1. What is sweet corrosion? A quick introduction.

    Corrosion is a common challenge in many industries, particularly those dealing with oil, gas, and petrochemical processing. One of the lesser known yet equally detrimental forms of corrosion is “sweet corrosion.” This type of corrosion can lead to severe damage in pipelines, storage tanks, and other metal structures if not properly managed. Using stainless steel components in environments where sweet corrosion occurs can mitigate damage and extend the service life of equipment.

    Oil and gas industry

    What is sweet corrosion?

    Sweet corrosion, also known as carbon dioxide (CO₂) corrosion, occurs in environments where carbon dioxide is present, particularly in oil and gas production. When CO₂ dissolves in water, it forms carbonic acid (H₂CO₃), which can aggressively attack metal surfaces, especially carbon steel. This process can lead to significant metal loss, pitting, and cracking. Carbon dioxide corrosion differs from “sour corrosion,” which involves hydrogen sulfide (H₂S) and tends to be more localized and aggressive. While generally less aggressive than sour corrosion, it can cause widespread damage if not adequately addressed.

    Which industries encounter carbon dioxide corrosion? 

    Oil and Gas Production and Transport

    • Oil Wells and Gas Reservoirs: prevalent in oil wells and gas reservoirs where CO₂ is naturally present in the hydrocarbons being extracted. When these fluids are brought Sweet corrosion in chemical industry to the surface, the CO₂ can dissolve in water, forming carbonic acid and leading to corrosion in pipelines and well tubing.
    • Pipelines: Pipelines that transport oil and natural gas containing CO₂ are particularly susceptible to sweet corrosion. The internal surfaces of these pipelines can be exposed to carbonic acid, resulting in metal loss and potential leaks.
    • Processing Facilities: Refineries and gas processing plants that handle CO₂-rich fluids are also at risk. Carbon steel equipment, such as separators, heat exchangers, and storage tanks, can experience CO₂ corrosion if not adequately protected.

    Geothermal Energy Systems

    In geothermal energy systems, CO₂ is often present in the steam and hot water extracted from underground reservoirs. When this CO₂ mixes with water, it can form carbonic acid, leading to CO₂ corrosion of metal components in piping and equipment used in geothermal plants.

    Chemical and Petrochemical Industries

    • Chemical processes that involve CO₂ as a reactant or byproduct can also create conditions for CO₂ corrosion. Storage tanks, reactors, and heat exchangers in these industries are at risk, especially when water is present.

     

    How does sweet corrosion occur?

    The sweet corrosion process involves several stages:

    1. Formation of Carbonic Acid: When CO₂ gas comes into contact with water, it dissolves and reacts to form carbonic acid (H₂CO₃). This acid lowers the pH of the environment, making it more corrosive.

    2. Electrochemical Reaction: Carbonic acid dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻). The hydrogen ions react with the metal surface, leading to the formation of iron carbonate (FeCO₃), a protective layer that can slow down the corrosion process. However, this protective layer can be unstable and easily disrupted, especially under high flow rates or varying temperatures.

    3. Corrosion of the Metal: When the protective iron carbonate layer is damaged, the underlying metal is exposed to further attack, leading to pitting and metal loss.

    Geothermal energy

    Why is sweet corrosion a problem?

    Carbon dioxide corrosion poses several risks to industries, particularly in oil and gas operations:

    Equipment Failure: Over time, CO₂ corrosion can lead to the thinning of metal components, causing leaks, ruptures, and potential equipment failure. This can result in costly repairs, unplanned shutdowns, and safety hazards.

    Operational Costs: Mitigating sweet corrosion often involves frequent maintenance, corrosion inhibitors, and protective coatings. These measures, while effective, can be expensive and may not always provide long-term solutions.

    Environmental Impact: Corrosion-induced leaks can result in environmental contamination, particularly in oil and gas operations. This can lead to regulatory penalties and damage to a company’s reputation.

