Rp Bearings

For Internal

Circulation Only

Reliance Industries Limited

Copyright: Reliance Industries

Limited, India

Prepared by: Himanshu Dayal Page: 1 of 15Checked by : K Gopalakrishnan

Group Manufacturing Services Engineering Services Dept Date: 9-Mar-07

Approved by : A Venkatraman DOC. No: GMS/RP/27 Revision no.: 0.0

Best Practices For

Bearings

Please send your comments and suggestions to the author.

This document is intended for guidance purpose and may be adopted with minor modifications by any functional department within RIL group of companies.

Reproduction of this document or parts thereof in not allowed unless written permission is obtained

from the Approving authority.

For Internal

Circulation Only



Limited, India




INDEX 1. INTRODUCTION …………………………………………………………………………………………………. 3 2. SCOPE ……………………………………………………………………………………………………………… 3 3. TRAINING AND INSTALLATION........................................................................................................................ 3 3.1 TRAINING ................................................................................................................................................................ 3 3.2 INSTALLATION: ..................................................................................................................................................... 3 3.2.1 Cleanliness – a clean installation environment is important.................................................................................. 3 3.2.2 Pre-Installation checks ........................................................................................................................................... 4 3.2.3 Mounting Procedure – Critical for Bearings with Tapered Bore (K). ................................................................... 4 3.2.4 Mounting Tools – Use the Right Tools ................................................................................................................... 4 3.2.5 To work out what tools are required:...................................................................................................................... 4 3.2.6 Dismounting Procedures:........................................................................................................................................ 5 3.3 REPLACING SEALED BEARINGS: ....................................................................................................................... 5 4. BEST PRACTICES IN BEARING LUBRICATION ............................................................................................. 5 4.1 PERSONNEL: ............................................................................................................................................................ 5 4.2 STORAGE AND HANDLING:.................................................................................................................................. 5 4.3 SAFETY:..................................................................................................................................................................... 6 4.4 TRAINING: ................................................................................................................................................................ 6 4.5 FLUSHING OF GEARBOXES: ................................................................................................................................ 6 4.6 LABELLING:............................................................................................................................................................. 7 4.7 RELUBRICATION QUANTITIES: ......................................................................................................................... 7 4.8 RATIONALISATION:............................................................................................................................................... 7 4.9 AUTOMATIC LUBRICATORS:............................................................................................................................... 7 4.10 SOFTWARE AND SCHEDULING:........................................................................................................................ 8 4.11 MAGNETS, BREATHERS AND PURGE HOLES:................................................................................................ 8 5. ROOT CAUSE FAILURE ANALYSIS & RELIABILITY IMPROVEMENTS ................................................. 8 5.1.1 Best Practices in Bearing Reliability Improvement................................................................................................. 8 5.1.2 Specific Bearing Failurr Information ...................................................................................................................... 9 5.2 SUPPLIER TECHNICAL SUPPORT....................................................................................................................... 13 5.3. TECHNOLOGIES THAT CAN IMPROVE RELIABILITY ................................................................................. 13 5.3.1 Two-Bearing Units for Fans................................................................................................................................... 13 5.3.2 ConCentra (Pop-Release) Bearing Units. ............................................................................................................. 13 5.3.3 CARB Toroidal Bearings........................................................................................................................................ 14 5.4 COST-BENEFIT ANALYSIS .................................................................................................................................. 14 APPENDIX 3 - REFERENCE MATERIAL............................................................................................................... 15

For Internal

Circulation Only



Limited, India




1. Introduction: Bearings are at the heart of rotating equipment and their reliability is often critical to the operation of plant and equipment. The purchase cost of bearings is proportionally very small compared to the maintenance cost of replacement and potential lost production caused by failure. The purpose of this procedure is to discuss the various factors affecting the bearing performance and share practices that have been successfully implemented to overcome known problems. 2. Scope The scope of this document has been broadly classified into four areas : 1. Training and Installation 2. Lubrication 3. Root Cause Failure Analysis & Improvements 4. Stock & Suppliers 3. Training and Installation Bearing failures due to incorrect installation are reported to account for between 16% and 36% of all premature bearing failures. The root cause of the incorrect installation in most cases is lack of specific bearing installation training, incorrect use of tools, use of the wrong tools, and contamination during fitting and incorrect tolerances of shafts and housings. These can all be avoided and the path to best practices in bearing reliability and maintenance starts with addressing these issues : 3.1 Training

