To achieve Severe Duty, you will need to meet as a minimum the lateral stiffness and impact resistance criteria as set out in BS 5234 Part 2. 

The maximum height of a partition is limited to a lateral deflection of 10mm when tested in line with this standard.

Impact resistance is down to board selection. Any combination of two boards (at least 12.5mm thick) will meet the impact criteria. For single board solutions, 15mm LaDura, Megadeco, Universal are required.