Optimum Reference States for Precision Maintenance

Of all the various strategies associated with the maintenance and reliability of production equipment in the manufacturing and process industries, none is more salient than precision maintenance when it comes to increasing production availability and reducing life-cycle ownership costs of assets.

Precision maintenance focuses upon managing the root causes of failure. When properly implemented, it results in quieter-, smoother-, and cooler-running equipment. In addition to improving equipment uptime, reducing maintenance and life-cycle ownership costs, and extending the life of assets, precision maintenance decreases energy costs and associated greenhouse gases (GHGs) by targeting and eliminating sources of friction.

I’ve organized my approach to precision maintenance into what I call “FLAB Management.” FLAB is the acronym for and electrical and mechanical Fasteners, Lubrication, Alignment, and Balance—in other words, the foundation of electromechanical reliability. As listed here, I’ve created about 70 Optimum Reference State (ORS) conditions associated with the four elements of FLAB and the overarching category of FLAB management.

Each ORS statement is written as a positive statement to enable you to evaluate your organization’s performance. These statements certainly don’t reflect a complete or comprehensive definition of the entire universe of precision maintenance. They do, however, represent a credible cross-section. Use them to gauge your operation’s relative strengths and weaknesses in precision maintenance.

FASTENERS

We include torque values, fastener lubrication requirements, and required fastening sequence in all corrective- and preventive-maintenance-work instructions.

We employ properly selected and specified (e.g., grade, material, etc.) and sized fasteners and washers for fastener applications, and the fastener type, size, and material are clearly defined in maintenance-work instructions.

Fasteners are audited at least twice a year, and a routine audit of fasteners will reveal no loose, missing, improperly sized, or damaged fasteners in the plant.

Torque wrenches are employed for tightening fasteners in the plant, and when a specialized torque wrench is required, it is specified in the maintenance-work instructions.

Foundation-mounting bolts are properly selected, sized and grouted, and machines are correctly shimmed, when installed, to eliminate soft foot.

Belts on belt-driven equipment are properly tensioned with a spring or vibration tensiometer upon installation, re-tensioned shortly after start-up to adjust for relaxation or belt seating and required tension values, and tensioning instructions are explicitly included in corrective- and preventive-maintenance -work instructions.

Belts are inspected visually (or with a stroboscope), at least once a month, and checked for tension at least once a year.

Ultrasonic analysis is routinely employed for finding, tagging, and correcting air and other pressurized gas leaks. Leaks are fixed as found and recorded where possible.

Machines are routinely inspected for liquid leaks. Leaks are found, tagged, and corrected. Where required, fluorescent dye is employed to identify the location of leaks. Leaks are fixed and found and recorded, where possible.

All mechanical crafts people are properly trained and qualified on the theory and practice of applicable forms of fasteners, belt installation and tensioning, and leak detection and management. Where appropriate, specialized monitoring is contracted out to qualified experts.

Mechanical looseness is routinely monitored utilizing vibration analysis, where appropriate.

Looseness or soft foot issues revealed by vibration analysis or other inspection techniques are attended to with a high priority, before damage to bearings, gears, and other components can occur.

Electrical connections, including circuit breakers, fuses, contactors, overloads, disconnects, lug connections, etc., are routinely tested with thermography, motor analysis or other inspection techniques.

All electrical craft persons are properly trained and qualified on electrical-fastener theory and practice, to include monitoring and inspection techniques. Where appropriate, specialized monitoring is contracted to qualified experts.

Electrical fastener and circuit problems revealed by thermography, motor-circuit analysis, or other techniques, are corrected promptly before they can lead to equipment damage and/or functional failure.

LUBRICATION

The required viscosity grade and viscosity index have been analyzed for each application. The analysis considers the operating temperature and range. Viscosity and base-oil type requirements are written into material-specification standards for greases and oils.

The required additive system has been evaluated relative to the performance requirements of the application. Additive requirements, along with associated performance-property requirements, are written into material-specification standards for greases and oils.

The appropriate grease thickener has been selected for grease-lubricated applications, and measures have been taken to minimize cross-contamination of thickeners (e.g., instructions to motor-rebuild shops specify the exact grease to use for initial fill).

The required re-lubrication interval has been technically evaluated for each application to consider component type and size (e.g., bearings), operating speed, vibration, contamination in the area, shaft orientation, operating temperature, leakage rate, etc. The analysis produces ideal re-grease and oil-change intervals, where condition monitoring is not employed to determine the interval.

The required re-lubrication volume has been calculated for greased bearings considering the component size and type (e.g., bearing), seal configuration, etc., and precision methods are employed to ensure that the correct volume is applied.

Oil-lubricated machines are equipped with non-intrusive means to check oil level, and these levels are monitored and adjusted, as required, at least once per week (more often where leakage is common).

