Penetrant Testing 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 Penetrant Testing flashcards as text
What is the primary purpose of the dwell time in liquid penetrant testing?
Answer: To allow the penetrant to seep into surface discontinuities by capillary action
Dwell time allows the penetrant to remain on the surface long enough for capillary action to draw it into any open discontinuities.
Which type of penetrant system uses an emulsifier applied after penetrant to make excess penetrant water-washable?
Answer: Post-emulsifiable penetrant system
Post-emulsifiable (PE) systems require a separate emulsifier step after penetrant dwell to render the surface penetrant removable with water.
According to ASME standards, what is the minimum dwell time for penetrant when testing for lack of fusion in welds at room temperature?
Answer: 10 minutes
ASME standards typically specify a minimum 10-minute dwell time for most weld discontinuities under standard temperature conditions.
What type of discontinuity CANNOT be detected by liquid penetrant testing?
Answer: Subsurface voids
LPT relies on capillary action into surface-open discontinuities; subsurface defects with no opening to the surface cannot be detected.
What is the function of the developer in liquid penetrant testing?
Answer: To draw penetrant back out of discontinuities and provide a contrasting background
Developer acts as a blotter to pull entrapped penetrant out of discontinuities and provides a white background that enhances contrast of the indication.
Which lighting condition is required when examining parts with fluorescent penetrant?
Answer: Ultraviolet (black) light in a darkened area
Fluorescent PT indications are only visible under UV-A (black) light in a darkened inspection booth, typically less than 2 fc ambient light.
What does the term 'false indication' mean in penetrant testing?
Answer: An indication produced by poor technique or contamination rather than a true discontinuity
A false indication results from improper cleaning, poor rinsing, or contamination and does not represent an actual discontinuity in the material.