• Utilise vendors where possible for short training courses on site • Make training also available for contractors to ensure they get up skilled as well. • Include Engineers, Supervisors & Planners in Training courses as it cannot be assumed that

they understand the need for getting the basics right. • It’s particularly important that Supervisors are knowledgeable about bearing installation so

they can supervise contractors who may not be trained in this area. • Include examples of the costs of failures in training to emphasise the importance of correct

installation. 3.2 Installation: 3.2.1 Cleanliness – a clean installation environment is important

• Ensure the workshop area where bearings are fitted is clean • When installation is in the open, create a wind break and cover the bearing to prevent

contamination. • Don’t unpack or unwrap until ready to install to reduce risk of contamination. • Wash out contaminants if the dust has blown on the bearing.

For Internal

Circulation Only



Limited, India




3.2.2 Pre-Installation checks

• Find out what the tolerances should be from manufacturer’s drawings or bearing catalogues. • Check shaft and housing tolerances for wear and conformity. This is a critical step that is

often not done. Shafts and housings must be checked dimensionally in 3 positions in 3 planes. • Use a Straight-edge and bearing blue when checking and repair if there is not a minimum of

80% contact. 3.2.3 Mounting Procedure – Critical for Bearings with Tapered Bore (K)

• Have mounting instruction for Self Aligning Double-Row Ball and Roller Bearing supplied with the bearing.

• Supply mounting detail checklist with the bearing to record actual mounting clearances. • Download mounting instructions from manufacturer’s websites. e.g. www.skf.com/mount • These issues increase in importance when contractors and casuals are doing the installation

and their skill in this area in not known. • Document worksheets for critical jobs and include the instructions in the CMMS. • Record installed clearance dimensions of large bearings to enable calculation of wear by

measurements taken at some future date. • For infrequent and critical installations, contact bearing supplier to provide an engineer for

on-site supervision.

3.2.4 Mounting Tools – Use the Right Tools

• Bearing Magnetic Induction heaters will do 80% of all tight inner-ring fit bearings. • Ensure the heaters have a working temperature probe and check its accuracy with a contact • Thermometer. Get training on the use of the heater from the supplier. • Use an Impact mounting kit for small bearings (up to 50mm bore) instead of pipes and

homemade dollies. • Use correct “C” (hook) or impact spanners for lock nuts for adapter sleeves. • Use Hydraulic Nuts for bearings on adapter sleeves and tapered journals over 100mm where

possible. • Dial indicators can be useful for measuring drive-up distances and can be fitted to the newer

hydraulic nuts. Use hydraulic pumps with calibrated gauges for connecting to hydraulic nuts. • Ensure fitters have a good set of Feeler Gauges for checking clearance when mounting

tapered bore bearings. Feeler gauges can be made a stores stock code so that they are re-ordered automatically.

3.2.5 To work out what tools are required :

• Get a list of bearings from the store (and their usage) and sort by part number and criticality. • Bearings with the suffix “K” (Tapered bore) will generally need fitting with hook spanners or

hydraulic nuts.

• Order the tools that are not already in the tool store so they are available for the next

For Internal

Circulation Only



Limited, India




installation. 3.2.6 Dismounting Procedures :

• Use hydraulic removal pullers wherever possible. • Adapter sleeves over 150 mm shaft should be ordered with oil injection holes to enable safe

and fast removal by high pressure oil injection e.g. Sleeve number OH 3134 H. • Avoid grinding right through a bearing inner ring and damaging the shaft - inner rings can be

cracked with a cold chisel and hammer if a grinding cut is made nearly all the way through. 3.3 Replacing Sealed Bearings :

• Improved life can be achieved when Ball Bearings with double shields (2Z) are converted to the double sealed (2RS) type. The 2Z bearings are suitable for light-duty environments where low friction is required whereas 2RS types have higher friction but give better protection from moisture and contamination. e.g. small electric motors e.g. 6305-2Z replaced by 6205-2RS

4. Best Practices in Bearing Lubrication : 4.1 Personnel:

• For an effective lubrication program, it is a must that a dedicated Lubrication person or team to do the job. It should not be a job relegated to the least skilled people on site. A starting point is to have a job specification and a title for the role that reflects its importance. e.g. “Lubrication Technician”. If the role is not given importance, it will not be treated with the importance it deserves.

