student guide - the society for protective · pdf filestudent guide august 2010 / version 10....

NAVSEA BASic PAiNt

iNSPEctor trAiNiNg

Developed under the direction of NAVSEA 05M1 by Naval Surface Warfare Center, Carderock Division, Code 614.

Student Guide

August 2010 / Version 10

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NAVSEA Basic Paint Inspector Training:Schedule

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1. IntroductionPreamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1—1Course Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1—5Course Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1—6Course Completion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1—6Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1—7Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1—8

2. CorrosionGeneral Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—1Corrosion Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—2Electrochemical Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—3Anodes and Cathodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—4General Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—5Galvanic Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—5Types of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—6

Uniform Surface Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—6Dissimilar Metal Corrosion (Galvanic) . . . . . . . . . . . . . . . . . . . . 2—7Pitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—7Crevice Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—8Stress Corrosion Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—8Intergranular Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—8Exfoliation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—9

Environmental Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—10Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2—10

3. Corrosion ControlBarrier Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3—2Sacrificial Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3—2Inhibitive Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3—3Cathodic Protection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3—3

Sacrificial Anode Cathodic Protection . . . . . . . . . . . . . . . . . . . . . 3—3Impressed Current Cathodic Protection (ICCP) Systems . . . . . . . 3—4

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3—6

Table of Contents

SECTION PAGE NUMBER

NAVSEA Basic Paint Inspector Training: Table of Contents

TOC—ii

4. NAVSEA DocumentsNSTM Chapter 631 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4—1NAVSEA Standard Item 009-32 Overview . . . . . . . . . . . . . . . . . . . . 4—4NAVSEA Standard Item 009-04 Overview . . . . . . . . . . . . . . . . . . . . 4—4NAVSEA Coating Performance Specifications . . . . . . . . . . . . . . . . . 4—4NSTM Ch . 631 Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4—5Documentation Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4—8Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4—9

5. Non-Mechanical Cleaning MethodsSolvent Cleaning (SSPC-SP 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—1Acid Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—2Steam Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—3Pickling (SSPC-SP 8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—3Alkaline Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—3Detergent and Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—4Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—6

6. Mechanical Cleaning MethodsHand and Power Tool Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6—1Power Too Cleaning to Bare Metal . . . . . . . . . . . . . . . . . . . . . . . . . . 6—3Commercial Grade Power Tool Cleaning . . . . . . . . . . . . . . . . . . . . . 6—4Factors Affecting Surface Preparation . . . . . . . . . . . . . . . . . . . . . . . . 6—4Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6—5

7. Abrasive Blast CleaningAbrasive Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—1Abrasive Blast Cleaning Specifications . . . . . . . . . . . . . . . . . . . . . . . 7—3

Characteristics of Degrees of Blasting . . . . . . . . . . . . . . . . . . . . . 7—4Abrasive Blasting of Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—5Environmental Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—7Surface Profile and Residual Chloride . . . . . . . . . . . . . . . . . . . . . . . . 7—7ISO 8502-3 Dust Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—10Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—11Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—11

8. Waterjetting and Alternate Surface Preparation MethodsWaterjetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—1

Types of Waterjetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—2Specifying and Inspecting Waterjetted Surfaces . . . . . . . . . . . . . . . . 8—4Alternative Blasting Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—6

Wet (Slurry) Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—6Bicarbonate of Soda Stripping . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—6Ice Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—7Carbon Dioxide Pellets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—7Sponges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—8

New Coating Removal Technology and Trends . . . . . . . . . . . . . . . . . 8—8Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8—9

SECTION PAGE NUMBER


TOC—iii

9. Surface Preparation Method SelectionMethod Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—1Substrate Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—2

Previously Painted Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—2Metallic Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—2Galvanized Steel Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—2Aluminum Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—3

Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—3Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9—4

10. CoatingsPaint Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—2Volatile Organic Compounds (VOCs) . . . . . . . . . . . . . . . . . . . . . . . . 10—4Elements of a Coating System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—5Typical Navy Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—6

Silicone Alkyd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—6Fire Resistant Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—6Epoxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—6Antifouling Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—8Polyurethane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—9Zinc-Rich Primers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—10Polysiloxanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—10Rust converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—10

Curing Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—11Evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—11Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—12Polymerization by Crosslinking . . . . . . . . . . . . . . . . . . . . . . . . . . 10—12

Data Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—13Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—13Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—14

11. SafetyMaterial Safety Data Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—1NFPA Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—3Personal Protective Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—5

Eye Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—5Foot Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—5Hand Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—6Respirators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—6Hearing Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—7Protective Clothing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—7Hard Hats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—8

Safety for Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—8Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—9

SECTION PAGE NUMBER


TOC—iv

12. Coating ApplicationPaint Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—1Paint Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—2Induction Time and Pot Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—3Environmental Requirements for Paint Application . . . . . . . . . . . . . 12—3Application Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—4

Brushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—4Rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—4Conventional Spray Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—5Airless Spray Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—6High Volume Low Pressure Coatings Application . . . . . . . . . . . . 12—6Plural Component Spray Systems . . . . . . . . . . . . . . . . . . . . . . . . 12—7

Paint Thickness Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—7Paint Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—8Paint Application Inspection Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—10Paint Clean-Up and Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—10Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—11PA 2 Team Exercise (Mandatory) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—13Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—18

13. Coating Defects and FailuresTypical Paint Failures on Metallic Substrates . . . . . . . . . . . . . . . . . . 13—1

Bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—2Blistering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—2Chalking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—2Checking (Alligatoring) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—3Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—3Delamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—4Fish Eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—4Mud Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—4Orange Peel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—4Dry Spray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—4Overspray (also Dry Spray) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—5Pinholing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—5Pinpoint Rusting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—5Sags (also Runs or Curtains) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—5Undercutting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—6Wrinkling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—6Cratering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—6

Prevention of Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—6Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13—7

14. Specialty Coatings and SurfacesComposites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—1Special Hull Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—2Sonar Domes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—3Passive Countermeasure System Materials . . . . . . . . . . . . . . . . . . . . 14—3Powder Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—4

SECTION PAGE NUMBER


TOC—v

Thermal Spray Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—6Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—8

15. Coating Inspector PreparationCoating Work Plan and Inspection Plan . . . . . . . . . . . . . . . . . . . . . . . 15—1Pre-Job Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—2References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—3Certified Coating Inspectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—5NAVSEA Standard Item 009-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—6Cleaning and Painting Requirements; Accomplish . . . . . . . . . . . . . . 15—6Team Exercise (Mandatory) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—7NAVSEA Standard Item 009-32 Team Exercise (Mandatory) . . . . . . 15—8Inspection Plan Team Exercise (Mandatory Homework) . . . . . . . . . 15—10Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—10

16. Condition AssessmentBasic Inspection Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—1Documentation of Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—3Preservation Program and Planning . . . . . . . . . . . . . . . . . . . . . . . . . . 16—3Shipboard Corrosion Survey Guidance . . . . . . . . . . . . . . . . . . . . . . . 16—4

Corrosion Prone Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—4NAVSEA Technical References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—5Paints Containing Lead, Cadmium, and Chromate . . . . . . . . . . . . . . 16—6CCIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—7

