SURVEY. The corrosion survey is conducted to ensure
adequate cathodic protection still exists as proven on the last close-interval corrosion
survey. The procedures are the same as the close-interval corrosion survey, with
different minimum requirements for the potential measurements. The close-interval
corrosion survey data should be used to determine where potential measurements must
be taken to reasonably ensure that the criteria of cathodic protection are being met for
the entire structure being protected and no interference problems exist on any foreign
Maintenance Interval. A corrosion survey must be conducted at the
Thirty days after major modification to the cathodic protection system or
the protected structure.
After any corrosion leak on the protected structure.
After any inspection or survey which indicates that the current requirement
of the last corrosion survey are not valid (low or high potential
measurements at the proper current output level).
One year from last close-interval corrosion survey or corrosion survey
which satisfied the criteria in Chapter 6.
Using data from the most recent close-interval corrosion survey, or using
sound engineering practices, choose a sufficient number of locations for potential
testing to ensure the entire structure has adequate cathodic protection (for criteria, refer
to Chapter 6). Test CP system components in accordance with Table 4-3. Table 4-4
presents requirements for potential testing of the protected structure.