API 571 Corrosion Mechanisms 2

Question 1

What pH range is generally associated with aggressive acid corrosion in refinery process systems?

Accepted Answer

Below 4

Answer

7–9

Answer

4–7

Answer

Above 9

Question 2

Atmospheric corrosion is most severe in which type of environment?

Accepted Answer

Marine or coastal environment

Answer

Arid desert climate

Answer

High-altitude location

Answer

Cold arctic environment

Question 3

Corrosion under insulation (CUI) is primarily driven by what mechanism?

Accepted Answer

Moisture penetrating insulation and concentrating corrosive species against the pipe

Answer

Galvanic coupling at the metal surface

Answer

Microbiological activity inside insulation

Answer

Oxygen exclusion under the insulation

Question 4

What is the primary damage mechanism for carbon steel in amine treating systems?

Accepted Answer

Amine corrosion from degradation products and stress corrosion cracking

Answer

High-temperature acid corrosion

Answer

Alkaline corrosion from fresh amine

Answer

High-temperature oxidation

Question 5

Microbiologically influenced corrosion (MIC) is most commonly caused by which organisms?

Accepted Answer

Sulfate-reducing bacteria (SRB)

Answer

Aerobic bacteria only

Answer

Nitrate-reducing bacteria

Answer

Fungi and mold

Question 6

Which factor does NOT directly influence the electrochemical corrosion rate of carbon steel in water service?

Accepted Answer

Water color or turbidity

Answer

Temperature

Answer

pH level

Answer

Dissolved oxygen content