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—7Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—8Coatings and Corrosion Assessments . . . . . . . . . . . . . . . . . . . . . . 16—8Equipment Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—8Tank and Void Inspection Form . . . . . . . . . . . . . . . . . . . . . . . . . . 16—8Underwater Hull Inspection Form . . . . . . . . . . . . . . . . . . . . . . . . 16—9Dry Docking Report Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—9Paint Condition Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—10Evaluation of Blisters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—11

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—12

17. NonskidTypes of Nonskid Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17—1Nonskid Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17—4Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17—7

18. Instrument ExercisesPurpose and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—1Daily Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—1

Day 1 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—1Day 2 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—3Day 3 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—4Day 4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—5Day 5 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—8

SECTION PAGE NUMBER


TOC—vi

Appendix A: Homework Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . A—1Appendix B: Conversion Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B—1Appendix C: Glossary of Terms/Acronyms . . . . . . . . . . . . . . . . . . . . . . C—1Appendix D: Corrosion Control PMS MIPs . . . . . . . . . . . . . . . . . . . . . D—1Appendix E: Instrument Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . E—1

SSPC-VIS 1: Guide and Reference Photographs for Steel Surfaces Prepared by Dry Abrasive Blasting . . . . . . . . . . . . . . . . E—1

Testex Tape and Micrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—1Surface Thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—2Sling Psychrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—2Psychrometric Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—3Wet Film Thickness (WFT) Gage . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—3Magnetic Pull-Off Dry Film Thickness (DFT) Gage . . . . . . . . . . . . . E—4Fixed Probe Dry Film Thickness (DFT) Gage . . . . . . . . . . . . . . . . . . E—4Low Voltage Holiday Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—5Conductivity Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E—6

Appendix F: SSPC/NACE Standards . . . . . . . . . . . . . . . . . . . . . . . . . . F—1SSPC-SP 1: Solvent Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F—1SSPC-SP 2: Hand Tool Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . F—3SSPC-SP 3: Power Tool Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . F—5SSPC-SP 5/NACE No . 1: White Metal Blast Cleaning . . . . . . . . . . . F—7SSPC-SP 6/NACE No . 3: Commercial Blast Cleaning . . . . . . . . . . . F—13SSPC-SP 7/NACE No . 4: Brush-Off Blast Cleaning . . . . . . . . . . . . . F—19SSPC-SP 8: Pickling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F—25SSPC-SP 10/NACE No . 2: Near-White Blast Cleaning . . . . . . . . . . . F—27SSPC-SP 11: Power Tool Cleaning to Bare Metal . . . . . . . . . . . . . . . F—33SSPC-SP 12/NACE 5: Surface Preparation and Cleaning of

Metals by Waterjetting Prior to Recoating . . . . . . . . . . . . . . . . . . F—39SSPC-SP 15: Commercial Grade Power Tool Cleaning . . . . . . . . . . . F—51SSPC-SP 16: Brush Off Blast Cleaning of Coated and Uncoated Galvanized Steel, Stainless Steels, and Non-Ferrous Metals . . . . . . . . . . . . . . . . . . F—57SSPC-PA 2: Measurement of Dry Coating Thickness

with Magnetic Gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F—63Appendix G: Psychrometric Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . G—1Appendix H: Preservation Process Instruction Core . . . . . . . . . . . . . . H—1Appendix I: Hazardous Materials Users Guide (HMUG) . . . . . . . . . . I—1Appendix J: Preservation Departures from Specifications

Process Decision Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J—1Appendix K: NAVSEA Approved Preservation

Process Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K—1Appendix L: Paint Failure Photographs . . . . . . . . . . . . . . . . . . . . . . . . L—1Appendix M: Calculation Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M—1Appendix N: Documentation Team Exercise Supporting

Documents (Page 4—8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N—1Appendix O: SSPC Guide for Planning Coatings Inspection . . . . . . . . . . . . . . .O—1

SECTION PAGE NUMBER

This course will teach you the steps needed to make sure that painting done on Naval vessels will be of high quality and will last as long as possible. In this sense, the course is really about painting Quality Assurance (QA). It is not intended to train you in assessing the condition of paints and coatings that have been in service. However, there will be some discussion on coatings assessment in a later chapter for your information.

Topics Overview of:

Certified paint inspector duties•Formal inspection responsibilities•Course objectives•

Scope This unit provides an overview of the NAVSEA Basic Paint Inspector Course and the course learning objectives.

Learning OutcomesAt the end of this course, the student will be able to:

Plan the job•Recognize chain of authority (Technical Authority)•Appreciate coatings assessment•Select surface preparation methods and proper coatings•Measure environmental conditions•Evaluate newly painted surfaces•Appreciate the practical aspects of the preservation process•Identify health and safety precautions•Locate preservation information•

The duties you will perform, if certified as a paint inspector, will vary greatly depending on the job. These duties may include:

• Conductingformalinspections• Assisting other Naval activities in paint and coatings related quality

assurance issues• Conductingtrainingsessionsfortheship’sforce

1 Introduction

NAVSEA Basic Paint Inspector Training: Introduction

1—2

The best way to be ready for all of these responsibilities is to prepare ahead of time. This includes thoroughly reading and understanding both specification and work item, applicable Product Data Sheets (PDS), and applicable Material Safety Data Sheets (MSDS). By understanding the nature of the work to be completed, you will have a better idea of what type of measurements you will need to take as well as at what stages of the work you will need to be on hand for.

During a formal inspection you will be responsible for:• Attendingthepre-jobmeeting• Affirmingpropersafetypracticesarefollowed• Evaluating the condition of the surface after surface preparation is

complete and immediately prior to application• Ensuring thepaint systemhasnot exceeded its shelf life and that the

condition of the paint in the can is good• Ensuringthepropercoatingsareused• Ensuringthecoatingisproperlyapplied• Measuringenvironmentalconditions• Measuringcoatingdryfilmthickness• Recordingalldataaccurately,completely,andconcisely• Writingafinalreport

These responsibilities will be discussed in greater detail throughout the rest of this course.

NAVSEA Technical Authority is the authority to Establish and Approve theNAVSEAtechnicalspecificationsforUSNavyships.Waterfrontexecutionof Technical Authority is a process of Maintaining, Enforcing, and following those specifications to ensure a safe and reliable system is delivered to the Fleet.

NAVSEA technical specifications can be questioned, but the questions mustbeansweredbytheRegionalMaintenanceCenter(RMC)orSupervisor’sEngineering Department. If the NAVSEA technical specification cannot be followed, then the Technical Authority process will generally lead to the identification of a range of technically acceptable alternatives to resolve an engineering issue, along with associated risk and value assessments. Final dispositionforanon-conformancelieswithin theregion’sTechnicalWarrantHolder.Noothershavethisauthority.Anapprovednon-conformancemustbesigned by aNAVSEATechnicalWarrant holder before proceedingwith anychangetoNAVSEAtechnicalspecifications(009-32orNSTM631).

