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Utilizing 26 high-precision cold rolling mills and 6 cold drawing machines, we ensure dimensional accuracy and superior mechanical properties.
904L Super Austenitic Stainless Steel Tube
ASTM A213 / A269 | UNS N08904 | High Ni-Mo-Cu Super Austenitic Grade | PREN ≥ 34
ISO 9001 | PED | TS CertifiedRelated Products
Introduction
Bridging the performance gap between standard austenitic stainless steels and the far more expensive nickel-base alloys, 904L Super Austenitic Stainless Steel Tube delivers a compelling combination of corrosion resistance, mechanical performance, and weldability that positions it as the preferred material specification for a wide range of highly corrosive chemical processing, seawater handling, and industrial acid environments where 316L is inadequate but the full cost of Inconel or Hastelloy grades cannot be justified. Designated UNS N08904 and governed by ASTM A213, ASTM A269, and EN 10216-5 standards, 904L is a high-alloy fully austenitic grade characterized by its elevated nickel content (23–28%), significant molybdenum addition (4–5%), low carbon maximum of 0.02%, and a copper addition of 1–2% that collectively produce a corrosion resistance profile substantially superior to 316L and approaching the performance of 6Mo super austenitic grades in many industrial corrosive environments. The Pitting Resistance Equivalent Number (PREN) of 904L — approximately 34–36 — is comparable to standard duplex S32205, but the fully austenitic single-phase microstructure of 904L provides superior toughness, particularly at sub-zero temperatures, and eliminates the phase balance management requirements that complicate duplex alloy welding and heat treatment procedures. The low carbon content — maximum 0.02%, qualifying 904L as an "L" grade without the need for a separate low-carbon variant — ensures complete immunity to sensitization in as-welded condition across all practical heat input ranges, making it one of the most weldable high-performance corrosion-resistant alloys in the industrial alloy portfolio.
The corrosion resistance profile that defines 904L super austenitic tube's commercial value is anchored by its exceptional performance in sulfuric acid environments across a remarkably wide concentration and temperature range — a capability that directly reflects the synergistic effect of the copper addition working in conjunction with the elevated nickel and molybdenum content. In sulfuric acid service, the copper component forms a protective copper sulfate surface layer that dramatically reduces corrosion rates in the medium-concentration range (10–60% H₂SO₄) at temperatures up to 60°C, where standard 316L experiences unacceptably rapid attack. This sulfuric acid resistance, combined with 904L's superior resistance to phosphoric acid, acetic acid, and mixed organic acid environments, has established it as the standard specification for heat exchanger tubing, reactor vessel nozzles, and process piping in sulfuric acid manufacturing plants, phosphate fertilizer production facilities, and organic acid chemical processes worldwide. The elevated molybdenum content concurrently provides strong resistance to chloride-induced pitting and crevice corrosion, with a critical pitting temperature (CPT) in seawater typically exceeding 40°C — significantly higher than 316L (approximately 15°C) — making 904L suitable for seawater heat exchanger tubing in moderate-temperature coastal and offshore cooling water applications where 316L experiences chronic pitting failures.
The mechanical characteristics of 904L super austenitic tube reflect its fully austenitic single-phase microstructure, combining moderate yield strength with outstanding elongation and toughness that make it highly suitable for complex tube forming, bending, and expansion operations in heat exchanger fabrication. Unlike duplex grades, 904L does not exhibit the work hardening anisotropy associated with the two-phase duplex microstructure, providing more predictable and isotropic forming behavior that simplifies tooling design and process parameter optimization for complex heat exchanger tube bundle manufacturing. The alloy's immunity to chloride stress corrosion cracking — validated across its full composition range and the complete range of practical industrial temperature conditions — eliminates the SCC failure risk that represents the primary reliability limitation of standard 304 and 316 austenitic grades in warm chloride service. The combination of these properties with 904L's excellent cryogenic toughness — retaining high impact energy values down to -196°C without the ductile-to-brittle transition that affects ferritic and martensitic grades — extends its application range to liquefied gas handling, cryogenic heat exchangers, and cold climate industrial installations where low-temperature toughness is a design-governing requirement alongside corrosion performance.
