Student Guide - The Society for Protective Coatings 1 … · Student Guide May 2015/ Version 12. This page intentionally left blank. ... SSPC-SP WJ-3/NACE WJ-3 Waterjet Cleaning of

NAVSEA BASic PAiNt

iNSPEctor trAiNiNg

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

Student Guide

May 2015/ Version 12

This page intentionally left blank.

This page intentionally left blank.

NAVSEA Basic Paint Inspector Training Schedule

Day 1 0800-0900 Introduction (1) (0700-0800) Team Exercise (Alternate Start Time) 0900-1000 Corrosion (2) (0800-0900) 1000-1100 Corrosion Control (3) (0900-1000) 1100-1230 NAVSEA Documents (4) (1000-1130) Team Exercise 1 Team Exercise 2 1230-1330 Lunch (1130-1230) 1330-1430 Non-Mechanical Cleaning Methods (5) (1230-1330) 1430-1630 Mechanical Cleaning Methods (6) (1330-1530) Abrasive Blast Cleaning (7) 1630-1730 Day 1 Instrument Exercise (1530-1630) Initial Surface Evaluation, Power Tool Cleaning, and Abrasive Blasting Day 2 0800-1000 Abrasive Blast Cleaning (cont.) (0700-0900) 1000-1045 Homework Review (0900-0945) Day 1 Review Quiz 1

Day 2, cont. 1045-1200 Waterjetting (8) (0945-1100) 1200-1300 Lunch (1100-1200) 1300-1400 Surface Preparation Selection (9) (1200-1300) Team Exercise 1400-1530 Coatings (10) (1300-1430) Team Exercise 1530-1600 Safety (11) (1430-1500) 1600-1730 Day 2 Instrument Exercise (1500-1630) Environmental Conditions and Surface Cleanliness Day 3 0800-0900 Homework Review (0700-0800) Day 2 Review Quiz 2 0900-1200 Coating Application (12) (0800-1100) Team Exercise 1 Team Exercise 2 (PA 2) 1200-1300 Lunch (1100-1200) 1300-1400 Coating Defects and Failures (13) (1200-1300) Specialty Coatings (14) 1400-1500 Coating Inspector Preparation (15) (1300-1400)

Day 3, cont. 1500-1700 Day 3 Instrument Exercise (1400-1600) DFT Measurements Day 4 0800-0830 Homework Review (0700-0730) Day 3 Review 0830-1000 Team Exercise 1 (15) (0730-0900) Team Exercise 2 (15) 1000-1100 Condition Assessment (16) (0900-1000) 1100-1200 Nonskid (17) (1000-1100) 1200-1300 Lunch (1100-1200) 1300-1400 Nonskid, cont. (1200-1300) 1400-1430 Quiz 3 (1300-1330) 1430-1530 Inspection Plan Workshop (1330-1430) 1530-1730 Instrument Practice (1430-1630) Day 5 0800-0900 Evaluations (0700-0800)

Day 5, cont. 0900-1200 Instrument Practice (0700-1100) 1200-1300 Lunch (1100-1200) 1300-1600 Certification Exam

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

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—4Submarine Maintenance Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . 4—5NAVSEA Standard Item 009-32/009-34 Team Exercise . . . . . . . . . . 4—6Documentation 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—4Detergent and Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—4Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5—6

6. Mechanical Cleaning MethodsHand and Power Tool Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6—1Power Tool 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—4

Characteristics of Degrees of Blasting . . . . . . . . . . . . . . . . . . . . . 7—5Abrasive Blasting of Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—9Environmental Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—10Surface Profile and Residual Chloride . . . . . . . . . . . . . . . . . . . . . . . . 7—10ISO 8502-3 Dust Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—14Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7—15

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

SECTION PAGE NUMBER


TOC—iii

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

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—7Epoxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—7Antifouling Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—8Polyurethane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—9Zinc-Rich Primers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—9Polysiloxanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—10Rust converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—10Submarine coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—11

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

Data Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—13Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—13Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10—15

11. SafetySafety Data Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—1HCS Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11—4Personal 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—5Conventional Spray Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—5Airless Spray Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—6High Volume Low Pressure Coatings Application . . . . . . . . . . . . 12—6Plural Component Spray Systems . . . . . . . . . . . . . . . . . . . . . . . . 12—7Electrostatic Spraying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—7

Paint Thickness Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—8Paint Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—8Paint Application Inspection Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—10Paint Clean-Up and Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—11Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—12PA 2 Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—14Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12—19

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

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

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

SECTION PAGE NUMBER


TOC—v

14. Specialty Coatings and SurfacesComposites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—1Special Hull Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—2Sonar Domes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—3Passive Countermeasure System Materials . . . . . . . . . . . . . . . . . . . . 14—3Powder Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—5Thermal Spray Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—6Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14—8

15. Coating Inspector PreparationCoating Work Plan and Inspection Plan . . . . . . . . . . . . . . . . . . . . . . . 15—1Pre-Job Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—2References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—4Certified Coating Inspectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—5NAVSEA Standard Item 009-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—6Cleaning and Painting Requirements; Accomplish . . . . . . . . . . . . . . 15—6Team Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—7NAVSEA Standard Item 009-32 Team Exercise . . . . . . . . . . . . . . . . 15—8Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15—9

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, Chromate, and Cadmium . . . . . . . . . . . . . . 16—6CCIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—7

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—7Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—8Coatings and Corrosion Assessments . . . . . . . . . . . . . . . . . . . . . . 16—8Equipment Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—8Tank and Void Inspection Form . . . . . . . . . . . . . . . . . . . . . . . . . . 16—9Underwater Hull Inspection Form . . . . . . . . . . . . . . . . . . . . . . . . 16—10Dry Docking Report Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—10Paint Condition Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—11Evaluation of Blisters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—12

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16—13

17. NonskidTypes of Nonskid Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17—1Nonskid Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17—5Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17—7

Inspection Plan Workshop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I—1

SECTION PAGE NUMBER


TOC—vi

18. Instrument ExercisesDaily Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—1

Day 1 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—1Day 2 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—3Day 3 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—4Day 4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—5Day 5 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18—7

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

Testex Tape and MicrometerDigital Surface Profile GagesSurface ThermometerSling PsychrometerPsychrometric TablesWet Film Thickness (WFT) GageSSPC-PA 2 (DFT) Type 2 GageLow Voltage Holiday DetectorConductivity Meter

Appendix F: SSPC/NACE Standards . . . . . . . . . . . . . . . . . . . . . . . . . . F—1SSPC-AB 1: Mineral and Slag AbrasivesSSPC-AB 2: Cleanliness of Recycled Ferrous Metallic AbrasivesSSPC-AB 3: Ferrous Metallic AbrasiveSSPC-AB 4: Recyclable Encapsulated Abrasive Media(in a compressible cellular matrix)SSPC-SP 1: Solvent CleaningSSPC-SP 2: Hand Tool CleaningSSPC-SP 3: Power Tool CleaningSSPC-SP 15: Commercial Grade Power Tool Cleaning SSPC-SP 11: Power Tool Cleaning to Bare Metal SSPC-SP 7/NACE No . 4: Brush-Off Blast Cleaning SSPC-SP 6/NACE No . 3: Commercial Blast CleaningSSPC-SP 10/NACE No . 2: Near-White Blast CleaningSSPC-SP 5/NACE No . 1: White Metal Blast CleaningSSPC-SP WJ-1/NACE WJ-1 Waterjet Cleaning of Metals Clean to Bare SubstrateSSPC-SP WJ-2/NACE WJ-2 Waterjet Cleaning of Metals Very Thorough CleaningSSPC-SP WJ-3/NACE WJ-3 Waterjet Cleaning of Metals Thorough CleaningSSPC-SP WJ-4/NACE WJ-4 Waterjet Cleaning of Metals Light CleaningSSPC-SP 8: PicklingSSPC-SP 16: Brush Off Blast Cleaning of Coated and Uncoated Galvanized Steel, Stainless Steels, and Non-Ferrous MetalsSSPC-PA 17: Procedure for Determining Conformance to Steel Profile/Surface

