API 651 - 8 (Criteria for Cathodic Protection)

Question 1

A successfully operating cathodic protection system can usually be determined by measuring the minimum voltage across the structure- electrolyte interface relative to a saturated copper-copper sulfate reference electrode. This measurement should be at least how many volts?

Answer 1

-850mV

Question 2

A successfully operating cathodic protection system can usually be determined by measuring the minimum cathodic polarization between the structure surface and a stable reference electrode contacting the electrolyte. The formation or decay of this polarization can be used in this criterion. This measurement should be a minimum of how many volts?

Answer 2

100mV

Question 3

The standard method of determining the effectiveness of cathodic protection on a tank bottom is the tank-to- soil :

Answer 3

potential measurement

Question 4

Tank-to-soil potential measurements are commonly made with a reference electrode in the soil:

Answer 4

at the perimeter of the tank

Question 5

Tank -to-soil potential measurement at the tank perimeter:

Answer 5

may not represent the same tank-to-soil potential that would be found at the tank center .

Question 6

Tank-to-soil potential measurements are typically taken with:

Answer 6

the current applied

Question 7

monitoring the actual structure -to-soil potential under the tank should be considered . This may be done by:

Answer 7

using a permanently installed reference cell or by inserting a reference cell under the tank through a perforated tube.