SS Nozzle on Carbon Steel Tank 1

SEJohn · Jan 17, 2014

I am specifying a tank for 93% sulfuric acid following NACE SP0294-2006. The document recommends using carbon steel for the tank but appears to be recommending stainless steel for the nozzles. Is this normal? It seems like there would be a corrosion problem at interface of the stainless and carbon. Also, are there any special requirements on welding the dissimilar metals?
Thank you in advance.

MJCronin · Jan 18, 2014

SEJohn...

Storage of concentrated sulfuric acid is special..

Corrosion and degradation of the tank must consider both the conditions where the acid is still (uniform acid attack) AND when the acid is flowing more than ~2-3 ft/second (as would occur in a nozzle.)

Flowing 93% H2SO4 can eat away at the top (12 o'clock) internal surface of carbon steel piping...... that is why SS nozzles are sometimes specified.

There are also special requirements for dip tubes on the tank inlets as well as special conservation vents that must keep out moisture.

MJCronin
Sr. Process Engineer
Venture Engineering & Construction

http://www.VentureEngr.com

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SS Nozzle on Carbon Steel Tank 1

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