SECTION PAGE NUMBER

SECTION PAGE NUMBER

Appendix F: SSPC/NACE Standards . . . . . . . . . . . . . . . . . . . . . . . . . . F—1Roughness/Peak Count RequirementsSSPC-PA 2: Procedure for Determining Conformance to Dry Coating Thickness RequirementsSSPC-PA Guide 11: Protecting Edges, Crevices, and Irregular Steel Surfaces by Stripe Coating

Appendix G: Psychrometric Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . G—1Appendix H: (Discontinued)Appendix I: Hazardous Materials Users Guide (HMUG) . . . . . . . . . . I—1Appendix J: Preservation Departures from Specifications

Process Decision Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J—1Appendix K: (Disontinued)Appendix L: Paint Failure Photographs . . . . . . . . . . . . . . . . . . . . . . . . L—1Appendix M: Calculation Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M—1Appendix N: Documentation Team Exercise Supporting

Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N—1Appendix O: SSPC Guide for Planning Coatings Inspection . . . . . . . . . . . . . . .O—1

TOC—vii


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 pos-sible. 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:

• Conducting formal inspections• Assisting other Naval activities in paint and coatings related quality

assurance issues• Conducting training sessions for the ship’s force

The best way to be ready for all of these responsibilities is to prepare ahead of time. This includes thoroughly reading and understanding both the specification and work item, applicable Product Data Sheets (PDS), and applicable Safety Data Sheets (SDS). By understanding the nature of the work to be completed, you will have a better idea of what type of

1 Introduction

NAVSEA Basic Paint Inspector Training: Introduction

1—2

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:

• Attending the pre-job meeting• Affirming proper safety practices are followed• Evaluating the condition of the surface after surface preparation is

complete and immediately prior to application• Ensuring the paint system has not exceeded its shelf life and that the

condition of the paint in the can is good• Ensuring the proper coatings are used• Ensuring the coating is properly applied• Measuring environmental conditions• Measuring coating dry film thickness• Recording all data accurately, completely, and concisely• Writing a final report

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

NAVSEA Technical Authority is the authority to Establish and Approve the NAVSEA technical specifications for US Navy vessels. Waterfront execution of 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 must be answered by the Regional Maintenance Center (RMC) or Supervisor’s Engineering 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 disposition for a non-conformance lies within the region’s Technical Warrant Holder. No others have this authority. An approved non-conformance must be signed by a NAVSEA Technical Warrant holder before proceeding with any change to NAVSEA technical specifications (NAVSEA Standard Item 009-32 or NSTM Chapter 631).

In September 2006, NAVSEA created a “Preservation Departures from Specifications (DFS) Process Decision Tree.” This Decision Tree provides guidance for handling out-of-specification conditions on critical coated surfaces. 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 authority an out-of-specification decision can be accepted based on the “risk threshold” of premature coating failure. A copy of the Decision Tree is included in Appendix J.

VERSIONS

• The following documents were used in the creation of this manual and the accompanying slides

• NAVSEA Std. Item 009-32• NSTM Ch. 634• Core PPI-63101-000• MS No. 6310-081-015

• QA helps to provide the best quality preservation to protect the Navy’s assets for as long as pos-sible

• Required by NSTM Chapter 631 for critical coated areas

• May be required by Command

WHY QA?

Navy Basic Paint Inspector Training: Introduction

1—3

All DFSs must be concurred to by the Type Commander (TYCOM). Unless otherwise specified, action to document an out-of-specification condition still requires submittal of the NAVSEA Standard Item 009-32 QA Inspection Form.

Non-conforming conditions or circumstances where the technical process is not being followed must be reported. All questions or needs for clarifications of NAVSEA specifications should be submitted to the Engineering Authority.

On today’s complex Naval vessels, there are a wide variety of coatings applied to a diverse range of surfaces. Examples include common coatings used for corrosion prevention and cosmetic appearance, such as epoxies and silicone alkyds, as well as special function coatings such as nonskid, anti-fouling, and others. Examples of surfaces where coatings are applied include common materials 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 and cosmetic 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 materials associated with paints, cleaners, and solvents.

• NAVSEA Standard Item 009-32 is the governing document for almost all painting performed on Naval vessels and equipment, whether it is performed by intermediate maintenance, shipyards, or contractors. The QA requirements in NAVSEA Standard Item 009-32 predominantly apply to defined “critical coated areas” 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, surface cleanliness, surface roughness “profile,” dry film thickness, and sign off on key checkpoints in the painting process.

• The implementation of various types of TYCOM directed shipboard preservation programs designed to be carried out by ship’s force, RMCs, or other military personnel. An example is the “Scheduled Preservation Upkeep Coordinated Effort” (SPRUCE) program conducted on submarines, which relies on a coordinator who has been trained in coatings application QA.


1—4

After successfully completing this course you should be able to:• Plan the steps needed to do a quality surface preparation and painting job, or interpret

the applicable steps that are contained in a previously prepared work specification.

• Recognize chain of authority (Technical Authority).

• Appreciate coatings assessment.

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

• Use the basic measurement tools and industry standards that a coatings inspector needs to determine if the environmental conditions (weather, etc.) are suitable for painting, if the surface is as clean as it should be, if it has the right “profile” before painting is started, and if the wet and dry film thicknesses of the applied paint are correct for the area being painted.

• Evaluate the newly painted surface for workmanship and paint defects, and recom-mend corrective actions.

• Appreciate the practical aspects of surface preparation and painting that a sailor or contractor may face on a Naval vessel.

• Identify the appropriate precautions that must be taken to ensure the 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 right source of information in order to answer any questions that you may not know the answer to.

Of course, not everyone who takes this training will have exactly the same needs and roles to play in Naval vessel painting. This will vary according to the painting job that you may be assigned to inspect or oversee. For example:

• If you are from a Naval Shipyard, you may be responsible for the role of a coatings QA inspector for in-house work governed by NAVSEA Standard Item 009-32. If you are from a Navy RMC Organization, you may be responsible for critical and non-critical area work governed by NAVSEA Standard Items 009-32, you may be responsible for signing off checkpoints. You will mainly oversee work performed by shipyard or contractor personnel, in accordance with an existing work specification that pre-defined the surface preparation and coating to be used.

• If you are from an RMC or Readiness Support Group (RSG), you may be overseeing shore-based or shipboard coatings work performed by military personnel. There may not be a detailed work specification for the coatings work being performed, so you may have to rely more on using NSTM Chapter 631 for the coating requirements.

• If you are a submarine SPRUCE coordinator, or from one of the RMCs, you may be overseeing programmed shipboard coatings work performed by ship’s force. You may have more responsibility with respect to planning and scoping the work required, selecting the appropriate surface preparation and coating, and providing technical assistance to ship’s force in everything from selection of personal protective


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• Metallic Path• Electrolyte

2. Describe and identify different types of corrosion.3. Describe methods of corrosion control.4. Be able to use and reference NAVSEA Standard Item 009-32 as it pertains

to:• Safety• Inspection gages• Surface preparation• Paint application• Submarine coating issues

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

6. Describe how to properly prepare surface for coating.7. Describe how to properly apply paint.8. Identify Navy single and multiple part paints.9. Describe and identify different types and functions of Navy coatings.10. Explain and identify different causes of coating failures or defects.

