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ASTM A312 UNS N08904 (904L) Seamless Tube: Super Austenitic Stainless Steel Tube for Extreme Corrosive Industrial Service
ASTMA312 UNS N08904 seamless tube, universally known as 904L super austenitic stainless steel tube, is a premium low-carbon high-alloy piping solution manufactured in full compliance with ASTM A312 boiler, heat exchanger, and process tubing standards. This UNS N08904 corrosion-resistant seamless tube features a specialized Cr-Ni-Mo-Cu alloy formula with ultra-low carbon content, designed exclusively to outperform conventional 316L and 317L stainless steel grades. It delivers exceptional resistance to sulfuric acid, phosphoric acid, chloride pitting, crevice corrosion, and stress corrosion cracking, making it the optimal choice for harsh industrial environments where standard stainless steel tubes fail to sustain long-term service.
The core competitive advantage of ASTMA312 UNS N08904 industrial heat exchanger tube lies in its optimized super austenitic microstructure. With a maximum 0.02% ultra-low carbon composition, this grade completely eliminates carbide precipitation and welding sensitization, requiring no post-weld heat treatment for on-site fabrication. The balanced combination of high nickel, molybdenum, and copper significantly enhances durability in reducing acidic media and high-chloride seawater environments. Every ASTMA312 904L seamless tube undergoes strict solution annealing and full non-destructive testing, including hydraulic pressure testing and ultrasonic inspection, ensuring precise dimensional tolerance and stable long-term operational reliability.
Strictly adhering to official ASTM A312 and UNS N08904 specifications, the standardized alloy ratio guarantees consistent extreme corrosion resistance and structural stability:
| Element |
Minimum (%) |
Maximum (%) |
|
Carbon (C) |
— |
0.02 |
|
Manganese (Mn) |
— |
2.00 |
|
Phosphorus (P) |
— |
0.040 |
|
Sulfur (S) |
— |
0.030 |
|
Silicon (Si) |
— |
1.00 |
|
Chromium (Cr) |
19.00 |
23.00 |
|
Nickel (Ni) |
23.00 |
28.00 |
|
Molybdenum (Mo) |
4.00 |
5.00 |
|
Copper (Cu) |
1.00 |
2.00 |
|
Nitrogen (N) |
— |
0.10 |
After standardized solution heat treatment, UNS N08904 high-pressure corrosion-resistant tube maintains excellent ductility and mechanical stability under cyclic thermal and corrosive loads:
| Mechanical Property |
Standard Value |
|
Tensile Strength (MPa) |
≥ 490 |
|
Yield Strength (MPa) |
≥ 220 |
|
Elongation (2 inch, %) |
≥ 35 |
|
Max Hardness (HRB) |
≤ 90 |
The unique super austenitic alloy structure endows ASTMA312 UNS N08904 seamless tubing with unmatched comprehensive corrosion resistance. It performs stably in low-pH acidic environments, high-salinity seawater, and fluctuating temperature working conditions, effectively resisting pitting, crevice, and intergranular corrosion. Its excellent welding and forming properties simplify custom processing and on-site installation, greatly reducing project construction cycles and operational maintenance costs for long-term industrial service.
ASTMA312 904L boiler and process tube is widely applied in petrochemical processing pipelines, acid treatment systems, seawater desalination heat exchangers, flue gas desulfurization equipment, and pulp & paper industrial piping. As a cost-effective super austenitic steel solution, it provides far longer service life than conventional stainless steel tubes in extreme corrosive scenarios.
As a professional ASTMA312 UNS N08904 tube supplier, we supply full-size standard and custom 904L seamless tubes with complete ASTM certifications and MTR test reports. All products pass strict dimensional calibration and multi-standard non-destructive testing, fully meeting global industrial engineering requirements. We deliver reliable, high-performance UNS N08904 seamless tube solutions for worldwide chemical, marine, power, and thermal energy projects.