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Extending Equipment Life through Improved Sealing Technology
Presented by David C. RobertsPresented by David C. Roberts
December 12, 2007 December 12, 2007
AGENDA
• WHY DO BEARINGS FAIL?
• HOW DO INDUSTRIAL SEALING DEVICES PREVENT BEARING FAILURE?
• HOW DO WE MEASURE EQUIPMENT PERFORMANCE?
• SEALING INNOVATIONS TO IMPROVE MEAN TIME BETWEEN FAILURES
• SEALING INNOVATIONS TO IMPROVE MEAN TIME TO REPAIR
Understanding Bearing Failure
Bearing Failure
Whether You Have…
CONVEYANCE SYSTEMS
Bearing Failure
PULVERIZERS
Bearing Failure
TURBINES
Bearing Failure
OR ANYTHING ELSE
Bearing Failure
YOU HAVE BEARINGS!!!
Bearing Failure
Why Do Bearings Fail?• Textbook Answer:
FatigueBall and roller bearing failures occur due to surface fatigue. Either the bearings or the raceways will begin to pit, resulting in an audible indicator in the form of noise.
• Real World Answer: Lack of Lubrication & Contamination
Only 1% [of bearings] actually fail due to pure fatigue. The majority of bearing failures are from a lubrication-related issue.
95% of bearing failures can be either prevented or have their service life extended.
Understanding The Sealing System
Mechanical SealsOil Seals Bearing Isolators
The Sealing System
Sealing systems can be broken into two main groups:
Contact SealsRadial Lip Seals (Oil Seals), Compression Packing, O-rings
Non-Contact SealBearing Isolators and Labyrinth Seals
Radial Lip Seals
• Depend on Hydrodynamic Sealing Effect
• Capable of Sealing on one side only (unless dual lip seal)
• Shaft must be specially finished for seal:– Min 30 Rockwell C – 10 to 20 µin Finish– No Lead
• Subject to Abrasive Wear• Also affected by:
– Temperature– Pressure– Misalignment & Runout– Bore Condition
Non-Contact Seals
Traditional Labyrinth Seal
• Uses complex pathway to separate fluids
• Rotor moves with shaft, while stator remains static in bore
Bearing Isolator Seal
• Uses basic labyrinth technology
• Incorporates centrifugal force, pressure differential, and drain back designs to maximize sealing effect
Equipment Reliability and
Maintainability GOAL:
Improve equipment efficiency through innovative sealing technology
REQUIREMENT: Method needed to measure equipment performance
TWO ESTABLISHED STANDARD INDICATORS:1. Reliability2. Maintainability
Equipment Reliability and Maintainability
RELIABILITY INDICATOR:MEAN TIME BETWEEN FAILURES (MTBF)
N
PTMTBF
Where:
MTBF = Mean Time Between Failures
PT = Productive Time
N = Number of Failures That Occur During Productive Time
“Average time the equipment performed its intended function between failures”
Equipment Reliability and Maintainability
MAINTAINABILITY INDICATOR:MEAN TIME TO REPAIR (MTTR)
N
RTMTTR
Where:
MTTR = Mean Time To Repair
RT = Total Repair Time
N = Number of Failures
Time required to retainor restore equipment to a
state such that it willcontinue to function as
designed
Sealing Innovations to Improve MTBF
IMPROVING MTBF:• Must extend life of operating
components• Bearing system typically fails due to
lubrication issues• As seals are primary bearing protector,
must understand why seals fail and determine ways to prevent such failure
Sealing Innovations to Improve MTBF
SEALS FAIL DUE TO:• Abrasion• Lack of lubrication• Chemical degradation• Changes in physical properties while in
service
Abrasive Wear Lack of Lubrication Swelling due to changes inPhysical Properties or
Chemical Attack
Sealing Innovations to Improve MTBF
MATERIAL INNOVATIONS• Factors that contribute to seal failure are directly related to
the properties of the materials used to manufacture sealing products
• Common sealing materials include: – Acrylonitrile Butadiene (Buna-N, NBR)– Hydrogenated Nitrile Rubber (HNBR) – Fluoroelastomer (FKM, Viton®)– Silicones– Polytetrafluoroethylene (PTFE, Teflon®)
• Garlock Klozure® engineered the Mill-Right® family of elastomers to offer significant improvements such areas as:– Abrasion resistance– Chemical resistance– Physical property retention
Sealing Innovations to Improve MTBF
IMPROVING ABRASION RESISTANCE
• Industry standard is Taber Test per ASTM D4060
• Significant improvements over industrial grade elastomers
• Mill-Right® Family includes engineered grades of NBR, HNBR, FKM
Sealing Innovations to Improve MTBF
LIMITATIONS OF CONTACT SEALS:
• Require minimum shaft hardness of 30 RC
• Require specially finished shaft
• Most are not suited to dry running
• Most only seal on one side
• Contribute to power losses
Sealing Innovations to Improve MTBF
Advantages of non-contact bearing isolators:
• Can run on soft shaft materials
• Only require surface finish of 64µin (1.63µm) or better
• Can run dry• Provide both oil
retention and contaminant exclusion
• Reduce power losses due to friction
Garlock Klozure® Guardian™Bearing Isolator
Sealing Innovations to Improve MTTR
IMPROVING MTTR:
• Identify steps required to repair equipment
• Determine time required for each step
• Determine how to reduce time consuming steps
Sealing Innovations to Improve MTTR
SPLIT BEARING ISOLATOR PROVIDES NON-CONTACT SPLIT SEAL:
• Same functionality as standard Guardian Bearing Isolator
• Split configuration allows for quick and easy installation
• Unitized one-piece assembly will not come apart when properly installed
Sealing Innovations to Improve MTTR
RATHER THAN REDUCING MTTR – ELIMINATE IT!!!
Garlock Klozure’s XPS™ Mechanical Seal is the first Repair-In-Place seal which virtually eliminates MTTR
Sealing Innovations to Improve MTTR
THE XPS™ SEAL - HOW IT WORKS…• Four additional sealing elements
are stored behind the primary elements
• Simple turn of the deployment screw moves a new sealing lip in place
• Thinly formed Gylon® lips running on a hardened sleeve
• Total of 6 Gylon® lips included with two initially deployed
CONCLUSION
• WHY DO BEARINGS FAIL?– Most often due to lubrication issues rather than fatigue
• HOW DO INDUSTRIAL SEALING DEVICES PREVENT BEARING FAILURE? – Retain lubrication or exclude contamination– Some seals can do both– Contact seals vs. non-contact seals
• HOW DO WE MEASURE EQUIPMENT PERFORMANCE? – Mean Time Between Failures, Mean Time To Repair
• SEALING INNOVATIONS TO IMPROVE MEAN TIME BETWEEN FAILURES– Engineered Material Innovations, High Performance Non-Contact
Seals
• SEALING INNOVATIONS TO IMPROVE MEAN TIME TO REPAIR– High Performance Split Seals, Repair in Place Seals
David C. RobertsDavid C. Roberts
Applications EngineerApplications Engineer
Garlock Klozure High-Performance Dynamic SealsGarlock Klozure High-Performance Dynamic Seals
Palmyra, NY USAPalmyra, NY USA
www.klozure.comwww.klozure.com
Questions?Questions?