PlantOps-PreventiveMaintenance

National Grain and Feed Associaton

1250 Eye St., N.W., Suite 1003, Washington, D.C. 20005-3922Phone: (202) 289-0873, FAX: (202) 289-5388, E-Mail: [email protected], Web Site: www.ngfa.org

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© Copyright 2008 by National Grain and Feed Association. All rights reserved. Federal copyright law prohibits unauthorized reproduction or transmis-sion by any means, electronic or mechanical, without prior written permission from the publisher, and imposes fines of up to $25,000 for violations.

Volume 10, Number 2, Nov. 7, 2008

Preventive Maintenance Programs That Work

By David A. FairfieldDirector of Feed Services

National Grain and Feed Association

[Editor’s Note: This is the first of a series of articles on preventive maintenance at grain handling, feed manufacturing and grainprocessing facilities. This article is pertinent to facility management and operations managers whose duties include overseeing thepreventive maintenance function and hiring maintenance personnel. Future editions will focus on particular aspects of successfulpreventive maintenance, with the next one focusing on preventive maintenance and the Occupational Safety and Health Administration’s(OSHA) grain handling safety standard. Be sure to route those future articles to operations and maintenance personnel within yourcompany responsible for this important function.]

Does the preventive maintenance program at your facility work?

As technology evolves, facilities involved in grain handling,feed manufacturing and grain processing increasingly rely uponautomated systems to produce quality products that satisfy cus-tomer needs in a cost-effective manner. By utilizing automatedsystems, facilities often become more labor-efficient and operationalcosts are reduced. In addition, the work centers within a facility maybecome more reliable by utilizing automation, resulting in lessproduction downtime and improved operating efficiencies. Auto-mated systems also may improve the quality and consistency offinished products.

Although there may be several benefits associated with using

automated systems, advances in technology also present somechallenges. Automated systems may be a highly complex integra-tion of mechanical, electrical, hydraulic and pneumatic equipment.These systems, along with other equipment routinely used withinfacilities, require an effective preventive maintenance program. An

effective program incorporates methods to maximize equipment lifeand minimize unexpected failures. Rather than waiting for a break-down, an effective program monitors equipment, thereby allowingfacilities to conduct maintenance work on a scheduled basis and ata lower cost.

The success of all aspects of grain and feed facility operations,

such as quality, safety, housekeeping and customer service, isaffected by the effectiveness of a facility’s preventive maintenanceprogram – making such programs a priority in today’s highlycompetitive market.

An effective preventive maintenance program typically con-

sists of the following major elements:

Goals or objectives. Program structure and organization. Management of the established program.

Preventive Maintenance Goals

Developing goals is the starting point in establishing an effec-tive preventive maintenance program. Most facilities establishgoals for production and/or handling-related activities, such as tonsor bushels per hour and cost per unit. But it also is important todefine goals and expectations for the preventive maintenance pro-gram, which provide needed direction and structure for the program

and its activities.

Effective goals or objectives, whether for a maintenance pro-gram or other area of facility operations, usually have the followingcharacteristics.

Realistic: A goal that is impossible to attain only discour-ages those trying to achieve it. Goals should be developedwith high standards, but be within reach. In addition, a goalis unrealistic if the employees involved have little controlover the outcome.

Measurable: Most goals should be quantifiable, whichmeans they have numbers or some metrics linked with them. No one will know if the goal has been accomplished if it isvague or cannot be assessed.

Time-Specific: Most goals should be associated withspecific time periods. Business results need to occur in atimely manner. Time-specific goals provide definitive guide-lines on when maintenance personnel should completeassigned projects.

Preventive maintenance goals may relate to several areas in the

facility, such as expenses, safety and productivity. Facility manag-ers may develop specific goals through the use of historical records,industry standards or computerized models. But every facility isunique, and managers should develop goals that meet the needs oftheir operation. It also is important that managers develop goalsafter receiving input of employees working within the maintenanceprogram. Involving employees in setting goals provides everyoneinvolved a sense of ownership in the program’s outcomes andsuccess.

Some possible examples of maintenance goals are:

Maintain facility maintenance labor and repair/equipmentexpenses within facility budget guidelines during the fiscalyear. Managers may choose to develop expense guidelinesby individual cost center on a total-dollar or per-unit basis,then compare actual expense results against establishedguidelines to monitor the results.

Ensure the equipment and facility complies with companyand government safety standards. Routine inspections ofthe facility’s equipment, building and grounds are neces-sary to ensure compliance with safety standards. Typically,maintenance personnel complete most of these inspectionswhile performing work assigned in established maintenanceschedules. Since facility safety is a top priority, managersmay choose to establish a goal to help ensure the mainte-nance crew completes these inspections in a timely andthorough manner. This type of goal could be measuredusing company safety and/or insurance audits.

Limit operation downtime to help achieve facility productiv-ity goals. Consider establishing productivity goals for themaintenance functions at the facility, just as is done inmeasuring operational efficiencies. It can be more difficultto quantify the efficiency of maintenance programs com-pared to other cost centers. But an effective maintenanceprogram is crucial to achieve overall productivity goals, andestablishing goals may help foster an atmosphere of timelycompletion of maintenance work.

Program Structure and Organization

To achieve established goals, an effective preventive mainte-nance program typically has several key elements, including:

Qualified maintenance personnel.Equipment data/history records.Maintenance schedules.Spare parts and parts-ordering criteria.Program organization.

Maintenance Personnel: Selecting good maintenance employ-ees can be a management challenge. As with any job, there is no idealstereotype for such individuals. Necessary backgrounds andtalents for maintenance positions will vary, depending upon themanagement approach and facility requirements. The following aresome characteristics that managers may wish to consider whenselecting employees for performing maintenance:

Mechanical Interest: Maintenance personnel need to en-joy and be challenged by mechanical work. The successfulmaintenance employee accepts the demands of maintainingequipment as a problem-solving exercise, and not as adrudgery of endless breakdowns and repairs. With this

attitude, maintenance employees will enjoy the challenge ofmonitoring and maintaining equipment before it fails, ratherthan performing maintenance only as a last resort to keep itoperating.

Self-Starter: Maintenance personnel, unlike most facilityemployees, do not perform the same duties each day. Effective maintenance employees need to have the ambi-tion to plan their work schedule to make the most of availabletime and resources. All facility employees need supervi-sion, but maintenance personnel need to be self-motivatedenough to accomplish tasks with minimal prompting. Aneffective maintenance employee will bring potential prob-lems to a manager’s attention, rather than waiting for theissuance of a work order.

Assertive: The facility’s organizational structure may placemaintenance personnel between the facility manager andother production employees. This structure may result indisagreements between maintenance personnel and pro-duction employees over the cause of maintenance issues. In these situations, maintenance employees need to be

2 Plant Operations Bulletin November 7, 2008

assertive enough to appropriately assess potential prob-lems and convey them to management for corrective action.

Mechanical Skills: Performing maintenance requires avariety of mechanical skills. These may include welding,metal fabrication, plumbing and hydraulics. Maintenancepersonnel often not only are required to perform mechanicalduties in these areas, but also must have knowledge andskills relating to the design aspects of the work they areperforming. Examples could include the ability to read andunderstand equipment and building blueprints and sche-matics, knowledge and understanding of applicable build-ing and equipment codes, a basic understanding of engi-neering terms and methods, and the ability to performnecessary mathematical calculations.

Electrical Skills: Many automated systems used by facili-ties incorporate process-control systems that consist ofprogrammable logic controllers and related electrical de-vices for system inputs and outputs. In addition, mostfacilities utilize a wide range of electrical systems for theiroperations, which may include low-voltage direct current(DC) and alternating current (AC) control wiring, single- andthree-phase low- and high-voltage DC and AC motor wiring,and a variety of electrical switchgear and other devices. Maintenance personnel may need to possess the neces-sary skills to troubleshoot and repair these electrical sys-tems. These skills may include: 1) the ability to read andunderstand electrical schematics and blueprints; 2) theability to measure and monitor electrical flow through sys-tems; 3) a basic knowledge and understanding of applicableelectrical codes, such as the National Electric Code; and 4)a working knowledge of electrical motors and control de-vices.

Managers should determine the mechanical and electrical sys-

tem skills they may need in their maintenance personnel, and includethose qualifications in the criteria for hiring. To evaluate whether apotential employee possesses these necessary skills, it may beappropriate to develop and administer tests during the hiring pro-cess.

Just as with other employees, it may not always be possible tofind all of the desired characteristics within one individual whenselecting maintenance personnel. Generally, when selecting a main-tenance person, it may be more beneficial to find an individual whohas a good mechanical interest and is a self-starter and assertive,rather than an individual simply possessing technical skills. Theformer type of individual usually can be trained and develop theadditional required skills to be successful in the position.

Maintenance Job Descriptions: Include a formal job descriptionfor maintenance personnel. Each facility operation is unique, so themaintenance job description should be tailored for each situation.The following are some practical job description elements to con-sider:

Maintenance personnel will report to the facility manager.

Maintenance personnel will coordinate with the supervi-sors of the day and night shifts concerning all maintenancework to be performed.

Maintenance personnel will make every effort to repair andmaintain equipment in a manner that will minimize produc-tion downtime.

Maintenance personnel will conduct and document routinelubrication and inspection of equipment according to estab-lished schedules. Maintenance personnel will document allmajor maintenance performed within the facility on repairlogs.

Maintenance personnel are authorized to order or purchasenecessary maintenance repair parts and services up to thespending limit designated by the manager.

The maintenance supervisor will establish a procedurewhereby requests may be made to perform maintenanceactivities on production equipment. If routine maintenancerequests are not performed in a timely manner, such requestsmay be made directly to the facility manager for action.

Maintenance personnel are responsible for maintenance ofall equipment present at the facility. This includes facilityrolling stock (e.g., forklifts, tractors, loaders) or any othertype of equipment directly related to the facility’s produc-tion operations. Additional duties of maintenance person-nel for major equipment are:

• Hammermills: Production personnel are responsiblefor replacing and rotating hammers, and changing ofhammermill screens. Maintenance personnel are re-sponsible for maintenance on hammermills as outlinedin the maintenance lubrication and inspection sched-ules. If problems arise concerning hammer wear, screendamage, leaking doors, etc., it is the responsibility ofmaintenance personnel to assist in correcting thoseproblems.

• Pellet Mills: Production personnel are responsible forroutine maintenance of the pellet mill, such as rolladjustment, roll and mainshaft lubrication, and roll anddie changes. Maintenance personnel are responsiblefor the maintenance of pellet mills as outlined in themaintenance lubrication and inspection schedules.

If production personnel are unable to correct problemsthat may arise with either pellet rolls or dies, it is theresponsibility of maintenance personnel to assist inresolving those problems. During periods of peak pro-duction, it may be necessary for maintenance personnel

November 7, 2008 Plant Operations Bulletin 3

to assist in changing pellet mill rolls or dies, as directedby the manager.

It is the responsibility of maintenance personnel torebuild pellet mill rolls and repair rolls in a manner thatwill ensure availability of rebuilt rolls at all times.

– Boilers: Maintenance personnel are responsible forservicing the boiler water treatment system. The watertreatment will be performed as recommended by thewater treatment supplier representative. Maintenancepersonnel will follow recommended blowdown proce-dures for the boiler.

– Air Compressors: Maintenance personnel will per-form a daily condensate blowdown of the air compressortank. All other air compressor maintenance will beperformed as outlined in the maintenance lubricationand inspection schedules.

– New Equipment: If equipment is added or modifiedwithin the facility, the maintenance supervisor andmanager will determine a maintenance schedule for suchequipment and insert that information into the mainte-nance lubrication and inspection schedules.

