JANUARY 31 2003
SCHEDULED PREVENTIVE MAINTENANCE
INTRODUCTION. To comply with environmental regulations, public law, and
industry standards, preventive maintenance is required for all installed cathodic
protection systems. Maintenance actions in this section are the minimum required.
CLOSE-INTERVAL CORROSION SURVEY. The close-interval corrosion
survey is an interrupted potential survey on impressed current systems and a non-
interrupted potential survey on galvanic (sacrificial) systems. The purpose of this
survey is to ensure that adequate cathodic protection, as defined in Chapter 6, is
maintained over the entire protected structure. It should be thorough and
comprehensive to identify problems within the protected structure, or any interference
problem on all foreign structures. The interruption cycle must have an ON cycle of
minimum duration four times longer than the OFF cycle, and the OFF cycle should not
exceed one second. For surveys on galvanic systems, measurement errors must be
considered, typically through application of sound engineering practices, which address
the location of the reference cell, the protected structure, the anodes, the condition of
the coating, the soil resistivity, and the depth of the protected structure (refer to Chapter
6). If test stations are installed at each anode, this also can be an interrupted potential
Maintenance Intervals. A close-interval survey must be conducted at the
Thirty days after cathodic protection system is installed and properly
Five years from the last close-interval corrosion survey.
Test CP system components in accordance with Table 4-1 and accomplish
potential measurements of the protected structure (Table 4-1).