Pass the API ICP Programs API-571 Questions and answers with CertsForce

According to API RP 571 and API RP 583:

“The most effective mitigation of CUI is the use of appropriate coatings underneath the insulation, which are resistant to moisture and chloride ingress.”

“Inspection and insulation selection are also important but are secondary controls.”

(Reference: API RP 571, Section 4.3.4 – Corrosion Under Insulation; API RP 583)

Hence, option D 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.

API RP 571 states under Galvanic Corrosion:

“Because galvanic corrosion usually manifests as thinning of the more anodic metal, ultrasonic thickness measurements taken near dissimilar metal joints are an effective way to detect this type of internal corrosion.”

“Surface NDE techniques like liquid penetrant or magnetic particle testing are not effective for detecting wall loss.”

Thus, option D (ultrasonic thickness testing) is correct.

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.

Comprehensive and Detailed Explanation From Exact Extract:

Per API RP 571, sulfidation corrosion is controlled by three primary variables:

Sulfur species concentration (e.g., H₂S, sulfur compounds)

Operating temperature

Metallurgy, especially chromium content

Chromium significantly improves sulfidation resistance by forming protective sulfide scales. All three factors must be considered in RBI assessments.

Referenced Documents (Study Basis):

API RP 571 – Section on Sulfidation Corrosion

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API RP 571 describes temper embrittlement as a subtle metallurgical change that reduces impact toughness without obvious macrostructural change:

“Temper embrittlement is not readily apparent by visual or standard tensile testing. It is confirmed by Charpy impact testing which measures toughness at low temperatures.”

“It typically affects Cr-Mo steels exposed to intermediate temperatures (650°F to 1100°F) for extended times.”

(Reference: API RP 571, Section 4.2.1.4 – Temper Embrittlement)

Thus, the condition is not visually or physically apparent, but is confirmed through impact testing, making option D correct.

As defined in API RP 571, under Hydrogen Blistering and HIC/SOHIC:

“SOHIC typically manifests as subsurface stepwise cracking, generally oriented perpendicular to the direction of stress.”

“This mechanism initiates below the surface, typically in weld heat-affected zones, and requires metallographic or advanced ultrasonic methods to detect.”

By contrast, SSC, caustic cracking, and amine SCC are primarily surface-initiated, stress-related cracking mechanisms.

Thus, SOHIC is the subsurface mechanism in this list, making option D correct.

API RP 571 discusses this under Wet H₂S Damage – Hydrogen Blistering, HIC, SOHIC:

“Hydrogen generation is reduced as pH increases. At pH 9 and above, the corrosion potential is less favorable for hydrogen charging and thus permeation into the steel is minimal.”

“Most wet H₂S cracking damage mechanisms are accelerated under acidic conditions (pH < 7).”

Hence, high pH (around 9) environments offer the most protection against hydrogen damage, making option D the correct choice.

As per API RP 571 Section 5.1.4.2 (Metal Dusting):

“Metal dusting is a type of carburization attack that typically occurs in high carbon activity environments, with temperatures generally between 900°F and 1200°F (480°C to 650°C), although damage has been reported as low as 600°F (315°C).”

Therefore, the commonly accepted operational range is best described by Option A: 600°F–1200°F (315°C–650°C).

API RP 571 discusses Hydrogen-Induced Cracking (HIC) and Blistering:

“Postweld heat treatment (PWHT) does not significantly reduce susceptibility to HIC, as the mechanism is primarily driven by hydrogen charging in wet H₂S environments and steel cleanliness, not residual stresses.”

“PWHT is more effective for SSC, SOHIC, and other stress-driven mechanisms.”

Thus, HIC will not benefit much from PWHT, making option C correct.