– Questionable Assignments: The manager will resolveassignments of questionable maintenance proceduresbetween maintenance and production personnel.

A well-defined job description will provide maintenance person-nel with a clear understanding of responsibilities. The job descrip-tion also will establish guidelines for authority, enabling employeesto work freely within established parameters.

Equipment Data/History Records: Eventually, every piece ofequipment at the facility will require maintenance attention. Thevarious components that comprise each piece of equipment shouldbe identified before determining a maintenance schedule. Theamount of information required to be identified will depend upon thecomplexity of the equipment and what information will be useful. Forsome equipment, information about motors, gearboxes, drive beltsand bearings will be adequate. For other machinery, it may benecessary to collect data on all mechanical, electrical, hydraulic andpneumatic items associated with the equipment.

Some of the sources of information for creating a data file for eachitem of equipment are:

Manufacturers’ bulletins and manuals.Facility blueprints.Purchase records.Facility walk-through. A facility walk-through probably isthe most effective method for collecting necessary informa-tion. It requires an inspection of all equipment and recordingof all the pertinent information.

In addition to having equipment data available, it is essential tomaintain historical repair records on equipment. Equipment historylogs need to be developed and major repair or adjustment workrecorded as maintenance work is completed. Repair logs providevaluable information for: 1) establishing inspection and lubricationschedules; 2) determining the need for spare parts; 3) tracking repaircosts; and 4) justifying equipment upgrades or replacement.

Maintenance Schedules: After equipment information is gath-ered, routine inspection and lubrication schedules need to beestablished. Management and maintenance personnel can worktogether utilizing their experience and manufacturers’ recommenda-tions to determine the best maintenance schedule and proceduresfor each piece of equipment.

Since a given facility may have considerable duplication of

equipment, similar equipment may be lubricated and inspectedwithin the same time intervals, such as weekly, monthly or quarterly.Consolidating equipment inspection and lubrication frequenciesinto the same intervals makes it easier to schedule work and managethe maintenance program.

Along with established frequency, equipment lubrication and

inspection schedules should outline the specific work to be com-pleted. For example, the maintenance schedule procedures for amachine should outline what to check during the inspection, andprovide information pertaining to the type and quantity of lubricantrequired. Again, because of the similarity of equipment within thefacility, the number of documents required to outline maintenanceprocedures may be relatively few.

Spare Parts and Parts Ordering: Because of cost and storageconsiderations, it is unrealistic to keep a full array of equipment spareparts onsite. But certain spare parts are essential to keep the facilityoperating in an efficient manner. How large of an inventory of spareparts should be maintained? How often should spare parts bereordered? Who is responsible for the parts inventory? These areall questions that need to be addressed within the maintenanceprogram.

To determine which and how many spare parts are needed for the

facility’s inventory, management and maintenance personnel shouldfocus especially on equipment associated with critical manufactur-ing or processing areas. For example, if a problem occurs with themixer motor or gearbox of a feed mill, the entire production operationmay cease. Can the facility afford to inventory a spare mixer motorand gearbox? Are necessary parts readily available from localsuppliers when needed? Or are the parts special orders? Byassessing the cost and availability of those critical items against thepotential cost of downtime, management can decide which spareparts should be inventoried. Each critical operational area in thefacility should be evaluated in the same manner.

In addition, equipment data and history repair records provide

a good source of information in determining which spare partsshould be in inventory. A review of the equipment data and repairhistory will:


Show which equipment has required repair parts in the pastand provides an indicator of which parts – both by type andquantity – may be necessary in the future.

Help identify common parts among different pieces ofequipment, which can reduce the quantity of spare partsrequired in inventory.

Assist in evaluating whether parts and equipment could bestandardized. When planning for the replacement or instal-lation of new equipment, management and maintenancepersonnel should evaluate opportunities to install similarmodels of equipment within the facility. Standardizingequipment may provide many advantages in terms of opera-tion, ease of maintenance and spare parts availability.

At many facilities, both management and maintenance person-nel are responsible for ordering parts. To establish guidelines inpurchasing authority, management typically determines a monetarylimit to which maintenance personnel may make purchases withoutfurther approval. This allows maintenance personnel to handleroutine jobs without continually consulting management for pur-chase-order authorization. The purchasing authority granted tomaintenance personnel should be established at a figure highenough to enhance efficiencies and yet not so great as to createpotential budget overruns during accounting periods.

Guidelines within the maintenance program should specify that

all major repair costs be directed to management for considerationand approval. Depending upon the size of the facility, the managershould either place the order or authorize the purchase order. Thiscontrol also may eliminate the confusion of double ordering.

Organizing the Maintenance Program

Documents associated with the preventive maintenance pro-gram, such as equipment data sheets, equipment history records,maintenance schedules, equipment manuals, spare parts inventoryand purchase records need to be stored and organized. This systemshould provide easy access to information and records, allowinformation to be readily updated and provide an effective way toschedule maintenance work and document required activities.

Two types of systems for organizing preventive maintenance

programs are:

Computerized maintenance systems.File folder maintenance systems.

Computerized Maintenance Systems: A variety of maintenancesoftware has been developed to help organize and monitor mainte-nance programs. Typically, computerized maintenance softwareprograms include systems for equipment data and repair history,parts inventory/ordering, preventive/predictive maintenance sched-ules, maintenance work scheduling and report generation. Fre-quently, each area within the program is interactive by design; anexample would be that as spare parts are used during maintenanceactivities, the spare parts inventory levels are reduced and equip-ment repair history updated. This type of interaction reduces thetime required to manually update separate records and helps im-prove recordkeeping accuracy.

Some common features typically found in maintenance software

programs include:

Equipment Data/History Records: Maintenance softwareprograms provide a database format to record informationabout all equipment. Database fields may be present toenter information, such as the equipment general ledgernumber and cost center assignment, equipment spare parts,

safety requirements, equipment repair history, service con-tract information and equipment nameplate information.

Parts Inventory/Ordering: Computerized maintenance pro-grams provide a system to create inventory and orderrecords for maintenance parts, and then track parts usageand cost. This system may include features to identifyvendors and manufacturers, a way to record quantities andreorder points for parts, and the ability to track the transac-tion history of different parts in the facility. System featuresrelating to parts ordering may include a way to generatevendor quotation requests for those parts in inventory thathave reached reorder levels, generation of purchase ordersand the ability to track purchase order history. The partsinventory/ordering system typically is integrated with theequipment data/history record system within the mainte-nance software program. As maintenance work is com-pleted and keyed into the system, parts inventories arereduced and equipment history information updated. Asparts are received at the facility, inventory levels for equip-ment are increased and costs applied to the appropriate costcenter.

Preventive/Predictive Maintenance Schedules: Preven-tive maintenance schedules are developed to help to maxi-mize equipment life and avoid untimely equipment failure. The frequency of routine maintenance lubrication andinspection schedules typically is based upon equipmentmanufacturers’ recommendations and experience. To moreaccurately predict needed equipment maintenance frequen-cies, many computerized maintenance programs incorpo-rate statistical predictive maintenance features to identifytrends in equipment repair history and inspection records.After sufficient equipment history and inspection data havebeen accumulated, the maintenance program can produce


certain predictions about the next potential equipment fail-ure. The maintenance program then can generate a reportthat alerts personnel to these statistical trends.

Maintenance Work Scheduling: Computerized mainte-nance programs have the ability to generate work schedulesfor routine maintenance lubrication and inspections. Theseprinted work schedules then may be distributed to mainte-nance personnel for completion. Details associated with theequipment may be incorporated into the schedules, too,such as safety instructions and specialized equipment infor-mation and procedures.

Report Generation: Computerized maintenance programscan generate a wide variety of reports and graphs to helpmanage the maintenance program. These reports may in-clude equipment lists, parts inventories, purchase orderhistories, maintenance employee records, work schedulereports, trend analysis and others. Reports usually may beprinted, viewed on screen or exported to other files.

A maintenance software program may provide a very powerfuland comprehensive method for organizing a maintenance program. However, some commercially available software systems are de-signed for very large industrial plants and may require more admin-istrative time and effort than acceptable for feed and grain facilities.When considering a computerized maintenance system, managersmay wish to ask the software vendor about the use of their systemin other feed or grain facility applications, as well as for a list ofreferences that can provide information about their experience usingthe software. Ultimately, the decision on whether to use a mainte-nance software system needs to be made by comparing the program’sbenefits to the costs of purchasing and administering it.

File Folder Maintenance System: Another effective way to orga-nize the maintenance program is to use a file folder system. This typeof system involves: 1) establishing file folders for each piece ofequipment; 2) developing standardized forms to record equipmentdata and repair history; 3) making a spare parts list; 4) puttingtogether routine equipment lubrication and inspection scheduleforms; and 5) providing a method to schedule non-routine mainte-nance work.

Equipment Data/History Records: Figure 1 (page 8) is anexample of a standard form that can be used to recordequipment data information. The form has headings formost of the common components associated with equip-ment to make completing the form easier. Extra space isprovided for specialized equipment information, if neces-sary, a different form could be developed for those needs. Figure 2 (page 9) is an example of a form that could be usedto record equipment repair history, and includes space todocument the date and details of equipment repairs. It maybe practical to incorporate both the equipment data form andthe equipment repair history form on the front and back ofone sheet. The equipment data/repair history form may beplaced in a file folder, along with other sources of informa-

tion about the equipment, such as equipment manuals,purchase orders and vendor information. Each piece ofequipment will have its own information folder. These filefolders may be organized by cost center, beginning with thereceiving department and following the flow of materialthrough the facility. Folders for support equipment, such asair compressors, air dryers, boilers, steam condensate tanks/pumps, motor control center systems, sprinkler systems,etc., may be placed at the end of the filing system. Equip-ment file folders may be numbered and named so they areidentifiable.

Spare Parts: With a file folder maintenance system, a spareparts list showing parts and quantities on hand, along withparts’ vendors, may be developed utilizing a word process-ing or spreadsheet program. This list may be printed andmaintained in a separate file folder for easy access.

Equipment Lubrication and Inspection Schedules: Main-tenance procedures for each type of equipment should bedeveloped that outline what maintenance personnel need tocomplete during equipment lubrication and inspection. Fig-ure 3 (page 10) is an example of a document that may be usedto designate specific equipment lubrication and inspectionguidelines. Because of the similarity of equipment, this typeof maintenance procedure form typically may be used for avariety of equipment. The form lists basic maintenancefunctions, required maintenance frequencies and providesspace to check off those functions. If additional functionsare required for special equipment, they may be added at thebottom of the form; or a different form could bedeveloped. Once completed, these equipment maintenanceprocedures may be printed and placed in a separate mainte-nance procedure file along with the equipment files.

After establishing equipment maintenance procedures, aneffective way to schedule and document equipment lubrica-tion and inspection is to put on a single list all required workthat falls within the same time interval, such as once permonth. Since specific lubrication and inspection mainte-nance procedures already are documented, there is no needto include detailed procedures on the inspection and lubri-cation checklist. Figure 4 (page 11) is a partial example ofa monthly lubrication and inspection schedule. Using sucha schedule, maintenance personnel may complete equip-ment lubrication and inspection throughout the month andsign off that the required activities have been completed. Additional checklists for equipment lubrication and in-spection could be developed for other time intervals, suchas six or 12 months. Completed equipment and lubricationschedules should be filed along with the other maintenancedocuments within the file folder system.