    In this older report you can read about incidents related to corrosion related incidents back from 1965 to 2012,  “Corrosion-Related Accidents in Petroleum Refineries – Lessons learned from accidents in EU and OECD countries” .

    Why using stainless steel in sweet corrosion environments?

    Stainless steel is widely regarded as the best material choice for environments prone to CO₂ corrosion. Here’s why:

    1. Corrosion Resistance: Stainless steel contains a minimum of 10.5% chromium, which forms a passive oxide layer on the surface. This layer acts as a barrier, protecting the metal from corrosive agents like carbonic acid. In CO₂ corrosion environments, stainless steel’s resistance to CO₂ attack is significantly higher than that of carbon steel.

    2. Durability and Longevity: Stainless steel’s corrosion resistance translates to a longer service life for components exposed to sweet corrosion. This means reduced maintenance costs and fewer replacements, leading to long-term savings.

    3. Strength and Reliability: Stainless steel maintains its mechanical properties in a wide range of temperatures and pressures, making it suitable for harsh conditions often encountered in oil and gas production. It can withstand the mechanical stresses associated with high-flow rates, which can exacerbate corrosion in less durable materials.

    4. Reduced Need for Corrosion Inhibitors: Using stainless steel can reduce or eliminate the need for chemical corrosion inhibitors, which are commonly used to control sweet corrosion in carbon steel systems. This not only cuts operational costs but also reduces the potential environmental impact of chemical use.

    5. Versatility: Stainless steel comes in various grades, such as 304, 316, and duplex stainless steels, each offering different levels of corrosion resistance and mechanical properties. This versatility allows engineers to select the most suitable grade for specific conditions, including the concentration of CO₂, temperature, and pressure.

    What stainless steel grade do I need to prevent CO₂ corrosion?

    While stainless steel is a superior material for CO₂ corrosion environments, it’s crucial to select the appropriate grade based on the specific operating conditions:

    Austenitic Stainless Steels (e.g., 304, 316): These are the most commonly used grades for their excellent corrosion resistance and mechanical properties. Grade 316 contains molybdenum, which enhances resistance to pitting and crevice corrosion, making it suitable for environments with higher CO₂ concentrations.

    • Duplex Stainless Steels: Duplex grades combine the best properties of austenitic and ferritic stainless steels, offering higher strength and improved resistance to stress corrosion cracking. They are ideal for high-pressure, high-temperature environments where sweet corrosion is a concern.

    Sweet corrosion is a pervasive issue in industries dealing with carbon dioxide-rich environments. Whereas inhibitors and organic compounds are excellent corrosion mitigators for industries with big installations, material selection for smaller components are of the essence. For Stainless Steel 316 components, such as bolts, autolok nuts, handles, clamps, hinges and band clamps, Anemo Engineering offers multiple solutions. Get in touch if you need help with your selection of the most adequate solution for your application or download the catalogue

    Band Clamps

    There is much more to CO₂ corrosion. 

    Read these articles if you want to learn more:

    High temperature sweet corrosion and inhibition in the oil and gas industry: Progress, challenges and future perspectives

    Key parameters affecting sweet and sour corrosion: Impact on corrosion risk assessment and inhibition

    FAnemo Engineering on Linkedinollow us on Linkedin for more articles, news and advancments about components such as fasteners and fastening devices. 

  2. Lido Key Lock M1-15-61-8

    M1-15-61-8

    lido-key-lock-M1-15-61-8
    Lido Key Lock M1-15-61-8 is a lock made of stainless steel 316. Lido Key locks contains the best products available on the market.

    For more information on A4 alloy stainless steel M1-15-61-8 or other AISI 316 variants, download the catalog at the link below.

    The Lido Key Lock M1-15-61-8 includes attractive recessed styling, a recessed handle and concealed fasteners. This gives these “push to close” closures an attractive appearance. In addition, they also have a low profile and small dimensions.

    Thanks to their corrosion-resistant construction, they remain functional for a long time, and they keep their good looks. Even in outdoor applications and when using saltwater, sulfuric or nitric acid.

