Big bearings boost offshore pipe laying SKF has supplied a huge order to Norwegian offshore equipment manufacturer National Oilwell Varco (NOV), amounting to more than 28 tons of bearings in three different types.
PIPES
Equipment used in the offshore industry is so expensive, sometimes costing hundreds of millions of dollars or Euros, that it must last for many decades. If market conditions dictate that equipment must start to run more efficiently (to extract more oil, for instance), the challenge is on to enable this. A common approach is to replace major bearings within the equipment, allowing it to handle more rigorous conditions such as higher loads or faster speeds. Recently, SKF helped Norwegian offshore equipment manufacturer NOV achieve just that by supplying it with a unique set of bearings. Among other things, NOV builds handling and pipe-laying equipment for offshore vessels. In a recent upgrade, it needed to ensure that the bearings on two cable drums could withstand the tough conditions of unspooling pipe into the sea from a pipe-laying vessel. Challenging conditions Conditions on this kind of vessel are hugely challenging, as the bearings are under constant loading, both radially
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Pipes, Pumps and Valves Africa - Nov/Dec 2020
(from the load itself) and axially (from the continuous motion of the ship on the sea). “It requires very complex engineering because of the uncertainty from the micro motions of the ship,� says Daniel Ortaga, Senior Business Developer at SKF. The challenge for the bearings had nothing to do with speed, as the drums turn at around one-third of a revolution per minute. Instead, the difficulty was to design bearings that could take enormous loads while moving at such slow rotation speeds.As well as achieving this, SKF managed to design bearings in standard ISO dimensions, meaning they can be found within its catalogue. Strange as it may seem, these are standard bearings, the largest ISOsized bearings that SKF has ever supplied. The order comprised six separate bearings in three different types: spherical roller bearings (SRBs); spherical roller thrust bearings (SRTBs); and self-aligning CARB bearings. The bearings were used on two different cable drums, one large and one small.The large drum used four bearings, in an alternating SRTB/SRB/SRTB/SRB