Scheduling Non-Routine Maintenance Work: Using equipmentand lubrication schedules provides maintenance personnel with aroutine work schedule. In addition to these normal work activities,the maintenance program needs to provide a way to ensure that


special or non-routine work is completed. Often a standard workorder form is used to make the maintenance department aware of thenon-routine work that needs to be accomplished. Figure 5 (page 12)is an example of such a work order form. Typically, the manager ormaintenance supervisor should issue and schedule work orders

with maintenance personnel, as needed. Written work orders pro-vide a good way to assign non-routine work and document itscompletion. Copies of written work orders should be filed with othermaintenance records.

Managing the Established Program

After establishing and implementing the maintenance program,results routinely need to be evaluated against the program’s goals.For example, are facility maintenance and repair costs in line? Doesequipment downtime prevent production goals from being achieved? Has the maintenance crew completed necessary inspections in atimely and thorough manner? By periodically reviewing the main-tenance program’s results compared to the program’s goals, areasneeding attention may be identified and plans made for correctiveaction. The overall success of the maintenance program relies uponreviewing results and taking the appropriate action to maintain andimprove the program.

If maintenance costs are too high, a review of equipment repair

history logs may indicate excessive problems with certain equip-ment. By maintaining accurate equipment repair history logs, it maybe possible to justify upgrading or replacing problem equipment.High maintenance costs also may be attributable to excessive laborcosts, in which case management may need to reinforce withmaintenance personnel the importance of timeliness in their work. Byestablishing and communicating realistic work expectations to main-tenance personnel, timely performance may be fostered.

If maintenance activities are not being completed on time or

correctly, a review with maintenance personnel may be needed to

identify causes and to develop a corrective plan. For example, areview of equipment repair history logs may show an excessiveamount of time being spent on unscheduled maintenance activitiesbecause of breakdowns. If equipment problem areas can be de-tected and corrected, maintenance personnel will have more timeavailable to complete necessary maintenance inspections. By moni-toring maintenance records and inspection schedules, managementreinforces to maintenance personnel the importance of timely andaccurate completion of these inspections.

When reviewing the maintenance program’s results, consider

involving maintenance personnel as much as possible. Mainte-nance personnel will take more ownership into the program if theyare updated on the progress of the maintenance program and askedfor their ideas on how to make improvements.

Managing the established maintenance program also should

include periodic meetings with maintenance personnel and provid-ing them formal feedback on their job performance. During themeeting, identify the employee’s strengths, along with weaknesses. Enhance employee skills in areas that will benefit the employee andthe facility. Most maintenance personnel want feedback fromsupervisors on their job performance and how they can improve theirskills and perform better.

Conclusion

Feed mills and grain-handling and processing facilities willcontinue to rely increasingly on automated systems to producequality products in a cost-effective manner. These automatedsystems, along with routine equipment, require an effective preven-tive maintenance program. A preventive maintenance program thatworks will:

Define specific goals for the program.Utilize qualified maintenance personnel.Have an organized and effective system for maintainingequipment records and scheduling maintenance work.Include periodic management reviews to evaluate and con-tinually improve the program.

Coming Next: Preventive Maintenance andOSHA’s Grain Handling Safety Standard


Sample Equipment Data Sheet

Equipment Name __________________________ Date Installed _______________________

Model Number __________________________ Serial Number ______________________

Manufacturer __________________________ Capacity ___________________________

Equipment Size __________________________ Type ______________________________

Additional Name Plate Data ____________________________________________________

Motor GearboxMake _______________________________ Make ________________________________

Horsepower ___________________________ Model ________________________________

RPM _______________________________ Size _________________________________

Voltage ______________________________ Ratio ________________________________

Phase _______________________________ Input Shaft ____________________________

Frame _______________________________ Output Shaft ___________________________

Full Load Amps ________________________ Input Sheave/Sprocket ___________________

Code _______________________________ Output Sheave/Sprocket _________________

Shaft _______________________________ V-Belt Size/Number _____________________

Sheave/Sprocket _______________________ Chain Size/Number _____________________

Coupler BearingsMake __________________________ Leg (top) _____________ (bottom) ____________

Model _________________________ Drag (Head) __________ (tail) _______________

Size ___________________________ Auger (Head) _________ (tail) _______________

Misc. Bearings ______________________________

Driven Equipment Misc. Bearings ______________________________

Driven Shaft ______________________ Misc. Bearings ______________________________Sheave/Sprocket __________________

Additional Data

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Figure 1

Sample Equipment History / Repair Log

Date Work Completed Parts Cost Labor Cost

Figure 2

Sample Equipment Inspection and Lubrication Checklist

Equipment_____________________________

Weekly Monthly 3 Months 6 Months 12 Months

1. Check / Grease Bearings

2. Inspect Gearbox / Check Oil

3. Change Oil

4. Inspect Motor

5. Inspect Drive Chain/Belts

6. Inspect Sprockets / Sheaves

7. Oil Chain

8. Check Belt / Splice / Alignment

9. Check Leg Cups

10. Check Head Pulley

11. Check Trunking Condition

12. Check Drag Chain Tension / Condition

13. Check Drag Flights

14. Check Condition of Safety Switches

15. Check Condition of Conveyor Housing

16. Change Oil Filters

17. Change Air Filters

18. Inspect Coupler and Grease

19. Check Limit Switches

Additional Maintenance:

Figure 3

Sample Monthly Equipment Inspection and Lubrication Schedule

Month_______________

Plant Area Equipment Date Completed By

Basement Receiving Conveyor

Receiving Leg

Hammermill Feeder

Hammermill

Rollermill

Grinding Conveyor

Grinding Leg

Mixer

Surge Conveyor

Mixing Leg

Pellet Cooler

Crumble Rolls

Pellet Conveyor

Pellet Chip Grinder

Pellet Leg

Molasses Pump

Fat Pump

Condensate Pump

Work Floor Ingredient Feeder Screws

Premix Dump Hopper

Pellet Mill Feeder

Pellet Mill Conditioner

Pellet Mill

Bagging Conveyor

Bagging Scale

Sewing Conveyor

Sewing Machine

Bag Belt Conveyor

Warehouse Bag Belt Conveyor

Forklift

Pallet Jack

Figure 4

Sample Work OrderWork to be Completed:

By______________________

Date____________________

Figure 5



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© Copyright 2008 by National Grain and Feed Association. All rights reserved. Federal copyright law prohibits unauthorized reproduction or transmis-sion by any means, electronic or mechanical, without prior written permission from the publisher, and imposes fines of up to $25,000 for violations.

Volume 10, Number 3, Dec. 18, 2008

Preventive Maintenance and OSHA’s Grain Handling Standard



[Editor’s Note: This is the second in a periodic series on various aspects of preventive maintenance programs for grain elevators,feed mills and grain processing facilities. The first, entitled “Preventive Maintenance Programs that Work,” was published and enclosedwith the Nov. 6 NGFA Newsletter. You are encouraged to share these publications with those at your facility responsible for preventivemaintenance and safety programs. The next edition will focus on preventive maintenance requirements under the Occupational Safetyand Health Administration’s general industry standards.]

The Occupational Safety and Health Administration’s (OSHA)grain handling standard (29 CFR 1910.272) contains severalrequirements pertaining to maintenance activities – most of whichtook effect in March 1988 – that apply to grain handling facilities,including grain elevators, feed mills, flour mills, rice mills, dustpelletizing plants, dry corn mills, soybean flaking operations and drygrinding operations of soycake.

Managers and maintenance personnel at effected facilities needto be aware of both the operational and equipment provisions of thegrain handling standard while performing and authorizing mainte-nance activities.

The operational requirements of the standard that may pertainto maintenance activities govern such things as:

hot work procedures;contractor notification; and

preventive maintenance.

The equipment requirements that may pertain to maintenanceactivities include provisions governing:

size openings of grates;grain stream processing equipment;monitoring devices for inside-located bucket elevator legs;grain dryers; andfabric dust collector filters.

Within the standard, certain requirements apply only to a “grainelevator.” The standard defines a “grain elevator” as a “facilityengaged in the receipt, handling, storage and shipment of bulk rawagricultural commodities, such as corn, wheat, oats, barley, sun-flower seeds and soybeans.” Importantly, grain elevators alsoinclude the elevator portions of processing and milling facilities,such as feed and flour mills, and corn and oilseed processing plants.

Operational Requirements

The operational requirements of the OSHA grain handlingstandard encompass the following:

Hot Work Procedures: At all grain handling facilities, employersare required to issue permits for all “hot work” (electric or gaswelding, cutting, brazing or “similar flame-producing operations”)

unless one or more of the following three conditions is met:

The employer or its representative (“who would otherwiseauthorize a permit”) is present while the hot work isperformed.


The hot work is performed in welding shopsauthorized by the employer.

The hot work is performed in employer-desig-nated areas outside the grain-handling structure.

The permit is required to certify that hot work require-ments contained in OSHA’s general industry standard[1910.252(d)] have been implemented.

Contractor Notification: At all grain-handling facili-ties, the standard requires contractors performing work,including maintenance activities, to be informed by theemployer about “known potential fire and explosionhazards related to the contractor’s work and work area.”The employer also is required to inform contractors of theapplicable safety rules of the facility, including emergencyprocedures.

Preventive Maintenance: At all grain handling facili-ties, a preventive maintenance program is to be imple-mented that consists of:

regularly scheduled inspections of “at least themechanical and safety control equipment asso-ciated with dryers, grain stream processingequipment, (grain) dust collection equipment(including filter collectors) and bucket eleva-tors.”

lubrication and “other appropriate maintenancein accordance with manufacturers’ recommen-dations or as determined necessary by prioroperating records.”

A “certification record” is to be kept of the mainte-nance performed of each inspection, including the date ofthe inspection, name of the person who performed it, andthe serial number (or other identification) of the above-listed equipment that was inspected.

Employers also are required to “promptly correct, or

remove from service, overheated bearings and slipping ormisaligned belts associated with inside bucket eleva-tors.” Employers are required to promptly correct dust-collection systems that are malfunctioning or operatingbelow design efficiency and also are required to implementprocedures for using both locks and tags that will prevent“the inadvertent application of energy or motion toequipment being repaired, serviced or adjusted whichcould result in employee injury.” The locks and tags areto be removed only by the employee installing them, or, ifthat person is unavailable, by the employee’s supervisor.

While not specifically required by OSHA, there areseveral options managers may wish to consider includingas part of their preventive maintenance program:

Work Orders: A work order permit is a methodmanagers can use to ensure that scheduled rou-tine inspections and preventive maintenance orrepair of equipment has been assigned and per-formed. The work order basically consists of aform that: 1) assigns inspection or maintenancetasks to a specific employee(s); and 2) providesinstructions to employee(s) on the type of main-tenance to be performed.

OSHA’s non-mandatory appendix to the grainhandling standard states that a work order “wouldbe an indication of an effective preventive main-tenance program.”

Monitoring Equipment: Facility managers maywish to consider using various motion- or tem-perature-detection devices (i.e., thermocouples)on bearings or other equipment to assist in moni-toring equipment condition and performance.However, with the exception of inside-locatedbucket elevator legs, these devices are not re-quired by OSHA, and managers instead may wishto utilize a daily walk-through of the facility as ameans of complying with the OSHA standard’sinspection requirements.

Equipment Requirements

The equipment-related requirements of the OSHA grainhandling standard encompass the following:

Size Openings of Grates: At all grain handling facili-ties, receiving pits – such as truck and rail dump pits – arerequired to have a maximum width opening of 2-1/2 inches.There is no length restriction on grate openings at receiv-ing pits. Facility managers may wish to consider incorpo-rating inspection of the size opening of grates into theroutine activities performed by maintenance personnel.

Grain Stream Processing Equipment: At all grainhandling facilities, grain stream processing equipment isto be equipped with “an effective means of removingferrous material from the incoming grain stream.”

