Get API-571 Exam Practice Questions - Real and Updated

Answer : B

From API RP 571 Section 5.3.3.2 (Caustic Corrosion):

''Caustic corrosion, also known as caustic gouging, occurs in boiler systems when caustic concentrates in under-deposit areas or due to improper steam drum and boiler water design. Good design and water treatment practices are key preventive measures.''

Temperature control or acid injection are not practical or effective mitigation techniques. Design considerations---such as proper water flow, material selection, and minimizing deposits---are essential.

Hence, the correct answer is Option C.

Answer : D

Per API RP 571, susceptibility to hydrogen embrittlement is strongly influenced by:

Material strength level

Microstructure

Heat treatment condition

Heat treatment determines:

Dislocation density

Trap sites for hydrogen

Residual stress state

The modulus of elasticity does not significantly affect hydrogen embrittlement susceptibility, making Option A incorrect.

Referenced Documents (Study Basis):

API RP 571 -- Section on Hydrogen Embrittlement

Answer : B

In API RP 571, Carbonate SCC and Alkaline SCC are both discussed under mechanisms that occur in basic (high pH) environments, often with similar contributing conditions and prevention methods. The document highlights:

''Carbonate SCC is considered a subcategory of alkaline stress corrosion cracking. It results from the concentration of alkaline carbonates under thermal insulation or deposits.''

''Both mechanisms involve the same key parameters: elevated temperatures, tensile stress, and high pH solutions.''

(Reference: API RP 571, 3rd Edition, Section 4.2.2.4 and 4.2.2.3)

Because these mechanisms share similar material susceptibility and operating conditions, they are indeed closely related---option B is therefore the accurate and supported answer.

Answer : C

API RP 571, under Chloride Stress Corrosion Cracking, notes:

''Cracking often appears as highly branched or 'crazed' networks on the surface, especially in austenitic stainless steels exposed to chlorides under tensile stress.''

''These cracks often initiate in the heat-affected zones or cold-worked areas and are intergranular in nature.''

This signature 'crazed' appearance with branching is diagnostic of Cl-SCC, making option C the correct and most descriptive answer.

Answer : B

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 800F to 1500F (427C to 816C), 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 (750F to 1500F / 400C to 815C) the most accurate and standard-aligned answer.