In September 2006, NAVSEA created a “Preservation Departures fromSpecifications (DFS) Process Decision Tree.” This Decision Tree provides guidance for handling out-of-specification conditions on critical coatedsurfaces. This table does not apply to NAVSEA 08 cognizant spaces as described in NAVSEA Instruction C92210.4, which specifically includes potable water tanks and reserve feed tanks. Rather, it describes at what level of

VERSIONS

• Thefollowingdocumentswereused in the creation of this manual and the accompanying slides

• NAVSEAStd.Item009-32• NSTMCh.631• NSTMCh.634• CorePPI-63101-000

• QAhelpstoprovidethebestquality preservation to protect the Navy’sassetsforaslongaspos-sible

• RequiredbyNSTMChapter631for critical coated areas

• MayberequiredbyCommand

WHY QA>

Navy Basic Paint Inspector Training: Introduction

1—3

authorityanout-of-specificationdecisioncanbeacceptedbasedon the“riskthreshold” of premature coating failure. A copy of the Decision Tree is included inAppendixJ.

All DFSs must be concurred to by the TYCOM. Unless otherwise specified, actiontodocumentanout-of-specificationconditionstillrequiressubmittaloftheStandardItem009-32QAInspectionForm.

Non-conformingconditionsorcircumstanceswherethetechnicalprocessis not being followed must be reported. All questions or needs for clarifications of NAVSEA specifications should be submitted to the RMC Engineering Department.

On today’s complexNaval vessels, there are awide variety of coatingsappliedtoadiverserangeofsurfaces.Examplesincludecommoncoatingsusedforcorrosionpreventionandcosmeticappearance,suchasepoxiesandsiliconealkyds,aswellasspecialfunctioncoatingssuchasnonskid,anti-fouling,andothers. Examples of surfaces where coatings are applied include commonmaterials such as steel, aluminum, and stainless steel, as well as special materials such as composites, passive countermeasure systems (PCMS), thermal and acoustic insulation, and special hull treatment (SHT) materials. This course is not intended to provide you with the details of applying all types of coatings over all types of surfaces. Overviews of some of the special application items are included, but most importantly, you should come out of this course with the knowledge of where to turn for further guidance for these specialty coating applications.

There are several reasons this course was developed for the Navy and for your attendance here. These include:

• The need to make all painting performed on Naval vessels last as long as possible, in order to minimize ship’s force maintenance andcosmetic recoating, minimize the amount of hazardous waste produced during surface preparation steps (paint chips, dust, etc.) and minimize the Navy’s usage, storage, and handling of the hazardous materialsassociated with paints, cleaners, and solvents.

• The addition ofQualityAssurance requirements in Section 11 of theNovember 1992 revision ofNaval Ship’sTechnicalManual (NSTM)Chapter 631, “Preservation of Ships In Service.” This NSTM is thegoverning document for almost all painting performed on Naval vessels and equipment,whether it is performed by ship’s force, intermediatemaintenance activities, shipyards or contractors. The QA requirements inNSTMChapter631predominantlyapplytodefined“criticalcoatedareas” such as the underwater hull, tanks and nuclear spaces, but they may be specifically invoked from time to time on other areas or equipment which require a high level of coating quality to prevent corrosion. For critical coated areas, trained and certified coatings inspectors are required to verify proper material storage and receipt inspection, verify key data points in the painting process such as environmental conditions, surfacecleanliness,surfaceroughness“profile,”dryfilmthickness,andsign off on key checkpoints in the painting process.


1—4

• The implementation of various types of Type Commander directedshipboardpreservationprogramsdesigned tobe carriedout by ship’sforce, RMC’s (Regional Maintenance Centers), or other militarypersonnel. An example is the “Scheduled Preservation UpkeepCoordinated Effort” (SPRUCE) program conducted on submarines, which relies on a coordinator who has been trained in coatings application QA.

After successfully completing this course you should be able to:• Planthestepsneededtodoaqualitysurfacepreparationandpainting

job, or interpret the applicable steps that are contained in a previously prepared work specification.

• Recognizechainofauthority(TechnicalAuthority).

• Appreciatecoatingsassessment.

• Select the appropriate surface preparation method and type of paintfor the area of the vessel to be painted, if not pre-determined by theapplicable work specification.

• Usethebasicmeasurementtoolsandindustrystandardsthatacoatingsinspector needs to determine if the environmental conditions (weather, etc.) are suitable for painting, if the surface is as clean as it should be, ifithastheright“profile”beforepaintingisstarted,andifthewetanddry film thicknesses of the applied paint are correct for the area being painted.

• Evaluatethenewlypaintedsurfaceforworkmanshipandpaintdefects,and recommend corrective actions.

• Appreciatethepracticalaspectsofsurfacepreparationandpaintingthata sailor or contractor may face on a Naval vessel.

• Identify the appropriate precautions that must be taken to ensurethe health and safety of personnel involved in surface preparation and painting operations, and the protection of the environment from pollution caused by these operations.

• Find the rightsourceof information inorder toansweranyquestionsthat you may not know the answer to.

Ofcourse,noteveryonewhotakesthistrainingwillhaveexactlythesameneeds and roles to play in Naval vessel painting. This will vary according to the paintingjobthatyoumaybeassignedtoinspectoroversee.Forexample:

• IfyouarefromaNavalShipyard,youmayberesponsiblefortheroleofacoatingsQAinspectorforin-houseworkgovernedbyNSTMChapter631.IfyouarefromaNavyRMCOrganization,youmayberesponsibleforcriticalandnon-criticalareaworkgovernedbyNAVSEAStandardItems 009-32 or 009-28, you may be responsible for signing offcheckpoints. You will mainly oversee work performed by shipyard or


1—5

COURSE OBJECTIVES

This course is not surface ship or submarine specific. The participants will be trained in the preservation materials using basic coating and inspection techniques which apply to both. Following this course, the trainee will be able to:

1. Define and identify:• Anode• Cathode• MetallicPath• Electrolyte

2. Describe and identify different types of corrosion.3. Describemethodsofcorrosioncontrol.

contractorpersonnel,inaccordancewithanexistingworkspecificationthatpre-definedthesurfacepreparationandcoatingtobeused.

• IfyouarefromanRMCorReadinessSupportGroup(RSG),youmaybe overseeing shore-based or shipboard coatings work performed bymilitary personnel. There may not be a detailed work specification for the coatings work being performed, so you may have to rely more on usingNSTMChapter631forthecoatingrequirements.

• IfyouareasubmarineSPRUCEcoordinator,orfromoneoftheRMC’s,you may be overseeing programmed shipboard coatings work performed by ship’s force. You may have more responsibility with respect toplanning and scoping the work required, selecting the appropriate surface preparation and coating, and providing technical assistance to ship’sforce in everything from selection of personal protective equipment to solving a specific problem.

Others who take this course may do so mainly for informational purposes, or to gain an appreciation of the factors that must be considered when performing Naval coatings work. These may include people responsible for planning and specifying coatings work to be performed during upcoming availabilities (PERAs,SUBMEPP,TYCOMs),orspecificequipmentIn-ServiceEngineeringAgents (ISEAs) who have specialized coatings needs for their equipment.