Importantly, this requirement pertains only to suchprocessing equipment as hammer mills, grinders and pul-verizers. It does not apply to scalpers, screens or othercleaning equipment used at grain handling facilities.


Although the standard does not mandate a specificmeans for complying with this requirement, OSHA statesin its non-mandatory appendix that “acceptable means forremoval of ferrous material include the use of permanentor electromagnets.” However, the standard does notprohibit the use of other methods to remove ferrous mate-rials, such as grain cleaners, screeners, gravity tables orother particle-separating equipment installed on grain-processing streams.

If facilities choose to utilize permanent or electromag-nets as a means to comply with this requirement, managersmay wish to consider incorporating the inspection andcleaning of these devices into the routine activities per-formed by maintenance personnel.

Inside Bucket Elevators: For grain elevators only,several requirements apply to “inside” bucket elevatorlegs [defined as a bucket elevator that has the boot andmore than 20 percent of the total leg height (above gradeor ground level) inside the grain elevator structure].Other bucket elevators that are not “inside” are exemptfrom the equipment requirements.

Three major sets of equipment requirements apply to“inside” bucket elevators:

1. Bearings are to be mounted externally to the legcasing; or be equipped with motion-detection ortemperature-monitoring devices or other meansfor monitoring “the condition of those bearingsmounted inside or partially inside the leg cas-ing.”

2. Motion-detection devices are to be installed thatshut down the “inside” bucket elevator when thebelt speed is reduced by no more than 20 percentof the normal operating speed.

3. Belt-alignment devices are to be installed that willinitiate an alarm to employees when the belt is nottracking properly; or provide another means ofkeeping the belt tracking properly, “such as asystem that provides constant alignment adjust-ment of belts.”

Exempt from all three of these requirements are “in-side” bucket elevators that are equipped with:

operational fire or explosion suppression sys-tems capable of protecting the head and bootsections; or

pneumatic or other dust control systems thatmaintain dust concentrations in the bucket eleva-tor at least 25 percent below the lower explosivelimit for grain dust at all times during operations.

Exempt from requirements 2 and 3 listed previously arefacilities having a “permanent” storage capacity of lessthan 1 million bushels, provided a daily visual inspection ismade of the bucket movement and tracking of the belt inthese facilities.

Further, the following requirements apply to all “in-side” bucket elevators in use by grain elevators, regardlessof special equipment or storage capacity:

A means of access is to be provided to allowinspection of the head pulley, lagging, belt anddischarge throat of the head section.

A means of access is to be provided to allowcleaning and inspection of the boot section,pulley and belt.

Jogging of choked inside bucket elevator legs isprohibited.

Belts and lagging purchased after March 30, 1988for inside bucket elevators must be conductive.Such belts shall have a surface electrical resis-tance not to exceed 300 megohms.

Grain Dryers: At grain elevators only, all direct-heatcontinuous-flow bulk raw grain dryers are required to beequipped with automatic controls that:

shut off the fuel supply in case of power or flamefailure or interruption of air movement throughthe exhaust fan; and

stop the grain from being fed into the dryer ifexcessive temperatures occur in the exhaust ofthe drying section.

While not an OSHA requirement, facility managersmay wish to consider incorporating periodic inspectionand testing of the required automatic controls installed ongrain dryers into the routine activities performed by main-tenance personnel.

Fabric Dust Collector Filters: At all grain handlingfacilities, two equipment-related requirements apply tofabric filters used to collect fugitive grain dust emissions(bag house filters).

Existing fabric dust collector filters are to beequipped with a monitor that indicates the pres-sure drop across the filter surface.

OSHA does not require the use of a specific typeof monitor. However, monitors commonly usedin the industry and suggested by OSHA as being


acceptable in its non-mandatory appendix are:photohelic gauges, magnehelic gauges and ma-nometers. OSHA further suggests that checkingthe pressure drop across fabric filters periodi-cally, consistent with the manufacturer’s recom-mendations, should be part of the facility’s pre-ventive maintenance program. As such, OSHAindicates that the monitors should be located sothey are accessible and readings can be obtainedas frequently as specified in the facility’s preven-tive maintenance program.

Importantly, not covered by the OSHA require-ment are filter collectors that are part of systemsnot designed to collect fugitive grain dust, suchas cyclone filters or filters that collect product (asopposed to fugitive grain dust).

New fabric dust collector filters installed on orafter March 30, 1988 are to be located:

• outside the facility; or

• in an area protected by an explosion sup-pression system; or

• in an area separated from the rest of thefacility by a fire wall with at least a one-hourfire-resistance rating. If this option is cho-sen, the filters also are to be located adjacentto an outside wall and be vented to theoutside. Venting and ductwork must be ableto resist rupture caused by an explosion.

Conclusion

These operational and equipment requirements under OSHA’s grain-handling safety standard are important elementsto include as part of a facility’s ongoing preventive maintenance program.

Coming Next: Preventive Maintenanceand OSHA’s General Industry Standards



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© Copyright 2009 by National Grain and Feed Association. All rights reserved. Federal copyright law prohibits unauthorized reproduction or transmission by any means,electronic or mechanical, without prior written permission from the publisher, and imposes fines of up to $25,000 for violations.

Volume 11, Number 1, January 15, 2009

Preventive Maintenanceand OSHA’s General Industry Standards – Part 1



[Editor’s Note: This is the third in a periodic series of articles on various aspects of preventive maintenance programs forgrain elevators, feed mills and grain processing facilities. The first two articles were published on Nov. 7 and Dec. 18, respectively.

This two-part edition focuses on how the Occupational Safety and Health Administration’s (OSHA) general industrystandards pertain to preventive maintenance activities. Each of the two-part series will examine five major provisions – a totalof 10 – found within the general industry standards frequently cited during OSHA inspections. You are encouraged to sharethese publications with those at your facility responsible for preventive maintenance and safety programs.]

The Occupational Safety and HealthAdministration’s (OSHA) general industry stan-dards (29 CFR 1910) contain several require-ments pertaining to maintenance activities thatapply to grain elevators, feed mills and grainprocessing facilities.

The nearby table summarizes frequentlycited federal and state OSHA standards forinspections that occurred at grain elevators,feed mills and grain processing facilities fromOctober 2007 through September 2008. Thetable excludes those citations related to OSHA’sgrain handling standard (29 CFR 1910.272),which were addressed in the Dec. 18, 2008 edi-tion of Plant Operations Bulletin.

Managers and maintenance personnel ataffected facilities need to be aware of the provi-sions of these and other applicable OSHA stan-dards while performing and authorizing mainte-nance activities.

(Continued on page 2)

OSHA CitationsGrain Elevators, Feed Mills, Grain Processing Facilities

October 2007 – September 2008

NumberDescription Standard Cited

Mechanical power-transmission apparatus 29 CFR 1910.219 41

Guarding floor and wall openings, and holes 29 CFR 1910.23 38

Control of hazardous energy (lockout/tagout) 29 CFR 1910.147 35

Wiring methods, components andequipment for general use 29 CFR 1910.305 34

Powered industrial trucks 29 CFR 1910.178 24

Walking-working surfaces; General requirements 29 CFR 1910.22 19

Fixed ladders 29 CFR 1910.27 19

General requirements – all machines 29 CFR 1910.212 13

Abrasive wheel machinery 29 CFR 1910.215 11

Oxygen-fuel gas welding and cutting 29 CFR 1910.253 10

2 Plant Operations Bulletin January 15, 2009

Maintenance Issues to Consider

Facility managers may wish to consider incorporatingcertain activities within the preventive maintenance program toassist in complying with the requirements found within OSHA’sgeneral industry standards.

The following provides information related to the majorprovisions of general industry standards listed in the precedingtable. Managers should consider these requirements when: 1)installing or modifying equipment or physical structures withinthe facility; and 2) developing the facility’s preventive mainte-nance inspection schedule. [Note: This general informationdoes not provide a complete description of all requirementsfound within each standard. Please refer to the individualOSHA standard for complete and specific information on howeach standard’s provisions may apply to a given facility.]

Mechanical Power-Transmission Apparatus (29 CFR 1910.219):Major provisions within this standard that addresses powertransmission equipment require:

All power-transmission equipment to be inspected at inter-vals not exceeding 60 days, and to be kept in good workingcondition at all times.

All belts, pulleys, sprockets and chains, flywheels, shaft-ing and shaft projections, gears and couplings, or otherrotating or reciprocating parts within 7 feet of the floor orworking platforms to be effectively guarded in accordancewith the standard’s specifications.

Projecting shaft ends to present a smooth edge and to notproject more than one-half the diameter of the shaft unlessguarded by nonrotating caps or safety sleeves.

Unused keyways to be filled up or covered.

Couplings with bolts, nuts, or set screws extending be-yond the flange of the coupling to be guarded by a safetysleeve.

Guarding Floor and Wall Openings and Holes (29 CFR 1910.23):This standard contains major provisions related to facilitybuildings and structures that require the following:

Every open-sided floor, platform or runway 4 feet or moreabove the adjacent floor or ground level is to be guardedby a standard railing with toeboard, except where there isentrance to a ramp, stairway or fixed ladder.

Open-sided floors, walkways, platforms or runways –regardless of height – that are located above or adjacent todangerous equipment and similar hazards are to be guardedwith a standard railing and toe board.

Where operating conditions necessitate the feeding ofmaterial into any hatchway or chute opening, protection isto be provided to prevent a person from falling through theopening.

Every flight of stairs having four or more risers is to beequipped with standard stair railings or standard handrailsas specified.

Control of Hazardous Energy - Lockout/Tagout (29 CFR 1910.147):This OSHA standard requires employers to establish proce-dures to isolate machines or equipment from their energysource, as well as affix appropriate locks or tags to preventunexpected energization, startup or release of stored energythat could injure employees.

Specifically, the standard requires employers to develop aprogram to lock and tag energy-isolating devices that includesthe following components:

Written energy-control procedures that ensure machinesand equipment are isolated and inoperative before anyemployee performs service or maintenance on such equip-ment.

An employee training program.

Periodic inspections to ensure the procedures are effec-tive.

Major aspects of the standard that pertain to maintenancepersonnel and maintenance activities require:

Employers are to provide specified initial training andretraining, as necessary, to ensure all employees under-stand the purpose, function and restrictions of the writtenenergy control program. All training is to be certified toinclude each employee’s name and the dates the trainingoccurred.

Retraining is to be provided when:

there is a change in job assignments, machines, equip-ment or processes that presents a new hazard;

there is a change in the energy-control procedures; or

the required periodic inspection reveals – or wheneverthe employer has reason to believe – that there aredeviations from, or inadequacies in, the employee’sknowledge about, or the use of, the energy-controlprocedures.

January 15, 2009 Plant Operations Bulletin 3

Employers are to ensure whenever new equipment ormachines are installed – or existing equipment is replaced,repaired, renovated or modified – that all energy-isolatingdevices for such machines are lockable.

Lockout or tagout devices to be:

Singularly identified, indicating the identity of theemployee applying the device(s).

The only devices used for controlling energy; theycannot be used for other purposes.

Standardized according to either color, shape or size.Tagout devices are to be standardized according toprint and format. Tags also are to warn againsthazardous conditions if the machine or equipment isenergized, and are to include a legend, such as thefollowing: “Do Not Start. Do Not Open. Do Not Close.Do Not Energize. Do Not Operate.”

Substantial enough to minimize early or accidentalremoval. Tags are not to be reused.

Employers are to evaluate the energy-control proceduresat least annually to ensure that each procedure continuesto be implemented properly and that employees are familiarwith their responsibilities. The employer is to certify thatthe periodic inspection has been performed, including thedate of the inspection, the identity of the machine orequipment on which the energy-control procedure wasused, the employee included in the inspection and thename of the person conducting the inspection.