Particle-contamination-control limits have been set for all oil-lubricated machines, and proper measures have been taken to exclude and remove particles as required to achieve those targets. Oil analysis is employed as the feedback mechanisms to ensure that targets are achieved.

Water-contamination-control limits have been set for all oil-lubricated machines, and proper measures have been taken to exclude and remove water contamination, as required, to achieve those targets. Oil analysis is employed as the feedback mechanisms to ensure that targets are achieved.

Lubricant-storage containers, transfer devices, lubrication tools, and machines are all fitted with intuitive tagging labels (g., shapes and colors) to identify lubricants and to avoid cross contamination.

Lubrication PMs are written clearly to specify proper methods for carrying out various lubrication tasks, and fits, tolerances, quantity, and quality details are included in the associated maintenance-work instructions.

Lubricant samples are drawn at the proper interval, from the proper location, and using appropriate methods to assure representative oil-analysis data, and the samples are tested to an appropriate test state, for which action limits and thresholds have been set.

All crafts persons are properly trained and qualified on the theory and practice of lubrication and oil analysis. Where appropriate, specialized testing and analysis is contracted out to qualified experts.

Transformer oils are correctly managed, maintained, and tested to ensure the necessary dielectric performance and to avoid the accumulation of potentially flammable, dissolved gases, such as acetylene.

All crafts persons are properly trained and qualified on the theory and practice of lubrication and oil analysis. Where appropriate, specialized testing and analysis is contracted out to qualified experts.

Lubrication, contamination or wear issues revealed by oil analysis, vibration analysis, or other inspection techniques are attended to with a high priority, before damage to bearings, gears, and other components can occur.

ALIGNMENT

Shaft- and sheave-alignment-maintenance-work instructions include allowable misalignment, so there is no guesswork for techs at the job site. Tolerances are calculated based on speed, and consider shaft length when calculating angular misalignment limits.

Thermal growth is considered when setting up alignment limits and maintenance-work instructions.

Laser-alignment tools are employed for aligning shafts and sheaves.

Flexible couplings are NOT used as an excuse to employ lazy and imprecise shaft-alignment practices.

Pipework is installed properly to minimize pipe strain. Thermal growth is considered when laying in pipework. Also, piping is properly mounted and secured to reduce movement-induced stress on joints and flanges.

All mechanical-craft persons are properly trained and qualified on alignment theory and practice for shaft- and sheave-alignment jobs. Where appropriate, specialized work, monitoring and testing is contracted out to qualified experts.

Mechanical misalignment is routinely monitored utilizing vibration analysis where appropriate.

Mechanical misalignment issues revealed by vibration analysis or other inspection techniques are attended to with a high priority, before damage to bearings, gears, and other components can occur.

Electrical-total-harmonic distortion (misalignment with sinusoidal power wave) is maintained to below 3% for electric-motor applications.

The presence of stray voltage is routinely monitored in equipment, where appropriate (e.g., motors, generators, panels, etc.). Stray voltage is the accumulation of electrostatic electrical potential. When the accumulation reaches a critical level, the potential is electrokinetically discharged, causing electrical-discharge erosion (fluting) and the potential for injury.

All electrical-craft persons are properly trained and qualified on theory and practice related to managing total-harmonic distortion in electric motors. Where appropriate, specialized monitoring and testing is contracted out to qualified experts.

Electrical-harmonic distortion and stray voltage are routinely monitored utilizing motor analysis and other technologies, where appropriate.

Electrical-harmonic distortion and stray voltage issues revealed by motor analysis or other inspection techniques are attended to with a high priority, before damage to motors and motor-control centers (MCCs) can occur.

BALANCE

Where appropriate, pumps, blowers, fans, etc., are shop-balanced to appropriate standards prior to being put into service.

Required balancing precision is included in contracts whenever equipment is rebuilt offsite (e.g., electric motor rebuild shops). Where required, at-speed (high-speed) balance is specified.

Where appropriate, machines that can be field-balanced are, when required. Fans and other air-handling units are a common example of such equipment.

When correcting balance problems in the field, care is taken to minimize the risk that the cure won’t create other problems. A common example is the wash-down of fan blades introducing water contamination into bearings.

All mechanical-craft persons are properly trained and qualified on dynamic-balance theory and practice and belt installation and tensioning theory and practice. Where appropriate, specialized work and testing is contracted out to qualified experts.

Mechanical imbalance is routinely monitored utilizing vibration analysis, where appropriate.

Mechanical-imbalance issues revealed by vibration analysis or other inspection techniques are attended to with a high priority, before damage to bearings, gears, and other components can occur.

Phase-to-phase-electrical-voltage imbalance is monitored and maintained to acceptable levels to assure maximum motor life. Failure to maintain phase-to-phase-voltage balance results in the generation of heat. Voltage imbalance should be managed to below 2%.

