Improve Manufacturing Reliability by Implementing Predictive Maintenance Authored by: Tom Williams, Reliability Engineer Kristin Scharf, Reliability Technology Consultant at New England Controls Frank Corden, Director of Life Sciences Industry at New England Controls The views and opinions expressed in this article are those of the individual contributors and should not be attributed to any company with which a contributor is now or has been employed or affiliated. INTRODUCTION Process Industries other than Life Science, such as Power, Pulp & Paper, and Refining, have been focused on improving equipment reliability for many years. One of the major proven comprehensive predictive diagnostic tools available is vibration monitoring of rotating equipment. As available capacity tightens and financial pressures mount in the Life Science industry, the impact of unexpected equipment failures has become more of an issue. Clean room air handlers, refrigeration units, compressors, and large clean utilities pumps can have a significant impact on process availability if there is an unexpected failure. With vibration monitoring and appropriate analysis, equipment problems can be detected early and relatively inexpensive corrective measures can be taken to extend equipment life and prevent unexpected failures. Early detection allows repair prior to a catastrophic event. It is not uncommon to find once a program is started, that 10% of assets can immediately benefit from monitoring and early remediation. The cost of resolving deviations associated with equipment failures adds up quickly. Opportunity costs due to lost productivity and possible product loss have an even greater impact. EQUIPMENT RELIABILITY CHALLENGES As illustrated in the diagram on the right, todays critical business challenges are interdependent, and equipment reliability affects many areas. Organizations that put into place a program to improve reliability reap substantial benefits in all of the areas shown. Copyright 2013 New England Controls, Inc. All rights reserved. www.newenglandcontrols.com 1
Studies of typical indicators of asset performance have shown that there is a lot of room for improvement for many North American plants to achieve the best-in-class performance achieved by the top 20%. The chart on the next page illustrates average performance of North American manufacturing plants compared to top 20% benchmark performance in several areas. The gap results in sacrificed capacity, quality, and additional costs. This performance gap can be addressed by operating more efficiently with the assets and personnel already in place. MAINTENANCE STRATEGIES 100 90 80 70 60 50 40 30 20 10 0 Asset Benchmark Versus Typical Performance Gap Utilization Overall Equipment Effectiveness Planned Maintenance Unplanned Downtime Reactive Maintenance Maintenance Costs (% of PRV) Benchmark Average Gap The table to the right describes different maintenance strategies currently in use, maintenance methods used for each, the benefits of each, and some examples of predictive maintenance technologies used for predictive and proactive maintenance. TYPES OF MAINTENANCE Strategy Methods Benefits Reactive Preventative Predictive Proactive Repair or replace after failure Repair or replace on a time-based schedule Monitor equipment condition to identify health Monitor condition to detect/address root cause No regular maintenance required Reduces some machine failures Minimizes cost and production impact of failed asset Prevents failure by eliminating root cause Predictive Maintenance Technology N/A N/A Vibration monitoring, oil analysis, thermography Contamination prevention, lube health, precision balancing/ alignment The illustration to the left shows some of the types of equipment available that can be used for predictive and proactive maintenance. If you would like more information on any of the equipment featured here, feel free to give New England Controls a call at (508) 339-5522 2 www.newenglandcontrols.com
USE OF VIBRATION MONITORING FOR PREDICTIVE MAINTENANCE The chart that follows shows how important maintenance can be to extend bearing life on rotating equipment. Most manufacturers specify bearing life on the assumption that basic preventive maintenance is being used (i.e. replacement on a scheduled basis). Bearings are often specified to give an L10 life. This is the life at which ten percent of the bearings in that application can be expected to have failed due to classical fatigue failure (and not any other mode of failure like lubrication starvation, wrong mounting, etc.). The L10 life of the bearing is the theoretical life and may not represent service life of the bearing. For a population of 26 bearings that were allowed to run to failure, four (red bars) would have failed prior to the recommended preventive maintenance replacement benchmark (L10). Eight (yellow bars) would have been replaced much sooner than necessary, as their life was as much as 5x theoretical life. Use of vibration monitoring technology for predictive maintenance would have been able to recommend maintenance prior to early failure for the shorter life bearings and would have allowed the longer life bearings to run until a problem was identified through monitoring. Running Time (10 revolutions) 350 300 250 200 150 100 50 0 SIGNIFICANT LOSS OF USABLE LIFE RANDOM FAILURE L10 It is not within the scope of this paper to define how to determine which assets in a facility warrant use of predictive and proactive maintenance technologies. However, it is important that a consistent, methodical, objective method be used to prioritize assets within a facility so that investment decisions can be made and maintenance strategies can be determined based on asset criticality. Using the selected asset prioritization methodology, a list of assets to be monitored can be developed. DESCRIPTION OF A VIBRATION MONITORING PROGRAM The detailed chart on the next page is an example of a Life Science Facility Vibration Monitoring Program Asset List based on a small sample taken from a much more extensive list. This sample contains a representative cross-section of the types of equipment that would typically warrant vibration monitoring in a Life Science Facility. A comprehensive vibration monitoring program should identify alert levels to be used and the level of concern associated with each of those alert levels. A trained vibration analyst takes readings on a monthly basis and analyzes the data to determine any conditions that warrant attention. A detailed report is provided for any asset that has a moderate, serious, or extreme condition, but all results are reported in a summary list to provide a quick view of which assets have a reportable condition, and how long that condition has existed. In order to ensure the highest return on investment for a vibration monitoring program, it is essential to also maintain a separate report to show corrective actions completed. This report should track the work order for each corrective action, including labor and material costs for repair, estimated avoided cost (due to unplanned downtime, equipment replacement, or loss of product if the issue had not been corrected), and work order completion date. It is essential to report results in order to provide ongoing justification for the vibration monitoring program. www.newenglandcontrols.com 3
