Specifications

USN52 L Operating Manual Page 61
9.1 General Notes on Calibration
Before the USN52 L can be used for flaw detection or thickness
measurement, the horizontal and vertical axes of the A-scan dis-
play must be calibrated.
Calibration assures that:
1. horizontal range of the A-scan display is adequate to display
the entire thickness of the test object,
2. horizontal position of echo signals can be used to determine
distance to discontinuity or backwall,
3. vertical amplitude of signals is adequate to detect the small-
est required flaw, and
4. flaw size can be evaluated by comparison with known reflec-
tors, for example, flat bottom holes.
Calibration is accomplished using a reference standard (test block).
USN52 L controls are adjusted until horizontal positions and verti-
cal amplitudes of echo signals from known test block reflectors
are correctly displayed. The specific test block used depends on
the application.
NOTE: All USN52 L calibration procedures require a refer-
ence standard of the same material, velocity of sound, and
temperature as the material to be inspected.
It is beyond the scope of this operating manual to provide detailed
procedures for specific applications. This chapter provides the
steps commonly required to perform basic, horizontal axis (thick-
ness/distance) calibrations for three general classes of ultrasonic
testing applications:
1. Straight beam inspection with a single element contact probe
2. Straight beam inspection with a dual element (TR) probe
3. Angle beam inspection with an angle beam (shear wave)
contact probe
After the general procedure for each class of application in this
chapter, a specific example is given that uses a commonly avail-
able test block.
9. Calibrating the A-scan Display