Angle beam sensitivity can be established using a feature of what size on the IIW reference block?

• A. 0.030 inch side-drilled hole
• B. 0.060 inch side-drilled hole
• C. 0.125 inch side-drilled hole
• D. 0.100 inch side-drilled hole

Answer: (B)

Angle beam sensitivity is set by referencing a known reflector on an IIW reference block. The instrument’s gain is adjusted so the echo from a side-drilled hole reaches a predefined indication on the display, establishing a repeatable baseline for flaw detection. The 0.060 inch side-drilled hole is used because it provides a reliable, mid-range echo: strong enough to be clearly detected across typical equipment, but not so large as to saturate the display or misrepresent typical flaw signals. Smaller holes can be too faint for stable calibration, while larger holes can give echoes that aren’t representative for everyday inspections. Using this hole size creates a practical and consistent standard for calibrating angle beam sensitivity.