This European Standard specifies a method for the estimation of the average grain size of copper and copper alloy products by ultrasound. This standard can be applied for seamless round tubes as well as for flat products. The method can be used in place of test methods according to EN ISO 2624, mentioned in the relevant product standards. As reference method and in case of doubt the intercept procedure or planimetric procedure has to be used. This European Standard (EN 16090:2011) has been prepared by Working Group 3 "Copper tubes (Installation and industrial)" (secretariat: DIN) within Technical Committee CEN/TC 133 "Copper and copper alloys" (secretariat: DIN, Germany) of the European Committee for Standardization (CEN). During the preparation of this standard the national interests were represented by Working Committee NA 066-02-03 AA "Kupferrohre (Installation und Industrie)" ("Copper tubes (Installation and industrial)") of the Non-ferrous Metals Standards Committee (FNNE) at DIN, the German Institute for Standardization e. V.