For lockout procedures, the periodic inspection is toinclude a review – between the person conducting theperiodic inspection and each employee authorized tolock out or tag out machines or equipment to performservicing or maintenance – of the latter employee’sresponsibilities under the energy-control proceduresbeing inspected.

For tagout procedures, a review of the standard-specified limitations of tags also is to be included in thereview between the person conducting the inspectionand each authorized employee, operator or other em-ployee working at the facility, concerning their re-sponsibilities under the energy-control proceduresbeing inspected.

Wiring Methods, Components, and Equipment for General Use (29CFR 1910.305): This standard, pertaining to facility electricalsystems, contains major provisions that require the following:

Live parts of electric equipment operating at 50 volts ormore are to be guarded against accidental contact through

the use of approved cabinets or other forms of approvedenclosures or means.

Each disconnecting means required for motors to be leg-ibly marked is to indicate its purpose, unless located andarranged so that the purpose is evident.

All pull boxes, junction boxes and fittings are to be pro-vided with covers identified for the purpose. Metal covers,if used, are to be grounded.

Unused openings in cabinets, boxes and fittings are to beeffectively closed with appropriate covers, plugs or plates.

Where live parts of motors or controllers operating at over150 volts to ground are guarded against accidental contactonly by location – and where adjustment or other atten-dance may be necessary during the operation of theapparatus – suitable insulating mats or platforms are to beprovided so that the attendant cannot readily touch liveparts unless standing on the mats or platforms.

Interior wiring systems are to include effective provisionsthat ensure metal parts of electrical raceways, equipmentand enclosures that serve as grounding conductors main-tain electrical continuity and the capacity to safely conductany fault current likely to be imposed on them.

Motor controller disconnecting means are to be capable ofbeing locked in the open position or be installed in thecircuit within sight of the motor controller.

Walking-Working Surfaces, General Requirements (29 CFR1910.22): Major provisions of this standard, pertaining towalking-working surfaces, require the following:

All places of employment, passageways, storerooms andservice rooms are to be kept clean and orderly, and in asanitary condition.

Where mechanical handling equipment is used, sufficientsafe clearances are to be allowed for aisles, at loadingdocks, through doorways and wherever turns or passageare made.

Aisles and passageways are to be kept clear and in goodrepair, with no obstruction across or in aisles that couldcreate a hazard.

Permanent aisles and passageways are to be marked appro-priately.

Appropriate covers and/or guardrails are to be provided toprotect personnel from the hazards of open pits, tanks,equipment, etc.

4 Plant Operations Bulletin January 15, 2009

Conclusion

These requirements under OSHA’s general industry standard are important elements to consider when maintenance personnelinstall or modify equipment or physical structures within a facility.

Managers also may wish to consider incorporating certain activities within preventive maintenance inspection schedules toassist in complying with these requirements.

Coming Next: Preventive Maintenanceand OSHA’s General Industry Standards

– Part 2



.....................................................................................................................................


(Continued on page 2)

OSHA CitationsGrain Elevators, Feed Mills, Grain Processing Facilities

October 2007 – September 2008

NumberDescription Standard Cited

Mechanical power-transmission apparatus 29 CFR 1910.219 41

Guarding floor and wall openings, and holes 29 CFR 1910.23 38

Control of hazardous energy (lockout/tagout) 29 CFR 1910.147 35

Wiring methods, components andequipment for general use 29 CFR 1910.305 34

Powered industrial trucks 29 CFR 1910.178 24

Walking-working surfaces; General requirements 29 CFR 1910.22 19

Fixed ladders 29 CFR 1910.27 19

General requirements – all machines 29 CFR 1910.212 13

Abrasive wheel machinery 29 CFR 1910.215 11

Oxygen-fuel gas welding and cutting 29 CFR 1910.253 10

Volume 11, Number 2, February 12, 2009

Preventive Maintenance and OSHA’s General Industry Standards –Part 2



[Editor’s Note: This is the fourth in a periodic series on various aspects of preventive maintenance programs for grain elevators, feedmills and grain processing facilities. The first three articles were published on Nov. 7 and Dec. 18, 2008, and Jan. 15, 2009, respectively.

This edition is the second of two articles that focuses on how the Occupational Safety and Health Administration’s (OSHA) generalindustry standards pertain to preventive maintenance activities. Each of the two-part series examines five major provisions – a total of10 – found within the general industry standards frequently cited during OSHA inspections. You are encouraged to share thesepublications with those at your facility responsible for preventive maintenance and safety programs.]

The Occupational Safety and HealthAdministration’s (OSHA) general industry stan-dards (29 CFR 1910) contain several requirementspertaining to maintenance activities that apply tograin elevators, feed mills and grain processing facili-ties.

The nearby table summarizes frequently citedfederal and state OSHA standards for inspectionsthat occurred at grain elevators, feed mills and grainprocessing facilities during the 2008 fiscal year (Oc-tober 2007 through September 2008). The tableexcludes those citations related to OSHA’s grainhandling standard (29 CFR 1910.272), which wereaddressed in the Dec. 18, 2008 edition of PlantOperations Bulletin.

Managers and maintenance personnel at af-fected facilities need to be aware of the provisions ofthese and other applicable OSHA standards whileperforming and authorizing maintenance activities.

2 Plant Operations Bulletin February 12, 2009

Maintenance Issues to Consider

Facility managers may wish to consider incorporating certainactivities within their preventive maintenance program to assist incomplying with the requirements found within OSHA’s generalindustry standards.

The following provides information related to the major provi-sions of general industry standards listed in the preceding table.Managers should consider these requirements when: 1) installingor modifying equipment or physical structures within the facility;and 2) developing the facility’s preventive maintenance inspectionschedule. [Note: This general information does not provide acomplete description of all requirements found within each stan-dard. Please refer to the individual OSHA standard for completeand specific information on how each standard’s provisions mayapply to a given facility.]

Powered Industrial Trucks (29 CFR 1910.178): This OSHAstandard contains safety requirements relating to fire protection,design, maintenance and use of fork trucks, tractors, platform-lifttrucks, motorized hand trucks, and other specialized industrialtrucks powered by electric motors or internal combustion engines.

Specifically, the standard contains provisions for:

Equipment specifications necessary for the types of trucks tobe used in different work environments depending upon thehazardous nature of the atmosphere.

Operational requirements related to the inspection, mainte-nance and safety requirements for powered industrial trucks.

Training requirements for employees who may operate a pow-ered industrial truck – including maintenance personnel – in theworkplace.

Major aspects of the standard that pertain to maintenancepersonnel and maintenance activities require that:

Powered industrial trucks bear a label or some other identifyingmark that indicates approval by a nationally recognized testinglaboratory, and that all such truck nameplates and markings arekept in place and maintained in legible condition.

Written approval from the manufacturer of the powered indus-trial truck prior to making any modifications or additions to thetruck that may affect its capacity or safe operation. If approvedchanges are made, capacity, operation and maintenance in-struction plates, tags or decals are to be modified accordingly.

Liquid and gaseous fuels used to power the truck be stored andhandled in accordance with NFPA Flammable and CombustibleLiquids Code and NFPA Storage and Handling of LiquefiedPetroleum Gases.

If the powered industrial truck is battery-powered, battery-charging be conducted in a designated area within the facilityfor such activities. The designated area is to contain theappropriate equipment to:

• Safely flush, handle and neutralize spilled electrolyte.

• Provide appropriate fire protection.

• Protect the battery charger from damage by trucks.

• Adequately ventilate fumes from gassing batteries.

• Properly handle batteries.

Powered industrial trucks be taken out of service when foundin need of repair, defective or in any way unsafe, or when a leakin the fuel system is detected.

Repairs on trucks be made only by “authorized personnel,” andrepairs to fuel and ignition systems be performed only inlocations designated for such repairs and never in Class I, II, andIII locations.

Powered industrial trucks be examined before being placed intoservice, and not be placed in service if the examination showsany condition adversely affecting vehicle safety. Examinationsare to be made at least daily. Industrial trucks used on a round-the-clock basis are to be examined after each shift. All defectsare to be reported and corrected immediately.

Employers implement a training program and ensure that onlytrained drivers who have successfully completed the trainingprogram operate a powered industrial truck. Training is to bea combination of formal (lecture, video, etc.) and practical(demonstration and practical exercise), as well as include anevaluation of operator performance in the workplace.

Employers are to evaluate an employee’s performance afterinitial training and at least once every three years thereafter.Refresher training also is to be provided when an operator:

• Has been observed to operate the truck in an unsafemanner.

• Has been in an accident or a near-miss incident.

• Has received an evaluation that indicated the operator isnot operating the truck safely.

• Is assigned to drive a different type of truck.

February 12, 2009 Plant Operations Bulletin 3

The employer is to certify that each operator has been trainedand evaluated, as required. The certification is to include the: 1)name of the operator; 2) date of the training; 3) date of the evaluation;and 4) name of the trainer(s).

Fixed Ladders (29 CFR 1910.27): This standard contains majorprovisions related to fixed ladders. It requires that:

The rungs of metal ladders have a minimum diameter of three-fourths inch. However, for those ladders located in an atmo-sphere that causes corrosion and rusting, individual metalrungs are to have a minimum diameter of 1 inch or are to bepainted or otherwise treated to resist corrosion and rusting.Rungs of wood ladders are to have a minimum diameter of1-1/8th inch. The distance between rungs, cleats and steps arenot to exceed 12 inches, and are to be uniform throughout thelength of the ladder. The rungs or cleats of ladders are to havea minimum clear length of 16 inches.

Cages or wells conforming to required dimensions be providedon ladders of more than 20 feet to a maximum unbroken lengthof 30 feet. Cages are to extend a minimum of 42 inches abovethe top of the landing, unless other acceptable protection isprovided. Cages also are to extend down the ladder to a pointnot less than 7 feet and not more than 8 feet above the base ofthe ladder.

When ladders are used to ascend to heights exceeding 20 feet,landing platforms be provided for each 30 feet of height.However, where no cage, well or ladder safety device is pro-vided, landing platforms are to be provided for each 20 feet ofheight. Each ladder section is to be offset from adjacent sec-tions.

All ladders be maintained in a safe condition and inspectedregularly, with the intervals between inspections being deter-mined by use and exposure.

General Requirements – All Machines (29 CFR 1910.212): Thisstandard, pertaining to the general requirements for all machines,contains major provisions that require:

One or more methods of machine guarding be provided toprotect the operator and other employees in the machine areafrom hazards, such as those created by the machine operation,nip-points, rotating parts and sparks. Examples of guardingmethods are barrier guards, electronic safety devices, etc.

Guards be affixed to the machine where possible, and securedelsewhere if attachment to the machine is not possible.

The “point of operation” of machines whose operation mayexpose an employee to injury be guarded. OSHA defines the“point of operation” as “the area on a machine where work isactually performed upon the material being processed.” Suchguarding devices are to be designed and constructed to prevent

the operators from having any part of their bodies in the dangerzone during the operating cycle of the machine.

Abrasive Wheel Machinery (29 CFR 1910.215): Major provi-sions of this standard, pertaining to abrasive wheel machinery,require:

Work rests on offhand grinding machines be securely clampedand kept adjusted closely to the wheel, with a maximum openingof 1/8th inch to prevent the work from being jammed between thewheel and the rest, which may cause wheel breakage.

All abrasive wheels be mounted between flanges that have adiameter of not less than one-third the diameter of the wheel.

The employee inspect and sound (ring test) all grinding wheelsimmediately before mounting to make sure they have not beendamaged. In addition, the employee is to check the spindlespeed of the machine before mounting of the wheel to be certainit does not exceed the maximum operating speed marked on thewheel. To perform the “ring test,” the employee should tap thegrinding wheel gently with a light nonmetallic implement, suchas the handle of a screwdriver for light wheels, or a woodenmallet for heavier wheels. If the grinding wheel sounds cracked(dead), the wheel is not to be used.

