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. For a carbon steel piping system operating at 700°F (371°C), which long-term metallurgical degradation mechanism must be considered in material selection?

    Answer: Graphitization and/or temper embrittlement

    Carbon steel exposed above ~650°F for extended periods can suffer graphitization (decomposition of pearlite to graphite) and low-alloy steels may experience temper embrittlement.

  2. Which ASTM/ASME specification applies to carbon steel butt-welding fittings (elbows, tees, reducers) for pressure service?

    Answer: A234/SA-234

    A234/SA-234 covers carbon and alloy steel wrought butt-welding fittings for moderate- and elevated-temperature service.

  3. What is the Nelson curve used for in piping material selection?

    Answer: Determining safe operating limits for carbon and alloy steels in hydrogen service to avoid HTHA

    Nelson curves (API RP 941) plot temperature vs. hydrogen partial pressure boundaries above which specific steels experience high-temperature hydrogen attack (HTHA).

  4. Titanium piping is most advantageously specified for which of the following service conditions?

    Answer: Wet chlorine gas and oxidizing acid service

    Titanium forms a highly stable oxide layer that makes it extremely resistant to wet chlorine, chlorinated solutions, and many oxidizing acids.

  5. The Pitting Resistance Equivalent Number (PREN) for stainless steels is calculated primarily from which alloying elements?

    Answer: Chromium, molybdenum, and nitrogen

    PREN = %Cr + 3.3×%Mo + 16×%N; higher values indicate better pitting resistance, with super-duplex grades typically requiring PREN ≥ 40.

  6. Which post-weld heat treatment (PWHT) temperature range is specified for P91 (9Cr-1Mo-V) alloy steel to restore creep strength?

    Answer: 1375–1425°F (746–774°C) — subcritical tempering

    P91 requires PWHT in the range of approximately 1375–1425°F to properly temper the martensite and achieve the required creep strength and toughness.

  7. In a fire water system, which material is most commonly specified for underground buried piping due to its corrosion resistance and low cost?

    Answer: Ductile iron with polyethylene encasement or cement lining

    Ductile iron pipe with polyethylene encasement is the standard choice for buried fire water systems, balancing cost, strength, and corrosion protection.