API 651 - 3 (Terms & Definition}) Flashcards
The electrode of an electrochemical cell at which oxidation (corrosion) occurs.
anode
The electrode of an electrochemical cell at which a reduction reaction occurs
cathode
A technique to reduce corrosion of a metal surface by making the entire surface the cathode of an electrochemical
cell.
cathodic protection
The portion of the tank bottom steel floor plate that extends horizontally past the outside vertical surface of
the shell
chime (or chine) or bottom extension
One or more anodes installed vertically at a nominal depth of 15 m (50 ft) or more below the earth’s surface in a single
drilled hole for the purpose of supplying cathodic protection
deep anode bed
The reduction or prevention of corrosion of a metal in an electrolyte by electrically connecting it to a more anodic
meta
galvanic cathodic protection
An electric current supplied by a device employing a power source that is external to the electrode system. (An
example is the direct current output of a cathodic protection rectifier.)
impressed current
The loss of electrons by a constituent of a chemical reaction.
oxidation
The change from the open-circuit potential of an electrode as a result of current across the electrode/electrolyte
interface.
polarization
The gain of electrons by a constituent of a chemical reaction
reduction
An electrode whose open-circuit potential is constant under similar conditions of measurement.
reference electrode
A group of cathodic protection anodes installed individually, spaced uniformly, and typically buried less than 20 ft (6 m)
below grade.
shallow anode bed
A conductor of a known electrical resistance through which current flow may be determined by measurement of the
voltage across the conductor and calculation using Ohm’s Law.
shunt
Current flowing through paths other than the intended circuit
stray current
An electromotive force, or a difference in electrode potentials expressed in volts. Also known as a potential.
voltage