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 of Planning and Engineering for Repair and Alterations (PERAs), Submarine Maintenance Engineering, Planning, and Procurement (SUBMEPP), and TYCOMs, or specific equipment In-Service Engineering Agents (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” as described in NAVSEA Standard Item 009-32. The responsibility for proper application including all processes for the application of the coating systems resides with the contractor. For contracted preservation work, the government acceptance role is typically under the executing RMC office or shipyard.

REMEMBER:

• Homework assignments are in Appendix A

• Review the day’s notes in prepa-ration for tomorrow’s quiz


1—6

11. Maintain or create a coating inspectors log book and record all key data and informa-tion associated with a coating job.

12. Check the shelf life and condition of paint in the can, and ensure that expired materials are not used and, if applicable, disposed of properly.

13. Identify coatings process problems.14. Ensure abrasive blasting requirements are met and documented in accordance with

(IAW) NAVSEA Standard Item 009-32.15. 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 NAVSEA Standard Item

009-32 requirements.17. Ensure paint procedures are IAW NAVSEA Standard Item 009-32 and paint

manufacturers instructions.18. Ensure all coats of paint are properly dried and cured per NAVSEA Standard Item

009-32.19. Ensure painted areas are inspected for workmanship.20. Demonstrate awareness of the newest technologies and latest Navy related informa-

tion 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. Identify applicable technical documentation24. Recognize and reference Maintenance Standard (MS) 6310-081-015.

COURSE OBJECTIVES (continued)


1—7

COURSE COMPLETION

COURSE GRADING

During the week, you will be given a written exam, an instrument exam with data entered into a log book and a specification navigation exam. The scores from each of these will be used to determine your final score for the course. All tests and quizzes are taken “closed book” except the specification navigation segment, which is an open book exam.

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 a certificate and your name will be entered into a Navy-wide database acknowledging achievement of paint inspector training for quality assurance.

To become certified, a person has to complete the NBPI training and pass the NBPI Certification Exam with a minimum score of 80% on each part. In addition to passing the course, the person must also document that he/she has a minimum of 2 years experience with marine coatings. 100% of the person’s actual work time does not have to be dedicated to marine coatings so long as dealing with “marine coatings” is part of the person’s normal job duties. Upon approval of their application, candidates can sit for the NBPI certification exam. The certification term will be four years from the date of the successful completion of the certification exam.

Entry-level persons are still welcome to take the course but they will not be able to obtain certification until they gain the requisite experience, regardless of whether they pass the NBPI course.

• A person without the 2 years of experience is allowed to take the NBPI Training and exams.

• These candidates would be sent letters after the training stating that they had taken 40 hours of training.

• Candidates without the experience who pass the NBPI test would be allowed to submit a letter with attestations of experience in the future (i.e., after they get the required years of experience) to allow them to get NBPI certification without re-taking the certification test.

• Once SSPC receives this letter, the person then takes an open-book NBPI exam online. Those who pass the exam with an 85% will be issued a wallet card from the date the open-book exam is graded. The fee to take the exam is $250 for SSPC Members and $350 for nonmembers.

For example, a person taking the class with 18 months of experience would be allowed to submit a letter with the required references after he/she completes six months of additional experience. The letter would attest to the fact that the individual completed his/her experience requirements, passed the test and as such should be certified.

• Before he/she has the full NBPI Certification, the person who simply completed the training would not be allowed to certify critical-coated

SSPC

• SSPC’s address:

40 24th Street, 6th Floor

Pittsburgh, PA 15222-4656

web site: www.sspc.org

• SSPC can be contacted at:

412-281-2331 (1-877-281-7772) ext. 2221 for training concerns or or ext. 2224 for technical questions.


1—8

area work but would be allowed to work under supervision of an individual with full NBPI certification to gain the required experience.

• Those who take the NBPI Training and fails the exam have to re-take the class.

SSPC maintains the database for all certified coatings inspectors in the program regardless of where they took their NBPI training or certification exams. This information is located on the SSPC web site at http://www.sspc.org.

Certified Coating Inspectors from the NAVSEA 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, including name, company, address, phone, fax, e-mail and expiration date. Updates for inspector contact information should be sent to SSPC: The Society for Protective Coatings at 40 24th Street, Pittsburgh, PA 15222, Attention NBPI Coordinator or via e-mail at [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% to maintain certification. Full details about NBPI Recertification are available at http://www.sspc.org/NAVSEA-Basic-Paint-Inspector-NBPI-Certification-Term-and-Renewal.

INTRODUCTION TEAM NAME OBJECTIVES EXERCISE

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 together periodically 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. Team Exercise Develop a “Top 10” list of things your team wants to learn or get out of this course.

3. Make Presentation Summary On flip charts, summarize your team’s work on this exercise and prepare to deliver a 3-5 minute

presentation to the entire group. Select a spokesperson to make your presentation.


Introduction (1)

NBPI Course Developed by Naval Surface Warfare Center, Carderock Division Code 614 under direction of

NAVSEA 05M1

NAVSEA Basic Paint Inspector Course (NBPI)

Topics

l Certified paint inspector duties

l Formal inspection responsibilities

l Course objectives

Scope

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

Learning Outcomes

l  Plan the job

l  Recognize chain of authority (Technical Authority)

l  Appreciate coatings assessment

l  Select surface preparation methods and proper coatings

l  Measure environmental conditions

l  Evaluate newly painted surfaces

Learning Outcomes (cont.)

l  Appreciate the practical aspects of the preservation process

l  Identify health and safety precautions

l  Locate preservation information

Duties of Inspector

l Formal inspections

l Assist Naval activities regarding coatings QA

l Train Ships’ Force


Responsibilities of Inspector

l Pre-job meeting l Affirm proper safety practices l  Inspect surface preparation l Check paint in can l Ensure proper application l Measure coating thickness l Observe, assess, document, report results

Coatings and Surfaces to be Protected

l Will be discussed throughout the program

Why Course Developed?

l Extend coating service life to – Reduce maintenance

– Reduce hazardous waste

l Trained personnel needed to implement NAVSEA Standard Item 009-32 QA requirements

Skills Learned

l  Steps needed to do quality surface preparation and application l  Recognize Technical Authority l  Recognize Decision Tree for Departures from Specifications

(Appendix J) l  Appreciate coatings assessment l  Select proper surface preparation methods and coating

materials l  Use available tools to perform inspections and tests l  Evaluate applications l  Recommend corrective actions l  Basic safety l  Identify sources of information

Course Outline

1.  Introduction 2.  Corrosion 3.  Corrosion Control 4.  NAVSEA Documents 5.  Non-Physical Contact Cleaning Methods 6.  Mechanical Cleaning Methods 7.  Abrasive Blast Cleaning 8.  Waterjetting 9.  Surface Preparation Method Selection 10.  Coatings

Course Outline (cont’d.)

