Material Selection & Properties Flashcards
7 cards from real AEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Material Selection & Properties flashcards as text
In the selection of gasket materials for high-pressure steam flanges in a power plant, which property is most critical?
Answer: Creep relaxation resistance at elevated temperatures
Gasket materials for steam flanges must resist creep relaxation under sustained bolt load and high temperature to maintain a leak-tight seal over time.
What is the significance of the Curie temperature for magnetic materials used in electrical equipment?
Answer: It is the temperature above which a ferromagnetic material loses its magnetic properties
Above the Curie temperature, thermal agitation destroys the magnetic domain alignment in ferromagnetic materials, causing them to become paramagnetic and lose their usefulness in cores.
Which type of insulating material is classified as a 'Class H' insulation system?
Answer: Silicone rubber or glass fiber rated up to 180°C
Class H insulation includes silicone elastomers and inorganic materials with a maximum continuous operating temperature of 180°C.
In underground cable systems, what is the primary purpose of a metallic sheath or shield surrounding the insulation?
Answer: To provide a ground return path and confine the electric field within the cable
The metallic shield confines the electric field to the cable insulation, provides a path for fault and charging currents, and ensures uniform radial electric stress distribution.
What does the 'temper designation' H14 indicate for aluminum alloy?
Answer: The alloy has been strain-hardened to approximately half-hard condition
In the H-temper series, H14 indicates strain-hardened to a half-hard condition (second digit 4 = halfway between annealed and full-hard).
Why is porcelain still widely used for high-voltage outdoor insulators despite newer polymer alternatives?
Answer: Porcelain has proven long-term performance, high compressive strength, and excellent resistance to UV and surface tracking
Porcelain insulators have decades of proven reliability in outdoor environments, offering excellent compressive strength, UV resistance, and resistance to surface contamination tracking.
Which destructive testing method would be used to examine the internal grain structure and detect weld defects in a cross-section of a pipe weld?
Answer: Metallographic examination (macro/micro etching)
Metallographic examination involves cutting, polishing, and etching a specimen cross-section to reveal the grain structure, weld fusion zone, and internal defects under a microscope.