Guidelines for Implementing a Portable Condition Monitoring Program 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Module Objective(s) To overview practical guidelines for implementing a portable vibration monitoring program Disclaimer Although many options have been considered in developing these standardized practices, it is important to remember that these are guidelines The judgment and experience of the service representative in the field is always key to successfully implementing the monitoring program 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Overview Standard method for implementing a condition monitoring program is based on three fundamental considerations: • Process Standardization - once the process is understood, collected information becomes repeatable and consistent • Repeatability and Data Integrity - this builds confidence in the data’s accuracy • Successful Screening, Reporting, and Quality Assessment - methods must be consistent to detect key events, yet be forgiving enough to permit normal operating transients associated with normal machinery operation 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Phase - Site Survey Factors that affect installation speed and accuracy: • • configurations of complex machine requiring more extensive installation long transit time between machines (mining, etc.) • access permit availability • environment • safety access, etc It is recommended the installation team consist of two individuals; one installation specialist, and one assistant Team installation procedures typically allow an average of 20 machines to be installed per day 2010-04-21 ©SKF Slide [Code] SKF [Organisation] On-Site Process • Walk-through • determine measurement locations and to develop a site plan for establishing measurement ROUTEs • Develop Machinery Data Sheets (Asset Information Pages) • for each unit 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Sensor Mounting Techniques • • • (Preferred) Stud mounted and torqued / direct adhesive mount (Good) Magnetically mounted • (As a last resort) Hand-held probe /steel extension probe affixed to hand-held probe (Poor) Double-sided adhesive / beeswax (low frequency applications only, generally not recommended for routine data acquisition in on-going predictive maintenance programs) 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Measurement Locations / Identification Measurement POINT numbering follows flow of power 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Measurement Identification Plane of data acquisition is identified by H for Horizontal measurements, V for Vertical, A for Axial, or R for Radial (typically for vertical pumps) 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Meas Identification / Vertical Pumps Vertical pumps have a radial reading (R) taken down the bearing’s plane of the system, 90° perpendicular to the plane of the discharge volume 2010-04-21 ©SKF Slide [Code] SKF [Organisation] Meas Id / Geared Driver/Driven Good engineering common sense dictates the application of the naming conventions 2010-04-21 ©SKF Slide 10 [Code] SKF [Organisation] Measurement Location / Notes Wrong - flat transducer magnets mounted on uneven surfaces allow excessive transducer freedom, resulting in non-repeatable data 2010-04-21 ©SKF Slide 13 [Code] SKF [Organisation] Consistency Consistency is imperative to a successful program • • • • * Consistent sensor placement (location) Consistent sensor contact angle Consistent machine speed Consistent surface condition for sensor placement Use of extension rods and hand-held probes not promote consistency 2010-04-21 ©SKF Slide 14 [Code] SKF [Organisation] Sensor Mounting Disks overhead view of sample disk showing sample POINT location side profile Note adhesive fillets at edges of disk-to-machine mating surfaces 2010-04-21 ©SKF Slide 15 [Code] SKF [Organisation] Sensor Mounting Disk Installation Good - adhesive fillets protect the disk from oil leaching underneath Bad - a concave adhesive fillet allows oil to leach under the disk, resulting in failure 2010-04-21 ©SKF Slide 16 [Code] SKF [Organisation] Sensor Mounting Options Counterbore Depression • In applications where bearing housings are a cast ferrous material, mounting a disk may be unacceptable due to the possibility of the disk coming loose and running through the machine An alternative is to take a counterbore and mill a flat depression in the machine surface, where you may attach a magnetic-coupled transducer Accelerometer Mounting Block (Seismic Blocks) • Machine applications that not provide adequate surface area for mounting a surface disk or counterbore depression (for example, milling/grinding machines), or if temperatures are too high for adhesive applications, an accelerometer mounting block may prove an acceptable alternative 2010-04-21 ©SKF Slide 17 [Code] SKF [Organisation] Closeout Walk Through Upon completing the machinery data sheets and