Practice Test Geeks(API 510) Certified Pressure Vessel Inspector Practice Test
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Corrosion, Welding & Material Defects Flashcards

7 cards from real API 510 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Stress corrosion cracking (SCC) in pressure vessels requires which three conditions to occur simultaneously?

    Answer: Susceptible material, tensile stress, and corrosive environment

    SCC requires a susceptible material, a specific corrosive environment (even in trace amounts), and sufficient tensile stress (residual or applied) — all three must be present simultaneously.

  2. According to API 510, what is the minimum required thickness formula variable 'C' used for?

    Answer: Corrosion allowance added to calculated minimum thickness

    In API 510 calculations, 'C' represents the corrosion allowance — the extra material thickness added to accommodate future corrosion over the vessel's remaining service life.

  3. Which type of cracking occurs in the heat-affected zone (HAZ) of welds in high-strength steels due to hydrogen embrittlement?

    Answer: Hydrogen-induced cracking (HIC)

    Hydrogen-induced cracking (also called cold cracking or delayed cracking) occurs in the HAZ when atomic hydrogen diffuses into the steel lattice, and combined with residual stress, causes cracking after the weld cools.

  4. What type of corrosion is most commonly found in stagnant or low-flow areas, crevices, and under deposits on a pressure vessel?

    Answer: Crevice corrosion

    Crevice corrosion occurs in confined spaces where stagnant solution becomes depleted in oxygen and enriched in corrosive ions, creating an aggressive local environment.

  5. Which weld defect is caused by gas pockets or voids trapped in the solidifying weld metal?

    Answer: Porosity

    Porosity consists of cavities or pores formed when gas (hydrogen, oxygen, or nitrogen) becomes trapped in the molten weld pool and cannot escape before solidification.

  6. High-temperature hydrogen attack (HTHA) in pressure vessels primarily affects which property of carbon steel?

    Answer: Tensile strength and ductility through decarburization

    HTHA causes decarburization as atomic hydrogen reacts with carbon in the steel to form methane gas, leading to internal fissuring, blistering, and significant loss of tensile strength and ductility.

  7. A liquid penetrant test (PT) can ONLY detect which category of defects?

    Answer: Surface-open discontinuities

    Liquid penetrant testing (PT) relies on capillary action drawing penetrant into open surface discontinuities; it cannot detect defects that are not open to the test surface.