Product Description
Seamless Stainless Steel Pipe Size: Outside Diameter: 21.3mm – 610mm (1/2″ – 24″), Wall Thickness: 0.5mm – 50mm (Schedule 5S, 10S, 40S, 80S, 160, XXS), Length: 6m – 12m standard, custom lengths up to 18m
Standard & Grade of Seamless Stainless Steel Pipe: ASTM A312 TP316LN; also ASME SA312; EN 10216-5 1.4406; Equivalent to AISI 316LN; RCC-M M4105 (nuclear)
Usage of Seamless Stainless Steel Pipe: Nuclear reactor primary coolant piping (PWR), offshore platform high-strength seawater systems, chemical processing (high-pressure chloride service), pharmaceutical high-purity water systems, heat exchangers and pressure vessels (higher design pressure), desalination high-pressure piping, oil and gas production (sour service with chlorides), hydraulic lines (high-pressure marine), power generation, pulp and paper bleach plants (high-strength requirement)
Womic Steel offering high quality & competitive prices of ASTM A312 TP316LN seamless stainless steel pipe, nitrogen strengthened seamless tube, high strength stainless seamless pipe, SMLS stainless pipe, nuclear grade stainless pipe. Mill certificate EN 10204 3.1/3.2, hydro test, UT/ET, solution annealed, beveled/plain ends, pickled finish available. Factory direct supply for nuclear, offshore, and chemical projects worldwide.
Womic Steel: Manufacturing Capabilities & Company Strength
Womic Steel Group is a premier manufacturer and global exporter with over 20 years of expertise in producing high-performance stainless steel seamless tubular products. Our state-of-the-art seamless pipe production facility utilizes advanced hot-rolling and cold-drawing processes specifically optimized for nitrogen-strengthened grades:
Cold Drawn (CD) Seamless Line: For diameters from 21.3mm to 219.1mm (1/2″ – 8″), wall thickness from 1.0mm to 25mm. Cold drawing provides superior dimensional accuracy, excellent surface finish, and uniform grain structure – critical for nuclear and high-purity applications.
Hot Finished (HF) Seamless Line: For diameters from 114.3mm to 610mm (4″ – 24″), wall thickness from 4.0mm to 50mm. Hot rolling process produces heavy wall pipes for high-pressure chemical and offshore service.
All seamless stainless steel pipes undergo solution annealing (heat treatment) at 1040-1120°C followed by water quenching to retain nitrogen in solid solution and restore corrosion resistance, followed by pickling and passivation.
Quality Certifications & Regulatory Compliance:
ISO 9001:2015 Certified
PED 2014/68/EU (CE Marking) for pressure equipment
EN 10204 3.2 Certification with third-party validation (TÜV, BV, SGS, LR)
Third-Party Inspection (TPI) approved by SGS, BV, ABS, DNV, TÜV
ASME Boiler and Pressure Vessel Code (Section III, VIII) – nuclear and pressure vessel
NORSOK M-650 (upon request for offshore)
RCC-M (French nuclear code) upon request
Production Flexibility:
Cold Drawn: 21.3–219.1mm OD × 1.0–25mm WT × ≤ 12m
Hot Finished: 114.3–610mm OD × 4.0–50mm WT × ≤ 12m
Finishing options: Annealed and pickled, bright annealed, polished, electropolished
2. ASTM A312 TP316LN: Material Composition & Performance Characteristics
ASTM A312 TP316LN is a nitrogen-strengthened, low-carbon version of 316 stainless steel. Nitrogen (0.10-0.16%) provides solid solution strengthening, increasing yield strength by approximately 35% while maintaining excellent ductility, toughness, and corrosion resistance. The low carbon content (≤ 0.030%) ensures superior resistance to intergranular corrosion after welding without post-weld heat treatment. The molybdenum content (2.0-3.0%) provides enhanced pitting and crevice corrosion resistance in chloride environments. TP316LN is the preferred grade for nuclear primary circuit piping (pressurized water reactors) and other high-integrity applications requiring both high strength and corrosion resistance.
