Naval Sea Systems Command and National Surface Treatment Center Rudder Coating Failures on Navy Ships SSPC October 2003 © 2003 Innovative Productivity,

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