ASME SA240 321 Stainless Steel Elliptical Head Dish End for
Pressure Vessel And Heat Exchanger
At the temperature of 800-1500°F(427-816°C), chromium carbide
precipitation conditions can still maintain good resistance to
intergranular corrosion. Due to the addition of titanium to the
composition, 321 alloy can still maintain stability in the case of
chromium carbide formation.
321 alloy stainless steel has the advantage of working in high
temperature environment due to its excellent mechanical properties.
Compared with 304 alloy, 321 alloy stainless steel has better
ductility and stress fracture resistance. In addition, 304L can
also be used to resist sensitization and intergranular corrosion.
Alloy 321(UNS S32100) is a very stable stainless steel. At the temperature of
800-1500°F(427-816°C), chromium carbide precipitation conditions
can still maintain good resistance to intergranular corrosion. Due
to the addition of titanium to the composition, 321 alloy can still
maintain stability in the case of chromium carbide formation. Alloy
347 is due to the addition of COQ and tantalum to maintain its
stability. .
321 and 347 alloys are commonly used for long-term operations at
high temperatures between 800 and 1500°F(427 and 816°C). If the
application only involves welding or short time heating, 304L can
be used instead.
The high temperature operating advantages of 321 and 347 alloys
also depend on their good mechanical properties. Compared with 304,
304L, 321 and 347 have better creep stress resistance and stress
rupture resistance. This allows these stable alloys to meet ASME
Boiler Code and pressure vessel specifications at slightly higher
temperatures. As a result, 321 and 347 alloys can be used up to
1500°F (816°C), while 304,304 L is limited to 800°F (426°C).
ASME SA240 321 Stainless Steel Elliptical Head Equivalent Grades
| Grade | UNS No | Old British | Euronorm | Swedish SS | Japanese JIS |
|---|
| BS | En | No | Name |
|---|
| 321 | S32100 | 321S31 | 58B, 58C | 1.4541 | X6CrNiTi18-10 | 2337 | SUS 321 |
ASME SA240 321 Stainless Steel Elliptical Head Chemical Compositions
| Grade |
| C | Mn | Si | P | S | Cr | Mo | Ni | N | Other |
|---|
| 321 | min.
max | -
0.08 | 2.00 | 0.75 | 0.045 | 0.030 | 17.0
19.0 | - | 9.0
12.0 | 0.10 | Ti×5(C+N)
0.70 |
ASME SA240 321 Stainless Steel Elliptical Head Mechanical Properties
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50 mm) min | Hardness |
|---|
| Rockwell B (HR B) max | Brinell (HB) max |
|---|
| 321 | 515 | 205 | 40 | 95 | 217 |
ASME SA240 321 Stainless Steel Elliptical Head Physical Properties
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100 °C (J/kg.K) | Electrical Resistivity (nΩ.m) |
|---|
| 0-100 °C | 0-315 °C | 0-538 °C | at 100 °C | at 500 °C |
|---|
| 321 | 8027 | 193 | 16.6 | 17.2 | 18.6 | 16.1 | 22.2 | 500 | 720 |
321 stainless steel is Ni-Cr-Mo austenitic stainless steel, its
performance is very similar to 304, but due to the addition of
titanium metal, so that it has better resistance to grain boundary
corrosion and high temperature strength. Due to the addition of
titanium metal, it effectively controls the formation of chromium
carbide.
321 austenitic stainless steel has good corrosion resistance in the
atmosphere and is widely used in petrochemical, electric power,
bridge and automobile industries. However, the "stainless steel" is
not absolute, due to the special service environment, stainless
steel will also corrosion. Medium concentration, pH value,
temperature and other factors will have a greater impact on the
corrosion resistance of stainless steel. For example, in the
sensitization temperature range of 450~850℃ for a long time,
stainless steel will occur intergranular corrosion. The mechanism
is that C combines with Cr at the grain boundary to form Cr23C6 and
precipitates, so that the Cr content at the grain boundary is
reduced, which is the so-called "chromium poor". The Cr element is
one of the main elements to inhibit intergranular corrosion, when
the Cr content at the grain boundary is less than 12%, the
probability of intergranular corrosion will be increased.
ASME SA240 321 Stainless Steel Elliptical Head Applications:
Oil and gas industry equipment
Offshore platforms
Heat exchangers
Underwater equipment
Fire fighting equipment
Chemical processing industry
Utensils and pipes industry
Desalination, high pressure RO equipment and submarine pipeline
Energy industry such as power plant desulfurization and
denitrification FGD system, industrial washing system, absorption
tower
Mechanical parts (high strength, corrosion resistance, wear
resistance parts)
