New generation of sealing rings

04 Dec 2013

SKF Blohm + Voss Industries has introduced the SC3 ring, a new lip sealing ring for the company’s Simplex-Compact stern tube seals, which features a new shape allowing the ring to function reliably and remain stable under extreme conditions and variable pressure.

“Requirements in ship newbuilding are becoming increasingly demanding. For instance, the cargo capacity of container ships has increased threefold over the past 20 years”, says Mathias Rusch, director shaft components. “The differences in a ship’s draught associated with the increasing cargo capacity place high demands on the seal’s performance. Because the greater the difference in draught, the more the pressure on the ring will vary.”

The redesign allows the SC3 ring to better handle such differences in pressure. It has been given a shorter lip which has allowed the pressure-loaded area to be reduced. A self-aligning annular spring adjusts to the actual pressure. Both of these changes mean that the friction acting on the ring – and the associated heat generation – are reduced, without limiting efficiency. Further new features include lubrication pockets embedded into the ring, to feed a larger volume of oil to the sealing gap, improving cooling and tribological performance along with a slow-down in the aging process.

An alternative elastomer mix is optionally available, which allows compliance with the new US EPA Vessel General Permit 2013 requirements, so that most biodegradable lubricants that comply with the EAL directive can be used.

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