Inspection Methods & Nondestructive Testing Flashcards

An inspector performing UT thickness measurement on a pressure vessel finds readings significantly lower than the original design thickness. Per API 510, what is the next step before determining corroded thickness retirement?

Answer: Establish a corrosion rate using historical thickness data to calculate remaining life

API 510 requires calculating short-term and long-term corrosion rates from historical data to establish remaining life and next inspection interval.

In radiographic testing of a pressure vessel weld, what is 'geometric unsharpness' (Ug) and how is it controlled?

Answer: Blurring of the radiographic image caused by source size and geometry, controlled by maximizing source-to-object distance and minimizing object-to-film distance

Geometric unsharpness is penumbra blur from finite source size; it is minimized by using a small source and maximizing SFD while minimizing OFD.

Which API 510 inspection category is defined as an internal inspection performed with the vessel open and entry made by the inspector?

Answer: Internal inspection

API 510 defines internal inspection as a formal inspection with the vessel out of service, opened, and entered by the inspector for direct examination.

During penetrant testing of a pressure vessel repair weld, the inspector notes a linear indication that is 3/4 inch long but fades after 7 minutes of development. What is the most likely cause?

Answer: The indication is a wide, shallow scratch that is bleeding out slowly — the linear pattern and fading suggest a superficial mechanical mark rather than a crack

Wide, shallow scratches often produce fading linear indications because there is limited penetrant volume trapped, unlike tight cracks which continue to bleed.

API 510 allows substitution of on-stream inspection for internal inspection under certain conditions. Which of the following is NOT one of those conditions?

Answer: The vessel is operating above its maximum allowable working pressure (MAWP)

Operating above MAWP is never a condition that permits on-stream substitution; it is a violation of the vessel's design envelope.

What is the primary advantage of pulsed eddy current (PEC) testing when inspecting an insulated pressure vessel?

Answer: It can detect wall loss through insulation, cladding, and coatings without requiring removal of the insulation

PEC penetrates insulation and coatings using time-domain analysis of induced eddy currents, enabling wall-loss detection without stripping insulation.

When applying ASME Section VIII, Div. 1 rules for a hydrostatic test of a repaired vessel, the test pressure is typically set at what multiple of the MAWP (adjusted for temperature)?

Answer: 1.3 times the MAWP

ASME Section VIII, Div. 1 (post-2000 editions) requires a hydrostatic test pressure of 1.3 × MAWP × (stress ratio for test temperature).