API ICP Programs API-571 Question # 16 Topic 2 Discussion
API-571 Exam Topic 2 Question 16 Discussion:
Question #: 16
Topic #: 2
300 series austenitic stainless steels susceptible to polythionic acid stress corrosion cracking (PTA SCC) can become sensitized when heated in the range of:
In API RP 571, under the section Polythionic Acid Stress Corrosion Cracking, it is stated:
“Sensitization of austenitic stainless steels occurs when the material is exposed to temperatures in the range of 800°F to 1500°F (427°C to 816°C), which causes chromium carbide precipitation at grain boundaries, depleting the adjacent areas of chromium.”
“Once sensitized, the steel becomes susceptible to attack in the presence of polythionic acids, particularly in environments containing sulfides and oxygen.”
(Reference: API RP 571, Section 4.2.2.5 – PTA SCC)
This makes option B (750°F to 1500°F / 400°C to 815°C) the most accurate and standard-aligned answer.
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