93% Sulfuric Acid Tank (Materials Selection)

[jmh1012]

For a relatively small tank (2000 gallon) I am curious what the drawbacks of 304ss as opposed to 316ss. Corrosion tables I've seen indicate 304 doesn't offer much more resistance than carbon steel, especially at temperatures over 80F-90F.

I'm interested in using a ss alloy because the tank will be of relatively small dimensions and portions of pipe will be small, exceeding the recommended limits in NACE SP0294. To prevent any dangers due to the higher velocities (wall thinning near tank inlet, accelerated pipe corossion) the ss alloy is a better choice. NACE says both 304 and 316 are adequate, but the tank will be located in ambient conditions so temperature effects may be a concern.

carbon steel may even be sufficient, but problems with corossion products in an existing system have negated this choice.

 

[ash9144]

You might want to consider a polypropylene tank. Cheaper and no corrosion.

 

[chrysa1975]

For 93% concentration SS 316 may be suitable for temperatures up to 50°C.Alloy 20 UNS N08020 up to 65°C.HASTELLOY C-276 UNS N10276 up to 100°C. CPVC is recommended for concentrations less than 60% and temperatures for sure less than 60°C.

 

[strider6]

if a s you said NACE tell you that both 304 and 316 are ok the only thing i can say is that 316 will give you more resistance in case you tank will be in a marine, chloride rich, atmosphere. As an example on Offshore platform the 304 is usually a banned materials due to the low corrosion resistance in offshore atmosphere.

S.

http://www.corrosionist.com

 

[ErnieWise]

Have you considered using carbon steel rather than ss with anodic protection applied? I don't know the figures but I believe it is a cheaper option and can provide an equivalent service life.