24 API RECOMMENDED PRACTICE 2D
2. Crane/Bearing Connection Integrity
The crane/bearing can be connected using bolts, welding
or combinations of the two. The integrity of this connection is
crucial to the life of the swing circle assembly. The crane and/
or swing circle assembly manufacturer should be contacted
for guidance when developing the inspection procedures, as
each crane is unique.
Bolts must be correctly preloaded to function properly and
the crane manufacturer may be the only source for proper
torque/preload procedures and values. General purpose bolt
torque charts may not be applicable due to the various bolt
materials, platings, surface Þnishes, joint designs, etc. found
in use. Loose or incorrectly preloaded mounting bolts is one
of the major causes of swing circle assembly failure.
3. Operating Characteristics
The operating characteristics of a bearing are another factor
to be considered in an inspection.
The crane should be rotated 360¡ in each direction at slow,
intermediate and full speed and the smoothness of rotation
monitored. Any irregular, jerky, bumpy, etc. motions should
be recorded and further inspection may be in order.