Inspection Techniques & Nondestructive Testing Flashcards

Eddy current testing (ECT) is most commonly used in pressure vessel inspection for:

Answer: Inspecting heat exchanger tubes for corrosion and pitting

ECT is widely used for rapid screening of heat exchanger tubes, detecting wall loss, pitting, cracks, and support plate wear without requiring the tube to be drained.

A vessel inspector suspects sulfide stress cracking (SSC) in a carbon steel vessel. Which NDT method is most appropriate for detecting SSC cracks at the surface?

Answer: Wet fluorescent magnetic particle testing (WFMT)

WFMT provides high sensitivity for detecting tight surface and near-surface cracks characteristic of SSC, which are typically too fine for RT to resolve reliably.

According to API 510, the maximum interval between external inspections for a pressure vessel in normal service is:

Answer: 5 years

API 510 specifies a maximum external inspection interval of 5 years for pressure vessels in normal service, though risk-based approaches may allow extensions.

During visual inspection of the external surface of an insulated vessel, the inspector notices wet insulation at a nozzle. The primary concern is:

Answer: Corrosion under insulation (CUI) on the vessel shell and nozzle neck

Wet insulation traps moisture against the vessel surface, creating conditions for accelerated CUI, which can cause significant metal loss that is hidden under the insulation.

Pulsed eddy current (PEC) testing offers an advantage over conventional ECT for pressure vessel inspection because it:

Answer: Can inspect through insulation and coatings without removal

PEC uses low-frequency pulsed fields that penetrate insulation and protective coatings, enabling corrosion screening without removing insulation—ideal for CUI surveys.

When performing hardness testing on a pressure vessel weld using a portable Brinell tester, what is the primary purpose in an inspection context?

Answer: Detecting softening or hardening associated with in-service damage mechanisms

Portable hardness testing on welds and HAZ can detect softening from high-temperature damage (e.g., graphitization, creep) or hardening from hydrogen embrittlement and SSC.

In API 510 terminology, a 'condition monitoring location' (CML) differs from a 'thickness measurement location' (TML) in that a CML:

Answer: Can include any monitoring technique, not just thickness measurement

A CML is a broader term encompassing any designated monitoring point where condition is assessed—including visual, chemical sampling, or other methods—while TML specifically refers to thickness measurement points.