SELECTION OF PROBE ANGLE:
There are three methods for selecting a probe angle, these are:

Based on groove angle:
Probe Angle (Ø) = 90 – α/2
Where, α – Groove angle and Ø Probe Angle

As per AWS:
 0 – 30 mm Thickness – 70^{0} Probe
 30 – 40 mm Thickness – 60^{0} Probe
 > 40 mm Thickness – 45^{0} Probe

As per approved procedure:
Third way of selection of Probe angle is as per the procedure approved by any competent person/client.
SKIP DISTANCE AND BEAM PATH (SOUND PATH) CALCULATION:

Skip distance calculation:
(Abbreviations: HSD – Half Skip Distance, FSD – Full Skip Distance)
Tan Ø = Perpendicular (BG)/ Base (AG) = AC (or HSD)/THK
Hence, Tan Ø = HSD/T
Or, HSD = T X Tan Ø
Similarly, FSD = 2T X Tan Ø
And, 11/2 Skip Distance = 3T X Tan Ø

Beam Path calculation:
(Abbreviations: HBP – Half Beam Path, FBP – Full Beam Path)
Cos Ø = Base (AG) / Hypotenuse (AB) = THK/HBP
Or, HBP = T / Cos Ø
Similarly, FBP = 2T / Cos Ø
And, 11/2 Beam Path = 3T / Cos Ø
NOTE: 1. Scanning area should be 11/2 Skip Distance i.e. 3T X Tan Ø
2. Probe Travel Speed shall not be more than 150 mm/S
Read more: How to write a Welding Procedure Specification (WPS)
Read more: Welding Positions
Read more: Preheating – How, When and Why
Read more: Welder Qualification test
Read more: Thickness range as per ASME Section IX
To learn more information.
To learn more information about ndt.
Dear Sandeep ji,
Can you please upload the Notes for basic of UT Machine calibration & Video for same.
Thanks