Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/325287
4 | May - June 2014 | www.machinerylubrication.com As I see It The Overall Lubricant Criticality (OLC) defines the importance of lubricant health and longevity as influenced by the probability of premature lubricant failure and the likely consequences (for both the lubricant and the machine). The Overall Machine Criticality (OMC) defines the likelihood and consequences of machine failure alone. The methods for calculating OLC and OMC were previously discussed. Like many such methods, the approach is not an exact science but nevertheless is grounded in solid principles in applied tribology and machine reliability. Building the Surveillance Planning Table Figure 2 shows an example of a Surveillance Planning Table (SPT) for a given machine, e.g., a reciprocating compressor. The SPT is used to define the degree of surveillance (oil analysis and inspection, for instance) for each of the ranked failure modes. These failure modes are ranked from one to seven on the left of the SPT. Tribo-analysts and reliability professionals are best suited to assign this ranking for individual machines. The list shown in Figure 2 is hypothetical for the compressor example to illustrate how to build an SPT. Across the top is the OMC range (see Part 1 for calculating the OMC score) from 10 to 100. A score of 100 represents high criti- cality from the standpoint of probability of failure and consequences of failure. In this example, the arrow shows the compressor to have an OMC score of 80. There are seven color-coded condition moni- toring zones corresponding to time-based surveillance levels. These are also represented by the designations CM1 to CM7. The surveil- lance levels range from CM1 (real-time) to CM4 (monthly) to CM7 (never). For an OMC of 80, the condition monitoring zones range from CM1 to CM4. The only things that change from machine to machine using the SPT are the failure mode rankings and the placement of the arrow corresponding to the OMC score. Otherwise, all SPTs look exactly the same. For instance, the compressor has particle contamination Oil Analysis Tests and Inspections OMC OR OLC SCORE PARTICLE CONTAMINATION WATER CONTAMINATION VARNISH AND SLUDGE LOW OIL LEVEL WRONG/ DEFECTIVE OIL MISALIGNMENT AERATION AND FOAM HEAT CROSS- CONTAMINATION METAL PARTICLES MICRODIESELING MFM 80 CM1 CM2 CM3 CM3 CM3 CM3 CM4 LFM 70 CM3 CM4 CM3 CM2 CM3 CM4 CM4 Viscosity L4 L4 Acid Number L4 L4 FTIR-Ox L4 FTIR-Nitr L4 L4 FTIR-Phenolic Inhibitor L4 L4 L4 L4 Linear Sweep Voltam. L4 L4 RPVOT E E MPC L6 L4 Particle Count R & L4 L4 Water - kF L4 Elemental Spectroscopy L4 L4 L4 L4 Ferrous Density L3 L4 Wear Particle I.D. E Inspection/Field Test: - Oil Color/Clarity - Oil Level - Oil Aeration & Foam - Magnetic Plug F2 F3 F2 F2 F3 F3 F2 F2 Real-time Sensors R Vibration Analysis F3 F = Field inspection (e.g., oil level inspection) or field instru- ment (e.g., portable patch test kit, portable vibration tools) 2 = Daily monitoring 3 = Weekly monitoring Figure 4. Combined Surveillance Planning Table for the Machine and Lubricant LEGEND E = Exception lab test (e.g., analytical ferrography) R = Real-time monitoring (e.g., an online particle counter) L = Routine lab testing (either onsite lab or offsite commercial lab) 4 = Monthly monitoring 5 = Bi-monthly monitoring 6 = Quarterly monitoring