Oxygen-Fuel Gas Welding and Cutting (29 CFR 1910.253): Thisstandard contains major provisions related to oxygen-fuel gaswelding and cutting. It requires that:

Cylinders be stored in designated places, away from sources ofheat. Such assigned storage spaces are to be located wherecylinders will not be knocked over or damaged by passing orfalling objects. Empty cylinders are to have their valves closed.

For those cylinders designed to accept a valve-protection cap,such caps always are to be in place and hand-tightened, exceptwhen cylinders are in use or connected for use.

Oxygen cylinders not be stored near highly combustible mate-rial – especially oil and grease – or near reserve stocks of carbideand acetylene, or other fuel-gas cylinders, or near any othersubstance likely to cause or accelerate fire.

Oxygen cylinders in storage be separated from fuel-gas cylin-ders or combustible materials (especially oil or grease) at aminimum distance of 20 feet, or by a noncombustible barrier atleast 5 feet high having a fire-resistance rating of at least one-half hour.

Cylinder valves be closed before moving cylinders and whenwork is finished.

Backflow protection be provided by an approved device thatwill prevent oxygen from flowing into the fuel-gas system or fuelfrom flowing into the oxygen system.


Conclusion

These requirements under OSHA’s general industry standard are important elements to consider when maintenance personnelinstall or modify equipment or physical structures within a facility.

Managers also may wish to consider incorporating certain activities within preventive maintenance inspection schedules toassist in complying with these requirements.

Coming Next: Preventive Maintenanceand Infrared Thermography



.....................................................................................................................................


Volume 11, Number 3, March 12, 2009

Predictive Maintenance and Use of Infrared Thermography



[Editor’s Note: This is the fifth in a periodic series on various aspects of preventive maintenance programs for grain elevators,feed mills and grain processing facilities. The first four articles in this series were published on Nov. 7 and Dec. 18, 2008, andon Jan. 15 and Feb. 12, 2009. You are encouraged to share these publications with those at your facility responsible for preventivemaintenance and safety programs.]

Ever wish you knew precisely the right time to performequipment maintenance to keep equipment operating efficientlyin a cost-effective way?

Now, there’s technology that can provide an assist. Infra-red thermography is a predictive maintenance tool that may beused to measure the temperatures of plant equipment, struc-tures and electrical systems to assist in determining if operatingconditions are within allowable temperature limits.

The term “infrared” refers to that range of invisible radia-tion wavelengths just longer than red in the visible spectrum.The term “thermography” refers to the use of techniques fordetecting and measuring variations in the heat emitted byvarious objects and transforming these indicators into visiblesignals. Thus, the term “infrared thermography” refers to thedetection of infrared radiation to determine the temperature ofan object.

Infrared thermography is termed a “predictive” mainte-nance tool because it is used to help determine the condition ofin-service equipment and systems to predict when maintenanceshould be performed. The ultimate goal of predictive mainte-nance is to perform maintenance at a scheduled point in timewhen the activity may be accomplished in the most cost-effective manner and before the equipment or system losesoptimum performance. This approach may offer cost savingsover routine or time-based preventive maintenance, becausetasks are performed only when warranted.

Through the use of infrared thermography, maintenancepersonnel or technicians may detect temperature discrepancies– areas that are hotter or colder than allowable – within equip-ment and systems. This information then can be used to takecorrective action before a costly shutdown, equipment damageor personal injury occurs.

How Does Infrared Thermography Work?

Infrared thermography equipment works on the principlethat objects having a temperature above absolute zero emitthermal energy or infrared radiation. The frequency of infraredradiation emitted from an object is related to its surface tempera-ture. Although infrared radiation has a wavelength longer thanthat of visible light, thermographic equipment detects the

radiation and converts it into an electrical signal that can bedisplayed in units of temperature or as an image.

Measuring temperature with infrared methods is compli-cated because three sources of thermal energy can be detectedfrom any object: energy emitted from the object itself; energy


reflected from the object; and energy transmitted by the object.Only thermal energy emitted from an object is important for thepurposes of predictive maintenance. Reflected and transmittedenergies may distort infrared data and need to be filtered out toperform meaningful temperature analysis.

Variations in surface condition, such as paint or otherprotective coatings, may affect the amount of thermal energyemitted as infrared radiation by plant equipment or systems.These variations may change the surface temperatures and heatdistribution recorded by the thermographic equipment. Main-

tenance personnel and technicians should compensate forthese possible variations when conducting infrared thermog-raphy inspections to ensure accurate results.

When using thermographic techniques, maintenance per-sonnel and technicians also need to consider the atmosphericconditions between the object and the measurement device.Water vapor and other gases may absorb infrared radiation.Airborne dust, some types of lighting and other variables alsomay distort infrared radiation measurements.

Types of Infrared Thermography Devices

Two general types of devices are used for infrared ther-mography within predictive maintenance programs: infraredthermometers and infrared imaging systems.

Infrared Thermometers: Infrared thermometers sometimesare called laser thermometers if a laser is used to help aimthe thermometer. Or, they may be referred to as non-contact thermometers to describe the device’s ability tomeasure temperature from a distance. Infrared thermom-eters provide the actual surface temperature at a single,relatively small point on a machine or surface. As such,these devices may be useful for measuring temperatureunder circumstances where thermocouples or other probetype sensors cannot be used or do not produce accuratedata for a variety of reasons. Infrared thermometers arecommercially available and are relatively inexpensive.

Infrared Imaging Systems: Unlike an infrared thermometer,infrared imaging systems provide the means to scan the

infrared emissions of complete machines, processes orsystems in a very short time. Most imaging systemsfunction much like a video camera. The user can view thethermal emission profile of a wide area simply by lookingthrough the device’s view finder. The cost of an infraredimaging system may be substantial, depending upon thefeatures of the system. Higher-end devices may feature amicroprocessor-based, color-imaging system. In contrast,lower-end devices may include features such as black-and-white images and limited storage capability.

Proper training and experience in the use of an infraredimaging system is essential to achieve accurate thermographicresults. As previously indicated, several variables may distortinfrared radiation measurements. The operator of the infraredimaging system should be trained in how to compensate forsuch variables to ensure the accuracy and repeatability ofresults.

Uses for Infrared Thermography

There are a variety of potential applications for infraredthermometers and infrared imaging systems to assist in deter-mining the condition of in-service equipment and systems atgrain elevators, feed mills and grain processing facilities.

All mechanical systems generate thermal energy duringnormal operations that allows infrared thermography to evalu-ate the operating condition of the equipment. One of the majorcontributors to the failure of mechanical systems can be exces-sive temperatures. Excessive temperatures may be generatedby friction, cooling degradation, material loss or blockages. Anexcessive amount of friction may be caused by wear, misalign-ment, over or under lubrication, and misuse.

Since most equipment or processes are designed to elimi-nate thermal energy under normal operation, simply identifyinga thermal pattern does not mean that a problem exists. Mainte-nance personnel and technicians using infrared thermographicdevices need to be familiar with the mechanical components

being evaluated. Once a normal thermal condition is obtainedand understood, deviations from this normal condition thenmay provide evidence that a potential problem is developing.

In mechanical applications, infrared thermal devices oftenare more useful for locating a problem area than for indicatingthe root cause of the excessive temperature. The temperaturesindicated by the device typically are produced within a compo-nent that is not visible directly. The measured heat mustconduct up through the material and present itself on thesurface of the object for the temperature to be displayed by thethermographic device. Further analysis of the mechanicalsystem usually is necessary to determine the cause(s) of theexcessive temperature.

The following are some potential uses of infrared thermom-eters and imaging systems within grain elevators, feed mills andgrain processing facilities:

March 12, 2009 Plant Operations Bulletin 3

Infrared Thermometers: Within a predictive maintenanceprogram, maintenance personnel may use infrared ther-mometers to measure the temperature at critical points onplant equipment or systems. Some applications may in-clude monitoring the temperatures of bearings, motorwindings, electrical components, steam distribution equip-ment and processing systems. Infrared thermometers maybe particularly useful in measuring the temperature ofmoving objects or where direct contact with the object isnot possible. Infrared thermometers also may be usefulwhen a fast temperature measurement is required.

Infrared Imaging Systems: An infrared imaging system cangenerate useful information concerning the mechanicalcondition of many common mechanical and electrical sys-tems present in grain elevators, feed mills and grain pro-cessing facilities.

Electric Motors: All motors have a normal thermalpattern, as well as given maximum operating tempera-ture. This temperature usually is stated on the name-plate of the motor and normally is given as a rise indegrees C above the ambient air temperature. Condi-tions such as inadequate air flow, partial discharge,unbalanced voltage, bearing failure, insulation failureand degradation in the rotor or stator can be identifiedwith an infrared thermal imaging system. Abnormalthermal patterns also can identify misalignment incouplings when these devices are used in conjunctionwith motors.

Belts and Pulleys: The friction between a pulleywheel and belt generates heat. In addition, the con-tinuous tension and compression of the belt causesinternal friction resulting in heat. The temperature risegenerated during both of these processes can bemonitored with an infrared camera. By comparing thethermal patterns of several pulley belt systems, poten-tial problems can be located.

Bearings: Bearing problems generally are found bya comparison of surface temperatures – comparing

one bearing to another working under similar condi-tions. Overheating conditions are documented as hotspots within an infrared imaging system.

Steam Traps: Steam traps perform an importantfunction of holding back live steam, while allowinggases and condensate to pass through. This allowsmore energy to be obtained from the steam for pro-cessing needs, thus raising the overall efficiency ofthe steam system. Steam traps, like any mechanicaldevice, eventually fail. Most are designed to fail in theopen position to maintain steam system operation.When they fail in the open position, they “blow” livesteam. This costs energy dollars for which the steamtrap was installed to save. Occasionally, steam trapsfail in the closed position. This causes condensatebackup in the steam system, which can reduce pro-cessing efficiency and produce a variety of otherpotential problems. Infrared thermal imaging systemscan identify steam traps that are blowing steam, as wellas those that may fail in a closed position.

Electrical Systems: An infrared imaging system maybe used to inspect the condition of common electricalcomponents, such as bus bars, controllers, starters,contactors, relays, fuses, breakers, disconnects, con-nections and wiring. Typically, thermal imaging per-formed for electrical inspection purposes is a com-parative process. Maintenance personnel or techni-cians generally do not need a specific temperaturemeasurement. Instead, they compare similar compo-nents under the same load conditions to identifyabnormal conditions. For best results in detectingpotential problems, the electrical equipment should beunder at least 40 percent of nominal load duringthermal inspection. Maximum load conditions areideal, if possible. Hot spots identified by the imagingsystem within an electrical system may be caused byseveral conditions, such as loose, over-tightened orcorroded connections, unbalanced phase loads, elec-trical overload, and failing components.

Conclusion

Managers of grain elevators, feed mills and grain processing facilities may wish to consider using infrared thermography asa component within their preventive maintenance programs to monitor the operating condition of equipment, so that necessarymaintenance procedures may occur in a cost-effective and timely manner.

Coming Next:

“Predictive Maintenance and Use of Equipment Vibration Analysis.”



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Volume 11, Number 4, June 30, 2009

Predictive Maintenance and Use of Vibration Analysis



[Editor’s Note: This is the sixth in a periodic series of articles on various aspects of preventive maintenance programs forgrain elevators, feed mills and grain processing facilities. The first five articles in this series were published on Nov. 7 and Dec.18, 2008, and on Jan. 15, Feb. 12, and March 12, 2009. You are encouraged to share these publications with those at your facilityresponsible for preventive maintenance and safety programs.]

