hastelloy B3 with ferric 2

[natthaphon11]

I'm so confuse about the performance of Hastelloy B3 with the ability to prevent the formation of pitting from HCl
but in term of service that's the existing occurrence, why is it forming a pitting. and i also found that the hastelloy B3 can't prevent when the exsiting of ferric is occurred but the mechanism of ferric salt can be started by the formation of iron (from chemical composition in itself) contact with HCl(in environment) then it oxidize to ferric salt .So why is it say that it could prevent the pitting from HCl

.....
service is only nitrogen , HCl and oxygen
material Hastelloy B3

where can i find the reference of this case //...

 

[EdStainless]

B3 is intended for service in NON-oxidizing media, clean HCl or H2SO4, and a few others.
Adding a strongly oxidizing species such as Fe can take you outside of what this alloy is designed to take.
If you look in the papers on the Haynes website you will see that some Fe is OK, but it greatly depends on the conditions (temp, acid, purity).

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P.E. Metallurgy, Plymouth Tube

 

[moltenmetal]

When you dissolve iron in HCl or H2SO4 under reducing conditions, you get ferrous (Fe+2) rather than ferric (Fe+3) ion.

If you contact dirty iron/steel with a reducing acid, you will dissolve ferric ion into solution which was present as orange rust or scale on the surface. The same will happen if you use a reducing acid under oxidizing conditions- the Fe+2 will oxidize to Fe+3.

Ferric ion is an oxidant which can, under the right conditions, serve as a means to initiate corrosion in alloy B3- an alloy which is designed for severe reducing conditions only.

This is the whole trick of alloy selection for corrosion service:

1) Nothing works for everything, and
2) Every material has an Achilles' heel, or two, or three...