Material Properties & Inspection Standards Flashcards
7 cards from real NDT 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 Properties & Inspection Standards flashcards as text
What is the significance of the 'nil-ductility transition (NDT) temperature' in boiler plate steels?
Answer: Temperature below which steel fractures with essentially no plastic deformation
The NDT temperature marks the point below which a material undergoes brittle fracture with no measurable plastic deformation, critical for cold-service pressure equipment.
In ultrasonic thickness testing of a boiler tube, a technician measures a wall thickness significantly below the design minimum. What action should follow?
Answer: Mark the location and report it for engineering evaluation and potential replacement
Sub-minimum wall thickness must be documented, reported to the responsible engineer, and evaluated against fitness-for-service criteria before a decision is made.
What material property is described by the area under a stress-strain curve up to the point of fracture?
Answer: Toughness
Toughness is the total energy per unit volume that a material can absorb before fracturing, represented by the area under the full stress-strain curve.
Which ASTM standard covers the standard practice for liquid penetrant examination?
Answer: ASTM E165
ASTM E165 is the standard practice for liquid penetrant examination for general industry, commonly referenced in boilermaker and pressure vessel inspection.
What effect does post-weld heat treatment (PWHT) have on the residual stresses in a welded boiler component?
Answer: It reduces residual stresses by allowing stress relaxation at elevated temperature
PWHT heats the component to a temperature where residual stresses relax through creep mechanisms, significantly reducing the peak stress levels in the weld region.
In the context of ASME pressure vessel codes, what does the 'Maximum Allowable Working Pressure' (MAWP) represent?
Answer: The maximum internal pressure a vessel is designed to safely withstand in service
MAWP is the maximum gauge pressure permissible at the top of a completed vessel in its operating position for a designated temperature.
Which type of corrosion mechanism preferentially attacks grain boundaries in a metal microstructure?
Answer: Intergranular corrosion
Intergranular corrosion attacks the grain boundaries of a metal, often due to precipitates or depletion of alloying elements at those boundaries.