Naval Sea Systems Command and National Surface Treatment Center Rudder Coating Failures on Navy...
Transcript of Naval Sea Systems Command and National Surface Treatment Center Rudder Coating Failures on Navy...
Naval Sea Systems Command and Naval Sea Systems Command and National Surface Treatment CenterNational Surface Treatment Center
Rudder Coating Failures on Navy ShipsRudder Coating Failures on Navy Ships
SSPC October 2003
© 2003 Innovative Productivity, Inc. All Rights Reserved.
OutlineOutlineProblem DefinitionLab TestingAttempted Solutions; Ship TestsSummaryConclusion
The ProblemThe Problem
Problem DefinitionProblem Definition
Rudder coating failure--12-18 monthsCauses not completely understoodFails to support docking cycleHigh Cost
– Recoating rudders, struts, etc. costs $25K to $100K+ per ship
– Sole source of supply
Number of Ships AffectedNumber 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
Ship Areas AffectedShip Areas Affected
Areas Affected (DDG 51 Class)Areas Affected (DDG 51 Class)
Rudders: 700 sq ft/shipStools: 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
Problem is Unique to USNProblem 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
Possible Causes and Possible Causes and Mechanisms 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
Lab TestingLab Testing
Ocean City Research (OCRC) 1986 Tested fourteen coating systems Tests included:
– Cavitation– Cathodic Disbondment– Seawater Permeability– Seawater Immersion
Lab Testing (cont.)Lab Testing (cont.)
OCRC Testing 198816 new coatings tested (cavitation only) Issues
– Cathodic disbondment– Cavitation
Lab Testing (cont.)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
OCRC Tests FindingsOCRC Tests Findings
1990Damage modes
– Damage at cavitation inducement point– Disbondment at coating scribe– Coatings resisted either cavitation or
disbondment, but not both3M Company’s EC-2216 coating
system determined to be most promising
3M EC-22163M EC-2216Tested 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
Penn State Applied Research Penn State Applied Research Laboratory (ARL) TestingLaboratory (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
Shipboard TrialsShipboard Trials
1997Elasto-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
Shipboard Trials Shipboard Trials (cont.)(cont.)
1998Polymer 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
Shipboard Trials Shipboard Trials (cont.)(cont.)
1999HVOF tungsten-carbide coating tested
on DDG-80– Initially promising; significant damage at
PSA– Replaced with elasto-ceramic polymer
paste coating system
Shipboard Trials Shipboard Trials (cont.)(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)
Summary ofSummary ofCoating Systems and Test Coating Systems and Test
ApplicationsApplications
Polyurea Coating SystemPolyurea Coating System
Polyurea coating system (NSWCCD)No previous test data availableShip tested in:
– USS UNDERWOOD (FFG 36) – USS BULKELEY (DDG 84)– USS LEYTE GULF (CG 55)
Polyurea Ship TestsPolyurea 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
USS LEYTE GULF (CG 55)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
Elasto Ceramic Polymer PasteElasto Ceramic Polymer Paste
Tested by ARL– Performed well under cavitating flow in
fresh waterTest application on DDG-60 ruddersSpecified for new construction (DDG-
68+) Conflicting performance reports Difficult to apply (60 mils +)
Currently applied to 36 ships
Elasto-Ceramic Polymer PasteElasto-Ceramic Polymer Paste (cont.)(cont.)
Two component, 100% solids, “fluid consistency elasto-ceramic polymer composite”
“…specifically formulated to surface and protect equipment subject to cavitation accelerated erosion/corrosion”
Elasto-Ceramic Paste / Elasto-Ceramic Paste / Polymer Tile Ship TestPolymer 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
Elasto-Ceramic Paste / Elasto-Ceramic Paste / Polymer Tile Ship Test Polymer Tile Ship Test (cont.)(cont.)
Polymer Tiles at PSAElasto-ceramic paste at PSA
Elasto Ceramic Paste / HVOF Ship Elasto Ceramic Paste / HVOF Ship TestTest
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
Elasto Ceramic Paste / HVOF Ship Elasto Ceramic Paste / HVOF Ship Test (cont.)Test (cont.)
Condition of rudders after ~1.5 years
HVOF tungsten carbide (top) and elasto-ceramic paste (bottom) showed failure, corrosion of substrate
Ultra Thick Elasto-Ceramic PasteUltra 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
Ultra Thick Elasto-Ceramic Paste Ultra Thick Elasto-Ceramic Paste (cont.)(cont.)
Two component, 100% solids “elasto-ceramic polymer composite”
Expensive
– Material cost– Application cost
Ultra Thick Elasto-Ceramic Paste Ultra Thick Elasto-Ceramic Paste Ship TestShip 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
Ultra Thick Elasto-Ceramic Paste Ultra Thick Elasto-Ceramic Paste Ship TestShip Test
Condition of rudders after ~2 years
Ultra thick formulation (top): little damage
Basic formulation only (bottom): significantly more damage
Ultra Thick Elasto-Ceramic Paste Ultra Thick Elasto-Ceramic Paste Ship TestShip Test
Condition of port rudder 2 years since last docking
Repair procedure/coating system ineffective
DDG-82 Sept 03 Drydocking
Twisted RudderTwisted 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
Twisted RudderTwisted Rudder (cont.) (cont.)
Performance:– No cavitation < 29
knots
Current rudder cavitates at 23 knots
Coating requirements remain
Twisted rudder in the LCC
Twisted Rudder Coating Ship TestTwisted Rudder Coating Ship Test
Top: Loss of anti-corrosive primer and damage to substrate
Bottom: Polyurea application to rudders and propellers
Twisted Rudder Coating Ship TestTwisted Rudder Coating Ship TestUSS BULKELEY—Dec 02USS BULKELEY—Dec 02
Twisted Rudder Coating Ship TestTwisted Rudder Coating Ship TestUSS BULKELEY—Dec 02USS BULKELEY—Dec 02
Twisted Rudder Coating Ship TestTwisted Rudder Coating Ship TestUSS BULKELEY—Dec 02USS BULKELEY—Dec 02
SummarySummary
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
ConclusionConclusion
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