Note that successful completion of this course, even if certified, does not qualify you as a coatings inspector “authorized to represent NAVSEA” asdescribed in NSTM Chapter 631. The responsibility for proper applicationincluding all associated processes for the application of the coating systems resides with the contractor”. For contracted preservation work, the government acceptanceroleistypicallyundertheexecutingRMCoffice.


1—6

REMEMBER:

• HomeworkassignmentsareinAppendixA

• Reviewtheday’snotesinprepara-tionfortomorrow’squiz

SSPC

• SSPC’saddress:

4024thStreet,6thFloor

Pittsburgh,PA15222-4656

• SSPCcanbecontactedat:

412-281-2331ext.2206or

1-877-281-7772

4. BeabletouseandreferenceNSTMChapter631asitpertainsto:• Safety• Inspectiongages• Surfacepreparation• Paintapplication• Submarinecoatingissues

5. Describe and demonstrate the use of environmental tests and coating inspection instruments.

6. Describehowtoproperlypreparesurfaceforcoating.7. Describehowtoproperlyapplypaint.8. Identify Navy single and multiple part paints.9. Describe and identify different types and functions of Navy coatings.10.Explainandidentifydifferentcausesofcoatingfailuresordefects.11. Maintain or create a coating inspectors log book and record all key data and

information associated with a coating job.12. Check the shelf life and condition of paint in the can, and ensure that

expiredmaterialsarenotusedand,ifapplicable,disposedofproperly.13. Identifycoatingsprocessproblems.14.Ensure abrasive blasting requirements are met and documented IAW

NSTMChapter631.15. Conduct post blasting/post surface prep inspection including condition of

surface, profile, residual soluble salts and readiness to paint.16.Ensure environmental conditions for painting are IAW NSTM 631

requirements.17.Ensure paint procedures are IAW NSTM 631 and paint manufacturers

instructions.18.EnsureallcoatsofpaintareproperlydriedandcuredperNSTM631.19. Ensure painted areas are inspected for workmanship.20. Demonstrate awareness of the newest technologies and latest Navy related

information on new paints and processes.21. Identify and use the most appropriate safety equipment.22. Demonstrate an awareness of hazardous areas related to paint and coatings

and their applications.23. Identifyapplicabletechnicaldocumentation.

COURSE OBJECTIVES (continued)


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COURSE COMPLETION

COURSE GRADING

During theweek, youwill begiven awritten exam, an instrument examwith data entered into a log book and a specification navigation exam. Thescores from each of these will be used to determine your final score for the course.All testsandquizzesaretaken“closedbook”except thespecificationnavigationsegment,whichisanopenbookexam.

In order to pass this class you must earn a minimum of 80% on each component. Upon successful completion of this course, you will receive acertificateandyournamewillbeenteredintoaNavy-widedatabaseacknowledging achievement of paint inspector training for quality assurance.

To become certified, a person has to complete the NBPI training and pass theNBPICertificationExamwithaminimumscoreof80%oneachpart.Inaddition to passing the course, the person must also document that he/she has aminimumof2yearsexperiencewithmarinecoatings.100%oftheperson’sactual work time does not have to be dedicated to marine coatings so long as dealingwith“marinecoatings”ispartoftheperson’snormaljobduties.Uponapproval of their application, candidates can sit for the NBPI certification exam.Thecertificationtermwillbefouryearsfromthedateofthesuccessfulcompletionofthecertificationexam.

Entry level persons are still welcome to take the course but they will not be abletoobtaincertificationuntiltheygaintherequisiteexperience,regardlessof whether they pass the NBPI course.

• The personwithout the 2 years of experience is allowed to take theNBPITrainingandexams.

• Thepersonwouldbesentaletterafterthetrainingstatingthatyoutook40 hours of training.

• If thepersonwithout theexperiencepassed theNBPI test, thepersonwouldbeallowedtosubmitaletterwithattestationsofexperienceinthefuture(i.e.,aftertheygettherequiredyearsofexperience)toallowhim/hertogetNBPIcertificationwithoutre-takingthecertificationtest.

Forexample,apersontakingtheclasswith18monthsofexperiencewouldbe allowed to submit a letter with the required references after he/she completes sixmonthsofadditionalexperience.Theletterwouldattesttothefactthattheindividualcompletedhisexperiencerequirements,passedthetestandassuchshould be certified.

• Beforehe/shehas the fullNBPICertification, thepersonwhosimplycompletedthetrainingwouldnotbeallowedtocertifycritical-coated-area work but would be allowed to work under supervision of an individualwithfullNBPIcertificationtogaintherequiredexperience.

• Ifhe/shetakestheNBPITrainingandfailstheexamyouwouldhavetore-taketheclass.


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One of the most important parts of your job will be to function as a member of a team. Communication and consensus are essential for any effective team. With this in mind, you will be made part of a team that will get togetherperiodically throughout this training. At the direction of your instructor(s), get together with your team and do the following:

1. Team Name Decide on a team name that represents your group, their purpose and their

intentions during this training.

2. TeamExercise Developa“Top10”listofthingsyourteamwantstolearnorgetoutofthis

course.

3. MakePresentationSummary Onflipcharts,summarizeyourteam’sworkonthisexerciseandprepareto

delivera3-5minutepresentationtotheentiregroup.Selectaspokespersonto make your presentation.

TEAM EXERCISE

All individuals who have been certified prior to the implementation of the newcertificationprogramwill retain their certification statusuntil theirnextscheduled renewal date.

SSPC maintains the database for all certified coatings inspectors in the program regardless of where they took their NBPI training or certification exams.ThisinformationislocatedontheSSPCMarketPlacewebsiteathttp://www.http://shopping.netsuite.com/sspcmarketplace.

Certified Coating Inspectors from the Navy Basic Paint Inspector (NBPI) course will be listed on the web site of SSPC: The Society for Protective Coatings at www.sspc.org. The site will list complete contact information, if provided,includingname,company,address,phone,fax,e-mailandexpirationdate. Updates for inspector contact information should be sent to SSPC: The Society for Protective Coatings at 40 24th Street, Pittsburgh, PA 15222, [email protected].

NBPI Certified Inspector status may be maintained for four years. Inspectors have to take an open book refresher exam online and pass with an 85% tomaintain certification. Full details about NBPI Recertification are available at http://www.sspc.org/training/nbpi_recert.html.

2 Corrosion

Topics• Componentsnecessaryforcorrosion• Thegalvanicseriesandgalvaniccorrosion• Commontypesofcorrosiononships• Environmentalfactorsthatcontributetocorrosion

Scope Thissectionacquaintsstudentswiththebasicprinciplesofcorrosion,espe-ciallythosethatoccurmostfrequentlyonNavyships.

Learning OutcomesAttheendofthissection,thestudentwillbeableto:

• Identifythebasicprinciplesofcorrosion.• Recognize the different types of corrosion most likely to occur onships.

• Discusstheenvironmentalfactorsthatacceleratecorrosionandthemostcorrosiveareasonships.