Our 904L super austenitic stainless steel tube program covers seamless and welded product forms in outer diameters from 6mm to 273mm with wall thicknesses from 0.5mm to 15mm, manufactured to ASTM A213 (seamless) and ASTM A249 (welded) standards with full EN 10216-5 compliance. The combination of small-bore precision instrumentation tubing and large-bore heat exchanger and process piping dimensions in a single certified supply program provides procurement efficiency for complex process plant projects requiring 904L across multiple size ranges. All tubes are supplied with EN 10204 3.1 Mill Test Reports including actual chemical analysis, mechanical properties, and non-destructive examination records. Hydrostatic pressure testing, eddy current inspection, and intergranular corrosion testing per ASTM A262 Practice E are available as supplementary testing options for the most demanding acid service qualifications. Our technical team provides alloy selection guidance comparing 904L against 316L, 2205 duplex, and 6Mo super austenitic alternatives for specific corrosive service environments where the optimal cost-performance balance must be determined from first principles of corrosion engineering.
Specifications
| Material Grade | 904L (UNS N08904) |
| Standard | ASTM A213, A249, A269, EN 10216-5 |
| Outer Diameter | 6mm - 273mm |
| Wall Thickness | 0.5mm - 15mm |
| Length | Up to 25000mm (Custom Available) |
| Finish | Bright Annealed, Pickled, or Polished |
Chemical Composition
| Element | C | Cr | Ni | Mo | Cu | Mn | N |
| Value (%) | ≤0.020 | 19.0-23.0 | 23.0-28.0 | 4.0-5.0 | 1.0-2.0 | ≤2.00 | ≤0.10 |
PREN ≥ 34H₂SO₄ ResistantCu-Enhanced
Mechanical Strength
Comprehensive Info
| MOQ | 200kg (Negotiable for stock) |
| Lead Time | 20 - 40 Days |
| Packaging | Plywood Crates / Bundles |
| Certifications | ISO 9001, PED, TS |
| Raw Materials | Premium High-Alloy Melt Sources |
| Customization | OD/WT, Length, IGC Test, Surface Finish |
Applications
Sulfuric Acid ManufacturingHeat exchanger and absorber tower tubes in contact acid and double-absorption H₂SO₄ production units
Phosphate Fertilizer PlantsPhosphoric acid evaporator tubes and slurry handling lines in wet process phosphoric acid production
Seawater Heat ExchangersTube bundles in coastal power plant cooling systems and offshore platform process coolers handling warm seawater
Pulp & Paper Bleaching LinesPiping and heat exchanger tubes in chlorine dioxide and hypochlorite bleaching circuits of pulp mills
Cryogenic Process EquipmentLow-temperature heat exchanger and process tubing exploiting 904L's superior cryogenic toughness to -196°C
Organic Acid Chemical ProcessingAcetic acid, formic acid, and mixed organic acid process piping where copper addition enhances corrosion resistance
Advantages
Sulfuric Acid Resistance via Cu
Unique 1–2% copper addition creates a protective copper sulfate film in H₂SO₄ service that dramatically extends service life in the 10–60% concentration range where 316L and duplex grades fail within months.
Cryogenic Toughness to -196°C
Fully austenitic single-phase microstructure maintains impact toughness at cryogenic temperatures without the ductile-brittle transition that restricts ferritic and duplex grades in low-temperature service.
Superior Formability
Isotropic single-phase austenite delivers more predictable tube expansion, bending, and forming behavior than two-phase duplex grades — simplifying heat exchanger bundle fabrication tooling and process qualification.
Nickel Alloy Bridge
PREN 34–36 performance at substantially lower cost than Inconel or Hastelloy grades — delivering the optimal cost-performance position for moderately aggressive acid environments that exceed 316L capability.
About Jiangsu Jend Tube Co.,Ltd.