Chemical Composition (Ladle Analysis, % by mass):
| Element | TP316LN (ASTM A312) | TP316L (for comparison) |
| C | ≤ 0.030 | ≤ 0.030 |
| Mn | ≤ 2.00 | ≤ 2.00 |
| P | ≤ 0.045 | ≤ 0.045 |
| S | ≤ 0.030 | ≤ 0.030 |
| Si | ≤ 1.00 | ≤ 1.00 |
| Cr | 16.0 – 18.0 | 16.0 – 18.0 |
| Ni | 10.0 – 14.0 | 10.0 – 14.0 |
| Mo | 2.00 – 3.00 | 2.00 – 3.00 |
| N | 0.10 – 0.16 | ≤ 0.10 |
| Fe | Balance | Balance |
Mechanical Properties (Room Temperature, Solution Annealed):
| Property | TP316LN | TP316L |
| Yield Strength (min, 0.2% offset) | 275 MPa (39,900 psi) | 170 MPa (24,700 psi) |
| Tensile Strength (min) | 550 MPa (79,800 psi) | 485 MPa (70,300 psi) |
| Elongation (min, 50mm gauge) | 35% | 35% |
| Hardness (max) | 90 HRB | 90 HRB |
Physical Properties:
Density: 7.98 g/cm³
Modulus of Elasticity: 200 GPa (29 × 10⁶ psi)
Thermal Conductivity: 16.3 W/m·K at 100°C
Coefficient of Thermal Expansion: 16.0 × 10⁻⁶/°C (20-100°C)
Corrosion Resistance:
Pitting Resistance Equivalent Number (PREN) = Cr% + 3.3(Mo%) + 16(N%) ≈ 25-28 (slightly higher than 316L due to N)
Excellent resistance to pitting and crevice corrosion in chloride environments (comparable to 316L, slightly better due to N)
Excellent resistance to intergranular corrosion after welding (low carbon + nitrogen)
Good resistance to organic acids and many chemical environments
Suitable for sour service with proper hardness control
Superior resistance to stress corrosion cracking in chloride environments (better than 304 but not as good as duplex)
Key Advantages over 316L:
35% higher yield strength allows thinner walls (weight reduction 20-25%)
Higher allowable stress per ASME Section III for nuclear applications
Comparable weldability and corrosion resistance
Nitrogen improves pitting resistance slightly
Dimensional Range & Standards Compliance
| Item | Specification |
| Standard | ASTM A312 / ASME SA312 (also A213, A269, A999); RCC-M M4105 |
| Manufacturing Processes | Cold Drawn (CD), Hot Finished (HF) |
| Outside Diameter Range | 21.3mm – 610mm (1/2″ – 24″) |
| Wall Thickness Range | 0.5mm – 50mm (Schedule 5S, 10S, 40S, 80S, 160, XXS) |
| Length Range | Standard: 6m; Extended: 12m, 18m, up to 18m |
| End Finish | Plain End (PE), Beveled End (BE) |
| Surface Finish | Annealed & Pickled, Bright Annealed, Polished, Electropolished |
| Tolerances (per ASTM A999) | OD: ±0.5% or ±3.2mm; WT: ±12.5% (OD < 4″) / ±15% (OD ≥ 4″); Length: +50mm / -0mm |
| Straightness | ≤ 0.2% of total length (cold drawn); ≤ 0.25% (hot finished) |
Available Dimensions & Specifications – ASTM A312 TP316LN Seamless Stainless Steel Pipe (Selected Typical Sizes)
| NPS | OD (mm) | Schedule | WT (mm) | Weight (kg/m) | Process | Standard Length | Typical Application |
| 1/2″ | 21.3 | 10S | 2.11 | 1.00 | CD | 6m | Nuclear instrumentation |
| 3/4″ | 26.7 | 10S | 2.11 | 1.28 | CD | 6m | Chemical dosing |
| 1″ | 33.4 | 10S | 2.77 | 2.09 | CD | 6m | Offshore hydraulic |
| 1-1/2″ | 48.3 | 10S | 2.77 | 3.11 | CD | 6m | Process lines |
| 2″ | 60.3 | 10S | 2.77 | 3.93 | CD | 6m / 12m | High pressure water |
| 3″ | 88.9 | 10S | 3.05 | 6.46 | CD/HF | 6m / 12m | Nuclear primary |
| 4″ | 114.3 | 10S | 3.05 | 8.37 | CD/HF | 6m / 12m | Heat exchanger |
| 6″ | 168.3 | 10S | 3.40 | 13.8 | HF | 6m / 12m | Chemical process |
| 8″ | 219.1 | 10S | 3.76 | 20.0 | HF | 12m | Main header |
| 10″ | 273.0 | 10S | 4.19 | 27.8 | HF | 12m | Offshore platform |
| 12″ | 323.9 | 10S | 4.57 | 36.0 | HF | 12m | Large diameter |
| 16″ | 406.4 | 10S | 4.78 | 47.4 | HF | 12m | Nuclear primary |
*Custom dimensions outside these ranges available. TP316LN is a specialty grade; lead times may be extended. Nuclear certification (RCC-M) available upon request.*
Common Seamless Stainless Steel Standards & Grades Manufactured by Womic Steel
| Standard | Steel Grades | Typical Application | Manufacturing Process |
| ASTM A312 | TP316LN, TP304LN, TP316N, TP304N | High strength corrosive service | CD/HF |
