304 vs 316 Stainless for WWTP

[profplan]

All,

Does anyone have experience specifying AISI Type 304 Stainless Steel for platforms and structural members supporting operating equipment and large pipelines in concrete oxidation ditches for Wastewater Treatment Plants. Type 316 was specified but questions of cost have arisen.

The steel is pretty close to the operating elevations, 6" to 18" of the effluent in the concrete basins and could be in contact often.


Thanks.

 

[ATSE]

Stick with 316.
When I talk with the materials engineers and Ni Institute, they all say the same thing: 304 is for sissies (not quite their vernacular).
When you walk around old plants, you will see that 316 in direct contact with wastewater does amazingly well.
The fabricators and contractors will always argue for 304 over 316.

 

[profplan]

ATSE,

Thanks. that was my thought but I don't have any experience with it. Rather puzzling though, it is actually the public utility that is interested in using Type 304 stainless steel rather than 316.

 

[jgailla]

Use 316. Do not use 304.
I am not an expert in this, but the 304 will corrode much more quickly when exposed to sewer gases.