Propeller Shaft Bearing Conversion Brochure - Thordon Bearings

T H O R D O N B E A R I N G S I N C.Eliminating SternTube Oil PollutionThe 12-Step ProcessConverting to a Thordon COMPACseawater lubricated bearing systemfrom an oil lubricated white metalpropeller shaft bearing systemCC2010.1

Why Convert to Seawater?Environmental legislation is getting tougher. And even well maintained ships leak stern tubeoil - a serious environmental issue facing commercial ship owners today. The simplest wayto eliminate oil from the stern tube is to use Thordon non-metallic seawater lubricatedCOMPAC shaft bearings. COMPAC is a pollution-free, high performance, low maintenancebearing system used on cruise ships, bulk carriers, tankers, ferries, AHTS's, dry cargo andtugs - operating around the world with excellent results.What is a COMPAC seawater lubricated stern tube bearing system?Seawater is used as lubrication instead of oil and non-metallic Thordon COMPAC bearings areused in place of white metal bearings. The seawater is taken from the sea, pumped through thebearings and returns to the sea (see page 3 for illustration). Use of Thordon seawater lubricatedbearings eliminates the aft seal, as well as the storage, sampling and disposal of oil. Thepotential impact of stern tube oil pollution is zero. One significant difference, however, is that thepropeller shaft and stern tube requires corrosion protection from the seawater. Corrosionprotection may mean a higher up-front cost for the stern tube bearing system as bronze linersare recommended. However, with the elimination of the aft seal and associated maintenance,the up-front costs are recouped in lower in-service costs along with no aft seal damage worriesnor heavy pollution fines and bad publicity.Thordon Bearings: The recognized leader in seawater lubricated bearingtechnologyThordon gained its experience with seawater lubricated propeller shaft bearings with many ofthe world's Navies and Coast Guards that have almost always used seawater for their propellershaft bearings for safety reasons and for its non-catastrophic failure mode. Today however,more and more commercial ship owners are seeing the proven performance with over 2000commercial ships currently operating with Thordon seawater lubricated propeller shaft bearings.Fitted to over 2000 ships, Thordon seawater lubricated propeller shaft bearing systemseliminate the risk of oil leakage from stern seals, provide excellent operational and bearing wearperformance as well as offering lower in-service costs.1

What would a COMPAC Conversion Package include?• An assessment of original bearing loading condition• Conversion design package and work schedule• Thordon COMPAC seawater lubricated (orange) bearings• Bronze shaft liners• Thor-Coat shaft coating• Water lubricated forward seal• Thordon Water Quality PackageTactics to minimize the cost of the conversion• Conduct engineering up front to anticipate problems• Utilize standard designs• Firm quotes for work• Tie conversion into tailshaft survey cycle• Plan ahead with plenty of time in advanceReview of Existing Ship ParametersBefore considering a Thordon COMPAC conversion, Thordon Bearings will require specificinformation from the ship to determine if the ship can be converted. Thordon will review thefollowing:1) that space is available for fitting of shaft liners to Classification Society requiredthickness2) that bearing loads are acceptable to Classification Society limits for water lubricatedbearings3) to determine bearing offsets and machining such as required etc. to maintain theexisting shaft centerline alignment.Once these topics are reviewed and deemed achievable, Thordon will advise if the conversionis possible. A typical COMPAC conversion will involve the following 12 step process.2

The COMPAC Conversion ProcessA Pictorial Overview of the 12 Step ProcessSTEP 1. Engineering and suitability reviewSTEP 2. Drain Oil, remove shafts, clean and verify dimensionsInspect FWD and Aft stern tubeRemove the original white metal bearings4

STEP 3. Machine shaft liner IDSTEP 4. Heat liners to 300ºC (570ºF) for interference fit on shaftLiners are heated and shrunk fit to the shaftShaft liner installation can be done horizontallyor verticallySTEP 5. Machine OD of shaft liners to correct size and finishShaft liners are machined on lathe5

STEP 6. Shaft preparation and application of Thor-Coat shaft coatingShaft between liners is cleaned and preparedfor shaft coatingShaft is coated with Thor-Coat corrosionfree coating and anti-fouling coatingSTEP 7. If bearing carriers are required, correctly position carriers and installSTEP 8. Machining COMPAC bearings6

STEP 9. Interference fitting of COMPAC bearings via freezingStern tube housing is coated with anti-.corrosion paintBearing is cooled in liquid nitrogen andfitted into stern tubeSingle Key Design - bronze key fitted at Split Tapered Key Design - allowing bearing12:00 removal with shaft in placeSTEP 10. Refit propeller shaftShaft is fitted back into stern tubeWhen refitting shaft, care is taken to protectshaft coating from damage from chains, etc.7

STEP 11. Fit seal and confirm seal integrityInlet water pipes connected to forward sealSTEP 12. Supply clean water to bearings with a Thordon Water Quality PackageThordon single pump, single separatorWater Quality PackageThordon double pump, double separatorWater Quality Package8

ConclusionThe seawater lubricated COMPAC stern tube bearing system operates with only one(FWD) shaft seal. Proven in the toughest marine environments, Thordon Bearings offer:• reduced seal maintenance costs (no aft seal)• elimination of stern tube oil• no storage of oil• no sampling of oil• no disposal of oil• no leaking of oilThordon seawater lubricated propeller shaft bearing systems eliminate oil leakage fromstern seals resulting in zero pollution risk, provide excellent operational and bearing wearperformance as well as offering lower in-service costs.CSL Acadian converted to seawater lubricated COMPAC from oil in 20069

T H O R D O N B E A R I N G S I N C.ZERO POLLUTION | HIGH PERFORMANCE | BEARING SYSTEMS3225 Mainway Drive, Burlington, Ontario L7M 1A6 CanadaTel: +1.905.335.1440 Fax: +1.905.335.4033www.ThordonBearings.com