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 A New Salt Measuring StripEquivalent to ISO 8502-9

Paul D. Gossen

National Surface Treatment Center 

NACE International Marine Coatings Summit

October 2008

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U.S. Navy Surface Salt Testing

• Corrosion control costs US$2.4B/yr 

• Potential 20 year coatings

 – High solids epoxies

 – Rigorous QA/QC

• Surface salt testing before painting

 –  All critical surfaces: tanks, underwater hull, landing areas

 – 5 readings per 100 m2

 – Non-immersed areas < 50 mg/m2

 – Immersed areas < 30 mg/m2

• 100,000 salt tests/yr 

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ISO 8502-9 Test

• Slow: 15 minute / test• Not accurate

• Frequent failures

Water under seals

Extraction Area

deformed

Leaks

Foam stuck to steel

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Salt Test Wish List

 Analytical   • 10% at 50 mg/m2

• Detection limit below 20 mg/m2

• Insensitive to operator technique

• No cross contamination

Field Utility   • Fast - don’t delay coating application

• Reliable

• Compact, rugged, safe

• Test flat or curved surfaces

• No residue

• Auditable result

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Field Conductivity Analyzer 

• Blood Glucose Meter  – High stakes analysis

 – Low operator training

• Disposable strip – Holds sample

 – Integrated sensor electrodes

 – No contamination

• Compact field reader 

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Batch vs. Flow Extraction

• Batch Extraction – Bath

 – ISO 8502-9 Patch

• Flow Extraction – Shower 

 – Water jetting

< 85% salt extracted3.0 mL H2O

> 99% salt extracted0.6 mL H2O

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• Pregnancy Test Strip – Robust

 – Reliable

• Engineered fibermembranes – Fluid contained

 – Flow metered

 – Volume controlled

Precision fluid management

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New Concept for Salt Testing

Deionized

Water 

SUBSTRATE

Engineered fiber component #1• Flow extraction of salt• Define area (A)

Engineered fiber component #2• Absorb extract• Control total volume (V): Wash steel 2X to 20X

Onboard ConductivitySensor Electrodes

Water Flow

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Salt ExtractionPad

ExtractSolution

Reservoir 

Conductivity SensorElectrodes

Salt Extraction Strip

Patents Pending

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Salt Strip Performance on Steel

Design Performance

• at 50 mg/m2, 7%

• at 20 mg/m2, 13%

0

50

100

150

0 50 100 150

ISO 8502-9 [mg/m^2]

   S  a   l   t   S   t  r   i  p   [  m

  g   /  m   ^   2   ]

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Strip Work Flow

1. Unwrap Package 0:05

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Strip Work Flow

2. Assemble Strip 0:13

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Strip Work Flow

3. Tack onto surface 0:15

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Strip Extracting Salt

Adhesive compression strip

Defined extraction pad area

compressed against steel

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Strip Work Flow

4. Extract Salt into Reservoir 1:15

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Strip Work Flow

4. Extract Salt into Reservoir 2:15

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Strip Work Flow

4. Test Done 3:15

Fluorescent“test done”

indicator 

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Strip Work Flow

5. Remove Strip from Steel 3:15

Salt extraction area

Extracted sample &conductivity electrodes

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Strip Work Flow

6. Insert Strip into Reader 3:20

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7. Read & Save Result3:25

• Strip reader adapter  – Fits off-the-shelf meters

 – Replaces standardconductivity probe

 – Temperature compensated

• Calibrate with drycalibration strip – No calibration fluids

3:25

Strip Work Flow

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Cycle Time – 400 m2 Tank

ISO 8502-9

• 15 minutes / test

• 20 tests in 4 hours

Salt Sensor Strip

• 4 minutes / test

• 20 tests in 12 minutes

• Labor savings – US$ 285 / tank (400 m2)

 – US$ 30,000 / Navy CVN overhaul

• Paint cycle time = dry dock time

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Salt Strip Field Utility

• Fast

•  Accurate – Minimum training

 – Insensitive to technique

 – Re-wet strip to audit results

• Robust –  Any substrate curvature or

orientation

 – No leaks

 – 30 min. hold time afterextraction until analysis

• Safe, Clean, Easy – Compact

 – No needles, bottles,solvents, calibrationsolutions

 – No residue on steel• Cost Effective

 – Cost approx ISO 8502-9Patch

 – 20X faster 

 –  Adapter for off-the-shelfconductivity meters

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Interested in Testing?

• Production started• U.S. Navy field testing underway

• Strips available for qualification testing

•  Adapters for conductivity meters

 – Jenway Model 4150

 – Jenco Model 3150

• email: SaltStrip@nstcenter.com