UNDERGROUND CORROSION CONTROL

Question 1

The first line of defense in corrosion control is

Answer 1

coatings

Question 2

cathodic protection is achieved by making the ______ the cathode and transferring the corrosion to the cathodic protection anodes

Answer 2

structure

Question 3

galvanic anode must be directly attached to the structure through a ______ conductor

Answer 3

metallic

Question 4

impressed current system consists of an external power source and ______

Answer 4

anodes

Question 5

how many recommended criteria

Answer 5

3
2 -850 millivolts
1 100 millivolts

Question 6

the first criterion, a potential of -850 mV obtained with current applied, is based on negligible IR drop

Answer 6

first criterion

Question 7

second criterion, a polarization potential of -850 mV, is based on eliminating IR drop during the measurement. IR drop is eliminated by shutting off the current. it is measured at the “instant off”

Answer 7

second criterion

Question 8

the 100 mV polarization criterion can be applied by either starting with a known corrosion potential (native or original “off” potential) or the polarized structure potential . momentarily interrupt current to determine “instant off” (polarized) potential. if the potential drops (becomes more positive) at least 100 mV, than criterion met.

Answer 8

100 mV critereon