• Where ever lubrication role is part of a plant-wide strategy for improving lubrication, there is greater chance of implementing a successful program.

• Whoever is involved in the program requires training – not just in the theory of lubrication but in storage, handling, and the various methods of application, safety, and disposal.

4.2 Storage and Handling:

• Try to ensure that a first-in/first-out (FIFO) system is used for drums. • Drums and containers should be stored in clean and dry locations away form all types on

contamination including dust and humidity. Ideally, drums should be stored horizontally on storage racks. With the bungs at 3 and 9 o’clock positions to below the lubricant level.

• Drums should not be stored outside where water can pool on the top of the drums. Water ingress from uncovered drums is a common source of contamination.

• If drums have to be stored outside, it is strongly recommended that they be covered by a shelter.

• A separate store for storage of lubricants is best practice. • Storage areas should have built in spillage areas to prevent spills from contaminating ground

water and the working areas. • It is essential that safe and ergonomic handling equipment is used for lifting, rotating moving,

and handling drums.

For Internal

Circulation Only



Limited, India




• The use of 10 litre Oil Safe containers is a good way of reducing the risk of cross contamination of oils, and can make filling containers faster and more efficient.

• Avoid galvanised containers as oil additives may react with the zinc plating causing the formation of metal soaps that can clog up lube Systems.

• Colour coding and clear labeling of drums, containers, hoses, and pumps reduces the risk of cross-contamination and dispensing the wrong lubricant.

• Oil containers should be stored in metal cabinets in they are not in a clean dedicated lubrication store.

• Each type of Oil should have a dedicated pump to reduce cross-contamination. • Desiccant breathers on drums are a good way to keep oil clean and dry while in storage. • Oils should be filtered (3 micron absolute) when transferring from bulk containers to

dispensing containers. • Disposal drums should be clearly marked so that oils are not mixed. Mixed oils (e.g. synthetic

and mineral oils) can cause serious problems during disposal or reclaiming. 4.3 Safety:

• MSDS must be readily accessible for all lubricants. • The handling of lubricants does have some health risks and appropriate safety procedures

should be followed (e.g. gloves). See table below. 4.4 Training: Following training courses are available which can be conducted at site for concerned persons:

• Noria : Noria is an independent Lubrication Knowledge company based in the USA. They run courses on Oil Analysis and Machinery Lubrication. The courses are usually followed by optional assessment with an IMCL (International Council for Machinery Lubrication) certification exam.

• Vendors : All the lube oil manufacturers run their own courses which are also recognised

internationally. 4.5 Flushing of Gearboxes:

• One suggested method is to flush a gearbox with a compatible low-viscosity oil variation of the service oil.

• Filter carts are good for flushing gearboxes on line. • Depending on the gearboxes age and the level of contamination and scaling, solvents can be

used which break up the deposits that normal flushing does not remove. • Some companies do a pre-flush and then a final flush.

4.6 Labeling:

• Tags should be used to indicate the correct lube -Grease or oil for the lubrication point.

For Internal

Circulation Only



Limited, India




• Silastic or Sikaflex can be used to ensure adhesion for labels. • TRAFFOLITE engraved labels also can be used.

4.7 Re-lubrication Quantities:

• OEM recommendations are a good place to start. • History and experience is used to fine tune re-lubrication quantities. • The best way is to calculate the re-lubrication amount required by using a calculator as

supplied by the bearing companies. (e.g. SKF Dialset or Lubeselect and FAG Relubrication Calculator).

• Bearing catalogues also give the re-lubrication amounts as a calculation of the bearing size, type, and speed.

• Using listening devices, vibration measurements (e.g. HFD, SEE) and temperature are a good way of determining when a bearing requires re-lubrication.

