Free NACE Cathodic Protection Principles Questions and Answers

Question 1

What is the primary purpose of cathodic protection (CP)?

Accepted Answer

To control corrosion by making the metal a cathode

Answer

The primary purpose of cathodic protection (CP) is to control corrosion by making the metal a cathode. By supplying an external current or connecting the protected metal to a more electrochemically active metal (sacrificial anode), CP forces the entire surface of the structure to act as a cathode, preventing the anodic reactions (corrosion) from occurring.

Question 2

Which of the following is a type of cathodic protection system?

Accepted Answer

Both galvanic anode and impressed current systems

Answer

Cathodic protection systems are broadly categorized into two main types: galvanic (or sacrificial) anode systems and impressed current systems. Both methods effectively control corrosion by making the protected metal a cathode, but they differ in how the protective current is generated and supplied to the structure.

Question 3

What is the typical material used for sacrificial anodes in seawater environments?

Accepted Answer

Zinc or aluminum alloys

Answer

Zinc and aluminum alloys are commonly used as sacrificial anode materials in seawater environments. These metals are more electrochemically active than steel, causing them to corrode preferentially and sacrifice themselves to protect the steel structure, thereby making the steel the cathode and preventing its corrosion.

Question 4

What is the criterion for effective cathodic protection of steel in soil?

Accepted Answer

A negative potential of -850 mV vs. CSE

Answer

A negative potential of -850 mV vs. CSE (Copper-Copper Sulfate Electrode) is a widely accepted NACE criterion for effective cathodic protection of steel in soil or water. Achieving this potential indicates that the steel surface has been sufficiently polarized to prevent active corrosion, ensuring long-term asset integrity.

Question 5

What is the purpose of a reference electrode in CP systems?

Accepted Answer

To measure the electrical potential of the protected structure

Answer

A reference electrode is a crucial component in CP systems used to accurately measure the electrical potential of the protected structure relative to a stable, known potential. This measurement allows engineers to assess the effectiveness of the CP system, ensuring adequate corrosion control and compliance with protection criteria.

NACE - National Association of Corrosion Engineers Certification Practice Test

NACE - National Association of Corrosion Engineers Certification Practice Test

Free NACE Cathodic Protection Principles Questions and Answers