Is the designation S355JRG3 correct?
S355JR is a steel grade in EN 10025 (Hot rolled products of non-alloy structural steel) edition 1990 + add. 93.
G3 is a designation for fully killed material in the same standard. The combination of S355JR and G3 is not stipulated in this standard. To have a fully killed steel, you should use S355J2G3. J2 = Charpy-V -20°C, JR = Charpy-V at +20°C (27J long).
Meanwhile this standard is revised. In edition 2003 of EN 10025-2, the steel designation is S355JR resp. S355J2. If you need normalized material, you should order +N.
EN 10029 is a standard for dimensional tolerances.
I can't identify the "8". Could it be a "B" indicating the thickness tolerance class?