8
When measuring on curved surfaces such as pipes or tubes make sure the coupling of the
transceiver is made properly. The acoustic layer interface of the transceiver must be aligned so as
to form a right angle to the axis of curvature of sample (longitudinal axis of tube). For small tube
diameters it is recommended to carry out two measurements: one with the layer interface in vertical
position to the longitudinal axis of tube, another one in parallel position to the longitudinal axis of
tube. The smaller of the two readings obtained should be used as the correct one for this measuring
spot.
(senkrecht = vertical)
1.1.2.6 Duplication of Reading
Do not measure in a range lower than the measuring range specified for the sensor. In such case,
the first back wall echo would not be strong enough for being processed whereas the amplitude of
the second one would be strong enough to be processed accordingly. As a result, the reading
obtained would be twice the actual wall thickness. In order to avoid such errors when measuring at
the limit of the measuring range it is recommended to verify results by using another sensor.
In critical cases, it is recommended to use display screen equipment to provide additional information
on the echo curve.
.