4.8 Rationalisation:

• When it is done correctly, lubrication rationalisation can have good benefits such as reduced inventory, reduced risk of applying the wrong lubricant, efficiency, and improved reliability.

• PPG have reduced their greases on site from eight types to one, using Molub-Alloy Multiservice grease 860-220-2,

• The rationalisation program must be driven for the right reasons, not just for cost reduction in purchases. Before rationalising, the details must be checked to ensure that the right lubricant is specified in the first place.

• Involve the supplier in the rationalisation process. • Do not reduce the viscosity of the lubricant when rationalising as this can greatly reduce the

life of bearings and gears. 4.9 Automatic Lubricators:

• The key to success with automatic lubricators (PermaLube, System 24, Memolube, etc.) is to ensure that they are part of a lubrication program that is managed by a CMMS or stand alone lube program.

• Automatic lubricators generally operate well as long as they are used within their range of suitable applications (temperature, length of line, correct re-lubrication interval, etc.).

• Installing fixed grease lines to make greasing more accessible gives good results. 4.10 Software and Scheduling:

• Lubrication Management needs to be run as a stand alone activity, separate to the main CMMS. This is because the detail required for lube scheduling is too detailed for a CMMS.

• The main methods used are :

- Lube- IT @ www.generationsystems.com - LMS2000 @ www.totalplantcontrol.com - In house programs using Excel, Access, etc.

For Internal

Circulation Only



Limited, India




4.11 Magnets, Breathers and Purge Holes:

• Oil Magnets have their place to help make decisions regarding machine problems when used along side Vibration analysis and Oil analysis.

• Oil magnets are common as drain plugs in non critical pump bearing housing applications where no other oil analysis is performed. They have proved to be successful for slow speed applications where vibration analysis has been uncertain.

• Breathers are good addition to oil lubricated machines as they can keep out both contaminants and moisture if selected correctly.

• Recommended specifications are for filters to have 3-5µ absolute (suppliers are Pall or Hydac) and for desiccant to be included for moisture removal.

• Grease purge holes are important for bearings at high speeds where over lubrication can be a problem (e.g. electric motors and fan housings).

• The SKF and FAG catalogues specify the correct hole sizes for different Plummer blocks and the housings can be ordered with the holes pre-drilled.

5. Root Cause Failure Analysis & Reliability Improvements The different approaches that companies have to investigate for improving bearing related failures. 5.1.1 Best Practices in Bearing Reliability Improvement The Best Practices in Reliability Improvement are :

1. Use an RCA investigation to determine the cause of the problem. 2. Investigate options to remove the cause, redesign, or employ new technology 3. Involve the product supplier or contracted vendor engineers for expert assistance. 4. Analyse the cost-benefit of the solution(s) to justify the choice and changes. 5. Get approval if necessary and implement the changes 6. Document the changes (not forgetting to update records, drawing mods, procedures,

inventory codes, specification change documentation, etc.) 7. Review the results.

5.1.2 Specific Bearing Failure Information The ISO standard ISO 15243:2004 for rolling bearings - Damage and failures - Terms, characteristics, and Causes has now been published and is available. When this is used by industry, it will ensure that all parties use the same language when reporting on bearing failures. Common bearing failure patterns are as below -

FAILURE PATTERN FAILURE REASON

For Internal

Circulation Only



Limited, India





Normal wear exhibits "Smooth" finish. Accelerated wear may be caused by fine abrasives left in from extended oil change intervals not monitored by analysis.

Bearing surfaces which reveal scratches or "Trenches" are typical of particle wear. The oil filter element should reveal the culprit.

Particles, sandwiched between bearing and bore, can create distortion and a "Hot Spot". Particle may be embedded and visible. (see arrow)

"Oil Starvation" can be attribued to a number of causes. Wiping, Blue Discoloration and "Adhesion" wear to shaft or pin are common indicators.

Water and/or antifreeze in the engine oil create milky, grey edging and possible black corrosion on the lining. Pitting and Flaking are progressive damage.

For Internal

Circulation Only



Limited, India





Worn, Pitted surfaces with dark green coloration, indicate fuel dilution of lube oil. This corrosive action may also pit crankshaft.

