Certex (UK) used modified spreader beams, to lift two nonidentical halves of a helipad onto a vessel from a gas rig in the Dutch Sector of the North Sea recently. The site was approximately 70 miles off the Danish coast.
Certex, accepted a scope of work to design and supply a below-the-hook solution for loading the helipad using a 300t capacity crane aboard a barge.
The heavier piece of the pad weighed 89t, while the smaller was less than half the weight at 35t. It was hexagonal in shape and measured 44m sq. when assembled. Interestingly, each piece was removed from the site one at a time (the smallest first) along with its corresponding spreader beam and rigging.
The beams combined with other rigging gear, such as wire rope slings and shackles, also supplied by Certex, to lift the pieces onto a separate supply vessel that shipped them back to port.
Different rigging equipment was used with each spreader beam.
Jason Griffen, technical sales at Certex (UK), explained: "We provided calculations in advance of the project so the spreader beams would be modified accordingly."
The modifications were required to eliminate the use of guide ropes and the requirement for personnel to work in proximity of the loads as they were landed on the supply vessel. Further, there was not a lot of margin for error and the modified beams simplified the process. Certex was able to utilise permanent lifting fixtures of both halves of the helipad.
Griffen added: "We worked closely with the client's engineering department to calculate the capacity, type and length of slings required, to complement the spreader beams. We also extracted additional information from the design plans for the helipad."
The rig is among a number of smaller satellite platforms in the area. The rig remains operational but personnel will now access it only by marine transport, not helicopter.