In the previous post, we saw what are the criteria for choosing between an AISI 304 stainless steel and an AISI 316 for aqueducts design. As promised, today we will find out which stainless steel is most suitable for this purpose.
Acqueducts design: we look at different materials
The substantial differences in chemical composition between AISI 304 and AISI 316 stainless steel are:
- the presence of molybdenum
- a higher concentration of Nickel.
AISI 316 is therefore more resistant than AISI 304 to a number of factors such as:
- exposure in saline environments
- aggression by chloride.
However, we must consider that AISI 316 is not entirely immune in the presence of certain concentrations of chlorides. Regarding the pipes, the factor that makes a difference (more than the structure and design of the particular) is the mode of implementation. If we arespeaking of welding, the advice is always the same: use low-carbon steels (AISI 304L – AISI 316L).
Disinfection methods of aqueducts: what to look out for?
Chlorination is the most common disinfection method for water hygiene, although, basic, sodium hypochlorite never has a good effect on stainless steel. It is true, however, that the concentration of chlorides becomes tangled towards these steels when it exceeds the 300 ppm (parts per million). Therefore, a percentage of 0.4 mg/L is well below the problem threshold.
In conclusion…
In addition to the one just mentioned, the temperature and low concentration of chlorides should not give problems of long-term exhalations in a closed place. However, it is always advisable to periodically ventilate the areas involved. The relative speed compared to the material does not vary for both choices. In conclusion, AISI 304 may be sufficient for this use but given the increasing presence of chlorine and mineral salts in drinking water it is advisable to opt for the AISI 316.
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