"Shiny" indicators on the back of the bearing insert are signs of movement. Bore Geometry and surface dimension must be checked.

This is "Cavitation Erosion", on the unloaded half of insert. "Entrained" air bubbles in oil may cause additional lubrication problems.

Cavitation Erosion (round flaked portion) caused by entrained air bubbles, along with embedded hard debris, can require a close examination for failure analysis.

Lack of lubrication can be attributed to engine oil dilution, breakdown or elevataed temperature. Causes must be investigated, too prevent further occurences.

For Internal

Circulation Only



Limited, India





"Cold Start" can destroy bearing surfaces and lead to progressive failure. "Cold Start" failure is caused by lack of lubrication and running up to full RMP before the engine is warm.

"Offside" wear is usually an indication of misaligned crankshaft or bore. This may not apply to "Offside" connecting rods.

"One Sided" wear is usually a misaligned or improperly adjusted assembly. Damage to adjacent bearings may occur.

Localized wear on main bearings showing a pattern along the shaft, for example, worst wear on the middle bearings, is evidence of a bent crankshaft.

Localized, symmetrical wear about a journal's axis is due to deviations in the journal's geometry

This indicator may be evidence of "loose" or "tight" fit. This bearing experienced excessive "crush", causing deformation in this area.

For Internal

Circulation Only



Limited, India





Localized wear on opposite sides of a pair's shell halves is normally caused by a bent connecting rod.

Loccalized, polished areas are on steel back (fretting); caused by improper crush or movement of insert within its respective bore. This may cause damage to housing and/or shaft.

Bearings improperly "Located" during installation can sometimes be hard to spot.

Excessive "End Play" can rapidly wear thrust washers. This can be caused by "abrupt" engagement or "riding the clutch".

5.2 Supplier Technical Support One of the best sources for assistance in technical information on bearing failures and assistance in reliability Improvements is the technical representatives from the various bearing companies. 5.3. Technologies that can improve reliability There are many new technologies available from bearing companies to improve service life. Some are related to steel quality, some to micro-internal design, some with respect to sealing, and some to increased capacity from geometry of rollers and flanges. The improvements can range from small percentage life increases to multiple life increases. Following are the few technologies that can make dramatic life improvements, where it is not unusual to have increases in MTBF of 10 or more. 5.3.1 Two-Bearing Units

For Internal

Circulation Only



Limited, India




Fans often had variable axial loads s and relatively low radial loads on the bearings. This does not always suit the traditional arrangement of self-aligning bearings in Plummer blocks. For these overhung fans, a two-bearing unit can have many advantages over a normal arrangement of 2 x Plummer blocks, such as:

• More choices in the bearings that can be installed (ball, angular contact, cylindrical, spherical or CARB, depending on the load and speed).

• Better seals can be fitted to the housings to keep out contamination. • They can run with grease or with oil lubrication. • They have easy installation, because it is only necessary to bolt the unit to its support surface.

(although its necessary to watch out for soft foot) • There is little risk of contaminating or otherwise damaging the bearings during installation.

These units come in standard sizes from SKF and FAG but can be made to suit most existing fan centre heights. Original equipment manufacturers, such as Flakt-Woods, can offer these with new fans installations if you specify them.

5.3.2 ConCentra (Pop-Release) Bearing Units These have been around for some years, but still prove to be a good economical technology improvement for some applications. Their main use is in reducing failures caused by contamination and installation. These are bearing units that come complete with the housing, bearing, seals, locking sleeve, lubricant and are pre-assembled, ready to mount. They are quick and easy to install. Once the bearing is correctly located on a shaft, mounting screws are tightened, axially displacing two paired precision-engineered serrated rings. The paired rings grip the shaft as the internal clearance in the bearing is reduced and expand evenly around the entire shaft circumference for a reliable fit. The versions with spherical rollers (as per the picture above) are best used on slower speed applications. They come in fixed and floating executions. There are versions available with ball bearings for lighter loads and higher speeds Their advantages include the following:

• Can be retrofitted to suit many existing shafts and Plummer block sizes. They can often replace standard size Plummer blocks (e.g. SN, SNA, SNH, SNL series from 35 mm to 75mm shaft size).

