Plant Services - August 2007 - (Page 25) WHAT WORKS Bearing failures banned in Memphis Isolators replace lip seals to eliminate refiner breakdowns emphis, Tenn.-based Buckeye Technologies Inc. develops and manufactures cellulose-based specialty products at plant sites in the United States, Canada, Germany and Brazil. Its Memphis plant produces cotton-based fiber products used in fine writing papers, filters, acetate films, thickeners, pharmaceuticals and more. The manufacturing process uses multiple refining technologies to modify the cellulose fibers, so it’s sensitive to refiner reliability problems. “You could count on frequent refiner failures,” says Eddie Kelly, Crew Leader of the Maintenance Technology Group and 29-year plant veteran. The root cause of the failure was lube oil contamination entering the bearing housing assembly. Buckeye personnel knew breakdowns were going to occur but weren’t able to predict when. Failure meant a shutdown for as long as eight hours to change the bearing housing assembly. In the 1980s, when the refiner was manufactured, the OEM used labyrinth seals to protect the bearings, which were installed next to the packing gland. Over the years, the refiner kept failing and Buckeye tried a number of other sealing methods, including double-lip seals with a grease barrier, which simply didn’t last. Invented in 1977, the bearing isolator has a rotor and a stator, and the two are unitized so they don’t separate while in use. Typically, the rotor turns with the rotating shaft while the stator is pressed into a bearing housing. The two components interact without contact to keep contamination out and lubricant in. Bearing isolators protect motor and pump bearings, machine tool spindles, turbines, pulpers, refiners, conveyor idlers, fans, gearboxes, paper machine rolls and a growing list of rotating equipment. The Buckeye Electrical and Instrumentation (E&I) Department had been using bearing isolators for years on its IEEE 841 motors. The IEEE 841 motor is an upgrade to the EPAct mandated motor that improves reliability, efficiency and performance by establishing simple design guidelines. One of these guidelines includes using bearing isolators. Kelly saw how bearing isolators provide increased reliability and longer motor life. He also knew that Goulds ANSI 3196 or 3175 paper stock pumps came standard with bearing isolators from Inpro/Seal (www.inpro-seal.com). August 2007 M Since flanged bearing isolators from Inpro/Seal were installed 14 months ago, Buckeye has not had a refiner bearing failure. Its backup refiner has remained in the storeroom. Using premium motors, pumps, bearing isolators and other upgrades is part of Buckeye’s Precision Maintenance program. (Precision Maintenance Training is a specialty of Reliability Solutions LLC (www.reliabilitysolutions.net), which has been working with Buckeye’s Memphis Plant to improve its maintenance systems.) Kelly says the extra dollars invested have paid big dividends over time. His group decided to try Inpro/Seal’s PMR bearing isolator on the refiners. The PMR was originally designed for paper machine rolls. On the wet-end rolls, they prevent water, pulp and paper stock from entering the bearing housings. On the dry-end rolls where oil can ruin the product, they eliminate leaks from oil-lubricated bearings. Inpro/Seal engineers modified the PMR design for the refiners by adding a flange that provides a secure fit, registering it directly to the bearing housing. The design can accommodate the axial movement of as much as 1.5 in. when the refiner plate loads up and its plate shifts. Since installing the flanged PMR bearing isolator 14 months ago, Buckeye hasn’t had a shutdown on the refiner. As part of its “Precision Maintenance” Program, Buckeye plans to add more bearing isolators as breakdowns occur. 25 www.PLANTSERVICES.com http://www.reliabilitysolutions.net http://www.inpro-seal.com http://www.PLANTSERVICES.com
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.