11.  Safety 12.  Coating Application 13.  Coating Defects and Failures 14.  Specialty Coatings/Surfaces 15.  Coating Inspector Preparation 16.  Condition Assessment 17.  Nonskid 18.  Daily Instrument and Inspection Workshops and

Exercises


Housekeeping Issues

l  Course schedule l  Course materials

l  Discussions/workshops l  Breaks/lunches l  Facilities

l  Emergency evacuation route

Housekeeping Issues

l Review the daily schedule

l Be prompt for class

l Turn off cell phones and electronic devices

l Please do not smoke in class

Introduction

l  Instructors: Who we are, What we do

l  Students: Who you are, What you do – Any Prior Coatings QA Experience?

l  Description of course materials

Why QA?

l Provide best quality preservation to protect Navy assets

l Required by NAVSEA Standard Item 009-32 and the Maintenance Standard 6310-081-015 Submarine Preservation for many coated areas

l May be required by Command

What are critical coated areas?

l  From NAVSEA Standard Item 009-32: Underwater hull, including

appendages and surfaces below the waterline up to and including the boot-topping Cofferdams Hangar, flight (including aircraft elevator), landing, catapult, and vertical replenishment decks

All Steel and aluminum Steel and aluminum


l  From NAVSEA Standard Item 009-32: RAST track trough

(including sumps) Well deck overheads and enclosed boat handling areas Surface ship bilges (including sumps)

Steel and aluminum Steel and aluminum Steel and aluminum



l  From NAVSEA Standard Item 009-32: Interior surfaces of vent

plenums, defined as combustion air intakes (gas turbine, diesel, and steam) and other vent system plenums with openings greater than 7 square feet Tanks and floodable voids (including sumps, Covers, and bolting rings); See Note (65)

Steel and aluminum Steel and aluminum


l  From NAVSEA Standard Item 009-32:

Non-floodable voids (at waterline or below) Gas turbine exhaust uptake spaces and trunks All recesses on submarines below the upper boot-top Interior surfaces of submarine sail (fairwater) and superstructure when SSPC-SP 10 is accomplished

Steel and aluminum Steel Steel Steel


l  From NAVSEA Standard Item 009-32: Aircraft Launch and Recovery Equipment (ALRE) System herein defined as catapult wing voids, catapult troughs, catapult exhaust blow-down trunks, barricade stanchions and wells, catapult jet blast deflector pits, and associated void spaces Arresting gear sheave foundations

NBPI Course Format

l  Lecture and discussions l  Demonstrations and workshops

l  NBPI Course Written Final Exam (closed book) l  NBPI Course Practical Instrument Exam (closed book) l  NPBI Specification Navigation Exam (open book)

Certification Process

l Pass NBPI Course (80% or better on each component)

l Document 2 years marine coatings experience

Work Experience

l  Work experience must be in one or more of the following areas: –  Inspection of Coating Application on Navy, Coast

Guard or similar vessel –  Repairs, Surface Preparation and Application of

marine coatings on Navy, Coast Guard or similar vessel

–  Project Management of Coatings Projects on Navy, Coast Guard or similar vessel


Work Experience (cont’d.)

–  Coating Specification and/or Contract Development on Navy, Coast Guard or similar vessel

–  Coating Equipment and Material Supplier Technical

–  Representative on Navy, Coast Guard or similar vessel

–  Failure Analysis of Coating on Navy, Coast Guard or similar vessel

Recertification

l  Maintained for 4 years

l  Take an open book refresher exam online

l  Pass with 85%

l  NBPI Recertification full details online (http://www.sspc.org/training/nbpi_recert.html)

Disciplinary Action Criteria (DAC) Read Carefully

l  Warning

l  Probation

l  Suspension

l  Revocation

**Disciplinary actions could result in suspension or revocation of certification**

Team Exercises

l  Important – Function as team l Make teams – Choose team name l Develop list of top 10 things your team

wants to learn or get out of this course l Flip charts – 5 minute presentation to group

– choose a spokesman

Professional Societies and Organizations

l  SSPC: The Society for Protective Coatings (previously Steel Structures Painting Council)

l  ASTM International (previously American Society for Testing and Materials)

l  ISO – International Organization for Standardization

l  NACE International (previously National Association of Corrosion Engineers)

2 Corrosion

Topics• Components necessary for corrosion• The galvanic series and galvanic corrosion• Common types of corrosion on ships• Environmental factors that contribute to corrosion

Scope This section acquaints students with the basic principles of corrosion, espe-cially those that occur most frequently on Navy ships.

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

• Identify the basic principles of corrosion.• Recognize the different types of corrosion most likely to occur on

ships.• Discuss the environmental factors that accelerate corrosion and the most

corrosive areas on ships.

Corrosion of metals is defined as their chemical or electrochemical reaction with the environment that results in their loss of material and/or properties. Why should you be taught the basics of corrosion in a course about the quality assurance of coatings on ships? It is because an understanding of how the metal components of ships corrode will help you understand how best to control this corrosion by using coatings. Some ship metals are more corrosive than others, and thus require more effective coating systems. Also, some ship areas are more corrosive than other ship areas and so require additional coating protection. Not only is the proper coating system selection important, but also proper surface preparation and coating application are necessary for optimum corrosion control.

As of Dec. 2013, the annual cost of corrosion to the Department of the Navy was approximately $7 billion per year with ships accounting for $3.2 billion of this cost. If nothing is done to halt corrosion... ...it gets worse. ...the later repairs are more costly. ...the pride of ownership is hurt. ...maintenance becomes difficult. ...fleet readiness may be compromised.

NAVSEA Basic Paint Inspector Training: Corrosion

2—2

Metals corrode because they are unstable in the free metallic state. Thus, energy must be given to metals in the smelting process to raise them to a higher energy but less stable state, and later, during use, the free metals corrode (oxide) to return to a lower, more stable condition (see Figure 2-1). In the oxidation process, the metals give up electrons that are consumed in other metal areas in the overall corrosion process. Metal areas that corrode are called anodes, and those that accept the electrons and are not corroded are called cathodes.

Figure 2-1: The Corrosion Cycle

CORROSION CYCLE

All of us have witnessed various forms of corrosion since it is a continuous process which occurs everywhere. We also have a general awareness of what causes corrosion. For instance, if there were a stream bed with three items in it, a steel nail, a piece of gold jewelry, and a plastic toy sailor, we would correctly guess that the nail would corrode away within a few years while the gold jewelry would be unharmed indefinitely. The toy sailor might discolor and look generally ugly but would essentially be intact after several years. However, if the environment were different, such as in the desert, we know that the resulting reactions would occur differently. In the hot, dry, and sunny environment, the nail might remain undamaged for centuries while the gold would remain unharmed by the environment. Of course, the toy sailor would deteriorate down to dust in just a few years. Again, the type of material and the type of environment are both important in understanding corrosion.

The Navy constructs virtually all of its ship structures using metals, mainly steel, and by definition has an abundance of wet environments to contend with, most having seawater as a principal component. Therefore, in the following discussions regarding corrosion, seawater and steel are the most used examples.

For the purposes of this course, corrosion is the deterioration of metal due to reaction with wet environments. Metals include all that are used on Navy ships including, but not limited to the common steels, corrosion resistant steels, copper alloys, nickel alloys, titanium alloys, and aluminum alloys. Corrosion of metals in a wet environment is referred to as electrochemical corrosion.

