Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

(1b) Flaw detection
As in high temperature thickness gaging applications, high temperature flaw
detection most commonly uses dual element or delay line transducers. All
standard Panametrics-NDT flaw detection duals offer high temperature
capability. Fingertip, Flush Case, and Extended Range duals whose
frequency is 5 MHz or below may be used up to approximately 425° C or
800° F, and higher frequency duals (7.5 and 10 MHz) may be used up to
approximately 175° C or 350° F. For a full list of transducers in this category,
see this link: Flaw Detection Duals.
All of the Videoscan Replaceable Face Transducers can be used with
appropriate high temperature delay lines in flaw detection applications. The
available delay lines for this family of transducers can be used in contact with
surfaces as hot as 480° C or 900° F. For a full list of transducers and delay
lines suitable for various maximum temperatures, see this link: Replaceable
Face Transducers.