GUIDELINES
FOR
MARINE
LIFTING
&
LOWERING
OPERATIONS
0027/ND Rev 11
Page 23 of 84
5.2
WEIGHT CONTINGENCY & CENTRE OF GRAVITY FACTORS
5.2.1
Weight Contingency and Centre of Gravity control requirements are given in Section 8 of 0001/ND,
Ref. [1], which in turn references ISO Standard 19901-5, Ref. [8].
5.3
MODULE TILT FOR SINGLE CRANE LIFTS
5.3.1
Object tilt due to CoG position and/or imposed horizontal loads (see Section 5.7 for possible causes of
horizontal loads) will influence the sling load distribution for most rigging configurations. The effect of
tilt should be considered in the load calculations where relevant.
5.3.2
The rigging geometry shall normally be configured so that the maximum tilt of the structure does not
exceed 2°. The sling angle should normally be as described in Section 6.4. Where calculated
maximum tilt is less than 2°, it is normally not necessary to consider related effects in the sling load
calculations.
5.3.3
Variable sling elongation, sling length and lift point fabrication tolerances could increase object tilt.
Where lifting points are located below the vertical CoG of the object, forces in the most utilised slings
will tend to increase due to sling elongation; in this case a suitable factor should be determined.
In special circumstances (e.g. flare booms, flare towers and cantilevered modules) the design angle of
tilt may require to be greater than 2°to permit the effective use of installation aids. These structures
shall be reviewed as special cases.
5.3.4
Where long slings are used and there are small distances between the lift points, the effect of the sling
tolerance on new slings is to be checked to ensure that excessive tilts are not introduced into the lifted
structure.
5.3.5
The effect of module tilt on multi hook lifts is covered in Section 5.4.
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