Seeking help in determining corrosion margin
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Dear experts, I am designing a container whose interior contains lithium carbonate and lithium hydroxide solutions. The material used for the container is S32168, and its designed service life is 20 years. How should the corrosion margin be determined? How is it calculated? It would be great if you could provide the calculation formula or indicate which standard should be used for this calculation Thank you, expert.
This is the experience value; to determine it accurately, it needs to be based on the corrosion rate and design life
Generally, the corrosion margin for stainless steel materials is set at 0. The corrosion margin for carbon steel is determined by the corrosion rate multiplied by the service life; however, I’m not sure about the effect of this medium on the corrosion of stainless steel. I hope other experts can provide an answer
Check the corrosion rate of the medium on the selected material under the design conditions.
The corrosion margin for stainless steel equipment is not necessarily 0; it is necessary to determine the corrosion rate of the material under the operating conditions in order to decide on an appropriate corrosion margin. The corrosion margin indicated on the drawings refers to the case of uniform corrosion of the material by the medium; for other types of corrosion, special considerations must be given in terms of material selection and manufacturing requirements.
With the required corrosion rate of the material and the service life of the equipment, the corrosion allowance can be calculated
The corrosion margin equals the corrosion rate multiplied by the equipment’s service life.
A coupon test is required to determine the corrosion rate; without this value, estimates can only be made arbitrarily
There is a manual called the \"Corrosion Data Manual\", which contains information on the annual corrosion rates of various media on different types of steel and iron. If there are no specific testing methods available to determine the corrosion margin, this manual can serve as a reference.
According to the corrosion manual, the corrosion rate of these two media on material 32168 is between 0.05 and 0.5, indicating that corrosion does occur. It is recommended to select the corrosion margin based on experience, experimental measurements, or process recommendations.