Application Notes - Elcometer SG80 Operating Instructions Manual

15 APPLICATION NOTES

15.1 MEASURING TUBING
When measuring a piece of pipe to determine the thickness of the pipe wall, orientation of the transducers
is important.
If the diameter of the pipe is larger than approximately 100 mm (4"), measurements should be made with
the transducer oriented so that the gap in the wearface is perpendicular (at right angles) to the long axis of
the pipe.
If the diameter of the pipe is small, two measurements should be performed, one with the wearface gap
perpendicular to the long axis of the pipe, another with the gap parallel to the long axis of the pipe - see
illustration. The smaller of the two displayed values should then be taken as the thickness at that point.
Perpendicular Parallel
15.2 MEASURING HOT SURFACES
The velocity of sound through a material depends upon the temperature of the material. As materials heat
up, the velocity of sound in the material decreases. In most applications with surface temperatures less than
approximately 100°C (~200°F), no special procedures are required. At temperatures above 100°C
(~200°F), the change in sound-velocity of the material being measured starts to have a noticeable effect
upon the accuracy of ultrasonic measurement.
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