I would like to ask if the UT equipment was calibrated with 10mm transducer and during the site inspection, we used 5mm transducer, do we need to calibrate again the equipment as per ASTM E317?
In accordance with AWS D1.1, the test instrument, with cable and transducer is required to be recalibrated using a standard calibration block any time the cable or transducer is changed, any time a batter is changed, any time the instrument is unplugged and plugged into a different socket, and every 2 hours if I remember correctly.
There are two types of "calibration" is ultrasonic testing. There is the "instrument calibration" (for lack of a better term) which is performed every few months; intervals range from 2 months for AWS D1.1 to 12 months for digital instruments for the ASME Code. This is the calibration stipulated in ASTM E317 and similar specs. During this calibration the performance of the instrument is verified. The horizontal, vertical and gain linearities are verified as accurate. This calibration will generally result in a calibration sticker placed on the instrument. The second "calibration" is a "test calibration" (again my term). This is the calibration performed at the job site using the specific equipment to be used for the test. The screen width and range as well as gain is set based on a specific calibration block of some sort. This test is repeated, as gtaw states, before and after each scan as well as periodically throughout the day. A different "test calibration" is required for each different transducer / angle combination to be used.
Finally to answer your question Pipoy04, the ASTM E317 "instrument calibration" does not have to be repeated with the equipment to be used for the exam (5 mm transducer vs 10 mm). However, a "test calibration" using the 5 mm transducer on the appropriate calibration block would need to be performed as part of the inspection.