0027/nd guidelines for Marine Lifting and Lowering Operations

GUIDELINES
 
FOR
 
MARINE
 
LIFTING
 
&
 
LOWERING
 
OPERATIONS 
0027/ND Rev 11 
 
Page 42 of 84 
12 
LIFT POINT DESIGN
12.1 
INTRODUCTION 
12.1.1 
In addition to the structural requirements shown in Sections 5 and 11, the following should be taken 
into account in the lift point design.
12.2 
GENERAL DESIGN REQUIREMENTS 
12.2.1 
Lift points and their attachments to the structure should be designed for the maximum sling load, any 
possible sling angles and local load effects.
12.2.2 
Lift point designs which may fail as a result of moderate deviations in sling force direction should be 
avoided. 
12.2.3 
For fabricated lift points, the direction of loading should generally be in line with the plate rolling 
direction. Lift point drawings should show the rolling direction. 
12.2.4 
Through-thickness loading of lift points and their attachments to the structure should be avoided if 
possible. If such loading cannot be avoided, the material used shall be documented to be free of 
laminations, with a recognised through-thickness designation. 
12.2.5 
\For subsea lifting operations, the lift rigging and lift points shall be designed to suit the planned subsea 
connection or disconnection of the rigging to the lift points. 
12.3 
LATERAL LIFT POINT LOAD 
12.3.1 
In the absence of a detailed study and assuming minimum anticipated relative deviations, it is normally 
adequate to consider a lateral load, acting simultaneously with the in-plane load, of 3.0% of the 
maximum sling force. The lateral load should be applied at the point of action, e.g. at the shackle bow 
or at the trunnion stopper plate, etc.
12.3.2 
Where it is necessary to install the lifted object at a prescribed tilt, the effect of any lateral loading this 
tilt causes on the lift point shall be considered and shall be added to the lateral lift point load as defined 
in Section 12.3.1. 
12.3.3 
If the lift point is not correctly orientated with the sling direction, then the computed forces acting 
transverse to the major lift point axis of the pin-hole or trunnion / padear geometric centre shall be 
added to the lateral lift point load as defined in Section 12.3.1 with the combined load applied at the 
point of action in accordance with Section 12.3.1.  The effective length of the hook prongs shall be 
considered when finding the intersection point of the slings above the hook prongs.
12.3.4 
If the lateral load has been calculated based on actual tolerances/measurements and has considered 
the effect of the hook prongs (see 12.3.3), then it is not normally required to add the 3% lateral load as 
defined in Section 12.3.1.  
12.3.5 
Where tugger lines are connected to the lift point or to the rigging local to the lift point, the effect of the 
lateral load from the tugger line on the lift point shall be considered and shall be added to the lateral lift 
point load as defined in the relevant Sections from 12.3.1 to 12.3.4. 
12.3.6 
Due to buoyancy, the tilt of the lifted object may change when being submerged. The effect of any 
change of tilt should be considered when determining the lateral load on the lift points.
12.3.7 
Where a structure is installed subsea using a dual crane lift, the effect of differential hook heights will 
impose additional lateral loads on the lift points. For dual crane subsea lifts, especially for deep water 
deployments, a method of monitoring the tilt should be provided to ensure that the lateral load 
limitations on the lift points are not exceeded.