0027/nd guidelines for Marine Lifting and Lowering Operations

5.8 
2-PART SLING FACTOR 
5.8.1 
Where a 2-part sling or grommet passes over, round or through a shackle, trunnion, padear or crane 
hook, other than at a termination, the total sling force shall be distributed into each part in the ratio 
45:55 to account for frictional losses over the bend. 
5.8.2 
Where upending a structure requires the sling or grommet to slide over a trunnion or crane hook 
utilising a 2-part sling or grommet, other than at a termination, the total sling force shall be distributed 
into each part in the ratio 32.5:67.5 to account for frictional effects as the wire slides over the bend.
For this condition, the ratio may be reduced if the lifting contractor can demonstrate through 
documented evidence or testing that a lesser value can be adopted. 
5.8.3 
Where a 2-part sling or grommet passes over a rotating greased sheave on a trunnion the total sling 
force shall be distributed into each part in the ratio 49:51 to account for the frictional losses over the 
rotating sheave on the trunnion. 
5.8.4 
Where slings or grommets are used in any more that a 2-part configuration, calculations shall be 
submitted for review, and will require special consideration by GL Noble Denton. The calculations 
submitted shall allow for the frictional losses contained in 5.8.1 or 5.8.2 (e.g. the 45:55 effect in a 
double doubled sling would be 0.55 x 0.55 on the design load in each leg of the sling or grommet).
5.8.5 
If a doubled sling consists of two parallel slings, the load distribution should be calculated considering 
the maximum sling length difference between the two slings and the maximum sling modulus of 
elasticity (E). 
5.8.6 
When using fibre slings or grommets (i.e. Dyneema, HMPE, Round slings or webbing slings) in a 
doubled configuration the 2-part sling factor referenced in Section 5.8.1 shall be used for guidance, but 
the specific recommendations of the sling supplier should govern, based on the planned mode of use 
and the specifics of the sling type.