API 653 Cathodic Protection Systems 3

Question 1

In a sacrificial anode cathodic protection system, what happens to the anode over time?

Accepted Answer

It is consumed (corrodes) as it provides protection to the steel

Answer

It gains mass due to electrochemical deposition

Answer

It remains unchanged as long as the protected structure is intact

Answer

It becomes more noble over time, reducing its driving voltage

Question 2

What is a 'CP survey coupon' used for in aboveground storage tank cathodic protection monitoring?

Accepted Answer

A small piece of metal installed in the soil to measure polarized potential and corrosion rate

Answer

A sample of soil for corrosivity testing

Answer

A calibration standard for reference electrodes

Answer

A measurement device to track rectifier output

Question 3

What soil property most significantly affects the performance and design of a cathodic protection system for an aboveground storage tank?

Accepted Answer

Soil resistivity

Answer

Soil color

Answer

Soil pH above 9

Answer

Soil temperature

Question 4

Per API 653 requirements, which document should be reviewed to understand the cathodic protection history of a tank prior to an inspection?

Accepted Answer

The tank's maintenance and inspection records including CP system records

Answer

The original API 650 construction data sheet

Answer

The product safety data sheet (SDS) for the stored product

Answer

The site stormwater pollution prevention plan

Question 5

Which of the following is a disadvantage of impressed current cathodic protection (ICCP) systems compared to sacrificial anode systems for tank bottoms?

Accepted Answer

Requires an external power source and ongoing electrical maintenance

Answer

Lower current output capacity

Answer

Cannot be used in low-resistivity soils

Answer

Provides less uniform current distribution

Question 6

When a tank is removed from service for internal inspection, what is a critical consideration regarding its cathodic protection system?

Accepted Answer

The CP system should be monitored to ensure the tank does not depolarize while out of service for extended periods

Answer

The CP system should be turned up to maximum output during the outage

Answer

The CP system must be completely disconnected during any internal inspection

Answer

The sacrificial anodes must be replaced at every scheduled internal inspection

Question 7

What is the primary purpose of a dielectric coating applied to the external bottom of an aboveground storage tank in conjunction with cathodic protection?

Accepted Answer

To reduce the current demand on the CP system by limiting exposed metal surface area

Answer

To eliminate the need for cathodic protection entirely

Answer

To increase the soil resistivity around the tank bottom

Answer

To provide thermal insulation for the stored product