Nace Basic Corrosion 2014 Manual

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(1)i. BASIC CORROSION Student Manual. July 2014 Version 2.01. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(2) ii. Important Notice Neither the NACE International, its officers, directors, nor members thereof accept any responsibility for the use of the methods and materials discussed herein. No authorization is implied concerning the use of patented or copyrighted material. The information is advisory only and the use of the materials and methods is solely at the risk of the user. Printed in the United States. All rights reserved. Reproduction of contents in whole or part or transfer into electronic or photographic storage without permission of copyright owner is expressly forbidden.. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(3) iii. Acknowledgements The time and expertise of a many members of NACE International have gone into the development of this course. Their dedication and efforts are greatly appreciated by the authors and by those who have assisted in making this work possible. The scope, desired learning outcomes, and performance criteria of this course were developed under the auspices of the NACE Education Administrative Committee in cooperation with the NACE Certification Administrative Committee. It is the intention of this task group to continue toward development of additional NACE courses on integrity management. On behalf of NACE, we would like to thank the task group for its work. Their efforts were extraordinary and their goal was in the best interest of public service —to develop and provide a much needed training program that would help improve corrosion control efforts industry-wide. We also wish to thank their employers for being generously supportive of the substantial work and personal time that the members dedicated to this program. Bopinder Phull, PhD. Consultant Corrosion & Cathodic Protection Specialist Wilmington, NC. Jerry Byrd. Byrd Coating Consultants Wellington, FL. Raul Castillo. Senior Metallurgical Specialist Dow Chemical Company Freeport, Texas. Dan Laury. Project Lead Vantage Force, Inc. Houston, TX. John P. Campbell. Head3 Interactive Project Manager/Coordinator The Woodlands, TX. Nina Pasini Deibler. Instruction Design Consultant Pittsburgh, PA. Scott Brady. Project Coordinator Vantage Force, Inc. Houston, TX. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(4) iv. Welcome to the Basic Corrosion Course Summary The goal of this course is to provide interested persons with a basic overview of corrosion including its causes, its impact of various materials, and measures used to inhibit, inspect, and monitor it. A person who successfully completes this course will know enough about corrosion to be able to pursue additional study and professional development through the NACE Certification Program.. Who Should Attend This course is for individuals interested in a basic survey of corrosion, including but not limited to: •. Engineers. •. Managers. •. Supervisors. •. Technicians. •. Salespersons. •. Inspectors. Prerequisites An understanding of basic chemistry at the high-school level is highly recommended. Very little time will be spent reviewing general chemistry basics during the course. Learners include high school or technical school graduates through college educated businesspersons and scientists/engineers. The course materials will be written in plain language and all technical terms will be clearly and simply defined and stated. The course will not assume any existing scientific knowledge or education of the learners.. Length The course begins on Monday (or Day 1) at 8:00 AM and ends on Friday (or Day 5) at 1:00 PM.. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(5) v. Delivery Media An instructor will present the course in-person to a classroom of attendees. Materials will include: •. Student manuals with images. •. PowerPoint presentations with images. •. Classroom delivery. •. Quizzes (ungraded for practice). •. Practical exercises (to reinforce concepts). •. 100 item assessment (graded exam). •. Reference materials. Quizzes and Examinations Each chapter will include self-test questions as a quiz for learners to complete as study aids. The final written exam, which will be given on Day 5, will consist of 100 true/ false and multiple-choice questions. The four-hour examination is open book and students may bring reference materials and notes into the examination room. Self-test and exam questions are drawn from the learning objectives and the material covered in the lectures and course manual. A score of 70% or greater is required to successfully complete the course and receive a course completion certificate and continuing education units (CEUs).. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(6) vi. DAILY SCHEDULE DAY ONE 8:00 AM–5:00 PM Morning Session. Chapter 1 Introduction to Basic Corrosion Chapter 2 Basics of Corrosion Electrochemistry. Afternoon Session. Chapter 2 Basics of Corrosion Electrochemistry (continued) Chapter 3 Corrosive Environments DAY TWO. 8:00 AM–5:00 PM Morning Session. Chapter 4 Materials. Afternoon Session. Chapter 5 Forms of Corrosion DAY THREE. 8:00 AM–5:00 PM Morning Session. Chapter 5 Forms of Corrosion (continued). Afternoon Session. Chapter 6 Designing for Corrosion Control DAY FOUR. 8:00 AM–5:00 PM Morning Session. Chapter 7 Corrosion Control Methods. Afternoon Session. Chapter 8 Inspection, Monitoring, and Testing DAY FIVE. 9:00 AM–1:00 PM Morning Session. Exam Briefing and Final Written Exam (4 Hours). *Schedule may vary based on individual instructor’s pace.. