Page 46: of Maritime Reporter Magazine (July 2020)

Tech Files

Innovative products, technologies and concepts

Big Bearings

Boost Offshore

Pipe Laying the tough conditions of unspooling pipe into the sea from a

As the offshore industry struggles with depressed pipe-laying vessel.

oil pricing for nearly six years running, more

Conditions on pipe-layers are hugely challenging, as the bear- than ever it is taking a sharp eye to the bottom ings are under constant loading, both radially (from the load itself) line, revitalizing equipment when practical and axially (from the continuous motion of the ship on the sea).

instead of buying new. Recently, SKF helped “It requires very complex engineering because of the uncer- tainty from the micro motions of the ship,” said Daniel Ortaga,

Norwegian offshore equipment manufacturer

Senior Business Developer at SKF. The challenge for the bear-

National Oilwell Varco (NOV) achieve just that ings had nothing to do with speed, as the drums turn at around by supplying it with a unique set of bearings … one-third of a revolution per minute. Instead, the difficulty was all told three different types of bearings totaling to design bearings that could take enormous loads while mov- more than 28 tons.

ing at such slow rotation speeds.

As well as achieving this, SKF managed to design bearings in

SKF supplied a huge order to Norwegian offshore equipment standard ISO dimensions, meaning they can be found within its manufacturer National Oilwell Varco (NOV), amounting to catalogue. Strange as it may seem, these are standard bearings, more than 28 tonnes of bearings in three different types. the largest ISO-sized bearings that SKF has ever supplied.

Equipment used in the offshore industry is expensive and ex-

The order comprised six separate bearings in three differ- pected to last for decades. If market conditions dictate that equip- ent types: spherical roller bearings (SRBs); spherical roller ment must start to run more efficiently, and a common approach thrust bearings (SRTBs); and self-aligning CARB bearings. is to replace major bearings, allowing the equipment to handle The bearings were used on two different cable drums, one more rigorous conditions such as higher loads or faster speeds. large and one small.

Among other things, NOV builds handling and pipe-laying

The large drum used four bearings, in an alternating SRTB/ equipment for offshore vessels. In a recent upgrade, it needed SRB/SRTB/SRB arrangement, which were mounted onto the to ensure that the bearings on two cable drums could withstand main shaft. This in itself is a unique arrangement. The smaller 46 Maritime Reporter & Engineering News • July 2020