• They have tight gripping triple-lip seals, which are good for keeping out contamination. • No special tools required – just an Allen Key that comes with the bearing unit. • They are protected against contamination during installation. • They allow logistics costs to be reduced as only one part has to be ordered, stored and

managed 5.3.3 CARB Toroidal Bearings The rollers of the CARB bearing are self-guiding, i.e. they will always adopt the position where the load is evenly distributed over the roller length - irrespective of whether the inner ring is axially displaced and/or misaligned with respect to the outer ring. The load carrying capacity of the CARB bearing is very high even when it has to compensate for angular misalignment or axial displacement, which should result in improved reliability. They are

For Internal

Circulation Only



Limited, India




intended exclusively as non-locating bearings. They simplify the bearing arrangement design for long shafts that are subjected to temperature variations. When using CARB bearings, it has also been proven that vibration levels are reduced, e.g. in paper machines or fans. CARB bearings have a lower required minimum load than equivalent sized spherical roller bearings, which means they are less inclined to skid under light load and high speed. Because they require less grease than equivalent sized spherical roller bearings, they can be prone to get hot if too much grease is applied at start-up. The CARB bearing is a single row bearing with long, slightly crowned symmetrical rollers. The raceways of both the inner and outer rings are concave and situated symmetrically about the bearing centre. They have been around for about 10 years now and have started to become a standard bearing for heavy-duty applications. 5.4 Cost-benefit analysis An important, and often neglected part of a reliability improvement project is the cost-benefit analysis. This is a useful tool in documenting both the projected pay-back time for an improvement as well as historical evidence of the improvement. This is a key aid in getting management approval for capital or additional resources to fund improvements. Appendix 3 - Reference Material Installation & Training

• Mounting Instructions www.skf.cm/mount • 10 Tips for Bearing Maintenance SKFRBO2016 • Tips for Bearing Mounting SKFRBO2017 • Bearing Basics – an overview SKF RBO2002 • Bearing Dismounting Methods SKF GSO4012 s • Proper practice for the cleaning, removal NTN9102/E • and mounting of bearings • Spherical Record Fitting Sheet CBC QA-FGR-01 • Self –Aligning Ball Installation Procedures CBC • Tapered Bore SRB Measurement NTN • Course in Bearing Technology & Maintenance www.skf.com.au

Best Practices in Lubrication • Oil Safe Products www.oilsafe.com..au • Training Courses www.noria.com • Lube- IT Software www.generationsystems.com • LMS2000 Software www.totalplantcontrol.com • Mobil Lubrication Course Michael Lennon - 03 9286 5076 • Bearing Lubrication SKFJMO2006 • Best Practices in Flushing Gearboxes Noria – Lubrication Excellence Conference 2003 • Best Practices for Lube storage & handling SKF Aptitude Exchange • Consolidating Lubricants Utility Service Associates

For Internal

Circulation Only



Limited, India




• Lube Practice – Let’s get Serious Noria – Asset Management 2005 Conference • How to set optimum cleanliness levels Noria • Pacesetter Performance through sound Premcor Refining Group Lubrication Practices • How to design a World Class Lube Room Clopay Corporation

RCA & Reliability Improvements • Rolling bearings - Damage and failures - Terms, characteristics and causes ISO 15243:2004 • NSK Bearing Doctor www.nskaustralia.com.au/page/6view.html • SKF Rolling Bearing failures and their causes Product Information 401E • FAG Rolling Bearing Damage Publ. No. WL 82 102/2 EA • SKF POP release bearings Publication 4255E • Rolling Bearing Handbook & Trouble shooting Guide Raymond A. Guyer, Jr. • Rolling Bearings in Service – Interpretations of Types of Damage T.S. Nisbet &G.W. Mullett • Root Cause Failure Analysis R. Keith Mobley • Root Cause Analysis Handbook RCA Rt, SIRF Roundtables • SKF Bearing Inspector www.aptitudexhange.com • Two Bearing Units www.aptitudexchange.com • NSK www.tec.nsk.com • Bearing Detective www.emersonbearing.com

Documents

Rp Bearings