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(7) vii. Code of Conduct While on site at a NACE course, appropriate behavior towards instructors, NACE/ class location staff, and fellow students is required. If appropriate behavior is not maintained, NACE has the authority to take proper action against the student(s) in violation, which could result in revocation of one or more of the following: NACE Certification, Membership, and current/future classroom attendance.. Classroom Policies To provide the best environment for training, please observe and follow these requirements: •. No smoking or other tobacco products.. •. Class starts at designated times.. •. Participants are responsible for their own learning and timekeeping.. •. Turn off mobile phone ring tones, and do not make or answer calls, text messages, or tweets while in the classroom.. •. Mobile phones, smart phones, tablets, notebooks, cameras and any other devices containing cameras are not permitted during quizzes and exam.. •. Observe designated times for lunch breaks, coffee breaks, and smoke breaks.. •. Note location(s) of restrooms and smoking facilities.. Policy Regarding Use of Electronic Devices During Examinations (Classroom, Lab, or Field) This includes, but is not limited to, laptops, smart phones, cell phones, communication devices, and cameras. Non-communicating, battery-operated, silent, non-printing calculators, including calculators with alphanumeric keypads, are permitted. Calculating and computing devices having a QWERTY keypad arrangement similar to a typewriter or keyboard are NOT permitted. Such devices include, but are not limited to, palmtop, laptop, handheld, and desktop computers, calculators, databanks, data collectors, organizers, smart phones, and cell phones. Also excluded are communication devices, such as pagers, cameras, and recorders of any type. All communication devices must be kept on silent mode and not answered during the exam(s). INSTRUCTIONS FOR ACCESSING SCORES ON-LINE. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(8) viii. Instructions for Completing the ParSCORETM Student Enrollment Score Sheet 1. Use a Number 2 (or dark lead) pencil. 2. Fill in all of the following information and the corresponding bubbles for each category:. √ ID Number: √ PHONE:. Student ID, NACE ID or Temporary ID provided Your phone number. The last four digits of this number will be your password for accessing your grades on-line. (For Privacy issues, you may choose a different fourdigit number in this space.) √ LAST NAME: Your last name (surname) √ FIRST NAME: Your first name (given name) √ M.I.: Middle initial (if applicable) √ TEST FORM: This is the version of the exam you are taking. √ SUBJ SCORE: This is the version of the exam you are taking. √ NAME: _______________ (fill in your entire name) √ SUBJECT: ____________ (fill in the type of exam you are taking, e.g., CIP Level 1) √ DATE: _______________ (date you are taking exam) 3. The next section of the form (1–200) is for the answers to your exam questions. x All answers MUST be bubbled in on the ParSCORETM Score Sheet. Answers recorded on the actual exam will NOT be counted. TM x If changing an answer on the ParSCORE sheet, be sure to erase completely. x Bubble only one answer per question and do not fill in more answers than the exam contains.. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(9) ix. It is NACE policy not to disclose student grades via the telephone, e-mail or fax. Students will receive a grade letter in approximately 6-8 weeks after the completion of the course by US mail or through their company representative. However, in most cases, within 7-10 business days of receipt of exams at NACE headquarters, the students may access their grades via the NACE web site. The following are step-by step instructions for this process. Spaces are provided below for you to fill in the information required to access grades. Please be sure to have this information filled in before leaving the course location. Keep this form with you upon leaving the course. You will not be able to access your grades without this information.. Go to the NACE Website at www.nace.org Under the Training & Education tab click on Check My Grades Then follow the 4 easy steps: Step 1: Find your Course Number in the drop-down list and click on it. COURSE NUMBER: ___________________ You may find your course number on your registration confirmation letter or it will be available from the instructor at the class. If your course number does not appear in the drop down list then grades have not yet been posted. Step 2: Enter your Student ID number. STUDENT ID:. ____________________. This will be your 6-digit NACE ID number or membership number (example 123456) OR a 10-digit temporary ID number assigned at the course. The 6-digit number is printed on the roster provided to the instructor as well on your registration confirmation. For courses where no roster is provided, the instructor will assign a 10-digit temporary ID number used only for accessing scores on-line. Step 3: Enter your Password:. PASSWORD: ______________________. This should be the last four digits of the telephone number you completed on your ParSCORE exam form. You may choose an alternate number but it must be in the last four spaces provided for the telephone number on the Scantron exam form Step 4: Click on “SEARCH” If you have trouble accessing your grade, please contact NACE International by e-mail at [email protected].. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(10) x. NACE Corrosion Network (NCN) NACE has established the NACE Corrosion Network, an electronic list server that is free to the public. It facilitates communications among professionals who work in all facets of corrosion prevention and control. If you subscribe to the NACE Corrosion Network, you will be part of an e-mail driven open discussion forum on topics A–Z in the corrosion industry, or you can review and respond to relevant topics online. Got a question? Just ask! Got the answer? Share it! The discussions will sometimes be one-time questions, and other times there will be debates. What do you need to join? An e-mail address. That’s all! 1. To subscribe, fill out the form and select the lists you wish to join at: www.nace.org/ncn. 2. You will receive a confirmation e-mail, which you will need to reply to in order to join the lists.. 3. To unsubscribe, click Unsubscribe for the lists you wish to leave at: www.nacecorrosionnetwork.com/read/all_forums. Technical Committees More than 2,000 NACE members participate in technical committee activities. The committees are led by the Technical Coordination Committee (TCC), which serves as the administrative and policy-making body to the committees. The technical committees are organized by Specific Technology Groups (STGs). STGs are assigned specific technical areas within three administrative classes: Industry-Specific Technology (N), Cross-Industry Technology (C), and Science (S). Technology Management Groups (TMGs) are formed under the TCC to provide a structure and a conduit for communication between the TCC and the various STGs within their respective areas. They provide assistance, when necessary, to help STGs achieve their objectives.. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

