12. MELtING TEMPERATURES OF METALS
86
Summary table metallic thermowell materials
Designation Nominal
composition
Max.
temp.
Meting range Application notes
(con´t.serv., air)
SS 304
18 % Chromium
81 % Nickel
1,652 °F
900 °C
2,550-2,640 °F
1,399-1,449 °C
The general purpose austenitic SS.
Subject to carbide precipitation in
the 480 to 870 °C range.
Corrosion resistant in the annealed
conditions. Not affected by steri-
lizing solutions, foodstuffs, most
dyestuffs, organic chemicals and
many inorganic chemicals.
SS 310
25 % Chromium
20 % Nickel
2,100 °F
1,148 °C
2,550-2,640 °F
1,399-1,449 °C
Very high elevated temperature
strength and scale resistance.
Superior to 304 in much high
temperature applications. Good
resistance to carburizing and
reducing environments. Subject to
carbide precipitation in the 480 to
870 °C range.
SS 316
18 % Chromium
12 % Nickel
2-3% Molybdenum
1,650 °F
899 °C
2,550-2,550 °F
1,399-1,399 °C
Higher corrosion resistance than
type 304. High creep strength.
Withstands sulphurous acid
compounds resists tendency to
pit in phosphoric and acetic acids.
Subject to carbide precipitation in
the 426 to 815 °C range.
SS 321
SS 347
Similar to 304
but carbide
stabilized
1,600 °F
871 °C
2,550-2,600 °F
1,399-1,426 °C
Carbide stabilized grade intended
to prevent harmful precipitation of
chromium carbides and the resul-
ting susceptibility to inter granular
corrosion. For corrosion conditions
and intermittent heating and coo-
ling applications between 426 to
815 °C range.