Navy Basic Paint Inspector Training: Corrosion

2—3

The natural tendencies of metals to corrode in a particular environment are measured in volts as chemical and electrochemical potentials. Voltage is a measure of the “pressure” of the mobile electrons contained in a metal. It is sometimes referred to as the electromotive force (EMF). It can be compared to the pressure of water in a garden hose. The water represents the electrons and the hose is the metal conductor. If the water pressure at one end of the hose is higher than the pressure at the other end, then water will flow toward the lower pressure end. In electrical terms, if the voltage (electro-negativity) is greater at one end of the hose than the other, then electrons will flow from the area of higher voltage to the lower one. Because metals have lots of mobile electrons in them, they make good electrical conductors.

One of the basic properties of all metals and alloys is that they will have a certain electrochemical potential, or voltage, that can be measured against a reference standard when they are exposed to an electrolyte. If you were able to look at a corroding metal under extremely high magnification, so that you could see what the atoms on the surface were doing, you might see that as each metal atom detaches from the structure, it donates one or two negatively charged electrons to the circuit. In a sense, the electrical potential of the corroding metal is a measurement of its ease of giving up its electrons and is therefore a measure of its tendency to corrode. Metals that will corrode easily have high electrochemical potentials. Examples of these include magnesium, zinc, and aluminum, and these types of metals are referred to as “active” metals. Metals which do not have a natural “desire” to corrode have low electrochemical potentials. Examples of these include gold and platinum. These are referred to as “noble” metals. Of course, there are very many metals and alloys with potentials that are somewhere in between these two extremes, and since differences in temperature, electrolyte chemistry, and physical conditions can change their potentials, corrosion and corrosion control are often not as simple as they seem!

ELECTROCHEMICAL POTENTIAL

You may ask why wet corrosion is referred to as an electrical chemical reaction. It’s because of the dual, electrical and chemical, nature of the corrosion reaction. In the reaction, electrons released at the anode flow to the cathode by a direct metallic path (electrical contact), and the electrical charge returns to the anode through the conductive path (e.g., sea water immersion or contamination) called the electrolyte. Thus, there are always four things necessary for electrochemical corrosion to occur: an anode, a cathode, a metallic path, and an electrolyte. An acronym (ACME) can be used to remember the name of the four circuit components:

AnodeCathodeMetallic pathwayElectrolyte

If any of these items are eliminated or controlled, metal corrosion can be controlled. This often provides a method for corrosion control.


2—4

Example: A simple flashlight battery (Figure 2-2) illustrates the four items necessary for corrosion to occur and we all know that this device can produce electrical flow. The center post is carbon which acts as a metal in this situation. Carbon has a relatively low electrochemical potential. The case is zinc, a metal with a relatively high electrochemical potential. The ammonium chloride paste is the electrolyte, and the light bulb and wire that connect the anode to the cathode are the external circuit. When the circuit is closed, it carries a flow of electrons from the zinc to the carbon through the external circuit which illuminates the light bulb. The zinc case corrodes in making the current. If the light is left on too long, electrically-resistant chemical products build up in the electrolyte near the cathode, so that the current no longer continues to flow.

An anode is the part of the electrochemical cell which has the most “desire” to dissolve in the given electrolyte. It is the component having the largest electrical potential and, thus, where corrosion occurs.

A cathode is the part of the electrochemical cell which has less tendency to dissolve in the given electrolyte. It has a lower electrochemical potential than the anode and thus, is where no corrosion occurs.

Depending on several factors, any metal can act as either an anode or a cathode. Anodes and cathodes can reside on different metals or on different areas of the same metal. In the bronze and steel cell shown in Figure 2-3, the bronze is the cathode and the steel is the anode. In the bronze, steel, and zinc cell shown in Figure 2-4, both the bronze and steel are the cathodes and the zinc is the anode. Note that the steel changed from an anode to a cathode due to the connection with the zinc, which has a higher potential.

NOTE: The examples given in Figures 2-3 and 2-4 are referred to as dissimilar metal corrosion cells or galvanic cells.

ANODES AND CATHODES

Figure 2-2: Dry Cell Battery

ELECTROCHEMICAL POTENTIAL (continued)


2—5

GENERAL CORROSION

GALVANIC SERIES

So far we have talked about corrosion which occurs because of the coupling of two different metals. But one might ask why a metal which is by itself corrodes when exposed to an electrolyte. For instance, if a piece of steel was simply left out in the rain, it corrodes in a uniform way. But where is the cathode and where is the anode in such a case?

When the surface of a piece of steel is exposed to the electrolyte, areas of slightly different character form anode/cathode pairs which result in corrosion at the anodes. Because these are so close together and somewhat small, they don’t even have to be fully immersed in the electrolyte. Small water droplets on the surface over a period of time are enough to promote corrosion. As the corrosion proceeds, the anode and cathode potentials reverse themselves resulting in more uniform rather than localized corrosion.

Figure 2-3: Simple Electrolytic Cell Figure 2-4: Bronze, Steel and Zinc Electrolytic Cell

GALVANIC CORROSION• Dissimilar metals in contact with

each other may undergo galvanic corrosion.

Different alloys and metals have different tendencies to corrode. It is possible to arrange the metals in a series ranked for this tendency from highest to lowest potential (tendency to corrode). Table 2-1, the “galvanic series in seawater,” lists metals in descending order from highest to lowest potential in seawater. The galvanic series is really a list of metals according to their electrical potential against a standard reference electrode in seawater. When two different metals come into electrical contact with each other in electrolyte, the one that is higher in the table becomes the anode, and the lower one in the table becomes the cathode in a galvanic (dissimilar metal) corrosion reaction. The corrosion rate will be accelerated from the normal metal corrosion rate. Also, the further that the two metals are from each other in the table, the greater will be the corrosion rate.


2—6

Other factors that have an important effect are: surface films, applied or residual stresses, concentration and type of ions (e.g., salts) in the solution, and operating temperature.

TYPES OF CORROSION

GALVANIC SERIES (continued)

Table 2-1: Galvanic Series in Seawater

More likely magnesium alloysto corrode zinc(anodic) aluminum alloys cadmium steel or iron 18-8 stainless; active brass bronze copper nickel alloys nickel inconel 18-8 stainless; passiveLess likely titanium alloysto corrode platinum(cathodic) graphite

Examples of different types of corrosion are shown below in Figures 2-5 thru 2-13.

Uniform Corrosion The simplest form of corrosion and the form found in most cases is direct surface attack corrosion resulting from the direct reaction of a metal surface with oxygen in the air or moisture. This form occurs frequently under normal shipboard conditions of exposure and is characterized by relatively uniform degradation over large areas of the metal. In this form of attack, the anode and cathode are both found on the surface of the metal and, as corrosion occurs, these change locations so that the corrosion products build up on the entire surface rather than in isolated locations. The rusting of steel or tarnishing of silver are examples of uniform corrosion.

Figure 2-5: No Corrosion


2—7

SENSITIZATION

• Stainless steels that are welded and not able to be heat treated afterwards may be “sensitized” in the heat affected zone, making them more prone to intergranular corrosion in sea water.

• Low carbon “L” grades (e.g., 304L, 316L) are often used to help prevent this.

Figure 2-6: Uniform Corrosion

Dissimilar Metal Corrosion (Galvanic) The corrosion rate between dissimilar metals depends on how great a difference there is between the metals on the series and on the surface areas of the metals involved. The larger the cathodic area relative to the anodic area, the more accelerated corrosion of the anode will be. This is known as the “area effect.” When an active metal is placed in contact with a more noble metal, the active metal will corrode preferentially. The rate of corrosion will be greater than the anodic material would be if it was not coupled.

