API 510 Corrosion, Welding & Material Defects 2

Question 1

Which type of corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte?

Accepted Answer

Galvanic corrosion

Answer

Galvanic corrosion occurs when two metals with different electrochemical potentials are in contact with each other and an electrolyte, causing the more active (anodic) metal to corrode preferentially.

Question 2

What is the primary purpose of post-weld heat treatment (PWHT) on pressure vessel welds?

Accepted Answer

To relieve residual stresses and improve toughness

Answer

PWHT is performed primarily to relieve residual stresses induced during welding and to improve notch toughness, which reduces the risk of brittle fracture.

Question 3

Which NDE method is MOST effective for detecting subsurface cracks in ferromagnetic pressure vessel materials?

Accepted Answer

Magnetic particle testing (MT)

Answer

Magnetic particle testing (MT) can detect both surface and near-subsurface discontinuities in ferromagnetic materials by revealing flux leakage at defect locations.

Question 4

Under API 510, what term describes corrosion that occurs uniformly over the entire internal surface of a pressure vessel?

Accepted Answer

General corrosion

Answer

General (uniform) corrosion attacks the exposed surface at a relatively uniform rate, making it predictable and easier to manage through corrosion allowance calculations.

Question 5

A weld discontinuity that is open to the surface and runs parallel to the weld axis is MOST likely a:

Accepted Answer

Longitudinal crack

Answer

A longitudinal crack runs parallel to the weld axis and can occur in the weld metal, heat-affected zone, or base metal, often due to hot cracking or hydrogen-induced cracking.

(API 510) Certified Pressure Vessel Inspector Practice Test

(API 510) Certified Pressure Vessel Inspector Practice Test

API 510 Corrosion, Welding & Material Defects 2