(11) xi. Standards and Reports NACE standards are prepared by the Association’s technical committees to serve as voluntary guidelines in the field of prevention and control of corrosion. These standards are prepared using consensus procedures. NACE offers its standards to the industrial and scientific communities as voluntary standards to be used by any person, company, or organization. Members may download PDF copies of standards at no charge. A technical committee report is a limited-life document developed by a technical committee. Typical categories for committee reports are 1) state-of-the-art reports that deal with the current science and technology of a method, technique, material, device, system, or other aspect of corrosion control work; or 2) informational reports that can be statements on a specific problem (summarizing its ramifications, controversial points, and possible solutions), surveys of common practices, bibliographies on special subjects, etc. Reports also may be downloaded at no cost by NACE members.. Certification Information Traditionally, NACE certification has been awarded to candidates who have met work and education requirements and have successfully completed an open book exam. “Parallel Path” is an alternative route to achieving certification. Under the Parallel Path, NACE certification is achieved by earning credits through successful completion of specified NACE training courses. Successful completion of the NACE Basic Corrosion course satisfies the examination requirement for Corrosion Technician Certification. To learn more about becoming certified or complete the application, please visit www.nace.org/Education/Courses and Programs. Certification candidates who do not meet the prerequisites at the time of course attendance will have five (5) years from the examination date to satisfy the course/ certification prerequisites and apply for certification.. List of References See these other resources for more information. The reference book, Corrosion and Its Control: An Introduction to the Subject, Second Edition by J.T.N. Atkinson and H. Van Droffelaar is provided.. ©NACE International 2000 July 2014. Basic Corrosion Student Manual.