The most comprehensive method for predicting early bearing wear and remaining bearing life is Emerson s unique PeakVue technology. The chart below indicates stages of bearing wear and PeakVue values for a typical rolling element bearing rotating at 1000-4000 RPM. PeakVue provides a definitive measurement of bearing wear that can be used to make the repair/ replace decision at the most optimum time. Detailed vibration analysis provides information on parts that will be required if the bearing is to be rebuilt. State Bearing Life Remaining Vibration (in/sec) PeakVue (g s) 0 20-100 0.15 0 1 <20% 0.15 4 2 <10% 0.20 8 3 <5% 0.25 12 4 <1% 0.45 25 Failure 0% >0.30 >40 4 www.newenglandcontrols.com
BUSINESS RESULTS FROM A VIBRATION MONITORING PROGRAM This paper details case histories on assets used in Life Science facilities that were being monitored as part of a vibration monitoring program. For these assets, the cost avoidance achieved through avoidance of unplanned down time and the maintenance cost savings from catching issues early were significant. CASE #1 Condenser Tower Water Pump This pump circulates condenser water through the condenser cooling water system - primary chillers, refrigeration compressors, and air compressor coolers. There are three Condenser Tower Water Pumps, with two of the three always in operation and one in standby, with rotation once a week. Pump: Centrifugal Center-Hung Bearings: Antifriction Coupling Type: Faulk Flexible / In-Line / Grid Lubrication: Grease Motor: General Electric 250 HP AC Motor 1790 Rated RPM Lubrication: Grease Fault Found: Vibration analysis found critical stages of bearing wear in the outboard pump bearing. Advanced stages of bearing wear were noted, escalating to critical stages seven months later (overall vibration sharply increasing, in addition to continuing increase of PeakVue acceleration). Decision made to run pump only in emergencies, use backup until corrective action is taken. Corrective Actions Taken: Rebuild the pump (replace bearings, seals, and volute). Potential Case, if Unexpected Bearing Failure: If pump fails in service, redundancy is available. However, if a second pumps fails in service, major impact to cold room HVAC capacity and chiller capacity, as the condenser water system is used to provide a heat rejection source for the chillers. Costs of Unexpected Bearing Failure of the Redundant Pump: Repair Costs: $13, 500 Downtime: Potential production delays (process dependent) Total Cost: Depends on Cost of Production Delays (think about what this cost would be for your operation) www.newenglandcontrols.com 5
CASE #2 Manufacturing Area Air Handler This air handler provides cooling to a manufacturing suite. Fan: Bearings: Seal Master: NP-23T / GXU 1-7/16 / Custom Air Handling Bearing Fan Sheave: Browning - BK72 1-7/16 Lubrication: Grease Belt: Gates A34 Motor: MagneTek - Century Electric 5HP AC Variable Speed Motor 3470 Rated RPM Motor Sheave: Browning - 1VP62X1 Lubrication: Grease Fault Found: Fan imbalance - may be a resonance condition being excited by one of the system s forcing frequencies. Motor imbalance most likely due to the variable pitch sheave on the motor. The unit has an A belt but a B sheave on the fan. 6 www.newenglandcontrols.com
Corrective Actions Taken: Replace the VPS on the motor with a fixed sheave. Balance the fan and motor. Confirm the proper belt for this unit. Potential Case, if Unexpected Fan Failure: Run to failure, replace motor and fan; possible damage to other components and personnel if catastrophic failure. Loss of cooling to manufacturing suite. Costs of Unexpected Fan Failure: Repair Costs: $4, 400 Downtime: Potential loss of product and production delays Total Cost: Depends on the Value of the Product (think about what this cost would be for your operation) www.newenglandcontrols.com 7
ADVANTAGES OF WIRELESS TECHNOLOGY Advanced equipment for local data collection and software for analysis of vibration has been available for a number of years. Monthly readings are recommended in order to gather sufficient data to establish a trend. More recently, wireless vibration transmitters have been introduced that can cost-effectively capture vibration data continuously online. A wireless gateway then provides vibration data to machinery health analysis software and/or to a building automation system or process automation system for trending. This is a good solution for essential plant equipment, where a continuous trend will provide better data for determining when a repair needs to be done and where missing a monthly reading (due to equipment not being running, for example) could mean the difference between catching an issue or not catching it before a catastrophic failure. Examples of essential plant equipment in a Life Sciences environment that are candidates for this type of monitoring are water distribution pumps (C IP, WFI, RO), compressors, and air handlers for clean room areas. INTERESTED IN LEARNING MORE? CONTACT US! Massachusetts : 9 Oxford Road Mansfield, MA 02048 P: (508) 339-5522 F: (508) 339-9144 Maine: 327 Target Industrial Circle Bangor, ME 04401 P: (207) 942-1400 F: (207) 942-2400 sales@newenglandcontrols.com The contents of this publication are presented for informational purposes only, and while every effort is made to ensure their accuracy, they are not to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are governed by our software licensing agreement, and terms and conditions, which are available on request. We reserve the right to modify or improve the designs or specifications of our product at any time without notice. The New England Controls logo is a mark of New England Controls Inc. DeltaV, AMS, Rosemount, Fisher, Baumann, and Micro Motion are marks of Emerson Process Management. Des-Case is a mark of Des-Case Corporation. Spectro is a mark of Ametek Materials Analysis Division. Visit us online at www.newenglandcontrols.com.