CRI Pipe & Pressure Vessel Inspection Flashcards

What characteristic radiographic appearance distinguishes internal corrosion in a pipe from a weld discontinuity?

Answer: Corrosion appears as irregular dark areas or pitting with no sharp edges, not aligned with weld features

Internal corrosion produces irregular, diffuse dark density variations that do not align with the weld geometry and typically show a pitted or channeled pattern.

For pressure vessel nozzle-to-shell welds, which examination technique is used when film cannot be placed inside the nozzle bore?

Answer: Double-wall single-image (DWSI) technique

DWSI technique is used for nozzle welds where film placement inside is impossible; the source is placed outside and the image of only the far-side wall is interpreted.

A pressure vessel radiograph shows a region of lighter density (less exposure) at the edge of the weld near the nozzle junction. What is the most likely cause?

Answer: Increased material thickness at the reinforcement pad reducing radiation transmission

A reinforcement pad or extra material at a nozzle junction increases local thickness, attenuating more radiation and producing a lighter (lower density) area on film.

Per ASME Section VIII, when is 100% radiographic examination required for pressure vessel Category A and B welds?

Answer: When the vessel is in lethal service or designed for over 1.5 times joint efficiency credit

ASME Section VIII Division 1 mandates full RT for vessels in lethal service and when the designer takes full (1.0) joint efficiency credit for weld design.

What is the primary reason that helical (spiral) weld seams in pipe require special consideration when planning radiographic examination?

Answer: The weld angle to the pipe axis affects the projection geometry and requires angled source placement to maintain proper coverage

The helical angle of a spiral weld means a straight radiographic beam would not be perpendicular to the weld plane, requiring angled source placement to properly image the weld cross-section.

In pressure vessel radiography, what does the term 'volumetric examination' mean?

Answer: Examination that detects discontinuities throughout the full weld cross-section volume, not just the surface

Volumetric examination means the full through-thickness volume of the weld is interrogated, distinguishing RT and UT from surface-only methods like MT or PT.