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(13) 1. Basic Corrosion Table of Contents Chapter 1: Introduction to Basic Corrosion Definition of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Importance of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Direct Costs of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Excessive Maintenance, Repair, and Replacement . . . . . . . . . . . . . . . . . . . . . . . 2 Lost Production and Downtime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Product Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Loss of Product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Loss of Efficiency: Oversizing and Excess Energy Costs . . . . . . . . . . . . . . . . 3 Accidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Increased Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Fines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Indirect Consequences of Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Safety Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Structural Collapse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Product Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Consumer Confidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Loss of Redundancy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Appearance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Increased Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Changes in Engineering Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Forms of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 List of Organizations Involved in Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Chapter 2: Basics of Corrosion Electrochemistry Corrosion Occurs Through Electrochemical Reactions . . . . . . . . . . . . . . . . . . . . . . 1 Terms Used in Corrosion and Electrochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Compound. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Atom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Molecule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. ©NACE International 2000 January 2014. Basic Corrosion Student Manual.

(14) 2. Electrolyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Oxidation/Reduction Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Corrosion as an Electrochemical Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Corrosion Requires a Complete Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Thermodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Reference Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Calomel Reference Electrode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Silver/Silver-Chloride Reference Electrode. . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Copper/Copper-Sulfate Reference Electrode. . . . . . . . . . . . . . . . . . . . . . . . . . 9 Comparison of Potentials Measured Using Different Reference Electrodes . . 9 The Galvanic Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Nernst Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 EMF Series. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Pourbaix Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Faraday’s Law. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 E log i Curves (Evans Diagrams) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Area Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Electrochemical Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Galvanic Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Concentration Cell Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Active/Passive Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Thermogalvanic Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Passivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20. Chapter 3: Corrosive Environments Atmospheric Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Marine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Rural . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Indoor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Corrosion Under Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Dissolved gases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Effects of Dissolved Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Effects of Mineral Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Effects of Liquid Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Effects of Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Microbiologically-Influenced Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. Basic Corrosion Student Manual. ©NACE International 2000 January 2014.

(15) 3. Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 High-Temperature Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14. Chapter 4: Materials Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Metallurgy Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Crystal Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Strengthening Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Mechanical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Forming Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Wrought vs. Cast Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Materials Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Carbon Steel and Low Alloy Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Carbon Steel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Low-Alloy Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Cast Irons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Martensitic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Ferritic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Austenitic and Super-Austenitic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Precipitation-Hardening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Duplex and Super Duplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Nickel-Based Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Copper Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Characteristics of Copper Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Titanium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Zinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Non-Metallic Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Degradation Mechanisms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Joining Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Components of Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Aggregate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Field Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29. ©NACE International 2000 January 2014. Basic Corrosion Student Manual.

(16) 4. Effects of Environment on Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Freezing and Thawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Aggressive Chemical Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Abrasion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Corrosion of Embedded Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Stray Electrical Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Corrosion Cells Within Concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Chemical Reactions of Aggregate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Repair of Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Use of Protective Coatings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Aqueous Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Underground Environments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Ceramics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Ceramic Materials vs. Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34. Chapter 5: Forms of Corrosion Forms of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Combination of Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 General Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Definition and Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Corrosion Rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Predictability and Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Performance of Metals and Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Control of General Attack Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Localized Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pitting Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pitting Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Pitting Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Predictability/Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Control of Pitting Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Crevice Corrosion Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Control of Crevice Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Filiform Corrosion Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13. Basic Corrosion Student Manual. ©NACE International 2000 January 2014.

