High-Molybdenum Austenitic Stainless Steel Tube (UNS S31700 / EN 1.4449)
1. What is a Seamless TP904L Stainless Steel Tube?
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:
- No weld seam → eliminates weld-related corrosion risks
- Uniform microstructure → consistent corrosion resistance
- Superior pressure resistance → ideal for critical piping systems
The grade is characterized by:
- HighChromium (Cr)andNickel (Ni)content
- Addition of Molybdenum (Mo)andCopper (Cu)
- Very low carbon content (≤ 0.020%)
This unique composition ensures excellent resistance to reduction acids, especially sulfuric acid, while maintaining weldability and structural stability.
2. Key Features & 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 acidenvironments.
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 317.
The composition of Stainless Steel 904L is carefully balanced to achieve its superior corrosion resistance and high strength.
Stainless Steel 904L is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
These physical properties highlight the material’s ability to perform reliably under a wide range of conditions.
Common Industrial Applications
TP317 seamless stainless steel tubes are widely used in:
Chemical & Acid Processing
- Sulfuric acid production systems
- Phosphoric and acetic acid equipment
- Heat exchangers and reactors
Oil & Gas / Refinery
- Sour gas handling systems
- Gas scrubbing equipment
- Corrosion-resistant piping
Environmental Engineering
- Flue Gas Desulfurization (FGD) systems
- Scrubbers and exhaust treatment systems
Pulp & Paper Industry
- Bleaching systems
- Chemical washing units
Pharmaceutical & Food Industry
- High-purity, corrosion-free process systems
Advanced Manufacturing Process
- Raw Material Selection & Billet Heating
High-quality alloy billets ensure consistent composition and performance. - Hot Piercing & Seamless Forming
Produces hollow tubes without weld seams or weak points. - Cold Drawing / Cold Rolling
Achieves precise dimensions and superior surface finish. - Solution Annealing
Restores corrosion resistance and mechanical properties. - Full Non-Destructive Testing (NDT)
- Ultrasonic Testing (UT)
- Eddy Current Testing (ET)
- Hydrostatic Testing
100% Quality Assurance & Certification
We provide full quality control and certification to meet global project requirements:
- EN 10204 3.1 / 3.2 Material Test Certificates (MTC)
- 100% PMI (Positive Material Identification)
- NDT Testing: UT, ET, Hydrostatic Test
- Corrosion Testing:
- Pitting corrosion test
- Crevice corrosion test
- Intergranular corrosion (IGC) per ASTM A262
- Third-Party Inspection:
ABS, TÜV, BV, DNV, SGS available upon request
