In flow wetted tubulars, OCTG carbon steels are known to suffer from mass loss corrosion in CO2 environments. 3% Chromium grades represent an alternative to reduce corrosion rate, at a lower cost than martensitic stainless steels (13Cr).
When carbon steels are exposed to sweet environments, they are susceptible of suffering CO2 mass loss corrosion.
Regular CS have an unstable protective layer from corrosion products, and this leads to a high and heterogenous corrosion behavior. The addition of 3% chromium to the alloy enhances the protectiveness of this layer, drastically reducing the corrosion rate, hence extending the life of the tubing string and making this product ideal for onshore or shallow water operations.
3Cr grades are suitable for use on:
- Mature fields
- Mild sweet environments
- Maximum service temperature of 90°C
- Environments with limited H2S resistance.
For higher temperatures and more severe sweet environments, martensitic stainless steel remain untouched, completely avoiding corrosion thanks to their chromium oxide passive layer.
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