Tech Resources

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: 

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

The Problem: 

The Problem

Problem Definition: 

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

Number of Ships Affected: 

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

Ship Areas Affected: 

Ship Areas Affected

Areas Affected (DDG 51 Class): 

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

Problem is Unique to USN: 

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

Possible Causes and Mechanisms : 

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

Lab Testing: 

Lab 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 1988 16 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 Findings: 

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

3M EC-2216: 

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

Penn State Applied Research Laboratory (ARL) Testing: 

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

Shipboard Trials: 

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

Shipboard Trials (cont.): 

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

Shipboard Trials (cont.): 

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

Shipboard Trials (cont.): 

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)

Summary ofCoating Systems and Test Applications: 

Summary of Coating Systems and Test Applications

Polyurea Coating System: 

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)

Polyurea Ship Tests: 

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

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 Paste : 

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

Elasto-Ceramic Polymer Paste (cont.): 

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”

Elasto-Ceramic Paste / Polymer Tile Ship Test: 

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

Elasto-Ceramic Paste / Polymer Tile Ship Test (cont.): 

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

Elasto Ceramic Paste / HVOF Ship Test: 

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

Elasto Ceramic Paste / HVOF Ship Test (cont.): 

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

Ultra Thick Elasto-Ceramic Paste : 

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

Ultra Thick Elasto-Ceramic Paste (cont.): 

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

Ultra Thick Elasto-Ceramic Paste Ship Test: 

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

Ultra Thick Elasto-Ceramic Paste Ship Test: 

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

Ultra Thick Elasto-Ceramic Paste Ship Test: 

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

Twisted Rudder: 

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

Twisted Rudder (cont.): 

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

Twisted Rudder Coating Ship Test: 

Twisted 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 TestUSS BULKELEY—Dec 02: 

Twisted Rudder Coating Ship Test USS BULKELEY—Dec 02

Twisted Rudder Coating Ship TestUSS BULKELEY—Dec 02: 

Twisted Rudder Coating Ship Test USS BULKELEY—Dec 02

Twisted Rudder Coating Ship TestUSS BULKELEY—Dec 02: 

Twisted Rudder Coating Ship Test USS BULKELEY—Dec 02

Summary: 

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

Conclusion: 

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