As China 904L Super Austenitic Stainless Steel Tube Manufacturers and Wholesale 904L Super Austenitic Stainless Steel Tube Factory, Established in 2011 and is a manufacturing enterprise with a complete manufacturing cycle from raw material selection to finished product delivery. The company currently has more than 100 employees, covers an area of 30015 square meters, and has a registered capital of 48 million yuan, annual production capacity of 3800 tons.
The company has passed ISO9001:2015 quality certification, domestic pressure vessel TS certification, and foreign pressure vessel PED certification. With rich experience and mature technology, we have been expanding our market internationally. At present, our products are exported to more than 50 countries and regions including Europe, America, Southeast Asia, and the Middle East.
The company adheres to different production norms and standards such as the American standard (ASTM), the European standard (EN), the German standard (DIN), the Japanese standard (JIS), the Russian standard (GOST), and the Chinese standard (GB).
Our company specializes in and customizes various specifications of Martensite TP410 (0Cr13, 1Cr13), Ferrite TP405 (1Cr13Al), TP430 (1Cr17), TP444 (0Cr18Mo2), TP439, TP409 (0Cr11Ti), It is also proficient in manufacturing Austenitic seamless stainless steel pipes of series such as TP304(L/H), TP316(L/H/Ti), TP310S, TP317, TP321(H) and TP347(H). Duplex such as S31803, S2205, S32750, S32304, and Nickel-based alloys Monel400, Monel600, Monel800, GH3030, 904L, Inconel 625, etc.
The company mainly produces seamless steel pipes with the following specifications: outer diameter: 3.18mm to 406.4mm, wall thickness: 0.3mm to 20mm, and the longest length is 25000mm. Additionally, it can customize seamless steel pipes with special materials and specifications according to customer requirements. The company attaches great importance to scientific innovation. The staff of the company vigorously develop technological research and development.
Jiangsu Jend Tube Co.,Ltd. will continuously accumulate professional knowledge and capabilities, striving to become a leader in the domestic market and even the world market. Strive to be the most reassuring pipe manufacturing enterprise for customers.
Precision Manufacturing and Process Optimization
We rely on precision equipment and optimized production technologies to achieve outstanding mechanical performance and consistent product quality.
Cold Rolling and Cold Drawing
Solution Heat Treatment
Natural gas solution treatment furnaces and BA solution treatment furnaces optimize the material's grain structure, enhancing corrosion resistance.
Precision Straightening and Polishing
10 straightening machines and 8 finishing polishing machines guarantee product surface smoothness and dimensional accuracy.
Automated Inspection and Quality Assurance
Real-time monitoring systems ensure the stable quality of every batch of products.
Product Usage Tips
Welding 904L
Weld with over-alloyed filler ERNiCrMo-3 (Inconel 625 type) or matching 904L filler where available. The over-alloyed filler compensates for dilution effects that would otherwise reduce weld metal corrosion resistance below parent material level. Maintain low heat input with interpass temperature below 150°C to minimize sensitization risk in the HAZ despite the low carbon content.
H₂SO₄ Service Concentration Limits
904L provides excellent performance in sulfuric acid from 0–98% concentration at ambient temperature. At elevated temperatures, performance varies significantly with concentration: optimal resistance is in the 10–80% range at up to 60°C. For concentrated H₂SO₄ above 80% at temperatures above 50°C, conduct site-specific corrosion testing before final material selection.
Seawater Chloride Temperature Limit
904L provides reliable pitting resistance in seawater up to approximately 40°C continuous service — significantly better than 316L (approximately 15°C) but less than super duplex S32750 (60°C+). For seawater heat exchanger tube service above 40°C outlet temperature, evaluate super duplex or 6Mo super austenitic grades to avoid crevice corrosion under tube support plates.
IGC Testing for Acid Service
Request ASTM A262 Practice E (Strauss test) intergranular corrosion testing for heat exchanger tube qualification in critical sulfuric acid service. Although 904L's 0.02% maximum carbon greatly reduces sensitization risk, IGC testing provides documented assurance that no grain boundary chromium depletion has occurred during tube manufacturing thermal cycles.
Value-Added Processing Services
We provide specialized processing for 904L heat exchanger, acid plant, and cryogenic system applications:
Precision Heat Exchanger Cutting
Fixed-length cutting to ±0.3mm for direct tube bundle assembly with dimensional report.
