Discontinuity Interpretation and Evaluation 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 Discontinuity Interpretation and Evaluation flashcards as text
An ASME code requires that any linear indication greater than 3/16 inch in a weld be rejected. A PT indication measures 3/16 inch exactly. The correct disposition is:
Answer: Accept — it does not exceed the limit
The code specifies 'greater than' 3/16 inch, so an indication exactly at 3/16 inch is acceptable under that criterion.
During UT inspection, multiple small signals appear scattered throughout the weld volume with low amplitude. The most likely cause is:
Answer: Distributed porosity
Scattered low-amplitude signals throughout the volume are characteristic of distributed porosity, where each pore produces a small reflection.
A radiographic image shows a dark, irregular line with a herringbone or chevron pattern along the weld centerline. This pattern is associated with:
Answer: Solidification (hot) cracking
Solidification cracks form along weld centerlines during cooling and often display a jagged or herringbone pattern following dendritic grain boundaries.
In magnetic particle testing, a broad fuzzy linear indication is observed. Compared to a sharp, crisp indication, this suggests the discontinuity is:
Answer: Deeper below the surface
Subsurface discontinuities cause broader, less defined magnetic particle indications because the leakage flux spreads as it reaches the surface.
An eddy current scan of a heat exchanger tube shows a signal whose depth reading is 80% through-wall. Per most fitness-for-service criteria, this tube should be:
Answer: Plugged or repaired immediately
Most industry standards (ASME, TEMA) require plugging or repair of heat exchanger tubes when wall loss reaches or exceeds 40–80% depending on code; 80% typically requires immediate action.
A surface-breaking crack detected by PT is evaluated and found to be relevant. The next required step per most codes is:
Answer: Assess against the applicable acceptance criteria
Once a relevant indication is identified, it must be compared against the applicable code acceptance criteria to determine accept or reject disposition.
During radiographic interpretation, the film shows an area of uniform density lighter than the surrounding base metal. This most likely represents:
Answer: Thicker section or added material
Lighter (less dense) areas on a radiograph indicate greater material thickness or higher density, which absorbs more radiation.