On the corrosion allowance for pipelines
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What does the corrosion allowance of a pipeline mean, and what factors are related to it? Is it about the wall thickness of the pipe?
These are the factors to consider when calculating the design thickness. . . This value is related to factors such as material, medium, temperature, and corrosion rate.
How is this measured? It is said that it cannot exceed three; if it does, the pipe needs to be replaced?
For ordinary media, the pipe corrosion allowance is at most 3 mm, while it is generally 6 mm for catalyst pipes.
Adding to what was said above, there are also graywater and blackwater, which are highly corrosive and may contain solid impurities that can cause abrasion; the wear amount in such cases can reach 4mm–6mm. Because changing the material of such pipes and increasing the corrosion allowance is not economical, nor is it necessary at all.
The corrosion allowance is used in calculating wall thickness and depends on the medium, material, and operating environment. Carbon steel is generally 1.5; 3 is used in harsh environments. Stainless steel is not considered.
Won’t such extensive corrosion cause any problems?
It depends on the medium; if it’s too high, considering changing the pipe material is an option
When calculating the wall thickness, the corrosion allowance is taken into account; theoretically, it’s no problem for there to be such corrosion
The corrosion margin is strictly determined by the corrosion rate measured in the laboratory and the design life; in other words, it refers to an increased wall thickness that enables the material to withstand corrosion over XX years. The value of C (corrosion margin) in the calculation formula cannot exceed 6 mm – if it exceeds this value, it is not recommended to use this material; instead, a more advanced material with better corrosion resistance should be used