Alloy 347 (1.4550) is a stabilized stainless steel tube which offers as its main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F (427 to 816°C). Alloy 347 is stabilized by the addition of columbium and tantalum.
Alloy 347 stainless steel pipe is also advantageous for high temperature service because of its good mechanical properties. Alloy 347 stainless steel tubing offers higher creep and stress rupture properties than Alloy 304 and, particularly, Alloy 304L, which might also be considered for exposures where sensitization and intergranular corrosion are concerns.
General Properties
Chemical Composition
Resistance to Corrosion
Physical Properties
Mechanical Properties
Elevated Temperature Oxidation Resistance
Heat Treatment
Fabrication
347 Stainless Steel Tube | 347H Stainless Steel Pipe
304 | 304L | 304H| 316/316L| 316Ti| 317L| 321/321H | 309S | 310S | 347/347H| S32205/S31803| S32750| 904L
Physical Properties of 347/347H Alloys in the Annealed Condition at -20°F to +100°F
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Tensile Strength |
Yield Strength |
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| Alloy |
UNS Designation |
Spec. |
psi |
MPa |
ksi |
psi |
MPa |
ksi |
Elongation in 2 inches (min.) % |
Grain Size Req. |
Maximum Harndess |
Modulus of Elasticity(x106 psi) |
Mean Coefficient of Thermal Expansion (IN./IN./°F x 10-6) |
Thermal Conductivity (BTU-in/ft2-h-°F) |
| 347 |
S34700 |
— |
75,000 |
515 |
— |
30,000 |
205 |
— |
35 |
— |
— |
29.0 |
9.2 |
— |
| 347H |
S34709 |
— |
75,000 |
515 |
— |
30,000 |
205 |
— |
35 |
7 or coarser |
— |
29.0 |
9.2 |
— |
| Grade |
347 |
347H |
| UNS Designation |
S34700 |
S34709 |
| Carbon (C) Max. |
0.08 |
0.04–0.10 |
| Manganese (Mn) Max. |
2.00 |
2.00 |
| Phosphorous (P) Max. |
0.04 |
0.04 |
| Sulphur (S) Max. |
0.03 |
0.03 |
| Silicon (Si) Max. |
0.75 |
0.75 |
| Chromium (Cr) |
17.0–20.0 |
17.0–20.0 |
| Nickel (Ni) |
9.0–13.0 |
9.0–13.0 |
| Molybdenum (Mo) |
— |
— |
| Nitrogen (N) |
— |
— |
| Iron (Fe) |
Bal. |
Bal. |
| Other Elements |
Cb+Ta=10xC-1.0 |
Cb+Ta=8xC-1.0 |
347/347H Product Range
| Alloy |
UNS Designation |
Werkstoff NR. |
Specifications* |
| 347 |
S34700 |
1.4550 |
A269, A/SA249, A/SA312 |
| 347H |
S34709 |
— |
A/SA249, A/SA312 |
*Note: The specifications noted including ASTM, ASME, or other applicable authorities are correct at the time of publication. Other specifications may apply for use of these materials in different applications.