Corrosionofmetalsisdefinedastheirchemicalorelectrochemicalreactionwith the environment that results in their loss ofmaterial and/or properties.Whyshouldyoubetaughtthebasicsofcorrosioninacourseaboutthequalityassurance of coatings on ships? It is because an understanding of how themetal components of ships corrode will help you understand how best tocontrolthiscorrosionbyusingcoatings.Someshipmetalsaremorecorrosivethanothers,andthusrequiremoreeffectivecoatingsystems.Also,someshipareasaremorecorrosivethanothershipareasandsorequireadditionalcoatingprotection.Notonlyisthepropercoatingsystemselectionimportant,butalsopropersurfacepreparationandcoatingapplicationarenecessaryforoptimumcorrosioncontrol.

The overall cost of corrosion and related impact to the United Stateshas recentlybeenestimated tobeon theorderof$276billionperyear. It isestimatedthattheUnitedStatesNavyspends$1billioneachyearincorrosionrepair,prevention,andcontrolforships. Ifnothingisdonetohaltcorrosion... ...itgetsworse. ...thelaterrepairsaremorecostly. ...theprideofownershipishurt. ...maintenancebecomesdifficult. ...fleetreadinessmaybecompromised.

NAVSEA Basic Paint Inspector Training: Corrosion

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Metalscorrodebecausetheyareunstableinthefreemetallicstate.Thus,energymustbegiventometalsinthesmeltingprocesstoraisethemtoahigherenergybutlessstablestate,andlater,duringuse,thefreemetalscorrode(oxide)to return toa lower,morestablecondition(seeFigure2-1). In theoxidationprocess,themetalsgiveupelectronsthatareconsumedinothermetalareasintheoverallcorrosionprocess.Metalareasthatcorrodearecalledanodes,andthosethataccepttheelectronsandarenotcorrodedarecalledcathodes.

Figure 2-1: The Corrosion Cycle

CORROSION CYCLE

Allofushavewitnessedvariousformsofcorrosionsinceitisacontinuousprocesswhichoccurseverywhere.Wealsohaveageneralawarenessofwhatcauses corrosion. For instance, if there were a stream bed with three itemsin it, a steelnail, apieceofgold jewelry, andaplastic toy sailor,wewouldcorrectlyguessthatthenailwouldcorrodeawaywithinafewyearswhilethegold jewelry would be unharmed indefinitely. The toy sailormight discolorand look generally ugly but would essentially be intact after several years.However, if the environmentwere different, such as in the desert,we knowthattheresultingreactionswouldoccurdifferently.Inthehot,dry,andsunnyenvironment, the nailmight remain undamaged for centurieswhile the goldwouldremainunharmedbytheenvironment.Ofcourse, the toysailorwoulddeterioratedowntodustinjustafewyears.Again,thetypeofmaterialandthetypeofenvironmentarebothimportantinunderstandingcorrosion.

TheNavyconstructsvirtuallyallofitsshipstructuresusingmetals,mainlysteel, and by definition has an abundance of wet environments to contendwith, most having seawater as a principal component. Therefore, in thefollowingdiscussionsregardingcorrosion,seawaterandsteelarethemostusedexamples.

Forthepurposesofthiscourse,corrosionisthedeteriorationofmetaldueto reactionwithwet environments.Metals includeall that areusedonNavyshipsincluding,butnotlimitedtothecommonsteels,corrosionresistantsteels,copperalloys,nickelalloys,titaniumalloys,andaluminumalloys.Corrosionofmetalsinawetenvironmentisreferredtoaselectrochemicalcorrosion.

Navy Basic Paint Inspector Training: Corrosion

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The natural tendencies ofmetals to corrode in a particular environmentaremeasured in volts as chemical and electrochemical potentials.Voltage isameasureofthe“pressure”ofthemobileelectronscontainedinametal.Itissometimesreferredtoastheelectromotiveforce(EMF).Itcanbecomparedtothepressureofwaterinagardenhose.Thewaterrepresentstheelectronsandthehoseisthemetalconductor.Ifthewaterpressureatoneendofthehoseishigherthanthepressureattheotherend,thenwaterwillflowtowardthelowerpressureend. Inelectrical terms, if thevoltage (electro-negativity) isgreateratoneendofthehosethantheother,thenelectronswillflowfromtheareaofhighervoltagetothelowerone.Becausemetalshavelotsofmobileelectronsinthem,theymakegoodelectricalconductors.

Oneofthebasicpropertiesofallmetalsandalloysisthattheywillhaveacertainelectrochemicalpotential,orvoltage,thatcanbemeasuredagainstareferencestandardwhentheyareexposedtoanelectrolyte.Ifyouwereabletolookatacorrodingmetalunderextremelyhighmagnification,sothatyoucould seewhat the atoms on the surfacewere doing, youmight see that aseachmetalatomdetachesfromthestructure,itdonatesoneortwonegativelycharged electrons to the circuit. In a sense, the electrical potential of thecorrodingmetalisameasurementofitseaseofgivingupitselectronsandisthereforeameasureofitstendencytocorrode.Metalsthatwillcorrodeeasilyhavehighelectrochemicalpotentials.Examplesof these includemagnesium,zinc, and aluminum, and these types of metals are referred to as “active”metals.Metalswhich do not have a natural “desire” to corrode have a lowelectrochemicalpotentials.Examplesoftheseincludegoldandplatinum.Thesearereferredtoas“noble”metals.Ofcourse, thereareverymanymetalsandalloyswithpotentialsthataresomewhereinbetweenthesetwoextremes,andsincedifferencesintemperature,electrolytechemistry,andphysicalconditionscan change their potentials, corrosion and corrosion control are often not assimpleastheyseem!

ELECTROCHEMICAL POTENTIAL

Youmay askwhywet corrosion is referred to as an electrical chemicalreaction. It’s because of the dual, electrical and chemical, nature of thecorrosionreaction.Inthereaction,electronsreleasedattheanodeflowtothecathodebyadirectmetallicpath(electricalcontact),andtheelectricalchargereturns to the anode through the conductive path (e.g., seawater immersionor contamination) called the electrolyte. Thus, there are always four thingsnecessaryforelectrochemicalcorrosiontooccur:ananode,acathode,ametallicpath, andanelectrolyte.Anacronym(ACME)canbeused to remember thenameofthefourcircuitcomponents:

AnodeCathodeMetallicpatElectrolyte

Ifanyoftheseitemsareeliminatedorcontrolled,metalcorrosioncanbecontrolled.Thisoftenprovidesamethodforcorrosioncontrol.


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Example: Asimpleflashlightbattery(Figure2-2) illustrates thefour itemsnecessaryforcorrosiontooccurandweallknowthatthisdevicecanproduceelectricalflow.Thecenterpostiscarbonwhichactsasametalinthissituation.Carbonhasarelativelylowelectrochemicalpotential.Thecaseiszinc,ametalwitharelativelyhighelectrochemicalpotential.Theammoniumchloridepasteis the electrolyte, and the light bulb andwire that connect the anode to thecathode are the external circuit.When the circuit is closed, it carries a flowof electrons from the zinc to the carbon through the external circuit whichilluminatesthelightbulb.Thezinccasecorrodesinmakingthecurrent.Ifthelightisleftontoolong,electrically-resistantchemicalproductsbuildupintheelectrolytenearthecathode,sothatthecurrentnolongercontinuestoflow.

