UNS N08904|1.4539|TP904L Seamless Stainless Steel Tube
Distinguished by its high Nickel and Molybdenum content with the strategic addition of Copper (Cu), our 904L tubing offers superior resistance to strong reducing acids, particularly dilute sulfuric acid, across the entire concentration range. These tubes are indispensable for mission-critical applications in chemical reactors, seawater cooling systems, and pharmaceutical processing. Through advanced cold-drawing and precise solution annealing, XinZhe ensures every tube maintains a uniform microstructure and optimized mechanical strength for the most demanding industrial environments.
PREN≥35,higher than TP316L PREN≥24
What Is a Seamless Stainless Steel TP904L Tube?
TP904L (UNS N08904) is a super austenitic stainless steel with 25% nickel, 20% chromium, 4.5% molybdenum and 1.5% copper. The high nickel content stabilises the austenitic structure and the copper addition improves resistance to sulphuric and phosphoric acids, giving TP904L a broad corrosion envelope spanning both oxidising and moderately reducing media.
Seamless TP904L stainless steel tube (UNS N08904 / W.Nr. 1.4539) is a high-alloy super austenitic stainless steel tube engineered for the most aggressive corrosive environments, particularly sulfuric acid (H₂SO₄) and mixed acid media.
Manufactured from a solid billet using a seamless process (hot piercing + cold drawing/finishing), TP904L provides:
The grade is characterized by:
This unique composition ensures excellent resistance to reduction acids, especially sulfuric acid, while maintaining weldability and structural stability.
Key Features and Technical Advantages
Outstanding Sulfuric Acid Resistance Specifically engineered for sulfuric acid service across a wide concentration range (under moderate temperatures). Also performs well in phosphoric acid and acetic acid environments.
Excellent Pitting & Crevice Corrosion Resistance High Mo (4–5%) and Cu content significantly improve resistance to localized corrosion, with a high PREN (Pitting Resistance Equivalent Number).
Superior Resistance to Chloride SCC Nickel content (23–28%) provides strong resistance to chloride-induced stress corrosion cracking (SCC), making it suitable for marine and industrial environments.
Outstanding Sulfuric Acid Resistance
Specifically engineered for sulfuric acid service across a wide concentration range (under moderate temperatures). Also performs well in phosphoric acid and acetic acid environments.
Excellent Pitting & Crevice Corrosion Resistance
High Mo (4–5%) and Cu content significantly improve resistance to localized corrosion, with a high PREN (Pitting Resistance Equivalent Number).
Superior Resistance to Chloride SCC
Nickel content (23–28%) provides strong resistance to chloride-induced stress corrosion cracking (SCC), making it suitable for marine and industrial environments.
Excellent Weldability & Fabricability
Low carbon content prevents sensitization, ensuring corrosion resistance in the heat-affected zone (HAZ) without the need for post-weld heat treatment.
Non-Magnetic Austenitic Structure
Remains non-magnetic even after cold working, suitable for specialized industrial and electronic applications.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Stainless Steel 904L.
The composition of Stainless Steel 904L is carefully balanced to achieve its superior corrosion resistance and high strength.
| Cr | Ni | P | S | Mo | Cu | Mn | Si | C |
| 19.00 - 23.00 | 23.00 - 28.00 | ≤ 0.040 | ≤ 0.030 | 4.00 - 5.00 | 1.00 - 2.00 | ≤ 2.00 | ≤ 1.00 | ≤ 0.02 |
Key Element: Copper (Cu) enhances resistance to sulfuric acid corrosion, making TP904L a preferred material for acid processing industries.
