Equipment material selection
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This post was last edited by wode*aohei on 2019-3-31 at 16:59. I would like to ask my friends: for the condensate water treatment equipment shown in the photo below, will a material with finned heat exchange tubes – where the fin thickness is around 1.0 mm – be sufficient? I’m initially thinking of using 304; should I go with 316L instead? Note: The pH value of the condensate water is 3–4, and the temperature is 30–40°C. The ion content is expressed in mg/L
Is the unit for Cl- mg/L or g/L? Is it oxygen-containing, and what is the oxygen content?
As long as there are chloride ions present, don’t use 304 – go straight for 316L. We’ve already suffered the consequences of using 304
For austenitic stainless steels, the chloride content is generally required to be less than 25 ppm; otherwise, stress corrosion, pitting corrosion, and intergranular corrosion may occur. In an environment like yours, 304 definitely won’t work. I don’t think 316L will work either; you can give it a try and see.
The unit is mg/L, for the condensed water in flue gas.
In terms of ion content, 304 is a good choice; the only concern is the concentration of chloride ions!
If 2205 is chosen, the cost will be too high.
I have used 304 and 316L materials for both flues and chimneys. We use acid-resistant mortar or coatings as linings, but these suffer from peeling due to thermal expansion; regular maintenance is required each year, which incurs high costs and also poses a risk of damage. I don’t know which system and which part you are using. In my opinion, although the initial investment is higher, the subsequent operating and maintenance costs are reduced, and the risk of equipment damage is avoided; therefore, it’s worth making the larger investment. Moreover, the total cost is not necessarily high; you need to consider all factors on your own.
Chloride ions are sensitive to concentration; the key issue is the corrosion caused by sulfate ions, so it’s better to use a non-metallic lining
2205 is not much more expensive than 304; if it needs to be thicker, a composite plate can be used.
In this case, impervious graphite can be considered