Ananodeisthepartoftheelectrochemicalcellwhichhasthemost“desire”to dissolve in the given electrolyte. It is the component having the largestelectricalpotentialand,thus,wherecorrosionoccurs.

Acathodeisthepartoftheelectrochemicalcellwhichhaslesstendencytodissolveinthegivenelectrolyte.Ithasalowerelectrochemicalpotentialthantheanodeandthus,iswherenocorrosionoccurs.

Dependingon several factors, anymetal canact as either an anodeor acathode.Anodes and cathodes can reside on differentmetals or on differentareasofthesamemetal.InthebronzeandsteelcellshowninFigure2-3,thebronzeisthecathodeandthesteelistheanode.Inthebronze,steel,andzinccellshowninFigure2-4,boththebronzeandsteelarethecathodesandthezincistheanode.Notethatthesteelchangedfromananodetoacathodeduetotheconnectionwiththezinc,whichhasahigherpotential.

NOTE: Theexamplesbelowarereferredtoasdissimilarmetalcorrosioncellsorgalvaniccells.

ANODES AND CATHODES

Figure 2-2: Dry Cell Battery

ELECTROCHEMICAL POTENTIAL (continued)


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GENERAL CORROSION

GALVANIC SERIES

So far we have talked about corrosion which occurs because of thecouplingoftwodifferentmetals.Butonemightaskwhyametalwhichisbyitselfcorrodeswhenexposedtoanelectrolyte.Forinstance,ifapieceofsteelwassimplyleftoutintherain,itcorrodesinauniformway.Butwhereisthecathodeandwhereistheanodeinsuchacase?

Whenthesurfaceofapieceofsteelisexposedtotheelectrolyte,areasofslightlydifferentcharacterformanode/cathodepairswhichresultincorrosionat theanodes.Because thesearesoclose togetherandsomewhatsmall, theydon’tevenhavetobefullyimmersedintheelectrolyte.Smallwaterdropletson the surface over a period of time are enough to promote corrosion.Asthe corrosion proceeds the anode and cathode potentials reverse themselvesresultinginmoreuniformratherthanlocalizedcorrosion.

Figure 2-3: Simple Electrolytic Cell

Figure 2-4: Bronze, Steel and Zinc Electrolytic Cell

GALVANIC CORROSION• Dissimilarmetalsincontactwitheachothermayundergogalvaniccorrosion.

Different alloys and metals have different tendencies to corrode. It ispossibletoarrangethemetalsinaseriesrankedforthistendencyfromhighestto lowest potential (tendency to corrode). Table 2-1, the “galvanic series inseawater”, listsmetals in descending order from highest to lowest potentialin seawater. The galvanic series is really a list ofmetals according to theirelectrical potential against a standard reference electrode in seawater.Whentwodifferentmetalscomeintoelectricalcontactwitheachotherinelectrolyte,theonethatishigherinthetablebecomestheanode,andtheloweroneinthetablebecomesthecathodeinagalvanic(dissimilarmetal)corrosionreaction.Thecorrosion ratewillbeaccelerated from thenormalmetal corrosion rate.Also,thefurtherthatthetwometalsarefromeachotherinthetable,thegreaterwillbethecorrosionrate.


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Other factors thathavean importanteffect are: surface films,appliedorresidualstresses,concentrationandtypeofions(e.g.,salts)inthesolution,andoperatingtemperature.

TYPES OF CORROSION

GALVANIC SERIES (continued)

Table 2-1: Galvanic Series in Seawater

Morelikely magnesiumalloystocorrode zinc(anodic) aluminumalloys cadmium steeloriron 18-8stainless;active brass bronze coppernickelalloys nickel inconel 18-8stainless;passiveLesslikely titaniumalloystocorrode platinum(cathodic) graphite

ExamplesofdifferenttypesofcorrosionareshownbelowinFigures2-5thru2-13.

Uniform Corrosion Thesimplestformofcorrosionandtheformfoundinmostcasesisdirectsurfaceattackcorrosion resulting from thedirect reactionofametal surfacewithoxygenintheairormoisture.Thisformoccursfrequentlyundernormalshipboard conditions of exposure and is characterized by relatively uniformdegradationoverlargeareasofthemetal.Inthisformofattack,theanodeandcathodearebothfoundon thesurfaceof themetaland,ascorrosionoccurs,these change locations so that the corrosion products build up on the entiresurfacerather than in isolated locations.Therustingofsteelor tarnishingofsilverareexamplesofuniformcorrosion.

Figure 2-5: No Corrosion


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SENSITIZATION

• Stainlesssteelsthatareweldedandnotabletobeheattreatedafterwardsmaybe“sensitized”intheheataffectedzone,makingthemmorepronetointergranularcorrosioninseawater.

• Lowcarbon“L”grades(e.g.,304L,316L)areoftenusedtohelppreventthis.

Figure 2-6: Uniform Corrosion

Dissimilar Metal Corrosion (Galvanic) The corrosion rate between dissimilar metals depends on how great adifferencethereisbetweenthemetalsontheseriesandonthesurfaceareasofthemetals involved.The larger thecathodicarearelative to theanodicarea,themoreacceleratedcorrosionoftheanodewillbe.Thisisknownasthe“areaeffect.”Whenanactivemetalisplacedincontactwithamorenoblemetal,theactivemetalwillcorrodepreferentially.Therateofcorrosionwillbegreaterthantheanodicmaterialwouldbeifitwasnotcoupled.

Pitting Pittingisasevereformoflocalizedcorrosion,andiscausedbyphysicalor chemical variations on a metal surface in the presence of a corrosiveenvironment(electrolyte).Aphysicalvariationmaybeimpuritiesinthemetalitself.Achemicalvariationcouldcomefromtheenvironmentsuchasfromsaltdepositsorfromlocalacidicareasinanelectrolyte.

Figure 2-7: Dissimilar Metal

Figure 2-8: Pitting


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Crevice Corrosion Crevicecorrosion(Figure2-9) isaspecial typeofpittingthatfrequentlyoccurswithincrevicesandothershieldedareasonmetalsurfacesareexposedto an electrolyte. This type of attack is usually associated with a stagnantsolutioncausedbygasketsurfaces,lapjointsandcrevicesunderboltandrivetheads.Corrosionunderwetsandanddirtisaformofcrevicecorrosioncalledunder-depositcorrosion.

Stress Corrosion Cracking Stress-corrosion cracking (SCC) (Figure 2-10) is the brittle fracture ofanalloy,exposedtoaspecificcorrodingmedium,atlowtensilestresslevelswithrespecttothedesignstrengthofthealloy.Onlypuremetalsareimmunetostress-corrosioncracking.Thetimetofailureineachenvironmentdependson the total stress, the temperature, and the effective concentration of theelectrolyte solution. In general, you cannot detect stress corrosion crackinguntilitistoolate.