Pitting Pitting is a severe form of localized corrosion, and is caused by physical or chemical variations on a metal surface in the presence of a corrosive environment (electrolyte). A physical variation may be impurities in the metal itself. A chemical variation could come from the environment such as from salt deposits or from local acidic areas in an electrolyte.

Figure 2-7: Dissimilar Metal

Figure 2-8: Pitting

Dissimilar Metal

• Dissimilar metals in contact.


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Crevice Corrosion Crevice corrosion (Figure 2-9) is a special type of pitting that frequently occurs within crevices and other shielded areas on metal surfaces exposed to an electrolyte. This type of attack is usually associated with a stagnant solution caused by gasket surfaces, lap joints and crevices under bolt and rivet heads. Corrosion under wet sand and dirt is a form of crevice corrosion called under-deposit corrosion.

Stress Corrosion Cracking Stress-corrosion cracking (SCC) (Figure 2-10) is the brittle fracture of an alloy, exposed to a specific corroding medium, at low tensile stress levels with respect to the design strength of the alloy. Only pure metals are immune to stress-corrosion cracking. The time to failure in each environment depends on the total stress, the temperature, and the effective concentration of the electrolyte solution. In general, you cannot detect stress corrosion cracking until it is too late.

Intergranular Corrosion Metal alloys are composed of grains or crystals which form as the metal is cooled following casting or certain high temperature heat treatments. Intergranular corrosion is a selective attack which occurs along grain boundaries of some alloys. Metal processing methods such as welding and heat treating can cause some of the alloying elements in the metal to form extremely small particles at the grain boundaries, called precipitates. Depending on the materials involved, precipitates may be either anodic or cathodic relative to the surrounding metal, but in either case, selective galvanic type corrosion occurs at grain boundary regions. Although intergranular corrosion can leave a metal surface roughened, definite diagnosis usually requires the use of a microscope. See Figure 2-11.

Figure 2-10: Stress Corrosion Cracking

TYPES OF CORROSION (continued)

Figure 2-9: Crevice Corrosion


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Exfoliation Exfoliation (Figure 2-12) is an advanced stage of intergranular corrosion and is characterized by a “delamination” of metal along grain boundaries. Rolled products, such as certain types of aluminum alloy plate, are particularly susceptible to exfoliation due to their longitudinal grain structure, as shown below in Figure 2-13. The process of delamination in exfoliation is assisted by the formation of corrosion products between grain boundaries as they separate.

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 cause a substrate to corrode, the environment can cause a coating system to fail as well.

Humidity Moisture in the atmosphere can collect on the substrate.

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

Salt When dissolved in water, readily conducts corrosion current thereby increasing corrosion rate.

Chemicals Different chemicals attack various metals differently.

Heat/Temperature Higher temperatures speed up electrochemical reaction rates.

Stack Gases The exhaust gas from diesel and gas turbine engines contain chemicals that react with air, moisture and sunlight to form acidic by-products.

Ultraviolet Radiation This radiation, in sunlight, can damage certain types of coatings or non-metallic materials.

DEHUMIDIFICATION

• Keeping the relative humidity (RH) below 35% will cause the corrosion rate of steel to drop greatly.

SUMMARY

Corrosion is a continuous process that occurs everywhere. Different alloys and metals have different tendencies to corrode, depending upon where they fall in the galvanic series. Corrosion is broken down into these types: uniform, dissimilar metals, pitting, crevice, stress cracking, intergranular, and exfoliation. Environmental factors play a significant role in corrosion.


Corrosion (2)

NAVSEA Basic Paint Inspector Training!

Topics

l Components necessary for corrosion

l The galvanic series and galvanic corrosion

l Common types of corrosion on ships

l Environmental factors that contribute to corrosion

Scope

l Acquaints students with the basic principles of corrosion, especially those that occur most frequently on Navy ships

Learning Outcomes

l  Identify the basic principles of corrosion

l Recognize the different types of corrosion most likely to occur on ships

l Discuss the environmental factors that accelerate corrosion and the most corrosive areas on ships

What Is Corrosion?

l Definition: – Deterioration of any material due to reaction

with the environment in contact with the material that results in loss of the material and its properties (e.g., loss of steel).

Cost of Corrosion!!

l Estimated annual cost of corrosion –  $7 billion for Navy

–  $3.2 billion of this number on ships

(Source: DoD Cost of Corrosion Annual Report; Dec. 2013)


“Environment” Meanings

l  What does term “environment” mean to a coating or metal with respect to corrosion? –  It’s not like our natural environment, such as the earth,

air, and water… –  It means the physical & chemical conditions they are

exposed to, such as salts, temperature, acids, ozone, etc.

l  Different environments have different effects on different materials.

Corrosion Cycle

Corrosion Cell Components

ACME Memory Trick

Anode

Cathode

Metallic Pathway

Electrolyte

Electrochemical Potential

l  Measured in voltage, and is a basic property of all metals & alloys.

l  Electrical current (electrons) flow from high potential areas to low potential areas.

l  High potential = more prone to corrosion = “active” metals.

l  Low potential = less prone to corrosion = “noble” metals.

Dry Cell Battery Electrolytic Cell


General Corrosion

Minute differences between individual grains leads to anode/cathode pairs and general corrosion.

Typical “grain” structure of metal

Corrosion Cell A Picture is Worth a Thousand Words

Anode Cathode Pairs in Steel Continue to be Active Over Time

See How Steel Will Waste Away

Corrosion Cells Can Continue Right Through to the Other Side

There’s Usually More Corrosion Than First Meets the Eye


Corrosion Cells Work Inside the Steel and Under the Preservation

Sometimes It’s Discovered Too Late.

Galvanic Series in Seawater

Magnesium Alloys Zinc Aluminum Alloys Cadmium Steel or Iron 18-8 Stainless; Active Brass Bronze Copper Nickel Alloys Nickel Inconel 18-8 Stainless; Passive Titanium Alloys Platinum Graphite

More likely to corrode (Anodic)

Less likely to corrode (Cathodic)

Types of Corrosion

l  Corrosion does not always look the same or occur for the same reasons

l  The appearance of corrosion is primarily affected by: –  Environment –  Materials of construction –  Configuration

l  Many forms of corrosion occur together.

No Corrosion

Uniform Corrosion

Fan Room!

Dissimilar Metal

Dissimilar Metal Embedded in Aluminum Creates Corrosion Cell


Dissimilar Metal

Brass shock mounts for light on aluminum mount.

Dissimilar Metal

Dissimilar Metal Pitting

Crevice Corrosion Crevice and Edge Corrosion


Crevice Corrosion

Aluminum alloy lap joint on an aircraft

Stress Corrosion Cracking

Stress Corrosion Cracking

Chloride SCC of stainless steel

Failure Caused by Blast Embedded Particles Initiating Corrosion

Intergranular Intergranular

Intergranular corrosion of sensitized stainless steel


Exfoliation Exfoliation

Aluminum alloy plate!

Exfoliation

Aluminum Grain Structure

Grains are flattened and elongated during rolling

of aluminum plate

General Corrosion

Environmental Effects

l Humidity/Oxygen

Corrosion of Underwater Hull!


l Humidity/Oxygen

l Salt Water

Corrosion of Battery Box Caused by Battery Acid


l  Humidity/Oxygen

l  Salt Water

l  Chemicals




l  Salt Water

l  Chemicals

l  Heat/Temperature

Corrosion of Steam Piping



l  Salt Water

l  Chemicals


l  Stack Gases

Paint failure caused by stack gases, without protection area, will soon begin to corrode!



l  Salt Water

l  Chemicals


l  Stack Gases

l  UV Radiation Chalking of an epoxy topcoat—

eventually coating will fail allowing corrosion of substrate!

