extending equipment life through improved sealing technology presented by david c. roberts december...

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?