BS ISO 19675:2017 pdf free
BS ISO 19675:2017 pdf free.Non-destructive testing一Ultrasonic testing一Specification for a calibration block for phased array testing (PAUT)
The pre-machined block shall be in accordance with the following.
a) It shall be free from internal discontinuities. For this purpose, an ultrasonic test shall be carried out after heat treatment, with a longitudinal wave straight-beam probe of at least 10 MHz nominal centre frequency and having a transducer size of 10 mm to 15 mm. The block shall be checked on all four long faces to cover the complete volume. With the probe positioned on the largest face of the block, the instrument’s gain shall be set to achieve a grain scatter noise of 10 % of full screen height. No echo shall have an amplitude greater than that of the grain scatter noise;
b) It shall be isotropic for transverse and longitudinal waves proved by velocity measurements in accordance with Annex A (see A.3). Probes shall be located around the mid-position of each of the three faces;
c) It shall present low sound attenuation.
NOTE Absolute measurements of attenuation may be difficult to obtain because echo amplitudes depend on many factors. The significance of attenuation can be estimated by simple qualitative tests. Relative attenuation measurements can be made by examining the exponential decay of multiple back wall reflections [a satisfactory attenuation generally is proven by the observation of at least four echoes above of 25 % of FSH when a probe as recommended in 5.2.3 a) is used]. See Figure 1.
The dimensions and tolerances of the phased array calibration block shall be determined and recorded in accordance with Annex A (see A.2) and shall be in accordance with Figure 2. All external surfaces shall be machined to a roughness value not greater than 0,8 μm Ra.
Permanent reference marks shall be engraved on the block in accordance with Figure 3 and Table 1.Reference marks shall be regular and not too deep (approx. 0,1 mm max.) and shall not be generated by a metal deformation process. Stamping shall not be used. Etching or laser engraving are the preferred marking processes.BS ISO 19675 pdf free download.
