Corrosion Engineering and its types, controlling
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The presentation by engineer Rahul Jarariya discusses corrosion, its types, causes, and prevention methods. It highlights various forms of corrosion such as crevice, stress cracking, galvanic, and microbial corrosion, along with factors contributing to corrosion in concrete structures. Prevention strategies include material selection, use of inhibitors, coatings, and cathodic protection to minimize corrosion effects.
Corrosion Engineering and its types, controlling
- 1. Stubborn Engineer Er. Rahul Jarariya
- 2. Presentation Contents Introduction Types of Corrosion High Temperature Corrosion Causes of Corrosion Prevention Ideas of Corrosion
- 3. • In general, corrosion is the process that turns refined metals into compounds that are more stable, including metal hydroxides, metal sulfides, or oxides. • Similar to this, when iron rusts, oxygen and moisture from the atmosphere combine to generate iron oxides. • According to science, corrosion is an irreversible, spontaneous process that transforms metals into far more stable chemical compounds, such as oxides, sulfides, hydroxides, etc. • In this presentation, we will examine corrosion in greater detail and learn about its various aspects, including types, meaning, avoidance, and more. Stubborn Engineer Er. Rahul Jarariya What is Corrosion ?
- 4. Crevice Corrosion: This type of corrosion that can happen anywhere there is a difference in ionic concentration b/w two local Portions of a metal. Stress Corrosion Cracking: Tensile stress on metal at certain high level temperature (ºC). Galvanic Corrosion: Tensile stress on metal at certain high level temperature (ºC). Pitting Corrosion: It happens on the surface in vertical direction. It can visible in non-structural format at corner metallic surface. Uniform Corrosion: It happens when attack on the metal is executed by the surface. Hydrogen Grooving It happens when attack on the metal is executed by the surface. Metal Dusting Corrosion occurs as a graphite layer is deposited on the surface of the metals from carbon monoxide (CO) in the vapor phase. In some cases, no M3C species may be observed. Microbial Corrosion It is referred to as microbiologically induced corrosion (MIC), is brought on by microorganisms. Corrosion can harm both metallic & non-metallic materials, whether O2 is present or not. TYPES OF CORROSION
- 5. High Temperature Corrosion Corroded Junction Metallic Surface High temperature (exceeding 500°C) *depending inter alia on the metal concerned • High-temperature corrosion of metals occurs in hot dry gases such as: Air Sulfur dioxide Hydrogen sulfide Common HTC Treatment Process: • Carburization • Metal dusting • High temperature oxidation or sulfidation
- 6. Causes of Corrosion Congested reinforcement in small concrete sections, Excessive water-cement ratio, Improper construction methods, Inadequate design procedure, Incompetent supervising staff or contractor, Initially rusted reinforcement before placing concrete, Insufficient cover to steel from the exposed concrete surfaces, Permeability of concrete which depends on various factors such as water- cement ratio, size of aggregate, curing, grading of aggregates, etc., Poor workmanship, Presence of moisture in concrete, Presence of salts, Type of atmospheric conditions surrounding the region of concrete, Unequal distribution of oxygen over the steel surface, Weak and porous cover blocks which are tied directly to the reinforcement or stirrups, etc.
- 7. Prevention from Corrosiveness 5 Major Strategies Selection of Materials Inhibitors Coating Cathodic Protection Design Some metals are highly resistant to corrosion (such as gold and platinum), while others have a low resistance to corrosion like sodium and magnesium) Some chemicals act to inhibit corrosion. These include silicates, phosphates, nitrites, and organic amines. Inhibitors are generally preferred in closed systems where the presence of the inhibitor can be more easily maintained (for example in heating and cooling system towers). Coating isolates the metal from the corrosive environment surrounding it. The coating may be metallic (for example, tin-plated steel).They may also work like galvanized steel in which the coating corrodes in preference to the metal beneath. Coatings are commonly non-metallic, such as paint, and may be either organic or inorganic. Cathodic protection works by applying an external electrical current so that the corrosion reaction takes place on a separate surface to the metal to be protected, with electrons forced to flow to the metal that is to be protected. Designing products and structures to eliminate or minimize the potential for corrosion helps to reduce maintenance and repair costs and time; for example, by designing with fewer crevices in which corrosion often develops.
- 8. Cathodic Protection Cathodic protection is commonly used on buried and submerged metallic structures like pipelines, underground storage tanks, locks, subsea equipment, offshore floaters, harbors, and ship hulls. The application of DC Current from the external source to prevent corrosion current from escaping anodic regions of the structure is known as cathodic protection. Corrosion is decreased by minimizing the potential difference between the anode and cathode. The entire pipeline of structure will be at one potential with the introduction of sufficient current, prevention the formation of anode and cathode sites. The principle of the Cathodic Protection system is determining the anode in a large corrosion cell for making the intended material as cathode overcoming smaller corrosion cells. Please see the Video for the next …………………………