46 CFR §34.50-20

1. (a)The frame or support of each size III, IV, and V fire extinguisher required by table 34.50-10(a) must be welded or otherwise permanently attached to a bulkhead or deck.
2. (b)If a size III, IV, or V fire extinguisher has wheels and is not required by table 34.50-10(a), it must be securely stowed when not in use to prevent it from rolling out of control under heavy sea conditions.