API RP 2X Reference Standard Set
American Petroleum Institute Reference Standard for Level “C” Examination for Recommended Practice 2X (RP 2X), Ultrasonic Examination of Offshore Structural Fabrication and Guidelines for Qualification of Ultrasonic Technicians. Set of four (4) blocks required. One block containing a square (buttress) notch and one each with V-notches for 45°, 60°, and 70° orientations for establishing scanning sensitivity for root reflectors. Note: 
Simulated references for rejectable flaws established by the Operator’s UT specialist should be added to this block for the calibration of internal reflectors. In accordance with API RP 2X.

Number 1: Square Notch

Number 2: 45° V-Notch

Number 3: 60° V-Notch

Number 4: 70° V-Notch