    The Lido Key Lock M1-15-61-8 is very easy to install. From the front of the panel, a single round hole allows you to attach the lock from the back with a mounting bracket and hardware. It fits flat on the panel when installed, with minimal bulking inside the cabinet.

  3. cross recess Z (Posi drive) countersunk flat head tapping screw with cone point DIN 7982C 2,9X19

    cross recess Z (Posi drive) countersunk flat head tapping screw with cone point

    cross recess Z (Posi drive) countersunk flat head tapping screw with cone point

    Norm: DIN 7982C

    Size: 2,9X19

    The Stainless steel 316 cross recess Z (Posi drive) countersunk flat head tapping screw with cone point is available in the size 2,9X19. DIN 7982C

    This product is made of A4 top grade quality steel to the norm DIN 7982C

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    cross recess Z (Posi drive) countersunk flat head tapping screw with cone point

     

  4. hexagon socket countersunk head screw DIN 7991 M6X22

    hexagon socket countersunk head screw

    hexagon socket countersunk head screw

    Norm: DIN 7991

    Size: M6X22

    The Stainless steel 316 hexagon socket countersunk head screw is available in the size M6X22. DIN 7991

    This product is made of A4 top grade quality steel to the norm DIN 7991

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon socket countersunk head screw

     

  5. hexalobular socket torx countersunk head screw DIN 965 TX30-M6X8

    hexalobular socket torx countersunk head screw

    hexalobular socket torx countersunk head screw

    Norm: DIN 965

    Size: TX30-M6X8

    The Stainless steel 316 hexalobular socket torx countersunk head screw is available in the size TX30-M6X8. DIN 965

    This product is made of A4 top grade quality steel to the norm DIN 965

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexalobular socket torx countersunk head screw

     

  6. hexagon socket countersunk head screw DIN 7991 M20X50

    hexagon socket countersunk head screw

    hexagon socket countersunk head screw

    Norm: DIN 7991

    Size: M20X50

    The Stainless steel 316 hexagon socket countersunk head screw is available in the size M20X50. DIN 7991

    This product is made of A4 top grade quality steel to the norm DIN 7991

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon socket countersunk head screw

     

  7. domed cup nut or acorn nut DIN 1587 M18-A

    domed cup nut or acorn nut

    domed cup nut or acorn nut

    Norm: DIN 1587

    Size: M18-A

    The Stainless steel 316 domed cup nut or acorn nut is available in the size M18-A. DIN 1587

    This product is made of A4 top grade quality steel to the norm DIN 1587

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    domed cup nut or acorn nut

     

  8. hexalobular torx socket countersunk head tapping screw DIN 7982 TX15-3,5X25

    hexalobular torx socket countersunk head tapping screw

    hexalobular torx socket countersunk head tapping screw

    Norm: DIN 7982

    Size: TX15-3,5X25

    The Stainless steel 316 hexalobular torx socket countersunk head tapping screw is available in the size TX15-3,5X25. DIN 7982

    This product is made of A4 top grade quality steel to the norm DIN 7982

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexalobular torx socket countersunk head tapping screw

     

  9. hexalobular socket torx countersunk head screw DIN 965 TX30-M6X10

    hexalobular socket torx countersunk head screw

    hexalobular socket torx countersunk head screw

    Norm: DIN 965

    Size: TX30-M6X10

    The Stainless steel 316 hexalobular socket torx countersunk head screw is available in the size TX30-M6X10. DIN 965

    This product is made of A4 top grade quality steel to the norm DIN 965

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexalobular socket torx countersunk head screw

     

  10. hexalobular torx socket pan head tapping screw ISO 14585 TX25-M5,5X45

    hexalobular torx socket pan head tapping screw

    hexalobular torx socket pan head tapping screw

    Norm: ISO 14585

    Size: TX25-M5,5X45

    The Stainless steel 316 hexalobular torx socket pan head tapping screw is available in the size TX25-M5,5X45. ISO 14585

