ISO INTERNATIONAL STANDARD 16809 Second edition 2017-11 Non-destructive testing Ultrasonic thickness measurement Essais non destructifs Mesurage de I'épaisseur par ultrasons Reference number IS0 16809:2017(E) ISO IS02017 IS0 16809:2017(E) Contents Page Foreword 1 Scope. 2 Normative references. 1 3 Terms and definitions.. .1 4 Measurement modes. 5 General requirements. .3 5.1 Instruments. 5.2 Probes. 5.3 Couplant 5.4 Reference blocks. 5.5 Test objects. 5.6 Qualification of personnel Application of the technique .4 6.1 Surface conditions and surface preparation 6.2 Technique.... .4 6.2.1 General. 6.2.2 Measurement during manufacture 5 6.2.3 In-service measurement of residual wall thickness 6.3 Selection of probe.. 6.4 Selection of instrument 6.5 Materials different from the reference material 6 6.6 Special measuring conditions .. 6.6.1 General. 6.6.2 Measurements at temperatures below 0 °C 6.6.3 Measurements at elevated temperatures. 6.6.4 Hazardous atmospheres. Instrument setting. 7.1 General. 7.2 Methods of setting. .8 7.2.1 General. 8 7.2.2 Digital thickness instruments .8 7.2.3 A-scaninstrument .8 7.3 Checks of settings. 8 Influence on accuracy 10 8.1 Operational conditions.. 10 8.1.1 Surface conditions. 10 8.1.2 Surface temperature. 10 8.1.3 Metallic coating. 11 8.1.4 Non-metallic coating. 11 8.1.5 Geometry. 12 8.2 Equipment. 12 8.2.1 Resolution 12 8.2.2 Range .. 13 8.3 Evaluation of accuracy. 13 8.3.1 General. 13 8.3.2 Influencing parameters .14 8.3.3 Method of calculation . 14 9 Influence of materials ..14 9.1 General 14 9.2 Inhomogeneity 14 9.3 Anisotropy .14 @ IS0 2017 - All rights reserved iii IS0 16809:2017(E) 9.4 Attenuation -14 9.5 Surface conditions. ..14 9.5.1 General. .14 9.5.2 Contact surface .15 9.5.3 Reflecting surface. .15 9.5.4 Corrosion and erosion .15 10 Test report. .16 10.1 General. 16 10.2 General information .16 10.3 Measurementdata. .17 Annex A (informative) Corrosion in vessels and piping ..18 Annex B (informative) Instrument settings .23 Annex C (informative) Parameters influencing accuracy .26 Annex D (informative) Selection of measuring technique .32 Bibliography .37 iv @IS0 2017 -All rights reserved