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Naval Sea Systems Command and National Surface Treatment Center

Naval Sea Systems Command and National Surface Treatment Center. Rudder Coating Failures on Navy Ships. SSPC October 2003. © 2003 Innovative Productivity, Inc. All Rights Reserved. Outline. Problem Definition Lab Testing Attempted Solutions; Ship Tests Summary Conclusion. The Problem.

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Naval Sea Systems Command and National Surface Treatment Center

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  1. Naval Sea Systems Command and National Surface Treatment Center Rudder Coating Failures on Navy Ships SSPC October 2003 © 2003 Innovative Productivity, Inc. All Rights Reserved.

  2. Outline • Problem Definition • Lab Testing • Attempted Solutions; Ship Tests • Summary • Conclusion

  3. The Problem

  4. Problem Definition • Rudder coating failure--12-18 months • Causes not completely understood • Fails to support docking cycle • High Cost • Recoating rudders, struts, etc. costs $25K to $100K+ per ship • Sole source of supply

  5. Number of Ships Affected • Severe coating failures: • ARLEIGH BURKE (DDG 51) class • 39 ships commissioned (10 under construction or planned) • Moderate coating failures: • TICONDEROGA (CG 47) class • 27 ships • SPRUANCE (DD 963) class • 19 ships

  6. Ship Areas Affected

  7. Areas Affected (DDG 51 Class) Rudders: 700 sq ft/ship Stools: 466 sq ft/ship Palms: 67 sq ft/ship Struts: 229 sq ft/ship Barrels: 136 sq ft/ship Total surface area affected = 1598 sq ft

  8. Problem is Unique to USN • Navy generally looks to industry for solutions • Similar commercial application • No marine driver in this case • Commercial fleets not experiencing • Transit speeds • Maneuvers • Ship Design • Shorter docking interval • Foreign Military not experiencing

  9. Possible Causes and Mechanisms • Possible causes • Ship design • Coating selection (unsuitable materials) • Likely mechanisms: • Flow-induced corrosion • Cathodic disbondment • Erosion • Cavitation/Surface Turbulence • A combination of the above

  10. Lab Testing Ocean City Research (OCRC) 1986 • Tested fourteen coating systems • Tests included: • Cavitation • Cathodic Disbondment • Seawater Permeability • Seawater Immersion

  11. Lab Testing (cont.) OCRC Testing 1988 • 16 new coatings tested (cavitation only) • Issues • Cathodic disbondment • Cavitation

  12. Lab Testing (cont.) OCRC 1989 - 1990 • Additional cavitation tests completed • Test protocol included • Total coating system thickness • Per coat thickness • Primer used • Conditions similar to previous tests, plus influence of cathodic protection

  13. OCRC Tests Findings 1990 • Damage modes • Damage at cavitation inducement point • Disbondment at coating scribe • Coatings resisted either cavitation or disbondment, but not both • 3M Company’s EC-2216 coating system determined to be most promising

  14. 3M EC-2216 • Tested by OCRC from 1986 to 1990 • Tested in seawater flow channel • Better cavitation resistance than MIL-DTL-24441 • More disbondment than MIL-DTL-24441 • Selected as baseline system • Only coating system specified in NAVSEA STD ITEM 009-32 for repair to cavitation-prone areas • Marginal performance in service

  15. Penn State Applied Research Laboratory (ARL) Testing 1996 • ARL tested cavitation properties • 1.5 inch cavitation tunnel • 115 knots for 20 hours • Tested 17 coating products • Test designed to assess metal loss due to cavitation • Test conditions were not designed to match actual rudder operating conditions • One of two coatings that showed promise was an elasto-ceramic polymer paste

  16. Shipboard Trials 1997 • Elasto-ceramic polymer coating (paste grade material) applied to DDG-60 rudders prior to sail-away • Inspected during Post-Shakedown Availability • Improvement over previous coating system • Also applied to DDG-68 rudders

  17. Shipboard Trials (cont.) 1998 • Polymer Tile surface treatment (applied via adhesively attached tiles) tested on DDG-78 • Applied with no prior test data or history • Tiles delaminated; replaced with elasto-ceramic paste during PSA

  18. Shipboard Trials (cont.) 1999 • HVOF tungsten-carbide coating tested on DDG-80 • Initially promising; significant damage at PSA • Replaced with elasto-ceramic polymer paste coating system

  19. Shipboard Trials (cont.) • Ultra thick elasto-ceramic polymer coating formulation tested on DDG-82 • Ultra thick (250 mils) patch applied to 30 sq ft of the outboard side of the stbd rudder in the area of highest stress • Basic elasto-ceramic paste formulation (60-90 mils) applied to rudders • Showed little damage during dry-dock inspection (22 months service)