There are a variety of methods that can be used by grain,feed and grain processing facilities to monitor the operatingconditions of equipment.

One such tool is vibration analysis – a predictive mainte-nance tool that may be used to measure machine vibration toassist in determining if operating conditions are within normallimits. By measuring and analyzing the vibration, maintenancepersonnel or technicians may detect changes or abnormalpatterns in the machine’s operating condition, and then use thisinformation to take corrective action before a costly shutdown,machine damage or personal injury occurs.

Vibration analysis is characterized as a “predictive” main-tenance tool because it is used to help determine the conditionof in-service equipment and systems to anticipate when main-tenance should be performed.

The ultimate goal of predictive maintenance is to performmaintenance at a scheduled point in time when the activity maybe accomplished in the most cost-effective manner and beforethe equipment or system loses optimum performance. Thisapproach may offer cost savings over routine or time-basedpreventive maintenance because tasks are performed onlywhen warranted.

Machine Vibration

Most machine vibration is attributable to one or more of thefollowing causes:

Repeating Forces: The term “repeating forces” refers tothose unbalanced forces that occur over and over againwithin a machine to create movement. Repeating forces inmachines are caused mostly by the rotation of imbalanced,misaligned, worn or improperly driven machine compo-nents. Examples of machine conditions that may create arepeating force include uneven electrical motor windings,worn fan blades, drive component misalignment, bent

drive shafts and worn drive components, such as bearings,gears and belts.

Looseness: Machine parts that are loose may cause themachine to vibrate. If parts become loose, vibration thatnormally is acceptable may become excessive and damag-ing. Looseness often may occur because of impropermounting of the machine, excessive clearances betweenmachine parts, inadequate machine foundation and im-proper tensioning of mounting bolts.

2 Plant Operations Bulletin June 30, 2009

Resonance: Resonance describes the tendency for anobject, such as a machine, to vibrate more when thefrequency of a repeating force matches the object’s naturalfrequency of vibration. Most machines have at least onenatural frequency of vibration, commonly referred to asnatural oscillation rate. Although a repeating force may besmall and result from the operation of a sound machinecomponent, such a repeating force potentially may matchthe machine’s natural oscillation rate and create reso-nance. When such a condition occurs, the effect of therepeating force may cause excessive and potentially dam-aging vibration within the machine.

What is Vibration and How Is It Described? One technicaldefinition for vibration is the mechanical oscillation of an objectabout a reference position. The term “oscillation” describes theback-and-forth or harmonic motion of an object, typicallymeasured in the time it takes for the object to move through onefull cycle. Therefore, machine vibration may be defined as theback-and-forth movement of a machine component as com-pared to a reference point over a period of time.

The two main numerical descriptors of machine vibrationare amplitude and frequency. Amplitude describes the severityof vibration, while frequency describes the oscillation rate ofvibration.

Amplitude: Amplitude describes the magnitude of machinemovement during vibration. As amplitude increases, sodoes machine movement and the likelihood that the ma-chine will experience damage. Generally, amplitude ofvibration relates to: 1) the length of the machine movement;2) the speed in which the movement occurs; and 3) the forceassociated with the movement. In many cases, it is thespeed of the amplitude or amplitude velocity that providesthe most useful indicator about the condition of a machine.

Frequency: The number of times that a machine componentcompletes a motion cycle during the period of one secondis called frequency. Frequency is measured in hertz (Hz),which describes cycles per second. A machine componenttypically vibrates at more than one frequency. This occursbecause a variety of forces generally act upon a machinecomponent during operation. For example, the componentmay experience simultaneous forces from bearing move-ment, drive component interaction and other mechanicalactivity.

Vibration also is described and displayed through twocommon graphical means: waveform and spectrum. A wave-form display illustrates how vibration changes over time, whilea spectrum display shows the various frequency levels at whichvibration is occurring.

Waveform: Waveform displays graphically depict thechange in velocity of vibration over a period of time. Thevalue of the information displayed depends upon theduration and resolution of the waveform. To be meaning-ful, the duration time of the waveform display should belong enough to provide a good representation of thevibration. The resolution of the waveform is importantbecause it provides a measure of the level of detail asso-ciated with how the vibration is displayed graphically.

Spectrum: A spectrum is a display of both the amplitudesand frequencies at which a machine component is vibrat-ing. Like a waveform display, the value of a spectrumtypically depends on two primary factors: 1) measuringand displaying an appropriate frequency range; and 2)using a resolution level that adequately characterizes theshape of the spectrum.

How is Machine Vibration Measured?

Vibration is measured by placing a sensor on the machinethat can detect vibration behavior. Various types of vibrationsensors are available. But frequently, a type called an “accel-erometer” is used to collect information for vibration analysis.An accelerometer is a sensor that produces an electrical signalproportional to the acceleration of the vibrating component towhich it is placed into contact or attached. The accelerationmeasurement provides an indication of how quickly the veloc-ity of the component is changing during vibration.

Maintenance personnel or technicians usually place ormount accelerometers near machine bearings associated withrotary mechanisms to obtain vibration measurements. Examplesof machine designs that use rotary mechanisms include motors,pumps, compressors, fans, belt conveyors and gearboxes. Thebearings that support the rotary mechanisms of such machines

bear the forces associated with rotary motion and vibration. Assuch, bearings often are the first place where adverse machinesymptoms may develop and, ultimately, where failure mayoccur.

Either hand-held probes or physically mounted accelerom-eters are used to obtain vibration measurements from machinecomponents. In either situation, the sensor must be firmly incontact with the vibrating component to obtain an accuratemeasurement. A loose accelerometer may produce a distortedsignal because of its own independent movements. Whenobtaining hand-held measurements, it also is important to placethe accelerometer at the same location during each reading tominimize measurement inconsistencies that may lead to inaccu-rate results.

June 30, 2009 Plant Operations Bulletin 3

Various methods are available for physically mounting anaccelerometer to a vibrating machine component. Such methodsmay include attaching the accelerometer with a threaded or ce-mented stud or using a strong magnet. Mounting the accelerometerto the measuring point in an appropriate manner is one of the mostcritical factors in obtaining accurate results from vibration measure-ments.

The signal produced by an accelerometer depends on theorientation in which the accelerometer is placed or mounted, sincethe amplitude of vibration varies in different directions. The accel-erometer should be oriented to meet specific machine situations. Forthe purposes of vibration analysis, it often is beneficial to obtainvibration readings from several axes, such as horizontal, vertical,axial (the direction of the centerline of a shaft or rotor), and radial (adirection perpendicular to the centerline of a shaft or rotor).

The acceleration signal produced by the accelerometer is trans-mitted to an electronic instrument that converts the signal into avelocity measurement. Typically, the electronic instrument thatreceives the accelerometer signal has a variety of adjustable param-eters. These parameters specify how the instrument will process thesignal and present information to the user. Parameters that areadjustable commonly include: 1) how much information is obtainedduring the measurement, such as frequency range, duration andresolution; 2) the number of measurements to be averaged toproduce a result; and 3) how the results will be graphically displayed.Depending upon the instrument, displays usually take the form ofeither a velocity waveform or a velocity spectrum. Generally,velocity spectrum displays provide the most useful information forvibration analysis. Such a display supplies information about theindividual frequencies at which a machine component vibrates, aswell as the amplitudes corresponding to those frequencies.

How Are Vibration Measurements Used? Machines seldom failwithout warning. Usually, the signs of an approaching failure arepresent long before the breakdown actually occurs. Machine failurealmost always is accompanied by an increased vibration level thatcan be measured on an external surface of the machine. By obtainingand studying vibration measurements, maintenance personnel ortechnicians can evaluate the cause of vibration and the condition ofthe machine.

Proper training and experience in obtaining vibration measure-ments and analyzing the results are essential to achieving a mean-ingful and useful vibration analysis. The operator of the vibrationmeasurement and analysis equipment should know about the typesof vibration measurements necessary to evaluate the condition ofvarious machines and the variables that may affect measurements.The operator also should know how to compensate for such vari-ables to ensure the accuracy and repeatability of results.

Once vibration measurements and analysis are complete, abasic question that maintenance personnel often need to address is:“What level of vibration is excessive?”

Generally, experience – acquired by monitoring machine vibra-tion over time – is the best guide in determining what constitutes anexcessive vibration level for a given machine component.

In the absence of experience, resources are available thatprovide guidance on acceptable vibration levels for several classesof common machines. Information used to compile such resourcesincludes industry standards, published specifications, manufactur-ers’ recommendations and field experience. Generally, the vibrationlevels recommended in such resources are economically achievableand represent values that will allow the machine to achieve a normallife in service.

How is Excessive Vibration Corrected? Vibration measurementand analysis provide a means to identify failing machine compo-nents. But how can a maintenance program prevent excessivevibration in the first place?

There are a variety of root causes that may create machinevibration. Among the potential root causes are:

Machine Component Design Defects: Design defects relate tothe improper sizing or proportioning of the part, or a fundamen-tal structural flaw. Conducting a vibration analysis immediatelyafter machine startup may help identify design defects.

Manufacturing Defects: Defects in manufacturing may occurduring the casting, machining, heat-treating or assembly of themachine component. These defects may cause the componentto fail shortly after start-up or at a later point in time. As in thecase of design defects, conducting a vibration analysis atmachine startup may assist in identifying manufacturing de-fects.

Operational Stress: Operational stress refers to the materialbuild-up or erosion that may occur within a machine componentas it operates. Such build-up or erosion may change the balancecondition of the machine component, resulting in vibration.Thermal expansion is another operational stress that may occurand cause a change in component alignment that may lead tovibration.

Maintenance Actions: Maintenance actions, or the lack thereof,may cause vibration and machine failure. Examples of impropermaintenance actions may include excessive belt tensions, shaftand bearing misalignments, lack of or excessive lubrication,inappropriate installation (such as hammering a bearing), andimproper tightening of fasteners.

Machine Aging: Long-term machine operation produces agingeffects that can lead to vibration. Over time, structural jointswithin a machine may wear and become out-of-tolerance. Shafts,gears, and other machine components may wear or bend andbecome a cause of vibration. An on-going vibration analysisprogram can assist in detecting these occurrences.

4 Plant Operations Bulletin June 30, 2009

There are a variety of potential applications for the use ofvibration analysis to assist in determining the condition ofmachine components within grain elevators, feed mills andgrain processing facilities.

Some of the machine conditions in which vibration analy-sis may be used include: 1) misalignment of couplings, bearingsand gears; 2) unbalance of rotating components; 3) looseness;4) deterioration of bearings; 5) gear wear; 6) aerodynamic/hydraulic problems in fans, blowers and pumps; 7) unbalanceof magnetic forces in motors; and 8) resonance issues.

Generally, the types of machines that managers may wishto consider monitoring with vibration analysis include:

Machines that require expensive, lengthy or difficult re-pairs if they break down.

Machines that are critical to production or general facilityoperations.

Machines that have experienced frequent breakdowns.

Machines that are being evaluated for their reliability.

The following are examples of machines and machinecomponents that may fit into the aforementioned categories:

Fans and blowers.

Reciprocating equipment.

Pumps.

Large motors.

Large gearboxes.

Air compressors.

Critical processing equipment, such as a pellet mill orhammermill.

Conclusion

Managers of grain elevators, feed mills and grain processing facilities may wish to consider using vibration analysis as acomponent within their preventive maintenance program to monitor the operating condition of equipment so that necessarymaintenance procedures may occur in a cost-effective and timely manner.

Coming Next:Reliability Centered Maintenance – What’s It All About?