installation of measurement disks, walk through the plant following the intended data collection ROUTEs, arranging the MDSs in same sequence Look for: • • • Duct tape inadvertently left on any machine Sample disks which may have become dislodged Litter or materials that were overlooked during installation 2010-04-21 ©SKF Slide 18 [Code] SKF [Organisation] Setting Up the Measurement Hierarchy At a minimum, complete hierarchy development includes: • • • • all POINT setups overall alarm setups spectral or narrow band alarm setups (where applicable) data collection ROUTE setups 2010-04-21 ©SKF Slide 19 [Code] SKF [Organisation] Machinery Monitoring Classifications • Critical - If a failure or shutdown occurs, production is stopped, or machine performance creates an unsafe environment • Essential - If a failure or shutdown occurs, production is disrupted • Non Essential or Redundant - If a failure occurs, production loss is inconvenienced, however, a redundant unit can be brought on-line, or a repair brings the production unit back on-line without significant loss of production 2010-04-21 ©SKF Slide 20 [Code] SKF [Organisation] Classifying Machinery - Special Considerations Special consideration should be given to machinery that affect: • Safety - Can failure or abnormal operating condition create unsafe conditions? • Catastrophic Failure or Unrecoverable Loss - Would loss of this machine create a catastrophic failure, or be financially disruptive? • Excessive Maintenance - Does this machine have a high frequency of failure, or require special attention or talent to keep operational and productive? • Excessive Repair Cost - Does the machine require high repair costs and/or special talent to support? 2010-04-21 ©SKF Slide 21 [Code] SKF [Organisation] Assigning Priority Levels • Priority CRITICAL - data indicates failure is imminent Machinery requires immediate attention, and an immediate repair shutdown should be seriously considered Machine should be monitored a minimum of once per shift • Priority ABNORMAL - data indicates operation is in the rough category Plans should be made to arrange repair outage at first availability • Priority MONITOR CLOSELY - typically employed when a change in machine performance or dynamics is detected, however, trends need to be observed to determine if the machine stabilizes, or if operational methods are causing the excursion Typically, measurement frequency is doubled during this period (monthly acquisition is doubled to bi-weekly, quarterly becomes monthly, etc.) • Priority NORMAL - No abnormal trends or performance is noted at the time of data acquisition, thus no action is typically recommended at this time, and data acquisition is scheduled for the next calendared date 2010-04-21 ©SKF Slide 22 [Code] SKF [Organisation] Typical Fmax Settings Shaft Speed (RPM) Set Velocity (ips) fmax at Set Acceleration (g) fmax at Hz CPM Hz < or = 1,200 100 6,000 kHz 60 kCPM 1,200 - 2,400 200 12,000 kHz 120 kCPM > 2,400 * 500 30,000 kHz kHz CPM Gas turbines, turbochargers, etc, with very high running speeds typically have acceleration fmax set to approximately 10 kHz (600 kCPM) 2010-04-21 ©SKF Slide 23 [Code] SKF [Organisation] Determining Spectral Resolution fres = fmax - fmin number of spectral lines where: fmax = maximum frequency of interest fmin = minimum frequency of interest fres = frequency resolution per filter line If data is collected from to 100 Hz, at 400 lines: 100 Hz 400 lines 2010-04-21 ©SKF Slide 24 [Code] SKF [Organisation] = 0.25 Hz resolution per line Gearmesh Acceleration Meas Settings • fmax should be (4 x calculated gearmesh frequency) + 10% ensures that the gearmesh frequency and three harmonics of the gearmesh frequency are available for examination, with enough “margin” to observe sideband modulation • Lines of resolution to a minimum of 400 lines, although a greater number of spectral lines enhances spectrum resolution 2010-04-21 ©SKF Slide 25 [Code] SKF [Organisation] Enveloped Acceleration Band Selection 2010-04-21 ©SKF Slide 26 [Code] SKF [Organisation] Setting Alarm Levels - Guidelines To be most conservative, the following provides a working screening technique: VELOCITY SET A1 OVERALL ALERT 0.314 ips (8 mm/s) SET A2 OVERALL ALERT 0.6 ips (15.2 mm/s) • 0.6 ips is considered unsafe for continued machine operation and personnel safety, and represents the frequency-dependent amplitude crossing the ISO general severity guideline’s ROUGH to VERY ROUGH threshold • It is most desirable to set alarm thresholds high enough to minimize extraneous alarms, yet conservative enough to not miss a critical excursion in machine condition • Use these alarm levels for preliminary database setup only These settings should be modified in accordance with the operational requirements of the monitored machine (as the database becomes qualified or as a result of baseline data acquisition) 2010-04-21 ©SKF Slide 27 [Code] SKF [Organisation]