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Corrosion Engineering

Pipeline Pigging, Cathodic Protection, Corrosion, Glossary

corrosion banner 2Corrosion engineering is a branch of engineering that focuses on preventing and controlling the deterioration of materials due to chemical reactions with their environment.  Corrosion is a major problem in many industries, including oil and gas, chemical processing, and transportation, as it can lead to equipment failure, safety hazards, and environmental damage.  The work of a corrosion engineer typically involves identifying the causes and mechanisms of corrosion, selecting appropriate materials and coatings to prevent corrosion, and developing strategies to control and mitigate the effects of corrosion.  They use a variety of tools and techniques to analyze the properties and behavior of materials in different environments, such as electrochemical testing, material characterization, and computational modeling.

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Corrosion Engineering

Corrosion engineers work in a variety of industries and settings, including research and development, design and construction, and maintenance and repair.  They may work on projects related to pipeline integrity, oil rig maintenance, or material selection for chemical processing equipment.  In addition to preventing and controlling corrosion, corrosion engineers may also work on projects related to material testing and certification, environmental monitoring and remediation, and safety and risk assessment.  They often collaborate with other engineers, scientists, and technicians to develop and implement effective corrosion management strategies.

Corrosion Branches

Chemical Corrosion (Dry)  -  Occures through direct chemical reactions between a material (usually metal) and gases or non-electrolyte environments, typically at elevated temperature and without the preseence ot an electrolyte.
Electrochemical Corrosion (Wet)  -  Occures through electrochemical reactions involving anodic and cathodic protection in the presence of an electrolyte (such as water or aqueous solutions), forming corrosion cells that drive metal dissolution. 
 

What Causes Corrosion

Corrosion is caused primarily by electrochemical reactions between a material (usually a metal) and its surrounding environment, which lead to the gradual deterioration of the material.  In most engineering situations, corrosion occurs when a metal reacts with oxygen, moisture, or other chemical species present in air, water, or soil.  These reactions convert the metal into more chemically stable compounds such as oxides, hydroxides, or sulfides.  For example, the corrosion of iron occurs when iron reacts with oxygen and water to form rust through oxidation–reduction reactions.

The fundamental mechanism involves the formation of electrochemical cells on the metal surface.  Within these cells, certain areas act as anodes where metal atoms lose electrons and dissolve into the environment, while other areas act as cathodes where reduction reactions occur.  The presence of an electrolyte (such as water containing dissolved salts or acids) allows ionic conduction, enabling the electrochemical process to continue.  Factors that commonly promote corrosion include moisture, dissolved oxygen, electrolytes (salts or acids), differences in metal composition, mechanical stress, and temperature, all of which can accelerate the electrochemical reactions responsible for material degradation.

Corrosion Types

Identify Flood Risks  -  Understand the sources of potential flooding (rivers, sea, surface water, or groundwater).
Assess Vulnerability  -  Determine the likelihood and severity of flooding and its effects on properties, infrastructure, and ecosystems.
Mitigate Risks  -  Propose measures to reduce flood risks, such as flood defenses, drainage improvements, or land-use changes.
Comply with Regulations  -  Ensure that development projects comply with local, regional, and national planning regulations regarding flood risk management.
Cavitation Corrosion  –  Surface damage caused by the collapse of vapor bubbles in a liquid, which removes protective films and accelerates corrosion.
Corrosion Fatigue  –  Accelerated fatigue failure of a material due to cyclic stress acting in a corrosive environment.
Crevice Corrosion  –  Localized corrosion that occurs in shielded areas where stagnant solution exists, such as under gaskets, washers, deposits, or lap joints.
Erosion-Corrosion  –  Accelerated corrosion resulting from the combined action of chemical attack and mechanical wear caused by fluid motion.
Exfoliation Corrosion – A form of intergranular corrosion in rolled or extruded metals that causes layers of material to lift or flake off.
Filiform Corrosion  –  Threadlike corrosion that propagates under coatings or thin surface films.
Fretting Corrosion  –  Corrosion damage occurring at contacting surfaces experiencing small oscillatory relative motion.
Galvanic Corrosion  –  Electrochemical corrosion that occurs when two dissimilar metals are electrically connected in an electrolyte, causing the more anodic metal to corrode preferentially.
Hydrogen Damage (Hydrogen Embrittlement / Hydrogen-Induced Cracking)  –  Degradation caused by hydrogen absorption into a metal, leading to embrittlement or cracking.
Intergranular Corrosion  –  Corrosion that occurs preferentially along grain boundaries of a metal due to compositional or microstructural differences.
Microbiologically Influenced Corrosion (MIC)  –  Corrosion initiated or accelerated by microorganisms through their metabolic processes.
Pitting Corrosion  –  Highly localized corrosion that produces small cavities or “pits” on the metal surface, often initiated by breakdown of protective passive films.
Selective Leaching (Dealloying)  –  Corrosion process in which one element is preferentially removed from an alloy (e.g., dezincification of brass).
Stress Corrosion Cracking (SCC)  –  Cracking caused by the combined influence of tensile stress and a specific corrosive environment.
Uniform (General) Corrosion  –  Corrosion that occurs relatively evenly across an exposed metal surface, producing a uniform loss of material thickness.
 

The Importance of Corrosion Management

Corrosion management is important for protecting the structural integrity, safety, and service life of engineering infrastructure and equipment.  Corrosion gradually deteriorates metals and alloys used in bridges, pipelines, buildings, water systems, storage tanks, and marine structures.  If corrosion is not properly monitored and controlled, it can reduce the load-carrying capacity of structural components, cause leaks in pipelines or tanks, and lead to sudden mechanical failure.  Effective corrosion management through inspection, protective coatings, cathodic protection, material selection, and maintenance, helps ensure that structures and systems continue to perform safely within their intended design limits.

Corrosion management is also essential for economic efficiency and asset reliability.  Corrosion related damage can result in costly repairs, unplanned shutdowns, and premature replacement of infrastructure.  By implementing systematic corrosion monitoring, prevention, and maintenance programs, engineers can extend the operational life of facilities and reduce life-cycle costs.  In addition, corrosion management plays a critical role in environmental protection and public safety, particularly in systems such as oil and gas pipelines, water distribution networks, and chemical processing facilities, where corrosion induced failures could release hazardous substances or disrupt essential services.

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Title
Corrosion Glossary
Corrosion Types
Pitting Resistance Equivalent Number (PREN)
Stress Corrosion Cracking

Subcategories

Cathodic Protection 24