When Should Vibration Analysis Be Used?



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Volume 11, Number 5, August 13, 2009

Reliability-Centered Maintenance – What’s It All About?



[Editor’s Note: This is the seventh and final installment in a series of articles on various aspects of preventive maintenanceprograms for grain elevators, feed and feed ingredient manufacturers, and grain processing facilities. The first six articles inthis series were published on Nov. 7 and Dec. 18, 2008, and on Jan. 15, Feb. 12, March 12 and June 30, 2009. The completeseries also is available on the NGFA’s website by clicking here. You are encouraged to share these publications with those atyour facility responsible for preventive maintenance and safety programs.]

“If it ain’t broke, don’t fix it.”

This old tenet is one approach that can be used to addressfacility maintenance issues.

An underlying premise for the “if it ain’t broke, don’t fix it”mindset is that the use of more proactive maintenance practicescan result in money being spent on unnecessary activities andrepairs.

That’s a legitimate concern, and one that a reliability-centered maintenance (RCM) program attempts to address.RCM can be defined as “an approach to maintenance thatcombines reactive, preventive, predictive, and proactive main-tenance practices and strategies to maximize the time that a pieceof equipment functions in the required manner.”

The goal of RCM is to find the “right” mix of maintenanceactivities that results in the minimal equipment and repair cost.

Types of Maintenance Practices

To better understand the concept of RCM, it’s helpful toreview the types of general approaches that may be used forfacility maintenance. These include:

Reactive Maintenance: This approach follows the “if it ain’tbroke, don’t fix it” or “run-to-failure” principle. Under thereactive-maintenance approach, equipment and facilitiesare repaired only in response to a breakdown or a fault. Areactive-maintenance program often is characterized byshort-term, intense work patterns. Because of this, somemaintenance experts define reactive maintenance as allmaintenance work that is scheduled less than 24 hoursbefore it is executed.

Preventive Maintenance: A preventive-maintenance pro-gram includes procedures for inspecting, testing, andreconditioning equipment and other systems at regularintervals according to specific instructions. The goals inperforming such procedures are to prevent failures inservice and to prolong the life of the equipment or system.

Within a preventive-maintenance program, personnel of-ten perform maintenance procedures at established timeintervals. For example, the program may specify that onetype of equipment is to be inspected and serviced weekly,while another type is to be inspected and serviced monthly.A basic assumption made when using a calendar-based

http://www.ngfa.org/files/misc/PlantOps-PreventiveMaintenance.pdf

2 Plant Operations Bulletin August 13, 2009

preventive-maintenance program is that equipment orsystem failure can be eliminated or controlled by perform-ing procedures at specified time intervals.

Typically, the next step up from a calendar-based preven-tive-maintenance program is one in which the frequency ofmaintenance practices is based upon equipment or systemrun time. Using a run-time method for determining thefrequency of inspecting and servicing equipment typicallyis an improvement over a calendar-based schedule. Equip-ment generally should not need to be repeatedly inspectedor serviced if it has not been used. It is the actual operationof the equipment that wears it down, so it makes sense tocheck the equipment after it has run a sufficient length oftime to incur some wear.

Unfortunately, there are a variety of other factors, inaddition to run time, that may influence the frequency ofequipment and system failure. Such factors may includeexternal environmental conditions, equipment and systemloading, and instances of severe stress.

As a result, a possible outcome from using either a calen-dar- or run-time-based preventive maintenance program isthat the “right” maintenance mix is not achieved. Whenthis occurs, a facility, in some instances, may experienceequipment failures caused by inadequate inspection andservicing. In other cases, it may be wasting maintenancedollars by spending too much time servicing and inspect-ing properly functioning equipment.

Predictive Maintenance: Predictive maintenance – oftenreferred to as condition-monitoring – may be defined as theuse of maintenance techniques to help determine the

condition of in-service equipment and systems to predictwhen maintenance should be performed. The ultimate goalof predictive maintenance is to perform maintenance at ascheduled point in time when the activity may be accom-plished in the most cost-effective manner and before theequipment or system loses optimum performance. Thisapproach may provide cost savings over routine or time-based preventive maintenance because tasks are per-formed only when warranted.

One example of a predictive-maintenance technique is theuse of infrared thermography, which provides a method formaintenance personnel or technicians to detect tempera-ture discrepancies – areas hotter or colder than allowable– within equipment and systems, which enables them totake corrective action before a costly shutdown, equip-ment damage or personal injury occurs.

Another example of a predictive-maintenance technique isthe use of vibration analysis. Maintenance personnel ortechnicians may use vibration analysis to measure andanalyze equipment vibration to potentially detect changesor abnormal patterns in the machine’s operating condition.

Predictive-maintenance techniques may work well to moni-tor the operating conditions of certain types of equipmentand systems. But such techniques generally cannot beapplied across all equipment within an entire facility. Insome cases, predictive-maintenance tools may not beeffective in monitoring equipment condition. In otherinstances, such techniques may be too expensive whencompared to the frequency, cost and consequences ofequipment failure.

How Does Reliability-Centered Maintenance Fit In?

The purpose in implementing RCM principles is to createa maintenance-program framework that helps ensure that theproper maintenance activity is performed at the right time, andthat the equipment is operated in a way that maximizes itsopportunity to achieve a level of reliability consistent with thesafety, environmental, operational and profit goals of the facil-ity. This is achieved by addressing the basic causes of equip-ment and system failures, and ensuring facility plans have beenimplemented to prevent or lessen the business impact of suchfailures when they occur.

Background of RCM: The aviation industry began develop-ing the RCM approach more than 40 years ago. In the late 1950s,airlines were experiencing high maintenance costs. At the sametime, the Federal Aviation Administration wanted to identifyaircraft-maintenance practices that potentially would providebetter results than those achieved through interval-basedmaintenance. In response, the airline industry in 1960 formed

a task force to study the effectiveness of airline preventive-maintenance programs and explore alternative maintenanceapproaches.

The principles contained within the subsequent reportissued by the airline industry task force were the precursors ofwhat eventually would become RCM. These principles definedand standardized the basic logic to be used in developing aneffective and economical maintenance program. Today, RCMformally is defined in the Society of Automotive Engineers’standard JA1011, Evaluation Criteria for Reliability-CenteredMaintenance Processes. This standard sets out the minimumcriteria for what constitutes RCM.

Although created by the aviation industry, RCM prin-ciples can be applied across many other industries, includingprocessing and manufacturing facilities.

August 13, 2009 Plant Operations Bulletin 3

RCM Principles: The major principles incorporated withinthe RCM approach to maintenance include:

The primary non-safety related purpose for maintenanceactivities is to preserve overall system functionality. Thisconcept differs from the typical maintenance philosophyof preserving equipment operation. Obviously, systemfunctionality ultimately is preserved through preservingequipment function. But the RCM process focuses first onthe desired system output or function, and only thendetermines how maintenance should be performed to bestpreserve the system output. Such an approach does notassume that every item of equipment is equally important,contrary to the theory that may apply under other mainte-nance approaches.

To preserve overall system functionality, maintenanceactivities need to address those equipment or componentfailures that potentially could disrupt system output.When using the RCM approach, a key question askedrelated to this concept is: “Can this system still provide itsprimary output or function if a component fails?” If theanswer is “yes,” then it may be appropriate to allow thecomponent to operate until failing.

Safety always comes first in any maintenance task. There-fore, when evaluating the cost-effectiveness of mainte-nance activities, the expense associated with safe workingconditions is not considered part of the overall programexpense. Once safety conditions are assured, the RCMapproach assigns costs to all other maintenance activities.

The tasks performed within the maintenance program areto reduce the number of output or function failures, or atleast to reduce the damage attributable to such failure(s).Under the RCM approach, tasks that fail to achieve thisobjective are to be redesigned or eliminated.

Maintenance activities are assigned to one of four estab-lished maintenance categories. The RCM approach usesa systematic method to screen maintenance tasks andenhance consistency in determining how to perform main-tenance on all types of facility equipment. Based upon thepotential severity associated with failure, each piece ofequipment is assigned one of four categories: 1) run-to-failure; 2) calendar or run-time-based maintenance; 3)condition monitoring, performed with predictive-mainte-nance techniques; or 4) proactive maintenance. Within theconcept of RCM, proactive maintenance is defined asapplying the lessons learned from past maintenance expe-rience to future situations.

The maintenance program is designed to gather informa-tion about results achieved and then evaluate such infor-mation to improve the program and future maintenanceactivities. Such an information-gathering and feedbacksystem is an important part of the proactive-maintenanceelement of a RCM program. Examples of potential proactive

practices could include changing old equipment specifica-tions that have proven to be inadequate or incorrect,rebuilding worn/failed equipment to better resist failure,performing failed-part analysis and conducting a root-cause failure analysis.

The RCM Process: Developing and implementing a RCMprogram involves following a systematic process called RCManalysis. During such an analysis, facility management care-fully considers and answers the following questions:

1. What systems exist, and what do they do? Every facility isdesigned to produce some desired output. To achieve thisoutput, equipment is grouped into systems that are usedto produce the end product. Within this part of the RCManalysis, facility management first identifies and definesmajor systems and their equipment components. Then, themanagement team describes the function of individualsystems, along with the expected performance standard.

2. What functional system failures are likely to occur? Thenext step in the RCM analysis is to identify the systemfailures likely to occur that could disrupt the system’sfunction. During this step, facility management shouldconsider and identify what could go wrong that wouldprevent the system from producing its desired function.

3. What are the possible causes for likely system failures?The purpose for implementing a RCM program is to preventfunctional failures from occurring. The cause for a func-tional failure may be the breakdown of some equipmentpart. But it also may be a failure in some human activity.Within this step, facility management should identify allfactors that are possible causes for likely system failures.

4. What are the likely consequences of each failure? Duringthis step of the RCM analysis, facility management shouldassess what happens when a failure occurs and what thelikely consequences of the failure are. Not all failures areequal in terms of their affect on system output. Onecriterion to consider during this assessment is the eventsthat will be required to bring the process back to normaloperating conditions. Another criterion to consider is thelikely severity of the failure. Facility management may wishto consider ranking the severity of failures using a critical-ity index, which is the result of combining probability andconsequence rankings together to yield a single numberthat may be used to develop a relative severity ranking ofpotential failures.

5. What can be done to prevent these functional failures?Once potential failures have been evaluated fully, facilitymanagement should consider what type of maintenancetasks, if any, may be used to prevent or predict suchfailures. The decision tree on page 4 outlines the RCM logicthat may be used to determine appropriate maintenanceactivities for equipment.

4 Plant Operations Bulletin August 13, 2009

Conclusion

The RCM approach provides a systematic way to deter-mine the optimum mix of applicable and effective maintenanceactivities needed to sustain the operational reliability of sys-tems and equipment, while ensuring their safe and economicaloperation and support.

For this reason, managers of facilities involved in grainhandling, grain processing and feed and feed ingredient manu-facturing may wish to consider using RCM concepts withintheir maintenance programs.

RCM Maintenance Task Decision Tree

Candidate forrun-to-fail?

Run-to-FailureMaintenance

Redesign system oraccept failure risk or

install redundantequipment

Proactive Maintenance

Develop andschedule an

interval-based task

Interval-BasedMaintenance

Perform condition-monitoring task

PredictiveMaintenance

Develop andschedule the condition

monitoring task

Is there a cost-effective interval-

based task available?

Is there a cost-effectivecondition-monitoringtechnique available?

Will the failure have adirect and adverse effecton environment, health,

security or safety? Will the failure have adirect and adverse impacton the quality or quantity

of system output? Will the failure result inother economic loss, (e.g.,

high cost of damage tomachines or system)?

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES YES