(17) 5. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Control of Filiform Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Galvanic Corrosion Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 The Electrochemical Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Galvanic Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Galvanic Corrosion Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Potential Difference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Nature of Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Spatial Effects: Area, Distance, and Geometric Effects . . . . . . . . . . . . . . . . 16 Electrolyte Resistivity Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Predicting Galvanic Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Performance of Metals and Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Control of Galvanic Attack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Materials Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Electrical Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Barrier Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Cathodic Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Modification of Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Environmental Cracking Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Recognition of Environmental Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Controlling Cracking Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Types of Environmental Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Stress Corrosion Cracking Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Hydrogen Induced Cracking and Sulfide Stress Cracking Description . . . . . . . 24 HIC Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 HIC Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Sulfide Stress Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 ANSI/NACE MR0175/ISO 15156, “Petroleum and Natural Gas Industries—Materials for Use in H2S-Containing Environments in Oil and Gas Production” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Liquid Metal Embrittlement (LME) Definition . . . . . . . . . . . . . . . . . . . . . . . . . 27 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Corrosion Fatigue Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29. ©NACE International 2000 January 2014. Basic Corrosion Student Manual.

(18) 6. Control of Environmental Cracking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Flow Assisted Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Erosion-Corrosion Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Performance of Metals and Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Aluminum and Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Carbon and Low-Alloy Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Stainless Steels and Nickel-Based Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Copper Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Impingement Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Water Drop Impingement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Cavitation Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Performance of Metals and Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Control of Flow Assisted Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Intergranular Corrosion Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Performance of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Intergranular Corrosion of Stainless Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Aluminum and Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Copper and Copper Alloys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Nickel and Nickel-Based Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Control of Intergranular Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Materials Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Design/Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Modification of Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Use of Proper Welding Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Heat Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Dealloying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Performance of Metals and Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Copper Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Brasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42. Basic Corrosion Student Manual. ©NACE International 2000 January 2014.

(19) 7. Bronzes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Cast Iron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Control of Dealloying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Materials Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Control of Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Use of Protective Coatings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Electrochemical Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Fretting Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Performance of Metals and Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Materials Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Use of Lubricants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 High-Temperature Oxidation/Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Oxygen Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Reaction Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Linear Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Parabolic Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Oxide Scale Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Scale Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Scale Adhesion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Internal Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Sulfidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Carburization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Decarburization (Hydrogen Effects) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Halide Effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Molten-Phases Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Performance of Metals and Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Carbon and Low-Alloy Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Alloy Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Nickel-Based Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Refractory Metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Control of High-Temperature Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Materials Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53. ©NACE International 2000 January 2014. Basic Corrosion Student Manual.

(20) 8. Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Modification of the Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Protective Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53. Chapter 6: Designing for Corrosion Control Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Construction Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Welding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Accommodating Other Corrosion Control Measures . . . . . . . . . . . . . . . . . . . . . . 2 Process Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Nominal Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Maximum Operating/Upset Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Minimum Operating Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Temperatures during Downtime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Velocity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Flow Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Flow Regime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pressure Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Drainage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Dissimilar Metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Crevices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Corrosion Allowance/Operating Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Maintenance and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Chapter 7: Corrosion Control Methods Materials Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Factors that Influence Materials Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Corrosion Resistance in the Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Availability of Design and Test Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Mechanical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Compatibility with Other System Components . . . . . . . . . . . . . . . . . . . . . . . . 3 Life Expectancy of Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Reliability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Appearance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Comparison with Other Corrosion Control Methods . . . . . . . . . . . . . . . . . . . . . . 3. Basic Corrosion Student Manual. ©NACE International 2000 January 2014.

