Prior to 1985, only oils without additives (P-28, MS-20, MS-14, TS-14.5, and T-30) were used to lubricate slide bearings with babbitt bushings, including fluid-film bearings (FFBs) used in rolling mills. These oils were obtained from unique low-sulfur Baku, Emba, Grozny, and Volgograd grades of petroleum. The sulfur content of these oils was 0.1-0,3 percent by weight. However, use of the oils did not prevent persistent darkening of the surface of the bushings, since the degree of corrosion undergone by babbitt metal depends not so much on the sulfur content of the oils as it does on the activity of the sulfur-bearing compounds - mainly sulfides and disulfides [1,2]. Modern technologies used both here and abroad for producing oils from high-sulfur grades of petroleum, involving deep selective cleaning and hydraulic cleaning, make it possible to remove such compounds from the oil to a satisfactory extent. Many years of experience with the use of different oils in the.FFBs of rolling mills shows that deep-cleaned additive-free oils such as Mobil Vacuoline 133 and Mobil Vacuoline 146 - with a sulfur content in the range 1.1-1.3 percent - do not cause excessive darkening of the surface of bushings made of tin-based babbitt.
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