Authentic API Certification Exam API-571 Questions Answers

As per API RP 945 (4th Edition, 2022):

“Post-weld heat treatment (PWHT) is the most effective method for reducing residual stresses that contribute to amine SCC. PWHT minimizes the stress intensity required for crack initiation and growth.”

Lowering temperature helps but is not always feasible.

Water content and amine concentration affect SCC but are not as impactful as PWHT.

Thus, Option A (Post-weld heat treatment) is the most effective mitigation.

According to API RP 571 Section 5.3.2.3 (Spheroidization):

“Spheroidization is the transformation of the microstructure of carbon and low alloy steels when exposed to elevated temperatures for long durations. The rate of spheroidization depends on temperature, prior microstructure, and exposure time... The microstructure becomes less effective at carrying loads, and strength is reduced.”

Key influencing factors for the rate of spheroidization are:

Temperature (higher accelerates the process),

Microstructure (initial phase distribution and morphology).

Pressure and hydrogen partial pressure are not relevant for this transformation, nor is stress a primary driver.

Therefore, Option D (temperature and microstructure) is correct.

API RP 571 defines Hydrogen Embrittlement as:

“Improper PWHT can trap hydrogen within the microstructure of carbon steel or fail to relieve residual stresses, both of which increase the risk of hydrogen embrittlement.”

“Moisture in electrodes contributes to hydrogen-induced cracking, but embrittlement from atomic hydrogen is more directly tied to heat treatment and microstructure.”

Thus, option D is the most accurate.