Liquid Penetrant Testing Process 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 Liquid Penetrant Testing Process flashcards as text
Why must a penetrant inspector allow their eyes to adapt to darkness before evaluating fluorescent indications?
Answer: To maximize eye sensitivity to low-level fluorescent light emitted by indications
Dark adaptation (at least 1 minute) increases the eye's sensitivity to faint fluorescent indications, reducing the chance of missing small discontinuities.
What is the primary advantage of using a hydrophilic emulsifier (Method D) over a lipophilic emulsifier (Method B)?
Answer: Greater process control and reduced risk of over-emulsification
Hydrophilic emulsifiers are applied as a rinse or spray and are diluted, making the process less sensitive to contact time variations and reducing over-emulsification risk.
Which penetrant testing process step is performed IMMEDIATELY before developer application?
Answer: Excess penetrant removal (washing/wiping)
Excess penetrant must be removed from the surface before developer is applied; applying developer over excess penetrant would mask indications.
A test block (also called a reference block or comparator) is used in liquid penetrant testing primarily to:
Answer: Verify the performance and sensitivity of the penetrant system in use
Reference blocks contain controlled discontinuities that allow inspectors to verify the penetrant system is producing acceptable performance prior to and during inspection.
When evaluating a penetrant indication, what does a 'ghost' or 'phantom' indication most often indicate?
Answer: Residual fluorescent penetrant left from a previous incomplete cleaning
Ghost indications are fluorescent residues from prior inspections or inadequate cleaning that reactivate under developer, not from actual present discontinuities.
Which of the following penetrant system combinations offers the HIGHEST sensitivity for finding fine cracks?
Answer: Type I (fluorescent), Method D (hydrophilic post-emulsifiable), Form d (non-aqueous wet developer)
Fluorescent penetrant with hydrophilic post-emulsification and non-aqueous wet developer is the highest-sensitivity combination, used in critical aerospace and power generation inspections.
In liquid penetrant testing, what is the consequence of applying developer too thickly?
Answer: It masks fine indications by absorbing and hiding the penetrant bleed-out
An excessively thick developer coat can trap and hide penetrant bleed-out within the developer layer, preventing visibility of small or fine indications.