(21) 9. Candidate Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Nonmetals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Modification of the Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Corrosion Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Types of Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Common Corrosive Species that Affect Corrosion Inhibition. . . . . . . . . . . . . 8 Applications of Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Gaseous Environments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Inhibitor Application Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Safety Considerations With Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Protective Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Coating Purposes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Mechanisms of Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Barrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Inhibitive Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Cathodic Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Desirable Properties of a Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Chemical Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Low-Moisture Permeability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Easy Application to Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Adhesion to Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Cohesive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Tensile Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Flexibility/Elongation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Impact Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Abrasion Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Temperature Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Resistance to Cold Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Dielectric Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Coating System Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Types of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Operating Conditions/Upset Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Substrate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Ambient Conditions During Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Environmental Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Application of Coating During Operation or at Shutdown . . . . . . . . . . . . . . 18 Time Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 New Construction/Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Shop/Field Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Design/Fabrication Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Surface Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19. ©NACE International 2000 January 2014. Basic Corrosion Student Manual.

(22) 10. Coating Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Spray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Production Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Surface Preparation Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Coating Application Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Wraps and Tapes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Metallic Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Coating Anodic to Base Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Coating Cathodic to Base Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Organic Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Coating Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Cathodic and Anodic Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 How Cathodic Protection Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Galvanic (Sacrificial) Anode Cathodic Protection Systems . . . . . . . . . . . . . . . . 27 Impressed-Current Cathodic Protection (ICCP) Systems. . . . . . . . . . . . . . . . . . 29 Impressed Current System Anodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Impressed-Current Cathodic Protection System Power Sources . . . . . . . . . . 31 Measurement of Cathodic Protection Effectiveness . . . . . . . . . . . . . . . . . . . . . . 32 Structure-to-Environment Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Test Coupons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Potential Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Regulatory Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Metal to be Protected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Life Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Total Current Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Variation in Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Electrical Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Stray Current Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Wire and Cable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Anode Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Protective Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Anodic Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35. Chapter 8: Inspection, Monitoring, and Testing. Basic Corrosion Student Manual. ©NACE International 2000 January 2014.

(23) 11. Introduction and Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Inspection Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Visual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Radiography (X-Ray and Radioactive Isotopes) . . . . . . . . . . . . . . . . . . . . . . . 3 Ultrasonic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Eddy Current Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Dye Penetrant Inspection (DPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Magnetic Particle Inspection (MPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Positive Materials Identification (PMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Thermographic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Significance of Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Corrosion Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Corrosion Probes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Mass-Loss (Weight-Loss) Coupons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Electrical Resistance Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Electrochemical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Linear Polarization Resistance (LPR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Tafel Extrapolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Galvanic Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Hydrogen Probes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Water Chemistry Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Suspended Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Microbiological Fouling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Cathodic Protection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17. ©NACE International 2000 January 2014. Basic Corrosion Student Manual.

(24) 12. Basic Corrosion Student Manual. ©NACE International 2000 January 2014.