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 490 MPa | ≥ 215 MPa | ≥ 35% | ≤ 192 HBW |
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.0 g/cm³ | 1300 - 1390 °C approx. | 16.5 µm/m·°C (20-100°C) | 13.9 W/m·K (20°C) | 195 GPa | 0.85 x 10⁻⁶ Ω·m (20°C) |
| Standard | OD(D) | Tolerance（MM) | Thickness(S) | Tolerance(MM) | Length | Tolerance | |
| MM | Common | High | MM | MM | |||
| EN 10216-5 HFD | 30≤D≤219.1（D2) | ±1.0% or ±0.5mm, whicever is the greater(取较大者) | T1, T≤4 | ±15% or ±0.6mm, whicever is the greater(取较大者) | L≤6M | +5/0 | |
| T2 | ±12.5% or ±0.4mm, whicever is the greater(取较大者) | ||||||
| 219.1≤D≤610 (D1) | ±1.5% or ±0.75mm, whicever is the greater (取较大者) | T≤0.05D | +22.5%/-15% | 6 | +10/0 | ||
| T1, 0.05D | ±15% or ±0.6mm, whicever is the greater(取较大者) | ||||||
| T2, T>0.09D | ±12.5% or ±0.4mm, whicever is the greater(取较大者) | L>12 | +by agreement/0 | ||||
| EN 10216-5 CFD | D3(D≤219.1) | ±0.75% or ±0.3mm, whicever is the greater(取较大者) | T3 | ±10% or ±0.2mm, whicever is the greater(取较大者) | |||
| D4(D≤219.1) | ±0.5% or ±0.mm, whicever is the greater(取较大者) | T4 | ±7.5% or ±0.15mm, whicever is the greater(取较大者) | ||||
| ASTM A213 HFD | D≤100 | +0.4/-0.8 | D<100,S≤2.4 | +40%/0 | HFD, all size | +5.0/0 | |
| +0.4/-1.2 | D<100,2.4 | +35%/0 | |||||
| +0.4/-1.6 | D<100,3.8 | +33%/0 | |||||
| D<100,S>4.6 | +28%/0 | ||||||
| 100 | +0.4/-1.2 | D>100, 2.4 | +35%/0 | ||||
| 200 | +0.4/-1.6 | D>100,3.8 | +33%/0 | ||||
| D>100,S>4.6 | +28%/0 | ||||||
| ASTM A213 CFD | D<25 | ±0.10 | D≤38.1 | +20%/0 | CFD, D<50.8 | +3.0/0 | |
| 25≤D≤40 | ±0.15 | ||||||
| 40 | ±0.20 | ||||||
| 50≤D<65 | ±0.25 | ||||||
| 65≤D<75 | ±0.30 | D>38.1 | +22%/0 | CFD, D≥50.8 | +5.0/0 | ||
| 75≤D≤100 | ±0.38 | ||||||
| 100 | +0.38/-0.64 | ||||||
| 200 | +0.38/-1.14 | ||||||
| ASTM A269 | D≤13 | ±0.13 | D≤13 | ±15% | D<38 | +3.2/0 | |
| 13 | ±0.13 | 13 | ±10% | ||||
| 38≤D<89 | ±0.25 | D>38 | +4.8/0 | ||||
| 89≤D<140 | ±0.38 | ||||||
| 140≤D<203 | ±0.76 | ||||||
| 203≤D<305 | ±1.01 | ||||||
| 305≤D<356 | ±1.26 | ||||||
| ASTM A270 | D<25 | ±0.13 | For weld pipe all size | ±12.5% | +3.0/0 | ||
| 25-50 | ±0.20 | ||||||
| 50-75 | ±0.25 | ||||||
| 75-100 | ±0.38 | For CD SMLS pipe D≤38.1 | +20%/0 | ||||
| 100-140 | ±0.38 | +5.0/0 | |||||
| 140-200 | ±0.75 | For CD SMLS pipe D>38.1 | +22%/0 | ||||
| 200-300 | ±1.25 | ||||||
Dimensional Standards and Tolerances
TP904L seamless tubes are supplied to the dimensional tolerances of ASTM B829 / B677 unless a tighter project specification applies.