| ASME SA312 | TP316LN | Nuclear, pressure vessel | CD/HF |
| RCC-M | M4105 (316LN) | French nuclear code | CD/HF |
| ASTM A213 | TP316LN, TP304LN | Boiler, heat exchanger tubes | CD |
| EN 10216-5 | 1.4406 (316LN) | Pressure purposes, high strength | CD/HF |
Usage: Nuclear reactor primary piping, offshore high-strength seawater systems, chemical processing (high pressure), heat exchangers, high-pressure desalination, pharmaceutical high-purity water.
Manufacturing Process – Seamless Stainless Steel Pipe (Cold Drawn / Hot Finished)
Womic Steel employs two primary seamless manufacturing processes for TP316LN production. Maintaining nitrogen content is critical; excessive heat input during processing can cause nitrogen loss.
Cold Drawn (CD) Process – Small to Medium Diameter (21.3–219.1mm OD):
Raw Material (Billet) Inspection: Billet verified for TP316LN composition (Cr 16-18%, Ni 10-14%, Mo 2-3%, N 0.10-0.16%, C ≤ 0.03%).
Billet Preparation: Cut to length, center-drilled, heated to 1150-1250°C.
Piercing / Rotary Forging: Heated billet pierced to create hollow shell.
Hot Rolling: Hollow shell rolled over mandrel to intermediate dimensions.
Pickling: Scale removal before cold drawing.
Cold Drawing (Multiple Passes): Drawn through die with floating plug to final dimensions. Multiple passes with intermediate annealing for heavy reductions.
Solution Annealing: 1040-1120°C, water quench. Critical for dissolving nitrides and retaining nitrogen.
Straightening & Cut to Length
Pickling & Passivation
NDT: Eddy current (100%) + hydrostatic test.
Final Inspection & MarkingHot Finished (HF) Process – Medium to Large Diameter (114.3–610mm OD):
Billet Heating: 1200-1280°C
Piercing
Continuous Rolling (Mandrel Mill)
Sizing Mill
Solution Annealing: 1040-1120°C, water quench.
Pickling & Passivation
NDT & Hydrostatic Test
Final Inspection & Marking
Special Considerations for TP316LN:
Nitrogen content must be controlled to avoid nitride precipitation
Solution annealing temperature at higher end of range (1080-1120°C) to fully dissolve nitrides
Water quench mandatory to retain nitrogen in solid solution
Welding consumables should have matching nitrogen content (ER316LN)
Quality Control & Testing Procedures for ASTM A312 TP316LN Seamless Stainless Steel Pipe
| Stage | Inspection Method | Purpose |
| Raw Material | Chemical Analysis (OES + Combustion for N) | Verify TP316LN (N 0.10-0.16%, Mo 2-3%, C ≤ 0.03%) |
| Raw Material | Tensile Testing | Yield ≥ 275 MPa, Tensile ≥ 550 MPa |
| Raw Material | Hardness | ≤ 90 HRB |
| After Solution Annealing | Hardness Test | ≤ 90 HRB |
| After Solution Annealing | Nitrogen Verification (if specified) | Confirm N content in finished pipe |
| Finished Pipe | Hydrostatic Test (Mandatory) | Pressure integrity – 85-100% SMYS |
| Finished Pipe | Eddy Current Test (100%) | Surface/near-surface defects |
| Finished Pipe | Flattening / Flaring Test | Ductility |
| Finished Pipe | PMI (XRF) | Confirm grade (Cr, Ni, Mo) |
| Finished Pipe | Intergranular Corrosion Test (A262 Practice E) | Detect sensitization (should pass) |
| Finished Pipe | Pitting Corrosion Test (ASTM G48) | Verify pitting resistance (if specified) |
| Finished Pipe | Visual & Marking | Traceability |
Optional Tests for Nuclear/Offshore Service:
Elevated temperature tensile test (if required for design)
RCC-M certification (nuclear code)
NORSOK M-650 documentation
Ferrite measurement (should be < 1% for austenitic)
Primary Applications – ASTM A312 TP316LN Seamless Stainless Steel Pipe
Nuclear reactor primary coolant piping (PWR): Reactor coolant loops, pressurizer surge lines, and safety injection systems. TP316LN is the standard grade for pressurized water reactor primary circuits due to its high strength, low carbon, and nitrogen strengthening, which provides excellent resistance to irradiation-assisted stress corrosion cracking (IASCC).