Open Forum

l  What other conditions or items can be found on board ship that could contribute to corrosion or coating deterioration? –  Examples:

•  Decontaminating solutions •  AFFF (Aqueous Film Forming Foam) •  Biofouling •  Smog and Acid Rain •  CHT and Sanitary Tanks

Summary

l  Corrosion continuously occurs everywhere.

l  Different alloys and metals have different tendencies to corrode

l  Corrosion is broken down into these types: –  Uniform –  Dissimilar metals –  Pitting –  Crevice –  Stress cracking –  Intergranular

l  Environmental factors play a significant role in corrosion

Topics: • Three mechanisms of corrosion control by coatings (barrier, sacrificial,

inhibitive)• Sacrificial and impressed current cathodic protection systems

Scope This section acquaints students with the basic mechanisms for controlling corrosion on Navy ships (coating and cathodic protection) and how they work well together.

Learning OutcomeAt the end of this section, the student will be able to:

• Define the different mechanisms by which coatings control corrosion and the basic properties of coatings used for corrosion control.

• Recognize the basic differences between sacrificial anode and impressed current cathodic protection.

The methods used to fight or control corrosion in the Navy are many and ingenious. Designers choose materials carefully to maximize corrosion resis-tance and avoid galvanic couples. Good corrosion design will also take into account other factors which increase the rate of corrosion such as crevices. Humidity in enclosed spaces, such as voids, is reduced with the use of desic-cants, and vapor phase corrosion inhibitors are used to protect these spaces. Designs are made such that certain metals sacrifice themselves, such as pieces in seawater piping systems, to protect other metallic surfaces. Galvanic corro-sion can even be used to our advantage through the use of sacrificial coatings and anodes.

The main way the rate of corrosion can be controlled is by breaking the corrosion cycle by eliminating or modifying one of the corrosion cycle elements: the anode, the cathode, the metallic path or the electrolyte.

Protective coatings can be used to provide thin films of protection between the electrolyte and the metal substrate. They can also be made to sacrifice themselves to protect the substrate. Coatings can control the migration or movement of water (electrolyte) to the substrate. That is, paints and coatings can be used as barrier films, sacrificial films, or can contain inhibitors to slow down or eliminate corrosion.

3 Corrosion Control

NAVSEA Basic Paint Inspector Training: Corrosion Control

3—2

SACRIFICIAL COATINGS

BARRIER COATINGS

A coat of paint can control corrosion by acting as a barrier, preventing contact between the metal and the corrosive elements. To act as an effective barrier, the paint film must demonstrate the following characteristics:

• Reduced permeability to moisture and oxygen: If moisture and oxygen readily pass through the paint film, corrosion may take place even though the coating is undamaged and appears to be intact. Large masses of rust will form under the coating, eventually lifting the coating off the surface. It is safe to assume that all coats are permeable to some extent.

• Tight adherence to the surface: A coating must be highly adherent, forming a tight membrane over the surface. Even if a coating allows some moisture to penetrate, it can still provide good protection if there is no area beneath the film in which the moisture can collect.

• Smooth and continuous film: The paint film must be applied evenly to avoid low areas and must be free of small skips, voids or pinholes. These tiny imperfections in the paint surface will allow water and oxygen to enter. A tiny spot of corrosion may quickly spread under the paint, stretching, cracking, and lifting the film as it progresses.

• Resistance to chemicals and abrasion: To successfully provide barrier protection, the paint used must be resistant to whatever environment it is exposed. Some exposures may require higher abrasion resistances than others.

A sacrificial coating is another form of corrosion protection. The pigments in the coating sacrificially react with corrosive elements in the environment. By forming a galvanic cell, these metallic pigments corrode before the substrate can be attacked. For example, when a scratch or a break occurs in a zinc-rich paint film, water (the electrolyte) and oxygen combine with the metallic zinc dust to form zinc oxide or “white rust” instead of the water and oxygen combining with steel. Over time, the zinc particles will corrode away and the paint’s protective ability will be lost. This method of protection will only work if a more anodic (top of the galvanic series) metal (zinc) is placed on top of the substrate you are trying to protect (steel).

NOTE: It is especially important to mix zinc-rich paints thoroughly when applying them so that all of the metallic dust particles that give this sacrificial protection are incorporated uniformly in the paint film. Constant agitation of the paint pot is usually recommended.

Navy Basic Paint Inspector Training: Corrosion Control

3—3


Inhibitive coatings contain special pigments that inhibit metal corrosion at the metal coating interface. Thus, they are typically primers. These pigments must be slightly water-soluble to be effective. Examples of some of these pigments and their mechanisms of corrosion inhibition are given below:

Inhibitive coatings, due to their toxicity, coatings containing lead, chromium, and other heavy metals have been phased out of the Navy (with some exceptions). For example, TT-P-645 was the specification for zinc chromate, which has been revised to TT-P-645C (or later) for alkyd primer.

Red Lead and Other Lead Pigments Read lead and other lead pigments were used effectively as corrosion inhibitors in oil-base paints for many years. Moisture combines with water and the oil to form lead soaps that wet the steel well and inhibit the corrosion reaction.

Zinc Chromate and Other Chromate Pigments Inhibitive chromate primers were once widely used by the Navy, especially on aluminum, because red lead primers did not protect it well. The leached chromate ion inhibited the corrosion reaction.

INHIBITIVE COATINGS

CATHODIC PROTECTION SYSTEMS

Cathodic protection is the process of protecting a metal from corrosion while it is submersed in water by forcing its entire exposed surface to be the cathode of the overall electrochemical cell. This is accomplished via one of two means: sacrificial anode system and impressed current system (NSTM Chapter 633 covers cathodic protection).

Note that cathodic protection does little or no good on surfaces which are not fully submersed, and only protects the metal which is exposed to the same electrolyte as the anode (i.e., the cathodic protection on the outside of the ship’s hull does not protect areas above the waterline such as the freeboard, nor will it protect areas inside the hull such as in bilges and tanks that contain water.) These interior, immersed areas require their own cathodic protection systems.

Sacrificial Anode Cathodic Protection This type of cathodic protection consists of protecting a submerged structure by attaching a more active metal to the structure. For a steel ship’s hull, these attached pieces of metal are normally zinc slabs; however, they can also be aluminum, magnesium, or low-voltage anodes (LVAs). The attached metal (anode) corrodes in the seawater providing electrons to the steel (cathode) through a ground (external circuit) and positive current through the seawater (electrolyte). Low-voltage anodes reduce the potential for hydrogen embrittlement of high-strength steel and nickel-based alloys.


3—4

CATHODIC PROTECTION SYSTEMS (continued)

Impressed Current Cathodic Protection (ICCP) Systems The second way to provide cathodic protection to the immersed portions of ships is to use permanent (non-sacrificing) metal anodes (usually platinum) connected to a DC power supply within the ship (Figure 3-1). The anodes are mounted at various locations on the submersed hull to provide adequate distribution of protective current. This is termed Impressed Current Cathodic Protection (ICCP) and is used to protect the hull of most surface ships and some late model submarines. The flow of the electrons in the metallic path and the flow of the ions through the sea water in this system are similar to those of the sacrificial anode system, as is the cathodic protection provided.