Common Industrial Applications
Chemical and Acid Processing
- Sulphuric and phosphoric acid plants
- Reactors and heat exchangers
- Acid storage and transfer lines
Oil and Gas / Refinery
- Process piping and heat exchangers
- Desalination and utility systems
- Offshore equipment
Environmental Engineering
- Flue gas desulphurisation systems
- Wastewater treatment plant
- Effluent handling pipework
Pulp and Paper Industry
- Bleach plant equipment
- Digester and liquor lines
- Heat exchangers
Pharmaceutical and Food Industry
- Sanitary process piping
- Heat exchanger tubing
- Corrosive media transfer
Quality Assurance and Manufacturing Process
Certification
All TP904L (UNS N08904) tubes are supplied to ASTM B677 / ASME SB677 and ASTM B673 / ASME SB673 with EN 10204 3.1 mill test certificates. Third-party inspection (SGS, BV, TUV, Lloyd's), PMI reports and full heat-number traceability can be provided on request.
Non-Destructive Testing (NDT)
Hydrostatic or eddy-current testing is performed on 100% of tubes. Ultrasonic testing (UT) and dye-penetrant inspection (PT) are available for critical service, with records retained for each production lot.
Material Verification
Positive Material Identification (PMI) and spectrometric analysis confirm that the chemical composition matches the ordered grade and that the ferrite/austenite balance is within the specified range.
Mechanical Testing
Tensile, yield, elongation and hardness tests are carried out per heat. Impact testing can be supplied at the project design temperature for subsea and low-temperature service.
Dimensional Inspection
Outside diameter, wall thickness, ovality and straightness are measured against ASTM A1016 / A1016M or ASTM A789 tolerances. Length, square-cut ends and end-finish conditions are verified before packing.
TP904L vs TP316L / 254SMO – Technical Comparison
TP904L is a super austenitic grade with unusually high nickel. Comparing it with TP316L and 254SMO shows what the extra nickel and copper buy.
Chemical Composition
- TP316L: 16–18% Cr, 10–14% Ni, 2–3% Mo — the general-purpose grade
- TP904L (N08904): 19–23% Cr, 23–28% Ni, 4–5% Mo, 1.0–2.0% Cu
- 254SMO (S31254): 20% Cr, 18% Ni, 6% Mo, 0.2% N — higher molybdenum
Acid Resistance
The high nickel content of TP904L stabilises the austenitic structure and the copper addition specifically improves resistance to sulphuric and phosphoric acid. This combination gives TP904L a broader acid envelope than TP316L, and better performance in reducing acid conditions than the higher-molybdenum but lower-nickel 254SMO.
Chloride Resistance
254SMO's 6% molybdenum gives it the higher critical pitting temperature and therefore the advantage in chloride service. TP904L resists chlorides well but is not the first choice for seawater duty.
Selection Guide
- Choose TP904L for sulphuric and phosphoric acid plants, and for mixed acid service where copper-bearing chemistry helps
- Choose 254SMO for seawater, brine and high-chloride streams
- Choose TP316L where neither acid nor chloride duty is severe
Frequently Asked Questions
What is TP904L tube?
TP904L (UNS N08904) is a super austenitic stainless steel tube with 25% nickel, 20% chromium, 4.5% molybdenum and 1.5% copper. The high nickel content stabilises the austenitic structure and the copper improves resistance to sulphuric and phosphoric acids.
What is the advantage of TP904L over TP316L?
TP904L's higher nickel, chromium and molybdenum contents give it a much broader corrosion envelope, with significantly better performance in sulphuric and phosphoric acid and in chloride-bearing process streams. TP316L is limited to general corrosion-resistant service.
What standard covers TP904L tube?
TP904L seamless tube is supplied to ASTM B677 / ASME SB677 for seamless tube and ASTM B673 / ASME SB673 for welded pipe, with ASTM B829 covering general requirements.
What is TP904L tube used for?
TP904L is used for sulphuric and phosphoric acid plants, refinery process piping and heat exchangers, flue-gas desulphurisation systems, pulp and paper bleach plants and pharmaceutical process equipment.
Ready to Request a Quotation?
Send your Seamless Stainless Steel TP904L Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements. Our technical team will confirm availability, testing scope and lead time.
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