FREE NACE Corrosion Control & Prevention Questions and Answers

Question 1

What is the primary purpose of cathodic protection in corrosion control?

Accepted Answer

To make the metal surface the cathode of an electrochemical cell

Answer

Cathodic protection is a corrosion control technique that works by transforming the entire surface of the metal to be protected into a cathode. By supplying electrons to the metal, it prevents the anodic (corroding) reactions from occurring. This is achieved by connecting the protected metal to a more active sacrificial anode or by using an impressed current system.

Question 2

Which type of corrosion occurs due to differences in metal composition?

Accepted Answer

Galvanic corrosion

Answer

Galvanic corrosion occurs when two dissimilar metals are in electrical contact and exposed to an electrolyte. The difference in their electrochemical potentials causes the less noble (more active) metal to act as an anode and corrode preferentially, while the more noble metal acts as a cathode and is protected. This phenomenon is a significant concern in material selection and design.

Question 3

What is the minimum protective potential for steel in seawater according to NACE standards?

Accepted Answer

-0.80 V vs. CSE

Answer

According to NACE standards, the minimum protective potential for cathodically protected steel in seawater is generally accepted as -0.80 V vs. a Copper-Copper Sulfate Electrode (CSE). This potential ensures that the steel surface is sufficiently polarized to prevent corrosion. Maintaining this potential helps to achieve effective long-term corrosion control in marine environments.

Question 4

Which coating defect appears as small, blister-like formations?

Accepted Answer

Blistering

Answer

Blistering is a common coating defect characterized by the formation of dome-shaped, localized swellings on the coating surface. These blisters occur when moisture, gas, or other fluids become trapped beneath the coating, causing a localized loss of adhesion and lifting the coating from the substrate. It indicates a failure in coating adhesion or permeability.

Question 5

What is the purpose of an insulating flange in pipeline systems?

Accepted Answer

To prevent electrical continuity between pipeline sections

Answer

An insulating flange is a critical component in pipeline systems designed to prevent electrical continuity between different sections of the pipeline. This electrical isolation is essential for effective cathodic protection systems, as it ensures that the protective current is directed only to the intended pipe segment and prevents stray current interference with other structures.

NACE - National Association of Corrosion Engineers Certification Practice Test

NACE - National Association of Corrosion Engineers Certification Practice Test

FREE NACE Corrosion Control & Prevention Questions and Answers