Depending on the required load carrying capacity, Single Row Ball or Triple Row Roller Slewing Rings (often with internal toothing) are used in offshore cranes.
Slewing Rings for offshore applications have to meet special approval requirements regarding material characteristics and safety under catastrophic load cases. The arduous environmental conditions require high performance sealing systems. Inspection and approval by the certifying authorities is often required.
Slewing Rings for offshore applications are always subject to special approval requirements from the respective certifying authority. The rolled rings must demonstrate a notched bar impact strength of an average of 42 J at -20°C.
The picture below shows the final assembly of a Triple Row, internal toothed Roller Slewing Ring for a large offshore crane.