Up Time Magazine- June/July 2008

Root Cause Analysis Root cause analysis (RCA) is an important part of a functional predictive maintenance program. Not only should you be able to predict when something is failing, but more importantly figure out WHY it failed to prevent it from happening again. Sometimes a minor modification to the equipment or how the equipment is operated makes all the difference. Henry Ford once said,”Failure is the opportunity to begin again more intelligently”. So why not learn from your failed equipment to see if you can prevent it from failing again? We have had several pieces of equipment that originally listed automotive lubricants, 5W 40, SAE 10, 20 or 30 for the OEM preferred lubricant. I have also found several OEM listings for new equipment with outdated lubricant specifications or name types. So why is this mentioned in an RCA discussion? After several failures from varnish and sludge problems on reciprocating compressors that were using SAE 30 engine oil, these were changed to turbine oil ISO VG 100 and the problems have gone away. Another new piece of equipment, a lobe type blower, specified 5W40 synthetic motor oil. The vendor was contacted to get approval to change the lubricant to an industrial type since the equipment was under warranty. They would not approve any other lubricants than what were listed. We ran the 5W40, but had to increase the change frequency from six months to three months based on sheer down and viscosity decrease. Fortunately one of the specialty lubricant companies got their product approved for use in the blowers. Once this was accomplished, their product along with a comparable product from our lubricant supplier where run in two different blowers as a test; There were no noticeable differences between them. I contacted the OEM with the test results and they accepted another industrial oil for use with the blowers. Since the change of products and sufficient time to flush out the old 5W40, we have increased the oil change frequency back to six months and continue to test which may prove to allow longer service yet. Another case for RCA revealing an oil related problem occurred in some of our motors with submerged coolers and hydraulic unit heat exchangers that were made of copper. Due to consolidation efforts we were using AW hydraulic oil in some of our motors with submerged copper coolers and copper was trending up significantly on ICB wear metals. We were experiencing a similar problem with some of our hydraulic systems with copper heat exchangers and increasing copper trends. Of course, with Figure 5 - Gear Reducer, before and after. the motors we could have switched to turbine oil, but we had to stay with AW gear reducer was failing every 3 to 5 weeks oil for the hydraulic systems. To stay from the ingress of fly ash (which looked with consolidation efforts we switched to an ashless, inherently biodegradable AW hydrau- like lapping compound) and was wearing the gears and bearings to failure. With some lic oil. With the removal of zinc or ZDDP basic improvements such as an increase in from the lubricant and system the copper lubricant viscosity, bearing isolators, kidney trends stopped increasing. It took a couple loop filtration, and better breathers we have of flushes to get everything stabilized but improved the time between failures to better the corrosion of copper was ended. We have than 3 years. The average cost per failure now been able to run extended oil changes was $5,000. The total cost for the gear of up to five years with no negative affects. reducer up-grades was less than $5,000 and a Figure 4 is a submerged cooler in one of our complete replacement system would have cost about $100,000. See Figure 5 (Before and after shots) The picture on the left is after 5 weeks run time of about 8 hours per day. The picture on the right was taken after 14 months run time when an output shaft broke due to bending fatigue. As can be seen there is quite a difference. Another opportunity for RCA came with our 25,000 CFM blowers mentioned earlier, which generally require a 25,000 hour inspection/rebuild. We experienced an inlet control and guide vane binding which took one of the blowers out of service at 15,000 hours run time. These blowers operate near our wet scrubbers and thus have the opportunity to ingress sulfuric acid, hydrochloric acid, and sodium chloride mists. Figure 6 shows the inlet hub and Figure 7 the control vane condition. Figure 4 - Immersion Heater vertical motors. Note: The copper tubing in figure 4 looks as though it has been acid washed. Knowing what your components are made of, and the possible effects of certain additives on certain metals, definitely helps with failure analysis. Another great example of a few minor changes to upgrade equipment came when our effluent processing facility was modified to produce synthetic gypsum from our scrubber slurry. This change in operating process placed some of the equipment in different operating parameters which, of course, caused problems. However, the plant modifications were well worth it, since it reduced our land fill use by up to 75%. One Figure 6 - Inlet Hub of 25,000 CFM Blower 48 june/july 2008

Table of Contents Feed for the Digital Edition of Up Time Magazine- June/July 2008

Up Time Magazine- June/July 2008 Contents Upfront Upclose: The True Cause of Most Machine Failures Information Technology: Finding Future Perfect Lubrication: Building an Oil Analysis Winner Maintenance Management: Hidden Ways to Increase Safety Infrared: Air Barriers Lower Energy Costs, Increase Profits Motor Testing: Efficient Motor Repair, Part Deux Precision Maintenance: Good Maintenance, Smart Maintenance Reliability: Common Errors in Root Cause Analysis Ultrasound: Avoid the Baghouse Blues Vibration: Don't Let Your Sensors Get Eaten Alive Upgrade: Lining It All Up

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.