Inspection Techniques and NDE Flashcards

Which nondestructive examination (NDE) method is most effective for detecting subsurface flaws in thick-walled pressure vessels?

Answer: Ultrasonic testing (UT)

Ultrasonic testing uses high-frequency sound waves to detect internal flaws, measure wall thickness, and characterize defects in thick-walled equipment, providing depth and size information for subsurface discontinuities.

What is the purpose of a Fitness-for-Service (FFS) assessment in RBI?

Answer: To determine if equipment with known flaws can continue to operate safely

FFS assessments, typically performed per API 579-1, evaluate whether equipment containing flaws, damage, or deviations from original design can continue operating safely, often avoiding unnecessary shutdowns or replacements.

What does corrosion rate monitoring using coupons involve?

Answer: Installing metal samples in process streams and measuring weight loss over time

Corrosion coupons are pre-weighed metal specimens installed in process streams for a defined period, then removed and weighed to calculate the corrosion rate based on weight loss, area, and exposure time.

When is radiographic testing (RT) preferred over ultrasonic testing for weld inspection?

Answer: When a permanent record of the inspection is needed and for detecting volumetric flaws

RT is preferred when a permanent film or digital record is needed, for detecting volumetric discontinuities (porosity, inclusions), and for initial weld acceptance inspection where permanent documentation is required.

What is the purpose of acoustic emission testing (AET) in RBI programs?

Answer: To detect active flaws by monitoring stress waves released during crack growth

AET monitors high-frequency stress waves emitted by active flaws (growing cracks, leaks, corrosion) in real-time, making it valuable for detecting actively deteriorating conditions during operation.

What is the minimum information needed to calculate a remaining life estimate for corroding equipment?

Answer: Current wall thickness, original/minimum required thickness, and corrosion rate

Remaining life is calculated as (current thickness - minimum required thickness) / corrosion rate. These three parameters are essential for estimating when equipment will reach its retirement thickness.