How is the corrosion allowance for pipes determined?
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Referencing Sinopec’s pipeline material grade table, the values for the corrosion allowance of pipelines are approximately 1.5 mm and 3 mm; in other words, there are two categories: normal corrosion and severe corrosion； However, after searching through GB150 and GB50316, I couldn’t find any information on how to determine the corrosion allowance specifically. Of course, the corrosion conditions vary depending on the medium involved; there’s enough material to write whole books and manuals on this topic. So my question is: what is the name of such a book or manual? I hope some experts who have read it can give me some advice; I really don’t know which manual to consult. . . . :L
Is this question boring? Posts can’t just disappear! :o
The corrosion allowance is not specified in any particular code; although many codes do provide relevant explanations. It is determined by comprehensively considering factors such as the nature of the medium, process conditions, and material selection to estimate the annual corrosion rate, and from this, the total amount of corrosion that will occur over the pipeline’s service life. For the standardization of the project, the final corrosion margin is set at 1.5 and 3; values of 4.5 are also used. If the corrosion margin is too large, it indicates that the material chosen is not appropriate. Some design firms may use values such as 1.6, 3.2, etc... I’m not sure if this is clear; I hope it helps you.
I understand perfectly, thank you so much! Actually, I pretty much realize that no standard will provide detailed guidance on this. What I want to know is how they determine the corrosion rate in order to decide between 1.5 and 3; it’s impossible for them to make such decisions arbitrarily or solely based on experience. There must be some book or manual that covers this topic, and I want to know what that book is~
It would be good to have a specification with explicitly defined values.