(25) i. Basic Corrosion List of Figures Chapter 1: Introduction to Basic Corrosion Figure 1.1: Corrosion of Steel on an Offshore Platform . . . . . . . . . . . . . . . . . . . . . 1 Figure 1.2: Costs of Corrosion1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Figure 1.3: Corrosion Allowance on an Offshore Platform Leg in Splash and Tidal Zone 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Figure 1.4: Structural Collapse, a Fatal Highway Bridge Collapse into the Ohio River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 1.5: Parking Garage Collapse Due to Deicing Salt-Accelerated Corrosion of Reinforcing Steel3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 1.6: Unsightly Corrosion on a Ship4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 1.7: 1965 Pipeline Explosion in Natchitoches, Louisiana2 . . . . . . . . . . . . . 5 Figure 1.8: Oil Containment Boom and Oil-Absorbing Papers on the Surface of a River to Minimize the Spread of Crude Oil from a Corroded Pipeline2 . . . . . . . 6 Figure 1.9: Ruptured Pipeline Resulting in 12 Fatalities2 . . . . . . . . . . . . . . . . . . . . 6 Figure 1.10: Internal Surface of Corroded Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 1.11: Short Circuit in Microelectronics due to Corrosion and Dendritic Growth5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Chapter 2: Basics of Corrosion Electrochemistry Figure 2.1: Electron vs. Conventional Current Flow . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 2.2: Corrosion Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Figure 2.3: Nernst Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Figure 2.4: Open-Circuit Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 2.5: Anode Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 2.6: Cathode Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 2.7: Combined Polarization of Complete Corrosion Cell . . . . . . . . . . . . . 15 Figure 2.8: Equal Anode and Cathode Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 2.9: Area Effects – Smaller Cathode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 2.10: Area Effects – Smaller Anode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 2.11: Reversal of Zinc-Iron Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 2.12: Illustration of Passivity (Active-Passive Behavior) of Certain Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 2.13: pH Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Chapter 3: Corrosive Environments Figure 3.1: Corrosion Environments on an AST1 . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Figure 3.2: Corroded Fins on a Window-Mounted Air Conditioner . . . . . . . . . . . . 2. Basic Corrosion Student Manual. ©NACE International 2014 January 2014.

(26) ii. Figure 3.3: Atmospheric Corrosion Testing at the NASA Kennedy Space Center Beachside Corrosion Site4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Figure 3.4: Simplified Diagram Showing the Effect of Relative Humidity and Pollution on the Corrosion of Carbon Steel 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Figure 3.5: Industrial Atmosphere Corrosion of a Sewage Digester1 . . . . . . . . . . . 3 Figure 3.6: Salt Shaker with Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 3.7: Marine Corrosion on a Steel Ship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 3.8: Marine Corrosion on Copper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 3.9: Problem Locations for Insulated Aboveground Pipelines . . . . . . . . . . 5 Figure 3.10: External Jacketing on Insulated Piping and Process Equipment . . . . 5 Figure 3.11: Condensation Leading to Corrosion on Indoor Chilled-Water Pipe . . 6 Figure 3.12: Minimal Corrosion in the Exterior of Insulated Steam Line . . . . . . . . 6 Figure 3.13: Condensate Channeling Corrosion in Gathering Line6 . . . . . . . . . . . . 7 Figure 3.14: Effect of Dissolved Gases on the Corrosion of Carbon Steel7 . . . . . . 7 Figure 3.15: Corrosion Rate of Iron in Air-Exposed Water with Varying Salt (Sodium Chloride) Concentrations8,9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 3.16: Zones of Corrosion for Steel Piling in Seawater10,11 . . . . . . . . . . . . . 8 Figure 3.17: Effect of pH on the Corrosion Rate of Iron in Water at Room Temperature2,8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 3.18: Corrosion Rate of Zinc in Water at Different pHs10 . . . . . . . . . . . . . . 9 Figure 3.19: pH of Pure Water at Various Temperatures1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 3.20: Carbonic Acid, Bicarbonate Ion, and Carbonate Distribution as a Function of pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Figure 3.21: Calcium Carbonate (Calcite) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Figure 3.22: Calcium Sulfate (Gypsum) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Figure 3.23: Boiler Scale in Steam Generating Piping . . . . . . . . . . . . . . . . . . . . . 11 Figure 3.24: Corrosion Due to Water Separation at the 6 o'clock Position on a Low-Velocity Crude Oil Gathering Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Figure 3.25: Corrosion at the Bottom of an Aqueous Film-Forming Foam Piping System in an Aircraft Hangar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Figure 3.26: Changes in Oxygen Solubility in Water Exposed to Air at Various Temperatures10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Figure 3.27: Pitting Under Microbial Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Figure 3.28: Corroded Pipeline at the Air-to-Soil Interface1 . . . . . . . . . . . . . . . . 13 Figure 3.29: Differing Soil Layers Leading to Differing Corrosive Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Figure 3.30: Radial Locations Where Corrosion is Most Likely to Occur on Buried Pipelines1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Chapter 4: Materials Figure 4.1: Body-Centered Cubic Crystal Structure1 . . . . . . . . . . . . . . . . . . . . . . . 2. Basic Corrosion Student Manual. ©NACE International 2014 January 2014.

