Rigs and vessels equipped with dynamic positioning thrusters are placing greater demands upon the manufacturers of mechanical shaft seals. The high operating stresses encountered by dynamic positioning thrusters may also be combined with higher water pressures, because rig thrusters are often situated deeper than conventional ships' propellers.
A high precision lapping process in the Roplan workshops ensures a leak-proof seal.
Despite these demanding operating conditions, the traditional drip of sea water through ship propeller shaft seals are considered unacceptable by Roplan, which has nearly 25 years experience in seal design.
At the company's headquarters in Tumba, south of Stockholm, an expansion program is underway that will boost production capability, enabling larger size seals to be manufactured. At present, Roplan can produce a wide range of seals in sizes from 80 mm to 700 mm. Customers include Rolls Royce, Alfa Laval, and Grundfoss.
Seal faces are manufactured from a variety of materials including ceramics and silicon carbide to tolerances of better than 1/1,000th mm. These are calculated to allow sufficient liquid ingress to provide essential lubrication, yet no more to pass through than can be dispersed by evaporation.
For more information, contact Tommy Edlund, Roplan. Tel:+46 8 449 99 00, Fax:+46 8 449 99 90, E-mail: [email protected]
