50% sulfuric acid and stainless steel
50% sulfuric acid and stainless steel
(OP)
Hello -
I use recovered 50% sulfuric acid. This liquid has a slight bluish hue or is clear.
When this comes in contact with stainless, there is a black discoloration.
This is black material leached nickel from the stainless?
Any help is appreciated.
I use recovered 50% sulfuric acid. This liquid has a slight bluish hue or is clear.
When this comes in contact with stainless, there is a black discoloration.
This is black material leached nickel from the stainless?
Any help is appreciated.





RE: 50% sulfuric acid and stainless steel
What is the black discolouration? Corrosion products. Which ones? Probably more iron than nickel in it.
RE: 50% sulfuric acid and stainless steel
RE: 50% sulfuric acid and stainless steel
RE: 50% sulfuric acid and stainless steel
A variety of plastic and elastomeric materials are used industrially for these diluted acid services. They are used alone, with FRP for exterior reinforcement, and as linings of carbon steel pipe, tanks, valves etc.. The required combination of pressure, temperature and mechanical robustness determine what system is best to use.
RE: 50% sulfuric acid and stainless steel
The following link shows a graph (Fig.2) about the corrosion of SS 316 by H2SO4 solutions:
RE: 50% sulfuric acid and stainless steel
RE: 50% sulfuric acid and stainless steel
http://chemicalengineeringmagazine.com, Free Chemical Engineering Magazine Subscription
RE: 50% sulfuric acid and stainless steel
The acid resistance of all metals and alloys depends on the acid concentration, temperature, the presence of co-contaminants, and many other factors. At room temperature, commercial concentrated sulphuric acid (93%) is compatible with ordinary austenitic stainless steels. The same is true at dilute concentrations in otherwise clean water (concentrations < 1% acid). However, between 1% and 93% even at ambient temperature is a no-mans land for many metals and alloys, with each having its own limits. Only tantalum is fully resistant across that entire range.
In a water treatment application, the injection quill and the section of pipe where dilution will happen, need to be designed properly, with materials selected to withstand both the dilute acid AND the heat of dilution which can be significant. This is a great application for plastics, many of which are immune to corrosion by acid within this range, provided that the heat of dilution is taken into account.
RE: 50% sulfuric acid and stainless steel