    This product is made of A4 top grade quality steel to the norm ISO 14585

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexalobular torx socket pan head tapping screw

     

  11. washer DIN 125A 7. 4 FOR M7

    washer

    washer

    Norm: DIN 125A

    Size: 7. 4 FOR M7

    The Stainless steel 316 washer is available in the size 7. 4 FOR M7. DIN 125A

    This product is made of A4 top grade quality steel to the norm DIN 125A

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    washer

     

  12. cross recess H (phillips) pan head screw DIN 7985H M6X 8

    cross recess H (phillips) pan head screw

    cross recess H (phillips) pan head screw

    Norm: DIN 7985H

    Size: M6X 8

    The Stainless steel 316 cross recess H (phillips) pan head screw is available in the size M6X 8. DIN 7985H

    This product is made of A4 top grade quality steel to the norm DIN 7985H

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    cross recess H (phillips) pan head screw

     

  13. hexagon socket head cap screw DIN 912 PT-M16X110

    hexagon socket head cap screw

    hexagon socket head cap screw

    Norm: DIN 912

    Size: PT-M16X110

    The Stainless steel 316 hexagon socket head cap screw is available in the size PT-M16X110. DIN 912

    This product is made of A4 top grade quality steel to the norm DIN 912

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon socket head cap screw

     

  14. hexagonal socket button head screw ISO 7380 M8X45

    hexagonal socket button head screw

    hexagonal socket button head screw

    Norm: ISO 7380

    Size: M8X45

    The Stainless steel 316 hexagonal socket button head screw is available in the size M8X45. ISO 7380

    This product is made of A4 top grade quality steel to the norm ISO 7380

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagonal socket button head screw

     

  15. hexagon socket head cap screw DIN 912 PT-M12X140

    hexagon socket head cap screw

    hexagon socket head cap screw

    Norm: DIN 912

    Size: PT-M12X140

    The Stainless steel 316 hexagon socket head cap screw is available in the size PT-M12X140. DIN 912

    This product is made of A4 top grade quality steel to the norm DIN 912

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon socket head cap screw

     

  16. hexagon socket head cap screw DIN 912 FT-M8X12

    hexagon socket head cap screw

    hexagon socket head cap screw

    Norm: DIN 912

    Size: FT-M8X12

    The Stainless steel 316 hexagon socket head cap screw is available in the size FT-M8X12. DIN 912

    This product is made of A4 top grade quality steel to the norm DIN 912

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon socket head cap screw

     

  17. hexagonal socket button head screw ISO 7380 M10X80

    hexagonal socket button head screw

    hexagonal socket button head screw

    Norm: ISO 7380

    Size: M10X80

    The Stainless steel 316 hexagonal socket button head screw is available in the size M10X80. ISO 7380

    This product is made of A4 top grade quality steel to the norm ISO 7380

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagonal socket button head screw

     

  18. hexagon head bolt form F DIN 933 M18X40

    hexagon head bolt form F

    hexagon head bolt form F

    Norm: DIN 933

    Size: M18X40

    The Stainless steel 316 hexagon head bolt form F is available in the size M18X40. DIN 933

    This product is made of A4 top grade quality steel to the norm DIN 933

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon head bolt form F

     

  19. threaded rod DIN 976 8X1000

    threaded rod

    threaded rod

    Norm: DIN 976

    Size: 8X1000

    The Stainless steel 316 threaded rod is available in the size 8X1000. DIN 976

    This product is made of A4 top grade quality steel to the norm DIN 976

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    threaded rod

     

  20. hexagon head bolt form F DIN 933 M27X100

    hexagon head bolt form F

    hexagon head bolt form F

    Norm: DIN 933

    Size: M27X100

    The Stainless steel 316 hexagon head bolt form F is available in the size M27X100. DIN 933

    This product is made of A4 top grade quality steel to the norm DIN 933

    The minimum order value is 2000 euros, only consult us if you’re ready to pay the minimum amount for this grade of material.

    hexagon head bolt form F

     

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