Test and Evaluation of Advanced Stern Seal Designs and Materials for Merchant Ships

摘要

Performance of lip seals and liners currently in stern tubes of sea-going surface ships results too frequently in costly and time-consuming repairs. This report presents the results of a methodical study that both lead to the selection of new seal and liner materials and produced novel and improved lip seal designs. Half of the scale tests performed on the new lip seal and liner combinations in oil yielded substantial improvements in seal performance. Leakage, wear, torque, and lip seal temperatures have been greatly reduced. These improvements were achieved with a new pressure-balanced lip seal configuration made of 20% graphite-filled Buna rubber operating against a chrome steel liner, and with Viton lip seals of conventional design operating against a titanium-dioxide-coated liner. The filled Buna rubber has demonstrated high resistance to hardening and cracking, a problem for years associated with Nitrile rubber lip seals. This resistance is largely attributable to reduced seal friction and, consequently, reduced temperatures at the seal-to-liner interface.