Practice Test Geeks(SPED) Society of Piping Engineers and Designers Certification Practice Test
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Materials Selection & Specification Flashcards

7 cards from real SPED 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. The maximum allowable hardness for carbon and low-alloy steel in NACE MR0175 sour service is:

    Answer: HRC 22 (approximately 237 HBW)

    NACE MR0175/ISO 15156 limits carbon and low-alloy steel hardness to HRC 22 (≈237 HBW) to prevent sulfide stress cracking.

  2. Galvanic corrosion risk is greatest when two dissimilar metals are:

    Answer: In electrical contact in the presence of an electrolyte

    Galvanic corrosion requires both electrical continuity between the metals and an electrolyte to complete the electrochemical circuit.

  3. SA-335 P91 alloy steel pipe is primarily used in which service?

    Answer: High-temperature, high-pressure steam service above 1000°F

    SA-335 P91 (9Cr-1Mo-V) is a creep-resistant alloy specifically developed for high-temperature steam piping in power generation applications.

  4. Which type of corrosion involves selective dissolution of one component of an alloy, commonly seen in brass in ammonia service?

    Answer: Dealloying (dezincification)

    Dezincification is the selective leaching of zinc from brass, leaving a porous copper matrix; it commonly occurs in stagnant or slow-moving water and in ammonia environments.

  5. When specifying a material for piping in hydrofluoric acid (HF) alkylation service, which alloy family is most commonly selected?

    Answer: Monel (Ni-Cu alloy, UNS N04400)

    Monel alloys (Ni-Cu) are the industry-standard material for anhydrous HF service due to their excellent corrosion resistance to this highly aggressive acid.

  6. What does the 'L' designation signify in stainless steel grades such as 304L and 316L?

    Answer: Low carbon content (≤0.030% C) to minimize sensitization

    The 'L' grade has a maximum carbon content of 0.030%, which reduces chromium carbide precipitation at grain boundaries (sensitization) during welding.

  7. Erosion-corrosion damage in piping is most likely to occur at which location?

    Answer: Elbows, tees, and reducers with flow direction changes

    Flow direction changes at elbows and tees create turbulence and impingement that strip protective oxide films, accelerating erosion-corrosion.