Intergranular Corrosion Metalalloysarecomposedofgrainsorcrystalswhichformas themetalis cooled following casting or certain high temperature heat treatments.Intergranular corrosion is a selective attack which occurs along grainboundariesofsomealloys.Metalprocessingmethodssuchasweldingandheattreatingcancausesomeofthealloyingelementsinthemetaltoformextremelysmallparticlesat thegrainboundaries,calledprecipitates.Dependingon thematerialsinvolved,precipitatesmaybeeitheranodicorcathodicrelativetothesurroundingmetal,butineithercase,selectivegalvanictypecorrosionoccursatgrainboundaryregions.Althoughintergranularcorrosioncanleaveametalsurfaceroughened,definitediagnosisusuallyrequirestheuseofamicroscope.SeeFigure2-11.

Figure 2-10: Stress Corrosion Cracking

TYPES OF CORROSION (continued.)

Figure 2-9: Crevice Corrosion


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Exfoliation Exfoliation(Figure2-12) isanadvancedstageof intergranularcorrosionand is characterized by a “delamination” of metal along grain boundaries.Rolledproducts,suchascertaintypesofaluminumalloyplate,areparticularlysusceptible to exfoliation due to their longitudinal grain structure, as shownbelow inFigure 2-13.The process of delamination in exfoliation is assistedby the formation of corrosion products between grain boundaries as theyseparate.

Figure 2-11: Intergranular

Figure 2-12: Exfoliation

Figure 2-13: Rolling of Aluminum

Flattened grain structure leads to exfoliation during corrosion of aluminum plate.


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ENVIRONMENTAL EFFECTS

The environment plays a large role in corrosion.Not only does it causeasubstrate tocorrode, theenvironmentcancauseacoatingsystemtofailaswell.

Humidity Moistureintheatmospherecancollectonthesubstrate.

Oxygen Causes metals to return to their more stable forms by oxidation(corrosion).

Salt When dissolved in water, readily conducts corrosion current therebyincreasingcorrosionrate.

Chemicals Differentchemicalsattackvariousmetalsdifferently.

Heat/Temperature Highertemperaturesspeedupelectrochemicalreactionrates.

Stack Gases Theexhaustgasfromdieselandgasturbineenginescontainchemicalsthatreactwithair,moistureandsunlighttoformacidicby-products.

Ultraviolet Radiation This radiation, in sunlight,candamagecertain typesofcoatingsornon-metallicmaterials.

DEHUMIDIFICATION

• Keepingtherelativehumidity(RH)below35%willcausethecorrosionrateofsteeltodropgreatly.

SUMMARY

Corrosionisacontinuousprocessthatoccurseverywhere.Differentalloysandmetals havedifferent tendencies to corrode, dependinguponwhere theyfallinthegalvanicseries.Corrosionisbrokendownintothesetypes:uniform,dissimilarmetals,pitting,crevice,stresscracking,intergranular,andexfoliation.Environmentalfactorsplayasignificantroleincorrosion.


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Topics: • Threemechanismsofcorrosioncontrolbycoatings(barrier,sacrificial,inhibitive)

• Sacrificialandimpressedcurrentcathodicprotectionsystems

Scope ThissectionacquaintsstudentswiththebasicmechanismsforcontrollingcorrosiononNavyships(coatingandcathodicprotection)andhowtheyworkwelltogether.

Learning OutcomeAttheendofthissection,thestudentwillbeableto:

• Definethedifferentmechanismsbywhichcoatingscontrolcorrosionandthebasicpropertiesofcoatingsusedforcorrosioncontrol.

• Recognizethebasicdifferencesbetweensacrificialanodeandimpressedcurrentcathodicprotection.

ThemethodsusedtofightorcontrolcorrosionintheNavyaremanyandingenious.Designerschoosematerialscarefully tomaximizecorrosionresis-tance and avoidgalvanic couples.Good corrosiondesignwill also take intoaccount other factorswhich increase the rate of corrosion such as crevices.Humidityinenclosedspaces,suchasvoids,isreducedwiththeuseofdesic-cants, andvapor phase corrosion inhibitors are used to protect these spaces.Designsaremadesuchthatcertainmetalssacrificethemselves,suchaswasterpiecesinseawaterpipingsystems,toprotectothermetallicsurfaces.Galvaniccorrosioncanevenbeusedtoouradvantagethroughtheuseofsacrificialcoat-ingsandanodes.

The main way the rate of corrosion can be controlled is by breakingthe corrosion cycle by eliminating ormodifying one of the corrosion cycleelements:theanode,thecathode,themetallicpathortheelectrolyte.

Protectivecoatingscanbeusedtoprovidethinfilmsofprotectionbetweenthe electrolyte and the metal substrate. They can also be made to sacrificethemselves to protect the substrate. Coatings can control the migration ormovementofwater(electrolyte)tothesubstrate.Thatis,paintsandcoatingscanbeusedasbarrierfilms,sacrificialfilms,orcancontaininhibitorstoslowdownoreliminatecorrosion.

3 Corrosion Control

NAVSEA Basic Paint Inspector Training: Corrosion Control

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Asacrificialcoatingisanotherformofcorrosionprotection.Thepigmentsinthecoatingsacrificiallyreactwithcorrosiveelementsintheenvironment.Byformingagalvaniccell, thesemetallicpigmentscorrodebefore thesubstratecan be attacked. For example, when a scratch or a break occurs in a zinc-richpaintfilm,water(theelectrolyte)andoxygencombinewiththemetalliczincdusttoformzincoxideor“whiterust”insteadofthewaterandoxygencombiningwithsteel.Overtime,thezincparticleswillcorrodeawayandthepaint’sprotectiveabilitywillbelost.Thismethodofprotectionwillonlyworkifamoreanodic(topofthegalvanicseries)metal(zinc)isplacedontopofthesubstrateyouaretryingtoprotect(steel).

NOTE: It is especially important to mix zinc-rich paints thoroughlywhen applying them so that all of the metallic dust particlesthat give this sacrificial protection are incorporated uniformlyin the paint film.Constant agitationof the paint pot is usuallyrecommended.

SACRIFICIAL COATINGS

BARRIER COATINGS

A coat of paint can control corrosion by acting as a barrier, preventingcontactbetween themetaland thecorrosiveelements.Toactasaneffectivebarrier,thepaintfilmmustdemonstratethefollowingcharacteristics:

• Reduced permeability to moisture and oxygen: If moisture andoxygenreadilypassthroughthepaintfilm,corrosionmaytakeplaceeventhoughthecoatingisundamagedandappearstobeintact.Largemasses of rust will form under the coating, eventually lifting thecoatingoffthesurface.Itissafetoassumethatallcoatsarepermeabletosomeextent.Ingeneral,thethickerthecoatingisapplied,thelesspermeablethecoatingwillbe.

• Tightadherencetothesurface:Acoatingmustbehighlyadherent,forminga tightmembraneover thesurface.Evenifacoatingallowssomemoisturetopenetrate,itcanstillprovidegoodprotectionifthereisnoareabeneaththefilminwhichthemoisturecancollect.

