system adjustment and during periodic monitoring should be recorded as
described in paras. 12.4 and 12.5 in order to detect trends in the readings.
Changes in potential readings are often more important than the actual values
themselves in determining the cause of improper system operation.
Rectifier Instructions. In order that all rectifiers in the system
can be properly maintained, adjusted, and repaired, instructions for the
rectifiers must be retained. An original copy should be retained in the
maintenance files and a copy should be kept within the rectifier enclosure for
Basic maintenance requirements are
Basic Maintenance Requirements.
a) Monthly. Take rectifier panel meter and tap setting readings.
Record readings (see sample form - Figure 127). Check rectifier connections.
b) Quarterly. Take structure-to-electrolyte potential readings at
selected locations (not less than four points per system). The test points
the point of least negative potential,
the point of highest negative potential, and
(3) two points of least negative potential not the same as
(1). Record readings (see sample form - Figure 128). Inspect anode-to-
structure connections in galvanic anode systems quarterly.
c) Annually. Inspect submerged sacrificial and impressed current
anodes for consumption. Inspect test stations for broken wires, loose
connections or other damage. Make structure-to-electrolyte potential readings
at all test points and submit data in accordance with Agency instructions.
In addition to the basic requirements listed above, opportunities
to inspect buried or otherwise inaccessible structure surfaces should be used
to inspect the surfaces for evidences of corrosion or coating deterioration.
Such opportunities may be presented by construction or maintenance in the
vicinity of the protected structure.
Guidance for Maintenance
Agency Maintenance and Operations Manuals. Agency Maintenance and
Operation Manuals, (MO-306, Corrosion Prevention and Control, and MO-307,
Cathodic Protection Systems Maintenance) give current guidance for the
maintenance and operation of cathodic protection systems and provide
information on other methods of corrosion control.