Since impressed current cathodic protection anodes operate at potentials up to 28 VDC, special consideration must be given to the paint system surrounding the anodes. A thick special purpose epoxy coating is applied to the areas within six feet of each anode to prevent shorting of the cathodic protection current to the hull and distribute the cathodic protection to a larger area of the underwater hull. This is termed the dielectric shield (also called the capastic shield). Since the voltage drop is steep when close to the anode, the applied voltage is reduced to a reasonable level by the time it reaches the hull paint surrounding the dielectric shield. Close to the anode, these shield materials often show a stained appearance resulting from chemical reactions occurring in the sea water at the anode (Figure 3-2). This staining is normal and acceptable.

Breakdown of the dielectric shield to ground is indicated by the formation of soft, but bulky, white deposits of calcareous material. These are produced from seawater due to high pH located at any strong cathode. Within the dielectric shield, this is considered detrimental since the shield should provide full blockage of the current trying to enter the hull at the anode to more fully and

Figure 3-1: Basic Impressed Current Cathodic Protection System


3—5

uniformly extend the cathodic protection. Note, that the normal underwater hull paint system is applied over the dielectric shield, not under it. The dielectric material must be applied directly to the white-metal blasted surface if it is to function properly.

Ideally, corrosion protection for underwater steel hulls and tanks uses both a cathodic protection system and a protective coating. For sacrificial anode systems, this makes the anodes last longer, and would require fewer of the heavy anodes to protect the steel. For ICCP systems, this prevents a huge current demand to protect massive areas of bare steel, and therefore allows a smaller and more economical power supply to be used. The real function of cathodic protection is to protect any areas of bare steel where the paint has been damaged from corrosion until the paint can be touched-up or renewed.

Both sacrificial anodes and ICCP systems can be effective in eliminating corrosion if applied correctly. Selecting the proper number of anodes, their capacities, their locations and the location of sensing reference cells is quite complex, and requires both experience and the use of sophisticated methods. Cathodic protection systems are covered in detail in NSTM Chapter 633.

SUMMARY

Corrosion is controlled on Navy ships by barrier, sacrificial, and inhibitive coatings. Two methods of cathodic protection, sacrificial and impressed current, are also employed. Impressed current uses permanent (non-sacrificial) metal anodes connected to a DC power supply within the ship to protect a submerged structure. Sacrificial anode protection works by attaching a more active metal to the structure.

Figure 3-2: Typical Staining of an ICCP Dielectric Shield


Corrosion Control (3)

NAVSEA Basic Paint Inspector Training!

Topics

l Three mechanisms of corrosion control by coatings (barrier, sacrificial, inhibitive)

l Sacrificial and impressed current cathodic protection systems

Scope

l Acquaints students with the basic mechanisms for controlling corrosion on Navy ships (coating and cathodic protection) and how they work well together

Learning Outcome

l Define the different mechanisms by which coatings control corrosion and the basic properties of coatings used for corrosion control

l Recognize the basic differences between sacrificial anode and impressed current cathodic protection for corrosion control

Corrosion Control

l Materials Selection

l Control Environment

l Design Details

Coatings to Prevent Corrosion

l Three primary ways coatings act to prevent corrosion on steel – Barrier Coatings

•  e.g. epoxy – Sacrificial Primers

•  e.g. inorganic zinc – Inhibitive Primers


Barrier Coatings

l Requirement: – Reduced permeability to moisture and

oxygen •  Both oxygen and moisture are required for corrosion

to occur •  No coating is completely impermeable •  Pigment selection can be important

Barrier Coatings

l Requirement: – Coating must adhere tightly to the

substrate with no breaks •  If the coating adheres tightly, moisture

cannot get close enough to the surface to cause corrosion

• Breaks in the coating allow corrosion to begin very quickly

Barrier Coatings

l Requirement: – Resistance to the environment

• Coatings must withstand the environment in which they are used

• For example: – Chemical (ballast tank, fuel tank, CHT tank) – Abrasion (non-skid, deck coatings)

Sacrificial Primers

Steel Substrate: Cathode!Zinc Rich!

Coating!Anode!

Topcoat!

Water!Electrolyte!

In sacrificial primers, pigments provide active electrochemical protection by reacting with the

environment.!

Sacrificial Primers

l Must be used as the primer—needs to be in electrical contact with steel.

l Generally, need a high loading of zinc powder by weight. – Adjacent particles must be in contact for

effective protection.

– Inorganic binders are typically more effective than organic (e.g. epoxy) binders.

Class Input

l Name some other types of sacrificial coatings processes – Galvanizing (zinc) –  Electroplating (zinc, cadmium) –  Metal Spray Coatings (zinc, aluminum)


Inhibitive Primers

Substrate!

Moisture Penetration!

Inhibitive Primer!

Inhibitive coatings react with moisture absorbed by the topcoat to form products

which inhibit the corrosion process.!

Inhibitive Primers

l  Must be used as primer coat—needs to be in contact with steel.

l  Examples: –  Red lead, lead oxide, lead chromate (Banned!) (form

inhibitive soaps)

–  Zinc chromate, strontium chromate, chromate conversion coating (Prohibited!)

–  TT-P-645C alkyd primer

Note: the latter dissolves to place inhibitors in solution.

Cathodic Protection

l Protects metal by forcing entire surface to be the cathode of the overall electrochemical cell.

l ENTIRE surface to be protected MUST be immersed in the electrolyte.

l Two methods: – sacrificial anodes –  impressed current cathodic protection

Sacrificial Anodes

l  Entire exposed, submersed surface becomes the cathode

l  Anodes made of a more active material than the substrate

l  Examples: zinc, aluminum l  Surface MUST be immersed

in electrolyte for sacrificial anodes to function

Sacrificial Anodes

The deterioration of the anode is indicative of a properly working anode.!

Sacrificial Anodes

In this photo, shipyard workers have nailed zinc anodes to wood docking blocks in an effort to prevent corrosion

of the steel strapping. Will this work?!


Where’s the bronze?

Unpainted bronze ship propellers provide a large area for galvanic coupling.

Sacrificial Anodes

l Zinc and aluminum anodes: “self-regulating” l Magnesium anodes and impressed current

systems: not “self-regulating” l Low-voltage anodes (LVA)

–  Electrochemical potential within the range of -850mV that are capable of supporting large anodic current densities

– Reduce potential for hydrogen embrittlement of high-strength steel and nickel-based alloys

Sacrificial Anodes

This poor guy really thinks he has a relic from the American Revolution!

Cathodic Protection

Basic Impressed Current Cathodic Protection (ICCP) System!

Failed Dielectric Shield (called Capastic Shield in NAVSEA Standard

Item 009-32)

Rust bleed through a dielectric shield indicates cracks which penetrate to the hull

Failed Dielectric Shield

Note calcareous deposits at failure sites in dielectric shield!


ICCP Components

Properly Operating ICCP Anode With Dielectric Shield Bleaching (often called a “Flame” pattern)

Cathodic Protection

l Why paint the ship’s hull if it has cathodic protection? –  Huge current demand—insufficient power supply

–  Zinc anodes deplete rapidly—large area effect

–  Antifouling needed to reduce drag friction

Cathodic Protection for Your Car

What’s missing?!

Summary

l  Corrosion is controlled on Navy ships by barrier, sacrificial, and inhibitive coatings

l  Sacrificial and impressed currents are two methods of cathodic protection

l  Impressed current uses permanent (non-sacrificing) metal anodes

l  Sacrificial anode protection attaches a more active metal to the structure