API-571 Exam Dumps : Corrosion and Materials Professional

According to API RP 571 Section 5.3.2.3 (Spheroidization):

“Spheroidization is a microstructural degradation that occurs in carbon steels and low alloy steels when exposed to elevated temperatures for long periods, typically beginning at temperatures as low as 650°F (345°C). It involves the transformation of lamellar pearlite into spherical cementite particles, reducing strength and hardness.”

Thus, Option A (650°F / 345°C) is the minimum threshold temperature for spheroidization to begin.

Same as above. Sigma phase formation is a microstructural phenomenon and not typically detected by NDE methods like magnetic particle or surface hardness testing.

Therefore, metallographic testing remains the definitive detection method, confirming option D again as the correct answer.

According to API RP 571, Section 4.2.1.1 – Sulfidation, and also echoed in API RP 939-C, the presence of certain compounds significantly increases sulfidic corrosion:

“Chlorides are known to accelerate sulfidation and other high-temperature corrosion mechanisms by forming low-melting eutectics and breaking down protective scales on alloy surfaces.”

“Chlorine-containing species also interfere with the formation of stable sulfide or oxide scales, leading to more aggressive metal loss.”

Therefore, chlorides are the most critical accelerant among the listed substances in high-temperature sulfur compound environments, making option C correct.