The Air Skate skid system based on virtually frictionless air film technology makes it possible to move industrial equipment weighing several dozen tons with ease. We recently put this ingenious solution to work in Nigeria, taking advantage of the system’s ability to move heavy loads in confined spaces with a high level of precision.
The Air Skate solution is made up of several casters fitted with an inflatable cushion, or diaphragm, that are placed under a load, around its center of gravity. Inflated by compressed air, the diaphragms gradually fill the space between the load and the floor. Once they are fully inflated, air is squeezed between the floor and the diaphragms, lifting the load off the ground. The equipment can then be easily floated on a thin film of air in any direction, with virtually no friction.
Replacing Two 32-Ton Coolers
This technology was used for the first time off the coast of Nigeria to replace two gas export compressor coolers on the Akpo floating production, storage and offloading (FPSO) vessel. The modules, installed in 2009, cooled the gas before it left the FPSO. For several years, successive failures in the coolers’ O-ring seals had become a safety hazard, creating the risk of a gas leak. Several different solutions were attempted to resolve this integrity issue, including injecting sealant to reinforce the O-rings, replacing the seals with more effective systems and replacing the modules’ cold heads.
As none of these solutions proved successful, a decision was made to completely replace the two coolers during a full field shutdown (FFSD) scheduled over a 26-day period in 2018. However, replacing modules this big and heavy on an operating FPSO had never been done before at Total. Several factors made this a major challenge:
- The old and new coolers would have to be moved in one piece because the time it would take to disassemble and reassemble the modules would exceed the FFSD timeframe. The move could also negatively impact the coolers’ performance.
- The FPSO Akpo was not designed to handle the delivery of fully assembled modules. Surrounded by a network of pipes, the vessel’s deck has a low hatch beam height and limited load capacity.
- Each cooler weighs close to 32 tons.
Air Skates Are the Answer
Thanks to Air Skate technology, the defective coolers were removed and the new equipment was installed smoothly and safely during the window of opportunity provided by the FFSD.
- Six Air Skates were used together to move the coolers on the FPSO. The system lifted the load just 69 millimeters off the ground, resolving the low clearance issue. The pathway was covered with high density polyethylene matting to create a flat, watertight surface so that the Air Skates could operate properly.
- A 40-ton-capacity gantry crane able to hoist the coolers was installed on the upper deck, as the FPSO’s own crane did not have sufficient capacity.
- The mezzanine deck hatch was widened so the equipment could be hoisted and the FPSO’s decks were reinforced to handle the structural constraints created by the coolers’ weight.
Air Skates were the answer for eliminating this integrity risk. This solution also put an end to the cycle of repairs, which had meant shutting down operations and losing production for at least five days every two years. The related savings exceed €26 million.
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