An assessment of ultrasonic reference block calibration methodology

Abstract

Illustration of an ultrasonic flat-bottom-hole reference block.The principal components of an ultrasonic calibration system for reference blocks:the transducer, the pulser/receiver , the primary reference standards, the reference blocks and the immersion tank and yoke system to suspend and manipulate the transducer relative to the targets.Echo amplitude data as a function of metal-path distance for an anomalous reference block set (diamonds), compared with typical values (solid line).A continuous profile scan of the back-surface echo amplitude from A) the anomalous block material, and B) the normal block material.Far-field center axis beam profiles of a ceramic (dashed line) and a quartz transducer (solid line).Reference-block-echo amplitude data taken with a ceramic transducer (discrete points), relative to that taken with a quartz transducer (solid line), as a function of metal path distance for a No. 5 hole set. Ceramic values using two distinct targets before the application of correction factors (diamonds and triangles), compared to the corrected values (stars) using a block target. 1 LIST OF TABLES Table 1 Table 2 Relative echo amplitude responses of a reference block (5-0050) and a steel sphere (5/16-inch diameter) as a function of pulse width.Steel sphere diameters used to set system sensitivity for the respective block hole sizes, according to ASTM E127. Suggestions for improving present practices are given, and extensive reference to the relevant technical literature is made.

Evaluation of new designed reference blocks for calibration and NDT by optical and ultrasonic techniques

“…Flat bottom holes (FBH) were used to demonstrate transducer sensitivity and characterize distinct holes on these constructed blocks. These blocks were typically rectangular in shape, with single-sized FBH positioned at various locations on the block surface [5].…”