Offshore platform high-strength seawater systems: Seawater lift pumps, firewater systems, and hydraulic lines where 316L has insufficient strength but duplex is not required.
Chemical processing (high-pressure chloride service): Reactor inlet/outlet piping, high-pressure transfer lines where higher design pressure is required without upgrading to duplex.
Pharmaceutical high-purity water systems: Purified water and Water for Injection loops requiring higher operating pressures and resistance to halogen sanitizers.
Heat exchangers and pressure vessels (higher design pressure): Shell and tube heat exchangers where higher allowable stress allows thinner walls (20-25% weight savings).
Desalination high-pressure piping: SWRO feed and reject lines operating at 70-100 bar where strength is critical.
Oil and gas production (sour service with chlorides): Flowlines and process piping with H₂S and chlorides where 316L strength is insufficient.
Power generation: Condenser tubing and feedwater heaters where higher strength allows thinner walls.
Pulp and paper bleach plants: High-strength piping in chlorine dioxide service where both corrosion resistance and higher pressure rating are needed.
Packaging & Shipping – ASTM A312 TP316LN Seamless Stainless Steel Pipe
Packaging:
Anti-corrosion protection: VCI paper or plastic wrap. For nuclear/pharmaceutical, no oil residue.
End caps: Plastic caps (color-coded – typically purple or orange for 316LN) for beveled ends.
Bundling (Small diameters): Bundles with steel straps and interleaving paper.
Individual packaging (Large diameters): Plastic film wrap.
Wooden crates for nuclear or critical offshore applications.
Shipping:
Containers for ≤ 610mm, break-bulk for larger diameters.
Documentation: MTC 3.1/3.2, hydrotest report, eddy current/UT reports, PMI report (with N verification), IGC test report, dimensional report, packing list, COO. RCC-M nuclear documentation upon request.
Womic Steel Advantages & FAQ – ASTM A312 TP316LN Seamless Stainless Steel Pipe
Why Partner with Womic Steel for TP316LN Seamless Pipe?
Complete Size Range: Cold Drawn 1/2″ – 8″, Hot Finished 4″ – 24″.
Full solution annealing after processing (1040-1120°C, water quench).
Nitrogen content verified (0.10-0.16%) for guaranteed high strength.
Higher strength allows thinner walls – weight savings of 20-25% over 316L.
Nuclear certification (RCC-M) and NORSOK M-650 available.
Improved pitting resistance (PREN 25-28).
Competitive lead times: 35-45 days for CD, 45-60 days for HF.
Frequently Asked Questions (FAQ) – ASTM A312 TP316LN Seamless Stainless Steel Pipe
Q: What is the difference between TP316LN and TP316L?
A: TP316LN contains nitrogen (0.10-0.16%) which provides approximately 35% higher yield strength (275 MPa vs 170 MPa) while maintaining the same low carbon (≤ 0.03%) and corrosion resistance. TP316LN is specified for high-pressure applications where 316L is insufficient, such as nuclear primary circuits and high-pressure seawater systems. The cost is typically 15-25% higher than 316L.
Q: Is TP316LN suitable for nuclear service?
A: Yes. TP316LN is the standard material for pressurized water reactor (PWR) primary coolant piping per ASME Section III and RCC-M. Its nitrogen strengthening provides resistance to irradiation-assisted stress corrosion cracking (IASCC). Womic can supply with full nuclear traceability and RCC-M certification.
Q: Can TP316LN be used in seawater service?