(27) iii. Figure 4.1: Face-Centered Cubic Crystal Structure . . . . . . . . . . . . . . . . . . . . . . . . . 2 Figure 4.2: Grain Boundaries in a Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Figure 4.3: Substitutional Solid Solution in a Crystalline Solid 2 . . . . . . . . . . . . . . 3 Figure 4.4: Interstitial Solid Solution in a Crystalline Solid 2 . . . . . . . . . . . . . . . . . 3 Figure 4.5: The Collapse of the Point Pleasant Bridge Across the Ohio River in 1967 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 4.6: Welded Ship That Cracked Due to DBTT Problems During Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 4.7: DBTT Cracking of an Interstate Highway Bridge in 2000 . . . . . . . . . . 4 Figure 4.8: Liquefied Hydrogen Storage Tank at the NASA Kennedy Space Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 4.9: Principal Directions of Rolled Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 4.10: Defects Associated with Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 4.11: Distortion of Exterior Plates Due to Weld Shrinkage . . . . . . . . . . . . . 7 Figure 4.12: Spiral-Welded Pipeline Under Construction . . . . . . . . . . . . . . . . . . . . 7 Figure 4.13: Weathering Steel Bridge Beams (Protective Rust Film Formed on Surface Indicated by Arrow) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 4.14: Brittle Fracture of a Cast Iron Water Pipe . . . . . . . . . . . . . . . . . . . . . 9 Figure 4.15: Flakes of Graphite in the Microstructure of Gray Cast Iron . . . . . . . 10 Figure 4.16: Rounded Nodules of Graphite in Ductile (Nodular) Cast Iron . . . . . 10 Figure 4.17: Stainless Steel Equipment Meter Runs in Wet CO2 Service . . . . . . 11 Figure 4.18: Stainless Steel Equipment Bubble Trays in Gas Stripping Tower . . 11 Figure 4.19: Cupronickel Seawater Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 4.20: Titanium Plates for Plate-and-Frame Heat Exchanger . . . . . . . . . . . 19 Figure 4.21: Titanium Alloys for Shell and Tube Heat Exchanger . . . . . . . . . . . . 19 Figure 4.22: Aluminum Coast Guard Cutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 4.23: Zinc Corrosion vs. pH of the Environment 9 . . . . . . . . . . . . . . . . . . 22 Figure 4.24: Rodent Bite Damage on Cathodic Protection Ground Bed Lead Wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Figure 4.25: UV Degradation of Polypropylene Rope After UV Exposure . . . . . 25 Figure 4.26: UV Degradation of New Polypropylene Rope . . . . . . . . . . . . . . . . . 25 Figure 4.27: Fiber-Reinforced Composite Walkway . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 4.28: FRP Piping Underneath a Pier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 4.29: Solvent Dissolved the Matrix of this Glass-Reinforced Polymer Pipe.12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Figure 4.30: Freeze-Thaw Damage on Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 4.31: Acid Attack Due to Spilled Chemicals on a Concrete Floor Slab . . 33 Figure 4.32: Rust Oozing From Cracks Formed in Concrete Due to Corrosion of Reinforced Steel in Sea Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 4.33: Reinforcing Steel on Highway Bridge Deck; Most of the Steel is in Good Condition Due to the Alkalinity (High pH) of the Concrete Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 4.34: Pitting Corrosion of the Base of an Aluminum Guard Rail on a. Basic Corrosion Student Manual. ©NACE International 2014 January 2014.

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