API-571 Exam Dumps - API ICP Programs Questions and Answers

As per API RP 571 Section 5.3.2.2 (Sigma Phase Embrittlement):

“Sigma phase embrittlement occurs in austenitic stainless steels (like 300 series) and duplex stainless steels exposed to 1000°F to 1800°F (540°C to 980°C)... This embrittlement results in a significant loss of toughness and ductility.”

Sigma phase is not a concern in Monel (nickel-copper alloy) or 5Cr steels.

400 series are ferritic and not typically affected by sigma phase.

Hence, Option A (300 series stainless steel) is correct.

API RP 571 provides detailed insights:

“Brittle fracture generally occurs at low temperatures, specifically below the ductile-to-brittle transition temperature as defined by the Charpy impact test.”

“Most carbon and low-alloy steels are ductile above their Charpy transition temperature but may fracture suddenly without ductility below it.”

(Reference: API RP 571, Section 4.2.1.2 – Brittle Fracture)

Hence, option C is correct and technically accurate based on the material behavior curve.

In TR 942-B and API RP 582, it is emphasized:

“Nickel-based buttering is often used as an intermediate layer to reduce thermal stress mismatch during welding of ferritic and austenitic materials.”

“Nickel alloys have a coefficient of thermal expansion closer to that of both stainless steels and carbon steels, reducing stress concentrations and mitigating dissimilar weld cracking.”

“This technique also assists in achieving metallurgical compatibility and mitigating solidification cracking.”

Hence, option C is correct as it directly relates to minimizing thermal expansion mismatches.

From API RP 571 Section 5.3.2.1 (Creep and Stress Rupture):

“Short-term creep rupture is often associated with localized overheating and results in bulging and thinning, often with a characteristic ‘fish-mouth’ rupture appearance. These failures occur under sustained load in a short time (hours or days), typically in high-temperature service due to a sudden increase in temperature or poor heat distribution.”

Thus, Option B accurately describes the mechanism and visual indications of short-term stress rupture.

API RP 571 notes under Sour Water Corrosion:

“Localized thinning or under-deposit corrosion in sour water services is best detected by profile radiography, which provides a visual comparison of wall thickness over a length of pipe.”

“This technique is especially useful for assessing localized metal loss due to under-deposit attack or flow regime effects.”

(Reference: API RP 571, Section 4.3.2.3 – Sour Water Corrosion)

Hence, profile radiographic testing is most effective, making option B correct.

API RP 571 – Polythionic Acid Stress Corrosion Cracking:

“Polythionic acid SCC may be mistaken for wet H₂S damage because both involve cracking in austenitic stainless steels under certain conditions.”

Thus, option D is correct.

According to API RP 571, under Naphthenic Acid Corrosion (NAC):

“The most severe corrosion is typically found in areas of high velocity and turbulence, such as at pump around nozzles, transfer lines, elbows, reducers, and orifices.”

“NAC is characterized by uniform thinning and can accelerate significantly where flow-induced erosion is present.”

(Reference: API RP 571, Section 4.3.4.1 – Naphthenic Acid Corrosion)

This clearly establishes that high velocity and turbulence increase NAC severity, making option D correct.

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.

API RP 571 explains the typical location of dissimilar metal weld (DMW) cracks as follows:

“DMW cracking usually occurs in the heat-affected zone (HAZ) on the ferritic side of the weld.”

“The difference in thermal expansion coefficients, grain structures, and creep rates between the ferritic and austenitic materials contributes to the development of high stress and strain concentrations in the HAZ of the ferritic material.”

(Reference: API RP 571, Section 4.2.1.6 – Dissimilar Metal Weld Cracking)

Thus, these cracks do not occur in the center of the weld or on the austenitic side, but rather at the ferritic HAZ, making option A correct.

API RP 571 on Naphthenic Acid Corrosion (NAC):

“NAC results in thinning, especially in areas of high velocity and turbulence. Standard UT or radiographic inspection followed by UT thickness monitoring is typically used to detect wall loss.”

“Advanced techniques like angle-beam or eddy current are not typically required.”

So, option A correctly reflects the most effective and widely used method.