How galvanic corrosion occurs between different metals in pressure vessels
Galvanic corrosion is an electrochemical process that can occur when two dissimilar metals come into contact with each other in the presence of a conductive liquid, such as water or chemical solutions.
In pressure vessels and process tanks, this can mean that the less noble metal is affected more quickly, while the more noble metal is less affected. This phenomenon can occur in combinations of, for example, stainless steel with copper, aluminum or carbon steel.
The choice of material and design can have an impact on how this type of corrosion is managed in different applications in the process industry.
Process surplus offers tanks and pressure vessels in stainless steel 304 and acid-proof 316/316L in different sizes and designs, where material and construction vary depending on the application and previous use.
Function and structure
Pressure vessels are designed to withstand high pressures and chemical stresses. Incorrect material combinations can lead to localized corrosion.
- Stainless steel main body
- Flanges and connections of different metals
- Gaskets and insulation materials
- Surface treatment and passivation
- Internal process equipment and piping
Materials and corrosion mechanisms
Stainless steel and couplings
When stainless steel in contact with copper or carbon steel is exposed to a conductive liquid, a galvanic element is formed where the less noble material corrodes faster. This can happen in welds, gaskets or flanges.
Material selection and countermeasures
- Insulate dissimilar metals with plastic or rubber spacers
- Use the same metal for all components in contact with the liquid
- Passivation of stainless steel
- Monitor the conductivity and chemical composition of the liquid
Pressurized and atmospheric solutions
Galvanic corrosion can occur in both pressurized tanks and atmospheric storage tanks. Pressure vessels with high liquid flow rates can disperse corrosion products faster, affecting underlying metal components.
Applications in industry
- Food industry – combination of stainless steel with pump and valve materials
- Chemical industry – acid and base solutions in metal connections
- Pharmaceutical production – flanges and piping in different metals
- Water treatment – copper, aluminum and stainless steel mixture
Technical options and preventive measures
- Using homogeneous metal combinations
- Insulating metals with non-conductive materials
- Surface treatment and passivation
- Check the conductivity of the liquid
- Avoid stagnant liquid in contact with different metals
Volumes and capacity
Galvanic corrosion can affect both small and large tanks. Larger pressure vessels often require special planning of material selection and insulation to avoid corrosion attack in critical components.
Benefits of correct material selection
- Reduced risk of galvanic corrosion
- Longer life and reduced maintenance
- Safe operation in high pressure and aggressive liquids
- Possibility to combine pressure vessels with pump and pipe systems
New and used tanks in stock
Processöverskott offers both new and used pressure vessels in various materials and designs for use in the process industry. The choice of material combination can have an impact on how different metals interact in a given application.
The range includes pressure vessels in stainless steel 304 and acid-proof 316/316L, with the design and choice of materials varying according to construction and previous use. This makes it possible to find options that suit different needs.
Some tanks may be available for relatively quick delivery.
Choosing the right solution
The right solution involves homogeneous metal selection, insulation of dissimilar metals and careful planning of connections. This ensures that galvanic corrosion is avoided even during long-term operation.
Executive summary
Galvanic corrosion occurs when dissimilar metals come into contact with a conductive liquid, leading to rapid corrosion of the less noble metal. The right material selection, insulation and design are crucial to ensure operational safety in pressure vessels and process tanks. Process Surplus offers solutions that minimize risks and ensure long service life in industrial environments.
Frequently asked questions about galvanic corrosion in pressure vessels
How does galvanic corrosion occur between different metals in pressure vessels?
Galvanic corrosion occurs when two dissimilar metals are in electrical contact and exposed to a conductive liquid. The less noble metal corrodes faster, while the more noble metal is protected. This phenomenon is common in welded joints, flanges and pipe connections in pressure vessels.
Which metals are most susceptible to galvanic corrosion?
Metals such as carbon steel, copper and aluminum are most often attacked when combined with stainless steel. The more noble metal acts as a cathode and is protected, while the less noble metal acts as an anode and corrodes faster.
How to prevent galvanic corrosion?
Preventive measures include using homogeneous metal combinations, insulating dissimilar metals with plastic or rubber, passivating surfaces, controlling fluid conductivity, and avoiding stagnant fluid in contact with dissimilar metals.
Does the composition of the fluid affect the risk of galvanic corrosion?
Yes, the conductivity, pH and chloride content of the liquid affect the corrosion rate. High conductivity or aggressive chemicals increase the risk of rapid galvanic corrosion between dissimilar metals.
Why is galvanic corrosion critical in pressure vessels?
Galvanic corrosion is critical because it can cause localized attacks that rapidly weaken the structure of pressure vessels and process tanks. This can lead to leaks, malfunctions and safety risks if the wrong materials are used.