Environmental Engineering Reference
In-Depth Information
Table 4.4 Some common nickel alloys and their nominal
chemical composition
Material
Composition (%)
Monel
63-66Ni, 29-31Cu, 1.4-2Fe
Inconel 600
76Ni, 16Cr, 8 Fe, 0.2Cu
Chlorimet 2
62Ni, 32Mo, 3 Fe, 1Si
Chlorimet 3
60Ni, 18Cr, 18Mo, 3Fe, 0.6Si
Hastelloy B
62Ni, 28Mo, 5Fe, 1Si
Hastelloy C
56Ni, 15Cr, 17Mo, 5Fe, 1Si, 4W
Hastelloy D
85Ni, 3Cu, 10Si
Incoloy 800
32Ni, 21Cr, 46Fe
Duranickel 301
94Ni, 0.05Cu, 0.15Fe, 4.5Al, 0.5Ti
Carpenter
35Ni, 20Cr, 25Mo, 3Cu
Source : Adapted from M. G. Fontana, Corrosion Engineering , 3rd ed.,
McGraw-Hill, New York, 1983.
Nickel alloys are also resistant to sulfuric acid at intermediate and higher concen-
trations. The 9-11 silicons are resistant to hot concentrated sulfuric acid. Nickel-
chromium-iron alloys with or without molybdenum addition are more resistant
to pitting, crevice corrosion, and SCC in chlorides than austenitic stainless steels.
Inconel (76Ni-16Cr-8Fe) has excellent resistance to SCC.
Nickel alloys are extensively used in chemical process plants, oil refineries,
acid-producing plants, and in seawater applications in the form of pipings, pumps,
tanks, vessels, and so forth.
4.1.7 Titanium and Its Alloys
Titanium, like aluminum, is a highly reactive metal that owes its corrosion resis-
tance to the adherent and highly protective oxide film developed on exposure to
oxygen and moisture. Titanium shows excellent corrosion resistance to many
aggressive solutions, i.e., nitric acid including fuming nitric acid; seawater and
chloride solutions including those containing heavy oxidizing chlorides such as
FeCl 3 and CuCl 2 ; wet chlorine; oxidizing acids like chromic and perchloric acids;
weak reducing acids like sulfurous, boric, and carbonic acids; and titanium is
resistant to alkalis. In strong reducing acids, like sulfuric and hydrochloric acids,
titanium performs well in the presence of oxidizing inhibitors. However, titanium
has a pyrophoric tendency in red fuming nitric acid and is attacked by hydroflu-
oric acid and fluoride solutions.
Titanium has the interesting properties of low density, high melting point, and
outstanding corrosion resistance. Its density is intermediate of aluminum and steel
 
Search WWH ::




Custom Search