  20. Summary ofCoating Systems and Test Applications

  21. Polyurea Coating System • Polyurea coating system (NSWCCD) • No previous test data available • Ship tested in: • USS UNDERWOOD (FFG 36) • USS BULKELEY (DDG 84) • USS LEYTE GULF (CG 55)

  22. Polyurea Ship Tests • USS UNDERWOOD (FFG 36) • Improper application; failed • USS BULKELEY (DDG 84) • Applied to twisted rudder, struts, props • USS LEYTE GULF (CG 55) • Applied to both rudders • Applied to SSPC-SP-10 surface

  23. USS LEYTE GULF (CG 55) • Inboard side of stbd rudder <1 year in service • Anti-fouling paint peeling off • 50% bare metal <2 years in service

  24. Elasto Ceramic Polymer Paste • Tested by ARL • Performed well under cavitating flow in fresh water • Test application on DDG-60 rudders • Specified for new construction (DDG-68+) • Conflicting performance reports • Difficult to apply (60 mils +) • Currently applied to 36 ships

  25. Elasto-Ceramic Polymer Paste(cont.) • Two component, 100% solids, “fluid consistency elasto-ceramic polymer composite” • “…specifically formulated to surface and protect equipment subject to cavitation accelerated erosion/corrosion”

  26. Elasto-Ceramic Paste / Polymer Tile Ship Test • Tested on USS PORTER (DDG 78) in ‘97 • Elasto-ceramic polymer paste applied by troweling; 60+ mil thickness • Failed in area of highest stress • Polymer tile system applied via adhesively attached tiles • Tiles delaminated

  27. Elasto-Ceramic Paste / Polymer Tile Ship Test (cont.) Polymer Tiles at PSA Elasto-ceramic paste at PSA

  28. Elasto Ceramic Paste / HVOF Ship Test • Both systems tested on USS ROOSEVELT (DDG 80) in 1999 • HVOF tungsten carbide coating applied to 40 sq ft area of port rudder • Elasto-ceramic polymer paste applied to remainder of port rudder, entire starboard rudder

  29. Elasto Ceramic Paste / HVOF Ship Test (cont.) • Condition of rudders after ~1.5 years • HVOF tungsten carbide (top) and elasto-ceramic paste (bottom) showed failure, corrosion of substrate

  30. Ultra Thick Elasto-Ceramic Paste • No laboratory testing • Applied to various ships; mixed results • Difficult to apply • Unusually thick coating (250 mils) • Used as barrier layer in high cavitation areas • Topcoated with basic elasto-ceramic paste formulation

  31. Ultra Thick Elasto-Ceramic Paste (cont.) • Two component, 100% solids “elasto-ceramic polymer composite” • Expensive • Material cost • Application cost

  32. Ultra Thick Elasto-Ceramic Paste Ship Test • Tested on USS LASSEN (DDG 82) in 1999 • Ultra thick elasto-ceramic paste formulation • ~30 sq ft on starboard rudder • 250 mils • Feathered at the edges • Basic formulation then applied to both rudders at 60 mils

  33. Ultra Thick Elasto-Ceramic Paste Ship Test • Condition of rudders after ~2 years • Ultra thick formulation (top): little damage • Basic formulation only (bottom): significantly more damage

  34. Ultra Thick Elasto-Ceramic Paste Ship Test • Condition of port rudder 2 years since last docking • Repair procedure/coating system ineffective DDG-82 Sept 03 Drydocking

  35. Twisted Rudder • Developed by NSWCCD • Twisted to align with propeller wash • Designed to reduce cavitation on rudder • Tested at NSWCCD’s Large Cavitation Channel (LCC) • Ship tests on USS BULKELEY (DDG 84) • Rudders installed Feb 00 • Polyurea installed Feb 01

  36. Twisted Rudder (cont.) • Performance: • No cavitation < 29 knots • Current rudder cavitates at 23 knots • Coating requirements remain Twisted rudder in the LCC

  37. Twisted Rudder Coating Ship Test • Top: Loss of anti-corrosive primer and damage to substrate • Bottom: Polyurea application to rudders and propellers

  38. Twisted Rudder Coating Ship TestUSS BULKELEY—Dec 02

  39. Twisted Rudder Coating Ship TestUSS BULKELEY—Dec 02

  40. Twisted Rudder Coating Ship TestUSS BULKELEY—Dec 02

  41. Summary • Multifaceted problem • But limited area; not tying ships to the pier • A costly annoyance (for now) • ICCP System designed to protect up to 15% of underwater hull • Inadequate laboratory testing • No root cause analysis • To date, the Navy has found no cost-effective solution to the rudder coatings failures

  42. Conclusion • No coating system currently approved or previously tested provides a viable, cost effective solution • The Navy is still seeking a coating system that will last for at least one full docking cycle (6-8 years) • Candidate coatings must allow application in a shipyard environment at a reasonable cost

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