0027/nd guidelines for Marine Lifting and Lowering Operations

19.10 
JUMPERS AND TIE-IN SPOOLS 
19.10.1 
Subsea jumpers and spools shall be arranged in such a way that they are appropriately supported 
during installation. In cases where the spool or jumper is significantly lighter than or buoyant relative to 
the supporting spreader bar, consideration should be given to using a “strongback” type spreader bar 
(strapped to the spool), as opposed to a “floating” spreader bar. 
19.10.2 
A dynamic lift lowering analysis shall be carried out to determine the dynamics in the lifting system 
under the design installation seastates. The installation analyses should be used to demonstrate that 
in the design seastates the integrity of the structure will be maintained for all stages of installation 
including the effects of slamming when lowering through splash zone. 
19.10.3 
The submerged and in-air weight of the spool shall be available from a weight report and include spool 
buoyancy. 
19.10.4 
The submerged and in-air CoG shall be included in weight reports in order that the correct value of tilt 
can be determined for installation and set-down. 
19.10.5 
Indeterminate rigging systems shall be designed accounting for actual sling lengths and the catenary 
effects of the rigging component self-weight. Means to adjust the sling lengths or geometry such as 
turnbuckles or moveable attachments can be used so that skew effects and loss of individual sling 
tension can be minimised. 
19.10.6 
Lift analyses for statically indeterminate rigging systems shall be carried out in order to quantify the 
load in each sling and show that the stress in the spool is within allowable limits. The maximum loaded 
sling(s) in the lifting arrangement should be removed in the analysis model to demonstrate that the 
rigging arrangement can support the spool without the spool being overloaded. In the absence of this 
analysis an SKL=1.75 shall be used for statically indeterminate rigging systems. 
19.10.7 
Trial lifting of spools and/or jumpers shall be carried out to verify the rigging geometry prior to load-out 
in order to: 

obtain the correct tilt angle when the inclination is critical or there is a significant difference 
between the in-air and submerged condition 

verify that all slings are in tension for spool lifts.
If the trial lift reveals that a sling is slack, the sling length shall be adjusted and the test lift repeated.
Small movements in the positions of slings on the spool can often be used to even out the loads in the 
slings. 
19.10.8 
All soft slings that are choked around the spool shall be designed in such a way that their release can 
be made effectively. 
19.10.9 
When lifting off the deck of a transportation barge and lowering through the splash zone adequate 
clearance (at least 3 m) should be maintained between the spool and the installation vessel.