0027/nd guidelines for Marine Lifting and Lowering Operations

GUIDELINES
 
FOR
 
MARINE
 
LIFTING
 
&
 
LOWERING
 
OPERATIONS 
0027/ND Rev 11 
 
Page 73 of 84 
19.8 
SUCTION PILES & FOUNDATIONS 
19.8.1 
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 demonstrate that for the 
design sea states the integrity of the pile will be maintained for all stages of installation including the 
effects of slamming when lowering through the splash zone. 
19.8.2 
Heading control using subsea or surface guide wires shall be provided where the pile heading is 
critical. Pre-installed mooring lines and / or chains can be used to assist in heading control. 
19.8.3 
A system to monitor the verticality of the suction pile during installation shall be provided. This can be 
a visual system such as a calibrated bull’s-eye. 
19.8.4 
The pile position shall be determined using a calibrated subsea positioning array. 
19.8.5 
The self-penetration of the suction pile should be estimated prior to the installation operations and 
compared to the actual value. This can provide information on the actual soil strength. If a large 
variation occurs the pile design should be re-evaluated.
19.8.6 
Penetration indicators (“draught” marks) on suction piles shall be used to allow the initial self-
penetration and final penetration of the pile to be determined visually. 
19.8.7 
On bottom stability of the pile prior to activating suction systems shall be calculated. For this aspect, 
short stubby piles are preferable to tall slender suction piles. 
19.8.8 
ROV mounted suction pumps should be integrated into the host ROV and have sufficient flow to 
evacuate the water from inside the pile without exceeding the limiting differential pressures imposed by 
the capacity of the pile. The pump flow shall be reversible to allow retrieval of the pile if needed. 
19.8.9 
Independent pump skids can also be used and in some cases these can also have heading monitoring 
systems, altimeters and gyro compasses integrated into their control systems. Pump skid flow shall be 
reversible. 
19.8.10 
Integration testing of the mating flange for the pump skid should be performed prior to deployment. 
19.8.11 
Pile hydrostatic collapse and piping of external seawater through the soil shall be prevented by 
ensuring that the differential pressure between the inside and outside of the pile is kept within limits.
Pump curves shall be provided and used. 
19.8.12 
Suction piles may have to be transported, over-boarded or lifted offshore from a barge horizontally due 
to limitations of the installation vessel, available crane hook height and to limit working at height 
offshore to connect the crane hook with installation rigging. In such conditions suction piles need to be 
upended before lowering to the seabed.
19.8.13 
Lowering a suction pile horizontally through the splash zone can generate additional hydrodynamic 
loading due to increased surface area of the pile being presented to wave and current. These 
possibilities should be investigated during an installation analysis and adequate mitigating measures 
should be put into the operational procedures. 
19.8.14 
Upending should be performed by the gradual transfer of load from horizontal transfer rigging to 
installation rigging at a water depth where there are no possibilities of the suction pile and rigging 
system reaching resonance. Analyses should be performed to confirm such possibilities do not exist. 
The water depth chosen should be away from the influence of the splash zone to limit hydrodynamic 
loads acting on the pile. Once upending is completed the transfer rigging should be slackened and 
removed. Installation of the suction pile continues with the pile in a vertical orientation with the heading 
of the suction pile ready for landing on the seabed.