API 510 Corrosion Mechanisms & Damage Assessment 2

Question 1

Which type of corrosion is characterized by a localized attack that produces small pits or cavities on the metal surface?

Accepted Answer

Pitting corrosion

Answer

Pitting corrosion is a localized form that creates small pits or cavities, often making it more dangerous than uniform corrosion because it is harder to detect.

Question 2

In API 510 inspection, what is 'stress corrosion cracking' (SCC)?

Accepted Answer

Cracking from the combined action of tensile stress and a corrosive environment

Answer

SCC results from the simultaneous presence of tensile stress and a specific corrosive environment, producing cracks that may not be visible without NDE.

Question 3

Which of the following environments most commonly causes stress corrosion cracking in carbon steel pressure vessels?

Accepted Answer

Caustic (sodium hydroxide) solutions

Answer

Caustic stress corrosion cracking (caustic embrittlement) occurs in carbon steel exposed to concentrated sodium hydroxide solutions, especially at elevated temperatures.

Question 4

What is 'hydrogen-induced cracking' (HIC) as it relates to pressure vessel inspection?

Accepted Answer

Planar cracks in steel caused by hydrogen diffusing into the metal and collecting at inclusions

Answer

HIC forms when atomic hydrogen diffuses into steel and recombines at internal defects, creating stepwise planar cracks without external stress being required.

Question 5

Erosion-corrosion in pressure vessels is best described as:

Accepted Answer

Accelerated corrosion from the combined effect of corrosive fluid and mechanical erosion

Answer

Erosion-corrosion occurs when the mechanical removal of protective films by flowing fluid is combined with chemical corrosion, accelerating metal loss.

(API 510) API 510 Inspector Certification Practice Test

(API 510) API 510 Inspector Certification Practice Test

API 510 Corrosion Mechanisms & Damage Assessment 2