Abstract
Several cases have occurred in which heavy wear of rotor shafts has been caused by the build-up of carbonaceous deposits in the oil baffles of steam-turbine bearings. Thois problem appears to have been confined to those designs of steam turbine in which the oil baffles operated at unusually high temperatures. A bearing rig has been constructed to reproduce as closely as possible the practical conditions at which the shaft failures occurred. Heat was applied externally so that the oil baffle temperature was 280°C and the rotor shaft temperature was 260°C. The type of failure which had occurred in service was reproduced in this rig, but could not proceed to the catastrophic extent encountered in practice owing to lack of power in the rig. A mechanism of failure is proposed, together with some suggestions for avoiding failure. These suggestions include restricting baffle temperatures and redesigning the baffles to reduce the tendency to form carbonaceous deposits.
Get full access to this article
View all access options for this article.