Inhibitor Na2Cr2O7 alternative for ammonia/water carbon steel
Inhibitor Na2Cr2O7 alternative for ammonia/water carbon steel
(OP)
Hello!
We use the salt Na2Cr2O7 as corrsion inhibitor for ammonia/water solution to protect the carbon steel equipment. This corrosion inhibitor is well known since a hundred years, but more or less toxic.
Is there any proven alternative available?
Will ammonia/water NOT affect stainless steel? (304 or 316)
Who can help me with some information or an appropriate link?
Kind regards
virk
We use the salt Na2Cr2O7 as corrsion inhibitor for ammonia/water solution to protect the carbon steel equipment. This corrosion inhibitor is well known since a hundred years, but more or less toxic.
Is there any proven alternative available?
Will ammonia/water NOT affect stainless steel? (304 or 316)
Who can help me with some information or an appropriate link?
Kind regards
virk





RE: Inhibitor Na2Cr2O7 alternative for ammonia/water carbon steel
We recovered Anhydrous NH3 from 20% Aqueous NH3 in CS columns and used a very small amount of NaOH, probably less than 1% , was added to prevent corrosion to the columns. If I recall correctly it prevented the formation of Ammonium Carbamate. The small amounts of CO2 came from our processes where we recovered the NH3 vapors by water scrubbing gas streams.
We routinely monitored the column tails for NH3, NaOH, Na2co3.
The columns (6) were approximately 3' in dia and 40' tall and used an “ice house condenser”.
All the equipment in this service was CS and all components stress relieved.
If I recall the columns operated at a little over 200°C @ 450 psig.
The columns were 25 years old when taken out of service and all were in excellent condition.
The columns were packed with ceramic Raschig rings.
We had no SS in this system except for a few instrument bodies, all of which were 316 SS.
There should be some literature on this process as it was the primary way to recover ammonia vapors from different processes at the time.
RE: Inhibitor Na2Cr2O7 alternative for ammonia/water carbon steel
Kind regards
virk