AS ISO 16809:2020 pdf free.Non-destructive testing — Ultrasonic thickness measurement.
5 General requirements
5.1 Instruments
The following types of instruments shall be used to achieve thickness measurement:
a) dedicated ultrasonic thickness measurement instruments with numerical display showing the measured value;
b) dedicated ultrasonic thickness measurement instruments with numerical display showing the measured value and A-scan presentation (waveform display);
c) instruments designed primarily for the detection of discontinuities with A-scan presentation of signals. This type of instrument can also include numerical display of thickness values.
See4.
5.2 Probes
The following types of probes shall he used; these are generally longitudinal wave probes:
— dual-element probes;
— single-element probes.
See3.
5.3 Couplant
Acoustic contact between probe (probes) and material shall be provided, normally by application of a fluid or gel.
The couplant shall not have any adverse effect on the test object, the equipment or represent a health hazard to the operator.
For the use of the couplant in special measuring conditions, see .
The coupling medium should be chosen to suit the surface conditions and the irregularities of the
surface to ensure adequate coupling.
5.4 Reference blocks
The measuring system shall be calibrated on one or more samples or reference blocks representative of the object to be measured, i.e. having comparable dimensions, material and structure. The thickness of the blocks or the steps should cover the range of thickness to be nwasured. Either the thickness or the sound velocity of the reference blocks shall be known.
5.5 Test objects
The object to be measured shall allow for ultrasonic wave propagation.
There shall be free access to each individual area to be measured.
The surface of the area to be measured shall be free of all dirt, grease, lint, scale, welding flux and spatter, oil or other extraneous matter that could interfere with the testing.
If the surface is coated, the coating shall have good adhesion to the material. Otherwise it shall be removed.AS ISO 16809 pdf download.