Daniel N. Hopkins

Reduce maintenance costs by using engineered surfaces to control friction and galling

Abstract Engineered surfaces consisting of thin metallic films may be deposited on a wide range of metallic and nonmetallic parts using the patented MagIon® enhanced vacuum-coating process. These films can beneficially modify an items surface characteristics and not affect the materials bulk properties. Laboratory tests of heavily loaded bolts that were exposed to elevated temperatures for 1 month showed that parts with MagIon-deposited engineered surfaces of relatively soft metals were significantly more resistant to galling than bolts installed using a conventional lubricant. Field experience with bolted connections confirms that these soft metal surfaces substantially improve the margin against galling. Valves with stems that have been MagIon-treated using soft metal surfaces appear to perform more reliably than valves with untreated stems. Controlled tests confirm the assembly procedures and practices that are used for standard bolting materials assembled with conventional lubricant also apply to joints assembled using MagIon-treated bolting materials with or without lubricant. Using parts with engineered surfaces in appropriate applications can help reduce the expenditures of time, money, and materials to repair avoidable galling-related damage. This can also decrease the excessive number of man-hours spent monitoring and maintaining troublesome mechanical equipment. Since 1992, TU Electric has installed more than 6000 MagIon-treated parts in its fossil and nuclear generating plants to improve operational reliability and to facilitate equipment disassembly.