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Soluble Salts in Coatings: Understanding, Detection, and Elimination

Learn about the impact of soluble salts on coating performance and how to reduce liability by recognizing and eliminating these contaminants. Discover sources of salts, testing methods, and the economic implications of salt-induced corrosion.

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Soluble Salts in Coatings: Understanding, Detection, and Elimination

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  1. Understanding Salts 101 Rugged Terrain Technologies, LLC A special presentation

  2. Awareness • Recognition • Elimination Objective:Reduce liability of premature coating failure. Goal: Achieve full life cycle coating performance.

  3. What are Soluble Salts? • Ionic contaminants • Water soluble inorganic compounds • Primarily chlorides, sulfates and nitrates • Non-visible contaminants

  4. Sources of Salts • Marine environments • Environmental fallout • Chemical plants • Deicing salts

  5. Salts: Osmosis and Permeation Coating failures resulting from salt induced corrosion

  6. Salt removal during Surface Preparation Why? • Salts are a leading cause of coating failure today. • ~80% of coating failures due to salts • Visual standards used are insufficient. • Visual standards were adequate for lead paint applications.

  7. Corrosion Cell

  8. Pack rust Coating failure Corrosion products Metallic pathway Cathode Anode Electrolyte

  9. Testing for Salts Two parts: • Extractions • Analysis

  10. Analysis methods Two distinct methods: • Conductivity – measures all conductive constituents. • Ion specific – measures the specific ion of concern; chloride, sulfate, or nitrate.

  11. Conductivity Method • Measures everything conductive in the sample. • Many species are not detrimental to the coating film nor induce premature coating failure. • Measures all minerals. • Conversion to chloride level is an estimate. • Assumes a lab correlation based on 100% chlorides. • Conductivity and reactivity are different.

  12. Ion specific method: • Measures the specific problematic ion. • Can measure different ions – chlorides, sulfates, and nitrates. • Reagent liquid chemicals can measure chlorides, but usually result in a range ( > to < ). • Field testing • 1. CHLOR*TEST for chlorides • 2. CHLOR*TEST ‘CSN’ for chlorides, sulfates and nitrates. • 3. CHLOR*TEST ‘W’ for water (or chemicals)

  13. CHLOR*TEST Components

  14. CHLOR*TEST ‘CSN’

  15. Quantitative Accuracy Source: KTA Laboratories

  16. Risk Levels for Soluble Salts:

  17. Bonding strength Why are salts left behind if they are water soluble? The electrochemical attachment of salts to the substrate are greater than the forces applied to remove them.

  18. Coatings Economics Goal: Achieve lowest cost/ft2/yr for the expect coating life Based on actual experience by NAVFAC since instituting revised specifications in 1995.

  19. Thank You! For further information: www.bryantfuelsystems.com

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