• Smoothandcontinuousfilm:Thepaintfilmmustbeappliedevenlytoavoidlowareasandmustbefreeofsmallskips,voidsorpinholes.These tiny imperfections in the paint surface will allow water andoxygentoenter.Atinyspotofcorrosionmayquicklyspreadunderthepaint,stretching,cracking,andliftingthefilmasitprogresses.

• Resistancetochemicalsandabrasion:Tosuccessfullyprovidebarrierprotection, thepaintusedmustbe resistant towhateverenvironmentitisexposed.Someexposuresmayrequirehigherabrasionresistancesthanothers.

Navy Basic Paint Inspector Training: Corrosion Control

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Inhibitive coatings contain special pigments that inhibitmetal corrosionatthemetalcoatinginterface.Thus,theyarealwaysprimers.Thesepigmentsmust be slightly water-soluble to be effective. Examples of some of thesepigmentsandtheirmechanismsofcorrosioninhibitionaregivenbelow:

Inhibitive coatings, due to their toxicity, coatings containing lead,chromium, andother heavymetals have beenphasedout of theNavy (withsome exceptions). For example, TT-P-645 was the specification for zincchromate,whichhasbeenrevisedtoTT-P-645B(orlater)forzincmolybdate.Thenewpaintisorangeorgreen,whichcanhelpyoudistinguishitfromtheolderyellowchromate-containingversion.

RedLeadandOtherLeadPigments Read lead and other lead pigments were used effectively as corrosioninhibitors in oil-base paints for many years.Moisture combines with waterandtheoiltoformleadsoapsthatwetthesteelwellandinhibitthecorrosionreaction.

ZincChromateandOtherChromatePigments InhibitivechromateprimerswereoncewidelyusedbytheNavy,especiallyon aluminum, because red lead primers did not protect itwell.The leachedchromateioninhibitedthecorrosionreaction.

ZincMolybdatePigments Zincmolybdatepigmentsinprimersactinthesamemannerasdochromatepigments.

INHIBITIVE COATINGS

CATHODICPROTECTIONSYSTEMS

Cathodic protection is the process of protecting ametal from corrosionwhileitissubmersedinwaterbyforcingitsentireexposedsurfacetobethecathodeoftheoverallelectrochemicalcell.Thisisaccomplishedviaoneoftwomeans:sacrificialanodesystemandimpressedcurrentsystem(NSTMChapter633coverscathodicprotection).

Notethatcathodicprotectiondoeslittleornogoodonsurfaceswhicharenotfullysubmersed,andonlyprotectsthemetalwhichisexposedtothesameelectrolyteastheanode(i.e.,thecathodicprotectionontheoutsideoftheship’shulldoesnotprotectareasabovethewaterlinesuchasthefreeboard,norwillitprotectareasinsidethehullsuchasinbilgesandtanksthatcontainwater.)Theseinterior,immersedareasrequiretheirowncathodicprotectionsystems.


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CATHODICPROTECTIONSYSTEMS(continued)

SacrificialAnodeCathodicProtection This type of cathodic protection consists of protecting a submergedstructurebyattachingamoreactivemetal to thestructure.Forasteelship’shull,theseattachedpiecesofmetalarenormallyzincslabs;however,theycanalsobealuminumormagnesium.Theattachedmetal(anode)corrodesintheseawaterprovidingelectronstothesteel(cathode)throughaground(externalcircuit)andpositivecurrentthroughtheseawater(electrolyte).

ImpressedCurrentCathodicProtection(ICCP)Systems Thesecondwaytoprovidecathodicprotectiontotheimmersedportionsofshipsistousepermanent(non-sacrificing)metalanodes(usuallyplatinum)connected to a DC power supply within the ship (Figure 3-1). The anodesaremounted at various locationson the submersedhull toprovide adequatedistributionofprotectivecurrent.ThisistermedImpressedCurrentCathodicProtection(ICCP)andisusedtoprotectthehullofmostsurfaceshipsandsomelatemodelsubmarines.Theflowoftheelectronsinthemetallicpathandtheflowoftheionsthroughtheseawaterinthissystemaresimilartothoseofthesacrificialanodesystem,asisthecathodicprotectionprovided.

Sinceimpressedcurrentcathodicprotectionanodesoperateatpotentialsupto28VDC,specialconsiderationmustbegiventothepaintsystemsurroundingtheanodes.Athickspecialpurposeepoxycoatingisappliedtotheareaswithinsixfeetofeachanodetopreventshortingofthecathodicprotectioncurrenttothehullanddistributethecathodicprotectiontoalargerareaoftheunderwaterhull.Thisistermedthedielectricshield(alsocalledthecapasticshield).Sincethe voltage drop is steep close to the anode, the applied voltage is reducedto a reasonable level by the time it reaches the hull paint surrounding thedielectricshield.Closetotheanode,theseshieldmaterialsoftenshowastained

Figure3-1:BasicImpressedCurrentCathodicProtectionSystem


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appearance resulting from chemical reactions occurring in the sea water attheanode(Figure3-2).Thisstainingisnormalandacceptable.Breakdownofthedielectricshieldtogroundisindicatedbytheformationofsoft,butbulky,whitedepositsofcalcareousmaterial.TheseareproducedfromseawaterduetohighpHlocatedatanystrongcathode.Withinthedielectricshield,thisisconsidered detrimental since the shield should provide full blockage of thecurrenttryingtoenterthehullattheanodetomorefullyanduniformlyextendthecathodicprotection.Note,thatthenormalunderwaterhullpaintsystemisappliedoverthedielectricshield,notunderit.Thedielectricmaterialmustbeapplieddirectlytothewhite-metalblastedsurfaceifitistofunctionproperly.

Ideally, corrosion protection for underwater steel hulls and tanks usesboth a cathodic protection system and a protective coating. For sacrificialanodesystems,thismakestheanodeslastlonger,andwouldrequirefeweroftheheavyanodestoprotectthesteel.ForICCPsystems,thispreventsahugecurrentdemandtoprotectmassiveareasofbaresteel,andthereforeallowsasmallerandmoreeconomicalpowersupply tobeused.Thereal functionofcathodicprotectionistoprotectanyareasofbaresteelwherethepainthasbeendamagedfromcorrosionuntilthepaintcanbetouched-uporrenewed.

BothsacrificialanodesandICCPsystemscanbeeffectiveineliminatingcorrosion if applied correctly. Selecting the proper number of anodes, theircapacities, their locationsand the locationofsensingreferencecells isquitecomplex,andrequiresbothexperienceandtheuseofsophisticatedmethods.CathodicprotectionsystemsarecoveredindetailinNSTMChapter633.

Figure3-2:TypicalStainingofanICCPDielectricShield


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SUMMARY

CorrosioniscontrolledonNavyshipsbybarrier,sacrificial,andinhibitivecoatings.Twomethodsofcathodicprotection,sacrificialandimpressedcurrent,are also employed. Impressed current uses permanent (non-sacrificial)metalanodesconnectedtoaDCpowersupplywithintheshiptoprotectasubmergedstructure.Sacrificialanodeprotectionworksbyattachingamoreactivemetaltothestructure.