UNS S31653|1.4429|TP316LN Seamless Stainless Steel Tube
Distinguished by the strategic addition of Nitrogen (0.10–0.16%), our TP316LN tubing offers significantly higher yield strength than standard 316L while maintaining excellent ductility and non-magnetic characteristics even after cold working. These tubes are indispensable for mission-critical applications in high-pressure chemical reactors, nuclear engineering, and cryogenic processing. Through advanced cold-drawing and precise solution annealing, XinZhe ensures every tube maintains a stable austenitic microstructure and optimized resistance to sensitization and pitting.
“TP316LN offers a minimum yield strength of 205 MPa, which is higher than the 170 MPa of standard TP316L.”
What Is a Seamless Stainless Steel TP316LN Tube?
TP316LN (UNS S31653) is the nitrogen-enhanced, low-carbon variant of the 316 austenitic grade, with 2–3% molybdenum and 0.10–0.16% nitrogen. The nitrogen addition raises the yield strength above standard 316L and improves resistance to pitting, while the low carbon and controlled nitrogen preserve weldability and intergranular corrosion resistance.
Seamless TP316LN stainless steel tube (UNS S31653 / W.Nr. 1.4406 / 1.4429) is a nitrogen-strengthened, ultra-low carbon austenitic stainless steel tube designed for demanding applications requiring high strength, corrosion resistance, and structural reliability.
Manufactured via a seamless process (hot piercing + cold drawing/finishing), TP316LN provides:
The designation “LN” indicates:
This results in a material with higher mechanical strength than TP316L, while maintaining excellent ductility and corrosion resistance.
Key Features and Technical Advantages
High Strength & Increased Design Stress Nitrogen addition (0.10%–0.16%) significantly increases yield and tensile strength, enabling thinner wall design and higher allowable stress compared to TP316L.
Excellent Pitting & Crevice Corrosion Resistance The combination of Molybdenum (Mo) and Nitrogen (N) enhances the PREN value, providing superior resistance in chloride-rich and marine environments.
Intergranular Corrosion Resistance Ultra-low carbon content (≤ 0.03%) prevents chromium carbide precipitation, ensuring resistance to sensitization during welding.
High Strength & Increased Design Stress
Nitrogen addition (0.10%–0.16%) significantly increases yield and tensile strength, enabling thinner wall design and higher allowable stress compared to TP316L.
Excellent Pitting & Crevice Corrosion Resistance
The combination of Molybdenum (Mo) and Nitrogen (N) enhances the PREN value, providing superior resistance in chloride-rich and marine environments.
Intergranular Corrosion Resistance
Ultra-low carbon content (≤ 0.03%) prevents chromium carbide precipitation, ensuring resistance to sensitization during welding.
Excellent Cryogenic Toughness
Maintains outstanding mechanical properties at low temperatures down to -196°C, making it ideal for LNG and cryogenic applications.
High Pressure & Structural Integrity
Manufactured according to:
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 316LN.
The composition of Stainless Steel 316LN is carefully balanced to achieve its superior strength and corrosion resistance.
Table 1: Chemical Composition of Stainless Steel 316LN
| Cr | Ni | Mo | N | P | S | Mn | Si | C |
| 16.00 - 18.00 | 10.00 - 14.00 | 2.00−3.00 | 0.10 - 0.16 | ≤0.045 | ≤0.03 | ≤2.00 | ≤1.00 | ≤0.035 |
Key Point: Nitrogen acts as a solid-solution strengthening element, significantly improving strength and pitting resistance without compromising ductility.
| Tensile Strength | Yield Strength | Elongation | Hardness | Brinell Hardness |
|---|---|---|---|---|
| ≥ 585 MPa | ≥ 290 MPa | ≥ 35% | ≤ 192 HBW | ≤192 HB |
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.0 g/cm³ | 1370 - 1400 °C | 16.0 µm/m·°C (20-100°C) | 16.3 W/m·K (20°C) | 193 GPa | 0.74 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
TP316LN seamless tubes are supplied to the dimensional tolerances of ASTM A213 / A1016 unless a tighter project specification applies.
Common Industrial Applications
Nuclear and Power Industry
- Nuclear island piping and tubing
- Steam generator components
- High-pressure coolant lines
Chemical and Petrochemical
- Reactors and heat exchangers
- Chloride-bearing process streams
- Storage and transfer piping
Cryogenic and LNG Systems
- LNG transfer and boil-off lines
- Cryogenic process piping
- Low-temperature heat exchangers
Offshore and Marine Engineering
- Seawater cooling systems
- Offshore process pipework
- Shipboard piping
Pharmaceutical and Food Industry
- Sanitary process piping
- Clean utility systems
- Heat exchanger tubing
Quality Assurance and Manufacturing Process
Certification
All TP316LN (UNS S31653) tubes are supplied to ASTM A213 / ASME SA213 and ASTM A312 / ASME SA312 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.
TP316LN vs TP316L / TP316 – Technical Comparison
TP316LN, TP316L and TP316 share the 316 base chemistry. The difference is in carbon and nitrogen, and that difference controls strength and weldability.
Carbon and Nitrogen Content
- TP316L: carbon 0.030% maximum, no nitrogen specification
- TP316: carbon 0.08% maximum, no nitrogen specification
- TP316LN: carbon 0.030% maximum with 0.10–0.16% nitrogen added
Mechanical Strength
The nitrogen addition in TP316LN raises the yield strength noticeably above TP316L — typically 30–50 MPa higher minimum — which allows thinner walls for the same design pressure. That is why TP316LN is specified for high-pressure and nuclear duty where weight and wall thickness matter.
Corrosion and Fabrication
Nitrogen also improves resistance to pitting, raising the PREN slightly above TP316L. The low carbon keeps the heat-affected zone free of sensitisation, so TP316LN retains excellent weldability together with improved strength.
Selection Guide
- Choose TP316LN where higher strength, cryogenic toughness or nuclear code compliance is required
- Choose TP316L for general welded corrosion service
- Choose TP316 where the standard carbon grade is specified
Frequently Asked Questions
What is TP316LN tube?
TP316LN (UNS S31653) is the nitrogen-enhanced, low-carbon variant of the 316 austenitic grade, containing 2–3% molybdenum and 0.10–0.16% nitrogen. The nitrogen raises the yield strength above standard 316L.
What does the nitrogen in TP316LN do?
Nitrogen raises the yield strength by typically 30–50 MPa above TP316L, improves resistance to pitting corrosion and increases toughness at cryogenic temperature. This combination allows thinner walls for the same design pressure.
What standard covers TP316LN tube?
TP316LN seamless tube is supplied to ASTM A213 / ASME SA213 and ASTM A312 / ASME SA312, with dimensional tolerances per ASTM A1016 / A1016M.
What is TP316LN tube used for?
TP316LN is used for nuclear island piping and steam generator tubing, high-pressure chemical and petrochemical lines, LNG transfer and cryogenic process piping, and offshore seawater cooling systems.
Ready to Request a Quotation?
Send your Seamless Stainless Steel TP316LN Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements including any cryogenic impact or nuclear code documentation required.
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