API 571 Stress Corrosion Cracking 2

Question 1

Wet H2S damage in API 571 encompasses which specific damage forms?

Accepted Answer

HIC, SOHIC, SSC, and stepwise cracking (SWC)

Answer

PTASCC and CSCC only

Answer

Cl-SCC and high-temperature hydrogen SCC

Answer

LME and thermal fatigue

Question 2

Hydrogen-induced cracking (HIC) preferentially initiates at which microstructural features?

Accepted Answer

Non-metallic inclusions and laminations within the steel plate

Answer

Grain boundaries near the surface

Answer

Weld fusion lines only

Answer

Machined external surfaces

Question 3

How does SOHIC (Stress-Oriented HIC) differ from standard HIC?

Accepted Answer

SOHIC cracks align perpendicular to applied stress and can link to form through-wall cracks

Answer

SOHIC only occurs in high-alloy stainless steels

Answer

SOHIC occurs at much higher operating temperatures

Answer

SOHIC requires no hydrogen — it is purely mechanical

Question 4

Sulfide stress cracking (SSC) most preferentially affects which type of steel?

Accepted Answer

High-strength steels with hardness exceeding HRC 22

Answer

Soft, low-strength carbon steel with low hardness

Answer

Austenitic stainless steels in all conditions

Answer

Copper alloys in H2S service

Question 5

NACE MR0175/ISO 15156 provides requirements for which application?

Accepted Answer

Material selection for equipment in H2S-containing sour service

Answer

High-temperature oxidation resistance of alloys

Answer

Cathodic protection system design for pipelines

Answer

Inspection intervals for pressure vessels

Question 6

Carbonate cracking in refinery systems is associated with which type of environment?

Accepted Answer

Alkaline carbonate/bicarbonate solutions in FCC and amine units

Answer

Crude oil distillation overhead systems

Answer

Amine regenerator overhead at elevated temperature

Answer

Hydrogen reformer effluent streams