API 510 Corrosion Assessment 3

Question 1

What is the primary driving factor for stress corrosion cracking (SCC) to occur?

Accepted Answer

Tensile stress, susceptible material, and corrosive environment simultaneously

Answer

SCC requires all three conditions to be present: a susceptible material, tensile stress, and a specific corrosive environment.

Question 2

A vessel shell has a measured thickness of 0.320 inches and a required minimum thickness of 0.285 inches. What is the corrosion allowance remaining?

Accepted Answer

0.035 inches

Answer

Remaining corrosion allowance = measured thickness minus required minimum = 0.320 minus 0.285 = 0.035 inches.

Question 3

Hydrogen-induced cracking (HIC) in pressure vessels is most commonly associated with which process environment?

Accepted Answer

Wet hydrogen sulfide (H2S) service

Answer

HIC is strongly associated with wet H2S environments where atomic hydrogen is generated and diffuses into the steel.

Question 4

When calculating remaining life using API 510, which formula is correct?

Accepted Answer

RL = (t_actual minus t_min) divided by corrosion rate

Answer

Remaining life = (actual thickness minus minimum required thickness) divided by the corrosion rate in thickness per year.

Question 5

Crevice corrosion is most likely to initiate in which location on a pressure vessel?

Accepted Answer

Tight gaps under gaskets or lap joints

Answer

Crevice corrosion initiates in occluded, low-oxygen areas such as under gaskets, lap joints, or threaded connections where stagnant electrolyte concentrates.

(API 510) API 510 Inspector Certification Practice Test

(API 510) API 510 Inspector Certification Practice Test

API 510 Corrosion Assessment 3