Corrosion in Chemical Industry PDF

YILDIZ TECHNICAL UNIVERSITY CHEMICAL ENGINEERING DEPARTMENT Corrosion in Chemical Industry SECTION 1 Prof. Dr. EMEK MÖRÖYDOR DERUN Res. Assist. ENİS MUHAMMET GÜL 1 INTRODUCTION Corrosion is defined as the undesirable deterioration of..………………... that adversely affects their chemical and mechanical pr...

YILDIZ TECHNICAL UNIVERSITY CHEMICAL ENGINEERING DEPARTMENT Corrosion in Chemical Industry SECTION 1 Prof. Dr. EMEK MÖRÖYDOR DERUN Res. Assist. ENİS MUHAMMET GÜL 1 INTRODUCTION Corrosion is defined as the undesirable deterioration of..………………... that adversely affects their chemical and mechanical properties.  Corrosion occurs naturally and ……………………………………………….… It is usually known as the destructive result of chemical reactions between a metal or metal alloy and its environment.  2 INTRODUCTION  Recent findings proved that like metals nonmetallic materials are affected from their environments but their corrosion mechanism is different from metals’.  Corrosion is an expected natural event for every field that metallic materials are used. 3 INTRODUCTION  Corrosion intrudes itself into many parts of our lives.  In addition to causing material loses, corrosion takes a significant role in human life and safety and pollute the environment.  Elimination of corrosion is not possible but it is engineer’s duty to minimize damage caused by corrosion. 4 FORMATION OF CORROSION  In nature metal atoms present in chemical compounds are such as oxides, sulphates.  In compounds, they are thermodynamically stable.  The metal compounds are processed to obtain metals and used in many areas. If alloying or any protection methods are not applied, they are inclined to turn their natural compounds.  The metals which are ……………………. 5 FORMATION OF CORROSION  Corrosion purports undesirable changes in a material structure.  For instance, rust of iron in a moisture environment or cracking of copper and copper alloys in an ammoniacal environment are unwelcome results of corrosion. 6 Chemistry and Electrochemistry Corrosion Engineering ……………………………………… ………… ……………… The most suitable material ……………………………………………… ……………………………… ……………………………………………… No metal has resistance of corrosion in all environments, but according to the environmental conditions that are the cause of corrosion, changes to the type of metal being used can also lead to significant reductions in corrosion 7 CORROSION ENVIROMENTS 1. Atmosphere Atmospheric - Wet - Vapor Oxygen N2, NO,CO2 Impurities, H2S, SO2, SO3, NH3, HCl, Solid particles 8 CORROSION ENVIROMENTS 2. Sea Water River water Underground water Biochemical Water 3. Chemical Acidic Neutral Alkaline Complex compounds Temperature, Pressure, Velocity, Motion 9 CORROSION ENVIROMENTS 4. Food Stuffs 5. Fused Salts 6. Liquid Metals 7. Organic Liquids and Solutions Not in aqueous environment 8. Gas Leakage 9. Chemical Smokes 10. Steams Dry Wet 11. Stress 12. Fatigue 13. Friction Mechanical and physical impacts 10 THE CLASSIFICATION OF CORROSION 1. According to Appearance of Corroded Metal ………………………………………..... ……………………………...… Macroscopic (Observable) Microscopic (Unobservable) 1.Pitting 1. Stress corrosion 2.Crevice 2. Fatigue 3.Selective 4.Stratification Erosion Hydrogen Damage Fretting 11 THE CLASSIFICATION OF CORROSION 2. According to Corrosion Environment Type ………………………. Wet corrosion occurs in the presence of an electrolyte. Any type of water and aqueous solution (acid, alkaline, salt solutions, humidity) can be caused wet corrosion. ………………………. Dry corrosion occurs because of gases at high temperatures. These gases can be listed as oxygen, halogens, H2S, SO, SO3 steams, gases in smoke. 12 THE CLASSIFICATION OF CORROSION 3. According to Corrosion Mechanism Physical Corrosion: It occurs in the presence of fused salts. Metals such as Hg, molten Al, Na cause corrosion on the surfaces of solid metals. ………………………………………………………………………………………….……………………... Chemical Corrosion: Metals react with their environment directly. Electron exchange can be during chemical reaction but there is not a specific interface. In chemical corrosion the other element is mostly O2 so the product of reaction is metal oxide. ……………………………………………………………………………………………………… Electrochemical Corrosion: Electrochemical corrosion happens by oxidation of metals in aqueous medium. ………………………………………………………………………… 13 Environment – Interface - Metal Corrosion Deposition of corrosion products on the surface of material Dissolution Homogeneous Change of surface properties Change of microstructure of material Regional Formation of crackmechanical damage Weight change Corrosion damage 14 IMPORTANCE OF CORROSION The three main reasons for the importance of corrosion are: …………………….…… ………….………………. …………………………….. Corrosion can compromise the safety of operating equipment by causing failure (with catastrophic consequences) of, for example, pressure vessels, boilers, metallic containers for toxic chemicals, turbine blades and rotors, bridges, airplane components, and automotive steering mechanisms. In economic terms, it has been estimated that approximately 5% of an industrialized nation’s income is spent on corrosion prevention and the 15 maintenance or replacement of products lost or contaminated as a result of corrosion reactions. IMPORTANCE OF CORROSION  Economic losses are divided into (1) direct losses and (2) indirect losses. ❖ Direct losses include the costs of replacing corroded structures and machinery or their components, such as condenser tubes, pipelines, and metal roofing, including necessary labor. ❖ Examples of indirect losses are as follows: ……………….... ……………………… …………………..... ………………….. …………………….… …………………... 16 ECONOMIC IMPACTS OF CORROSSION Cost in corrosionfree medium Extra spendings because of corrosion Cost of products used in corrosive medium 17 CORROSION COSTS a) ……………………………………………………....: Capital expenditures need to be redone due to corrosion. It covers up large capacity establishment and redundant operation of the plant. 18 CORROSION COSTS b)…………………………………………………..…: Control expenditures are the spendings that include corrosion controlling, maintenance and repair spendings. 19 CORROSION COSTS c) ……………………………………………………: Design Expenditures; ✓ Selection of materials to provide the structural integrity ✓ Selection of materials to provide product purity ✓ Additional operations that ensure corrosion resistance (For example, heat treatment ) 20 CORROSION COSTS d)………………………………………………………………: Product loss, discarding product that get dirty because of corrosion, corrosion engineering, additional spending for research and development, corrosion insurance, maintenance and storage of extra equipments. e) ………………………………….……………………. 21 22