Corrosion of metal columns in chemical environments is a serious problem for process control systems, the petrochemical, food, and pharmaceutical industries. This phenomenon causes millions of euros in direct and indirect losses annually. In this comprehensive article, we examine in detail the mechanisms of metal column corrosion, the factors influencing it, prevention methods, and modern protection technologies.
Part 1: Basics of corrosion of metal supports
1.1 Definition of chemical corrosion
Corrosion is the gradual deterioration of a material due to chemical or electrochemical reactions with its environment. In metal axles, this phenomenon is often exacerbated by contact with chemicals, moisture, or electrolytes.
1.2 Main mechanisms of column corrosion
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Uniform wear : Wear of a surface that occurs evenly over the entire surface.
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Electrochemical corrosion : When two different metals come into contact
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Bites : Form deep, localized bites.
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Crevice corrosion : in hard-to-reach places, for example under seals.
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Stress corrosion cracking : a combination of chemical attack and mechanical stress.
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Corrosion and abrasion : a combination of chemical attack and mechanical wear.
Part Two: Factors that influence axle wear
2.1 Environmental factors
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Chemical type : acid, base, salt, solvent
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chemical concentration
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Operating temperature
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Liquid flow rate
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Presence of solid particles in suspension
2.2 Mineral factors
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Shaft material : carbon steel, stainless steel, nickel alloy.
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Surface coating : chrome, nickel, ceramic coating.
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Surface hardness
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Surface microcracks
2.3 Design factors
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Stress concentration with changing cross-section
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Quality of the final surface
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Type of brands used
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A stagnation or dead zone is created.
Part III: Chemicals and corrosive effects
3.1 Acid
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Sulfuric acid : A very corrosive substance in moderate concentrations.
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Hydrochloric acid : Corrosive, especially at high temperatures.
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Nitric acid : different behavior depending on concentration and temperature
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Organic acids : Local corrosion of stainless steel
3.2 Basic concepts
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Caustic soda : A corrosive substance in high concentrations and at high temperatures.
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Ammonia : Risk of stress cracking in copper and its alloys.
3.3 Salt
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Chlorides : Cause corrosion in gaps and cracks.
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Sulfates : Corrosion under anaerobic conditions
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Halides : Corrosion increases at high temperatures.
3.4 Solvents
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Chlorinated compounds : destroy some protective polymers.
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Hydrocarbons : are absorbed by some sealants
Part four: Methods for corrosion assessment and monitoring
4.1 Destructive methods
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Mineralogical analysis : microscopic examination
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Accelerated corrosion testing
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Measuring weight loss
4.2 Non-destructive methods
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Ultrasound : residual thickness measurement
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Eddy current testing : detection of surface defects
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Thermal imaging : Detecting areas of active corrosion
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Monitoring corrosion potential
4.3 Laboratory methods
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Linear polarization
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Electrochemical impedance spectroscopy
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electron microscope
Section 5. Prevention and control strategies
5.1 Selection of suitable materials
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Stainless steel : Series 300 and 400
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Nickel alloys : Inconel, Hastelloy
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Titanium alloys : resistance to chlorides.
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Polymer compounds : in some applications
5.2 Protective coating
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Metal coating : hard chrome and nickel.
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Ceramic coating : metal oxide
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Polymer coating : epoxy resin, polyurethane.
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Composite floor : a combination of several materials
5.3 Electrochemical methods
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Cathodic protection : use of sacrificial anodes
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Anodic protection : surface passivation
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Corrosion inhibitors : chemical additives
5.4 Change of design
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Technical improvements to reduce stress concentrations
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Improved sealing system
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Use protective covers in critical areas.
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Maintenance-friendly design
Part 6: New technologies for corrosion resistance
6.1 Nanocoating
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Nanocoatings : increased adhesion and durability
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Nanomaterials : combination of the properties of several materials
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Intelligent coatings : The ability to self-heal
6.2 Hybrid paint
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A mixture of polymer and ceramic
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Multi-layer coating
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Phase change coating
6.3 New sealing method
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Magnetic sealing system
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modified polymer seals
Part Seven: Industry Standards and Guidelines
7.1 Material standards
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ASTM A276 : Standard for stainless steel
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ISO 15156 : Materials for use in H2S-containing environments
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NACE MR0175 : Corrosion resistance in the oil and gas industry
7.2 Test standards for corrosion resistance
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ASTM G48 : Pitting and crevice abrasion test
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ASTM G31 : Immersion test for corrosion evaluation
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ISO 9227 : Salt spray test**
7.3 Coverage criteria
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ISO 12944 : Protective coatings for steel structures
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ASTM D1654 : Evaluation of Organometallic Coatings
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NACE SP0169 : Corrosion protection by cathodic protection
Part Eight: Practical Research and Experience
8.1 Pump shaft wear in the chemical industry
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Cause : combination of acids and weathering.
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Solution : Use binary alloys.
8.2 Corrosion problems in mixers in the food industry
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Problem : Frequent cleaning and chlorinated environment
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Troubleshooting : Epoxy resin coatings
8.3 Successful experiences in the shipping industry
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Conditions : Seawater with high chloride content.
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Solution : Combination of cathodic protection and hybrid coatings.
Finally
Chemically induced corrosion of metal columns is a complex phenomenon that requires a systematic and comprehensive approach to prevention and control. The selection of appropriate materials, optimized design, the use of modern coatings, and the implementation of effective monitoring programs can significantly extend the service life of metal columns. The emergence of new technologies such as nanocoatings and smart materials opens up new opportunities to address this industrial challenge. Investments in research and development and the training of technical personnel are crucial for successfully combating corrosion of metal columns in aggressive chemical environments.