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Seawater Lubricated Propeller Shaft Bearings

Eliminating a source of oil pollution on ships operating in polar waters

DE 56February 13 2012February 13, 2012

Craig Carter, MBADirector of Marketing & Customer Service

Overview• Global merchant fleet uses oil lubricated shaft lines • Oil pollution discharges below the waterline – Is it a

problem?Operational dischargesAccidental discharges

• Can oil pollution discharges be eliminated?• Seawater Lubricated Propeller Shaft Bearing Systems

HistoryyCurrent TechnologyUsersPros and Cons

• Conclusion2

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Oil Lubricated Propeller

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The Suezmax tanker Vladimir Tikhonov, owned by SCF Group (Sovcomflot), passed Cape Dezhnev thereby completing her transit along the Northern Sea Route (NSR).

Shaft Bearing System

Seawater Lubricated Propeller

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The Vladimir Tikhonov tanker was escorted by the world’s two most powerful nuclear icebreakers 50 let Pobedy and Yamal following a new deep-water route to the north of the New Siberian Islands archipelago.

Seawater Lubricated PropellerShaft Bearing System

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Global Usage

• Global Commercial Fleet1

45,662 ships (vessels =>1000 GT)1.378 billion DWT

• Approx. 98% of ships use oil lubricated metal propeller shaft bearings2

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1 “Review of Marine Transport,” Report by the UNCTAD secretariat , 2011, United Nations, New York and Geneva, pp 442 Data related to Propulsion systems, IHS Fairplay database

Propeller Shafts Lubricated With Oil

• Typical stern tube system has 1500 to 3000 litres of mineral oil

OIL

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Oil Lubricated Aft Stern Tube Seal

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Stern Tube Lubricating Oil• Oil systems have been used since 1950’s

it replaced seawater lubricated wooden or phenolicbearings where shafts were required to be withdrawnbearings where shafts were required to be withdrawn ($$$) every 2.5 to 4 years for inspection (safety)

• Advantage for oil systembearing environment controlled (sealed system)allow condition monitoring

• oil sampling• temperature monitoring

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temperature monitoring

• Oil system allows for the shaft to remain in place without being withdrawn for inspection for 10 to 15 years (provided certain criteria are met!)

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Is there a risk usingoil lubricated

propeller shaft bearings ?

1) Operational oil discharges (normal operating consumption)

2) Accidental oil discharges

Operational Oil LeakageEnvironmental Research Consulting study

“Total annual inputs of lubricating oil worldwide from stern tubeTotal annual inputs of lubricating oil worldwide from stern tube leakage and other operational discharges into port waters is estimated to be between 37 million to nearly 61 million litres. If the same rates of discharge occur at sea as they do in port, the estimated worldwide annual inputs of lubricants to marine waters both in ports and harbours and at sea might be estimated to be about four times the port estimate. This assumes that each vessel spends, on average, three days at sea for every day in port.

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Total worldwide use of lubricants from operational leaks and discharges would then be about 130 million to 244 million litresannually.

Etkin, Dagmar Schmidt. Environmental Research Consulting “Worldwide Analysis of In-Port Vessel Operational Lubricant ,” Arctic and Marine Oilspill Program Technical Seminar of Environment Canada, 8 June 2010, Halifax, Canada

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Operational Oil LeakageKobelco Eagle Marine Engineering, a leading seal manufacturer states…g“In stern tube bearings, the radial movement of the shaft is considerably larger than that of bearings for general industrial application. In addition, external disturbances such as rough seas and vibration are considerable. It is impractically impossible to seal the stern tube oil perfectly. Therefore, one of the serious environmental issues in medium and large commercial vessels is stern

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issues in medium and large commercial vessels is stern tube oil leakage.”

Sada, Hiroyuki, Seiji Yamajo, David W. Hawkins and Tsuyoshi Kawazoe. Kobelco Eagle Marine Engineering Co. Ltd., Japan, “An Environmentally Compatible Lubricant for Stern Tube Shafting and Bearing Systems,” presented at the 11th Shafting Symposium of the Society of Naval Architects and Marine Engineers, Sept. 12-12 2006, Williamsburg, VA, U.S.A., pp 1.

DNV Report -Potential for High Oil Leakage Rates in Ice Operation

• Prepared for Norwegian Maritime Directoratefor consideration of Development of a Mandatory p yCode for Ships Operating in Polar Waters

• Discharges from shipping during regular operation in polar areas

• Presented at IMO DE 54 (Aug. 2010)As a potentially relative large source of operational oil discharge, however still not effectively regulated and of unknown exact

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y gmagnitude, stern tube leakage should be addressed as a particular environmental aspect in the polar environment as well as in other areas. Of particular importance under ice operation is the potential for especially high leakage rates, and the proximity to ice with regards to deposition of oil.

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Increased Oil Dischargesin Polar Waters

• Substantially more radial shaft movement d b ll h ft illi i icaused by propeller shaft milling in sea ice

• Vibration, worn seals Oil-tank

Inboard of vessel

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Oil-lost

Sealing lips Bearings

Accidental Oil Leakage

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Accidental Oil Leakage

Lloyd’s Register reports… “D f t t ti ti th l t 20 i di t th t th“Defect statistics over the last 20 years indicate that the aft stern bush represents 10% of shaft line failures, with the forward stern bush representing 4% of total failures. Interestingly, the aft stern gland (seal) and forward stern gland (seal) represent 43% and 24% of failures respectively.”