IGC Corrosion Testing
ASTM A262 Practice E intergranular corrosion test for acid service qualification documentation.
Eddy Current Inspection
100% eddy current testing for heat exchanger tube defect detection per ASTM E426.
U-Bending Service
Precision U-bend forming for shell-and-tube heat exchanger configurations in acid service.
Payment & Shipping
Payment Terms
- T/T (Telegraphic Transfer)
- L/C at Sight (Letter of Credit)
- Western Union
- Flexible terms for long-term partners
Shipping Options
- Sea Freight (FCL/LCL)
- Air Freight for urgent orders
- Express for small samples
- Seaworthy wooden cases or bundles with end caps
Certifications & Standards
Our 904L super austenitic tube complies with international acid service and process industry standards:
ISO 9001:2015
PED Certification
TS Pressure Vessel
ASTM A213 / A269
EN 10216-5
EN 10204 3.1 MTR
Frequently Asked Questions
What role does copper play in 904L's sulfuric acid resistance?
The 1–2% copper in 904L forms a protective copper sulfate surface layer in sulfuric acid service that dramatically reduces corrosion rates in the 10–60% H₂SO₄ concentration range. This copper-sulfate mechanism is unique to copper-bearing austenitic grades and explains 904L's sulfuric acid performance far exceeding that of molybdenum-only grades like 316L.
How does 904L compare to 6Mo super austenitic grades like 254 SMO?
254 SMO (UNS S31254) with 6% Mo and nitrogen addition achieves PREN 43–45 versus 904L's 34–36. In seawater above 40°C and aggressive chloride environments, 254 SMO is superior. In sulfuric acid service, 904L's copper addition gives it an advantage in the medium-concentration range. 904L is typically more cost-effective for sulfuric acid service while 254 SMO is preferred for high-chloride service.
Is 904L suitable for pulp mill bleaching environments?
Yes, 904L has a well-established track record in pulp mill bleaching circuits handling chlorine dioxide and hypochlorite solutions. Its elevated molybdenum and nickel content provide pitting resistance significantly superior to 316L in the warm, moderately oxidizing chloride conditions of modern bleaching sequences.
Can 904L be used for cryogenic applications?
Yes, 904L's fully austenitic microstructure maintains excellent impact toughness at temperatures down to -196°C (liquid nitrogen temperature). It is suitable for LNG, liquid nitrogen, and liquid oxygen process equipment where low-temperature toughness and corrosion resistance must be combined in a single material.
Does 904L require post-weld heat treatment?
No, 904L's maximum 0.02% carbon content virtually eliminates sensitization risk, and no post-weld heat treatment is required to maintain corrosion resistance. Solution annealing is beneficial for stress relief in highly restrained joints but is not a corrosion requirement. This makes 904L substantially easier to fabricate in the field than alloys requiring mandatory post-weld treatment.
What is the seawater pitting temperature limit for 904L?
904L has a critical pitting temperature (CPT) in synthetic seawater of approximately 40°C — more than double the 15°C CPT of 316L. For heat exchanger applications where seawater outlet temperature remains below 35–40°C, 904L provides reliable long-term service. Above these temperatures, super duplex or 6Mo grades are recommended.
What is the lead time for 904L super austenitic tube?
Standard heat exchanger dimensions are typically available within 20–35 days. Non-standard dimensions or supplementary IGC testing requirements add 5–10 days to the standard lead time. Contact our team for current inventory availability in common heat exchanger tube dimensions.
Do you export 904L tubes to sulfuric acid plant projects internationally?
Yes, we supply 904L super austenitic stainless steel tubes to sulfuric acid manufacturing, phosphate fertilizer, and pulp mill projects across Africa, Asia, the Middle East, and Latin America, with full ASTM A213 certification and IGC test documentation for acid service qualification.
Ready to Order 904L Super Austenitic Stainless Steel Tube?
The sulfuric acid and seawater specialist — contact us for IGC testing, cryogenic certification, and heat exchanger dimensions
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