Electrical-current imbalance is monitored and maintained to acceptable levels to assure maximum motor life. Failure to manage current imbalance causes heat generation and can stress electrical circuits. As a rule, current imbalance will be about seven times higher than voltage imbalance. However, current imbalance can be caused by the circuit, even if phase- to-phase voltage is in balance.

Phase-to-phase electrical-inductive imbalance caused by poor rotor condition is monitored and maintained to acceptable levels to assure maximum motor life. Inductive imbalance is an indication of wind quality. Limits are 7% for form-wound motors and 12% for loose-wound motors. The lower the better. This is an acceptance criterion for new or rewound motors.

Electrical-resistive imbalance is monitored and maintained to acceptable levels to assure maximum motor life. Resistive imbalance is a proactive indicator and often a precursor to current imbalance.

All electrical-craft persons are properly trained and qualified on electrical-balance theory and practice. Where appropriate, specialized work, monitoring, and testing is contracted out to qualified experts.

Electrical imbalance is routinely monitored utilizing motor analysis (current and circuit), where appropriate.

Electrical-imbalance issues revealed by motor analysis or other condition-monitoring or inspection techniques are attended to with a high priority, before damage to motors, MCCs, and other components can occur.

FLAB MANAGEMENT

As a matter of policy, proactively managing FLAB with precision-maintenance practices is a priority for management and not flippantly disregarded in lieu of fixing broken equipment.

Organizational roles pertaining to FLAB management and execution have been clearly defined and are visible on a responsible, accountable, consulted, or informed (RACI) chart. Individuals have received adequate FLAB education and training and are properly supported to fulfill their respective roles.

All preventive- and corrective-work practices are documented to identify best practice and to specify fits, tolerances, quantity, and quality details specific to each machine and application to ensure precision in the maintenance process without depending on “tribal knowledge.”

Inspections and condition monitoring (e.g., vibration analysis, oil analysis, etc.), as opposed to functional failure, drive the work request, planning, and scheduling process. And, condition-directed work is given a high priority so work requests don’t just sit in a backlog until the unit reaches functional failure.

The organization has a good balance of leading and lagging indicators that drive behaviors. For example, overall lubrication effectiveness (OLE) and overall vibration effectiveness (OVE) are leading indicators. Reliability, availability, cost per ton, etc., are lagging indicators.

Rewards are tied to achieving proactive goals (e.g., OLE and OVE), not just production goals or reacting effectively. Remember, rewards can be extrinsic (such as money), or intrinsic (such as recognition for effort). Historically, we’ve rewarded reacting to failure with overtime and pats on the back, rather than reward proactive behaviors that drive reliability.

The potential benefits in terms of avoided maintenance cost, increased production availability and utilization, and improved safety have been systematically analyzed and quantified in economic terms.

The organization employs world-class work management practices to ensure that proactive FLAB-related PMs and work that is identified and requested is properly planned, scheduled, and executed prior to damage occurring to the equipment.

Managers and supervisors have been trained and qualified on world-class asset management (e.g., to the five pillars of the Body of Knowledge set forth by the Society for Maintenance & Reliability Professionals [SMRP]).

The organization has access to a qualified reliability engineer who is an expert in all aspects of FLAB management, data mining and analysis, maintenance-work management, and other aspects of reliability engineering and equipment-asset management.

CONCLUSION
If you’re serious about increasing uptime, extending equipment life, and reducing maintenance and operations costs of production assets, precision maintenance should be a focal point. That’s where reliability hits the plant floor.

A “Focus on FLAB” is a great way to organize your efforts in targeting the root causes of friction, wear, and failure. It’s my sincere hope that this group of Optimum Reference States for precision maintenance will serve as a starting point for you to assess your organization’s relative strengths and weaknesses and, from there, formulate an action plan to leverage the opportunity to put precision maintenance to work for your operations.TRR

EDITOR’S NOTE: Threaded fasteners, along with many other critical aspects of proactive maintenance, are covered extensively in Drew Troyer’s course “Focus on FLAB with Precision Maintenance.” To access a recorded webinar presentation that introduces this course, CLICK HERE.

ABOUT THE AUTHOR
Drew Troyer has 30 years of experience in the RAM arena. Currently a Principal with T.A. Cook Consultants, he was a Co-founder and former CEO of Noria Corporation. A trusted advisor to a global blue chip client base, this industry veteran has authored or co-authored more than 250 books, chapters, course books, articles, and technical papers and is popular keynote and technical speaker at conferences around the world. Drew is a Certified Reliability Engineer (CRE), Certified Maintenance & Reliability Professional (CMRP), holds B.S. and M.B.A. degrees, and is Master’s degree candidate in Environmental Sustainability at Harvard University. Contact him directly at 512-800-6031 or [email protected].

Tags: fasteners, nuts, bolts, torque, tools, lubrication, alignment, balance, maintenance, workforce issues