SMO254 acidic seawater
SMO254 acidic seawater
(OP)
Would SMO254 Alloy (6-6.5%Mo) be usable, at 40°C in acidic seawater, pH 2.3 and in a very reducing environment? (SO23)
so wz have chlorides (seawaterà
SO2 / sulfuuric qsp pH 2.3
what worries me is SO2, creating a reducing environment
so wz have chlorides (seawaterà
SO2 / sulfuuric qsp pH 2.3
what worries me is SO2, creating a reducing environment





RE: SMO254 acidic seawater
Don't worry about the SO2, it is the pH that will kill you.
For these alloys each 2 pH units below neutral roughly lowers the Cl limits by an order of magnitude.
This alloy will handle natural seawater, 20k ppm Cl and pH 8, and we know that it would still be OK at pH 6.
Then at pH 2 the Cl limit would drop from 20,000 to perhaps 200ppm, or roughly similar to 316 in neutral environment......
At that pH you need either a Ni based alloy (C22/59/686 or go non-metallic (but watch the S02 with resin systems).
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Plymouth Tube
RE: SMO254 acidic seawater
SO2 / sulfites are not good, but that's still OK
RE: SMO254 acidic seawater
According to the OUTOKUMPU figure 254SMO looks suitable for pure HCl (1%) at 70°C (0.1mm/year corrosion)
sea water would have about the same chloride concentration.
You said that the acidity would kill me.
So where is the important difference?
Is it because the figure is limited to general corrosion?
Regards
Figure 254.tif uploaded
Bernard
RE: SMO254 acidic seawater
http://www.outokumpu.com/en/tools-and-downloads/pr...
There is one interesting point, Outokumpu refers to 254SMO as a 6% Mo alloy, this is it's max Mo.
The other nominal 6% Mo alloys such as AL-6XN, 1925hMo, and 25-6Mo all are likely to be 21-21.5% Cr and 6.3-6.5% Mo. These alloys will have PREN in the range of 44-48, while 254SMO is 40-42.
HCl is easy, this is very different chemically from acidified seawater.
Look at corrosion tables (http://tools.outokumpu.com/spt/corrosion/corrstart...) for HCL + iron chloride, or HCl + sodium chloride, those get you closer.
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Plymouth Tube