Machinery Lubrication magazine published by Noria Corporation
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2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 *2017 *2018 $ Cost of oil disposed of based on 12 pieces of vital equipment being preventively maintained semi-annually 12 | November - December 2019 | www . machinerylubrication.com exposed to streaming particulate matter. It occurs when high-velocity liquid or solid matter impacts a solid surface, causing intense points of compression and resulting in deformation and shear. Stress waves are emitted from the impact points, and debris is dislodged from the damaged surface. is failure mechanism can be prevented by protecting surfaces with energy-absorbing coatings. Electrical Discharge An electrical discharge can impact all stati- cally charged and electrically powered equipment, including electrical switches, circuits, breakers, transformers, controllers, motors, variable- frequency drives, generators, filters, shaft bearings and hous- ings. Electrons transported as sparks, partial discharges and arcs blast surfaces with intense local compression, causing deformation and shear. is results in a wide spectrum of mechanical and electrical energy. e electrons pass through gaps at supersonic speeds, emitting radio waves and sonic booms. is leads to heat damage on the surfaces and various gaseous substances, such as hydrocar- bons and ozone. An electrical discharge ionizes proximate matter to form a discharge or plasma track. It may be offset by maintaining clean and dry materials and compartments. is progressive mechanism can be triggered by moisture, dete- riorated insulation, ground faults, looseness and corroded contacts. COVER STORY Failure Mechanism Equipment Contributing Factors Proactive Measures Oil Analysis Vibration Analysis Stress Wave Analysis Thermal Imaging Inspection Abrasion Mechanical items Dust contamination, system surge, defective breather Contamination control; clean, dry, fit for use X X X Adhesion (Boundary Wear) Mechanical items Lubricant misapplication, slow speed, excess load, low viscosity Effective lubrication; correct speed, load, viscosity X X X X Fatigue Bearings, gears High dynamic load, improper fit Minimize resonance, misalignment and imbalance X X X X Corrosion Mechanical items, electrical items Water or coolant contamination, defective desiccant breather Contamination control; clean, dry, fit for use X X X Cavitation Impellers, pumps, valves, piping Speed, pressure and flow extremes Speed control, fluid dynamics and surface treatment X X X X Erosion Valves, pipes, windows, baffles, screens, throttles, impellers, sensors Exposure to streaming particulate Protective coating X X Electrical Discharge Electric-powered items, static-charged items Moisture, ground faults, deterioration, looseness, corrosion Contamination control; clean, dry, fit for use X X X Deposition Flow controls, filters, screens, valves, fans Temperature cycles, static charge Awareness and prevention X X Deposition Deposition results from a dysfunctional and progressive accumulation of foreign mate- rial on a critical component. Examples include precipitated varnish formation and accu- mulation on a control valve as well as f ibrous material accumulation on a fan. Any varnish accumulation on a control va lve may lead to plugging and sticking, while fibrous material accumulations on a fan may cause imbalance a nd a potentia l f ire risk. is failure mechanism can be prevented by detecting, interpreting and addressing t he specif ic accumu lation process. e corrective action plan should be specific to its characteristic process. FAILURE MECHANISM MONITORING TECHNIQUES Elemental Spectroscopy X-ray fluorescence (XRF) elemental spectroscopy of filter patch specimens is preferred for large particle failure mech- anisms including abrasion, fatigue and severe adhesion. Optical emission spectroscopy and XRF are both suitable for corrosion and mild adhesion mechanisms. Particle Count and Shape Classification Particle counts greater than 4, 6 and 14 microns enable condition monitoring for contamination control. Direct-ima ging automat ic particle shape classification or microscopic wear particle anal- ysis can help distinguish the failure mechanism. Table 1. Common failure mechanisms, equipment, contributing factors, proactive measures and condition monitoring for each