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Smith, Andrew, Lloyd’s Register Global Technology Leader-Engineering Systems ., “Shaft Alignment Problems Analyzed,” Marine Engineers Review April 2009, pp. 16

Accidental Oil LeakageSeals repaired due to oil discharges (as reported in the press since 2008)

Types of VesselsTanker 4

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Tanker 4Bulker 5Container 11Passenger/Other 6No info avail. 24

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Accidental Oil Leakage

• Typical causes of increased oil leakage f t t b l dfrom stern tube seal damage:

Fishing nets or rope caught in the propeller Propeller shaft misalignment or bent shaftsAged or worn lip sealsPropeller contact

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Propeller contactwith ice or ocean floor

Oil Slick Detectionsvia Satellite: 2008

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European Maritime Safety Agency Bulletin 2009 CleanSeaNet: Satellite-based monitoring service for marine oil spill detection and surveillance in European waters, pp 48-51

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Can oil pollution discharges below the waterline be

prevented?prevented?

…. YES!There is a proven

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proven alternativeto avoid this.

History

• Seawater as a lubricant dates back to li t d f h ft d i llearliest days of shaft driven propellers

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lignum vitae seawater lubricated bearings

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Still in Use!• Coast Guards and Navies still use seawater

lubricated propeller shaft bearingsp p g• WHY?

If shaft seals are damaged (oil leaks out or seawater leaks in), the ship is stranded!!! Seawater offers non-catastrophic safety mode

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Zero pollution risk in sensitiveenvironments

Coast Guards Know the Risks

U.S. Coast Guard Canadian Coast GuardIt has been Coast Guard policy to use water-lubricated propeller shaft bearings for all conventional propulsion shafts because we are able to get sufficiently reliable service from water-lubricated bearings and we avoid the leakage problems that inevitably occur with oil lubricated systems particularly when there is no drainable void separating the two sealed fluids. All seals leak eventually and their life can be very short when exposed to abrasives. A ti t b f i l b i

We use seawater lubricated bearings because of its non-catastrophic failure mode. If we had oil lubricated bearings and the propeller severely impacted ice, the oil seals may be damaged allowing oil leakage and subsequent damage to the sensitive Arctic ecosystem. Damage to the oil tight integrity could cause the bearings to seize on the prop shaft, leaving the ship on reduced power, or even being stranded. With using

t thi i t i Th b i

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Arctic waters can be fairly abrasive, so, there is greater risk of seal failure. For icebreaking service there are likely vibration benefits from use of elastomeric bearing materials as well.

seawater, this is not an issue. The bearings are forgiving in the harshest of ice conditions. Worthy of note that when in drydock, the effort of inspection and maintenance of these bearings are minimal.

Kevin Danahy, Propulsion Engineer U.S. Coast Guard Surface Forces Logistics CenterESD/NAME/Propulsion Systems

William G. Conway, Superintendent Vessel SupportCanadian Coast Guard- Newfoundland Region

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New Materials & Technologies

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Are Biodegradable Lubricants an Option?

• Knowledge of the effects of biodegradable oils-in-ice on the Arctic ecosystem is extremely limitedthe Arctic ecosystem is extremely limited

• There is some evidence that biodegradation may shut down at temperatures below freezing, but the reasons are not understood3

• Once bird feathers become matted in oil, weather proofing and insulating properties are lost, leading to either rapid chilling or overheating4chilling or overheating

• Leaves a sheen, and in Canada and USA is considered a pollutant and must be reported

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3 Pegau, W. Scott. “Biological Effects of Oil-in-ice in the Arctic”, Oil Spill Recovery Institute4 Berg, Catherine. “Best Practices for Migratory Bird Care During Oil Spill Response”, U.S. FISH AND WILDLIFE SERVICE, April 2002.

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Are There Commercial Ships Using Seawater Lubricated PropellerLubricated Propeller

Shaft Bearings?

• Carnival Corp., USA: 15 cruise ships + 3 on order

BP/Al k T k U S A 4• BP/Alaska Tankers, U.S.A.:4 tankers

• Carisbrooke Shipping, U.K.: 4 dry cargo ships on orderdry cargo ships on order

• Flinter Group, Netherlands: 24 dry cargo ships

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• Tidewater Corp., USA: 5 AHTS ships

N Y k Ci S I l d• New York City Staten Island Ferries, U.S.A.: 3 ferries

• BC Ferries, Canada: 10 f i10 ferries

• COSCO, China: 12 bulk carriers and 3 car carriers

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Great Lakes (USA/Canada) Bulk Carrier Fleet

• Maritime pollution laws similar to ships ti i loperating ocean-going vessels

• Higher risk of oil leakage detection• Industry leaders building new ships – all

with seawater lubricated propeller shaft bearingsbearings

Canada Steamship Lines: 5 on orderAlgoma Central Corp.: 6 on order

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Seawater Lubricated PropellerShaft Bearing System

Pros• Proven in operation for

Cons• Mild steel propeller shaft andProven in operation for

commercial ships• Life cycle costs much lower with

no aft seal and no oil consumption

• Experienced in polar waters -used by US and Canadian Coast Guard

• Mild steel propeller shaft and inside of stern tube requires corrosion protection

• May be higher upfront cost (bronze liners)

Guard• Non-catastrophic failure mode• Acoustically quieter• Zero pollution risk to a

sensitive environment

Conclusion• New materials and designs create

technical equivalenceqViable alternative to oil lubricated white metal propeller shaft bearings

• Proven operation in polar waters• Sustainable solution – available now • Eliminates oil pollution risk to the

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• Eliminates oil pollution risk to the polar environments

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Questions?

Thank you!