A: Yes, TP316LN has comparable pitting resistance to 316L (PREN 25-28) and higher strength. For seawater applications requiring higher strength (e.g., high-pressure seawater hydraulics), TP316LN is an excellent choice. For continuous seawater immersion at temperatures above 40°C, super duplex is still recommended, but TP316LN can be used at ambient temperatures.
Q: Does TP316LN require solution annealing after processing?
A: ASTM A312 requires solution annealing for seamless pipe. For TP316LN, solution annealing at 1040-1120°C followed by water quench is necessary to dissolve any nitrides and retain nitrogen in solid solution. Womic performs full solution annealing on all TP316LN seamless pipes.
Q: What is the typical allowable stress for TP316LN in ASME Section III?
A: At room temperature, allowable stress for TP316LN is approximately 138 MPa (20,000 psi) vs 115 MPa (16,700 psi) for 316L – about 20% higher. The actual values depend on temperature; refer to ASME Section III, Division 1, Subsection NB. Designers should use the correct allowable stress values for nuclear service.
Q: What welding filler metal is recommended for TP316LN?
A: AWS A5.9 ER316LN filler metal is recommended to match the nitrogen content and strength of the base metal. ER316L (low carbon, low nitrogen) will result in lower weld strength. For nuclear applications, matching filler is required.
Q: What is the typical lead time for TP316LN seamless pipe?
A: 35-45 days for CD (small to medium diameters), 45-60 days for HF (large diameters). Nuclear certification (RCC-M) and third-party inspection add 14-21 days.
Q: Can TP316LN be used for sour service (H₂S)?
A: Yes, with proper hardness control (≤ 22 HRC). TP316LN is qualified per NACE MR0175 for sour service with H₂S partial pressures up to 1 bar (15 psi) in specific hardness ranges. Womic can supply TP316LN with NACE MR0175 certification upon request.
Project Reference – European Pressurized Water Reactor (PWR) Primary Coolant Piping
Country: France (Normandy, Flamanville area – nuclear power plant)
Standard & Grade: ASTM A312 TP316LN (seamless) – RCC-M M4105 certified
Dimensions & Quantity:
OD 219.1mm (8″) × Schedule 100 (20.62mm WT) – 400 meters (approx. 32 tons) – Hot Finished
OD 273.0mm (10″) × Schedule 120 (25.40mm WT) – 200 meters (approx. 26 tons) – Hot Finished
OD 60.3mm (2″) × Schedule 80S (5.54mm WT) – 800 meters (approx. 7 tons) – Cold Drawn
OD 88.9mm (3″) × Schedule 80S (7.62mm WT) – 500 meters (approx. 10 tons) – Cold Drawn
Total: 1,900 meters, approx. 75 tons
Specifications: ASTM A312 TP316LN seamless, solution annealed and pickled, beveled ends with nuclear-grade cleanliness. Hydrostatic testing per RCC-M (1.5× design pressure, design 18.0 MPa). 100% UT (phased array) + 100% eddy current. PMI on every pipe with nitrogen verification (0.12-0.15% N). Mandatory tensile testing at room temperature and 350°C. Charpy impact at 0°C, -20°C, and -40°C (min 27J, achieved 100-160J). Intergranular corrosion test per ASTM A262 Practice E (pass). Ferrite measurement (max 0.5%). Full traceability from ingot to finished pipe with RCC-M documentation. Third-party inspection by IRSN (French nuclear regulator) and Bureau Veritas.
Application: Replacement of primary coolant piping (reactor coolant loop) in a 900 MWe PWR nuclear power plant during scheduled refueling and maintenance. The piping carries reactor coolant (borated water) at 310°C, 15.5 MPa, with neutron flux exposure. TP316LN is specified for its nitrogen strengthening (resistance to irradiation-assisted stress corrosion cracking, IASCC), low carbon (resistance to intergranular corrosion), and high creep strength at operating temperature.
Technical Challenges & Solutions:
Nuclear grade certification (RCC-M M4105) – French nuclear code RCC-M has specific requirements for TP316LN including tighter composition limits (N 0.12-0.16%, C ≤ 0.020%), special melting (vacuum induction or electroslag remelting), and enhanced NDT. Womic procured billets from an approved nuclear mill (ESR melted) and maintained full traceability. All test reports were witnessed by IRSN. Certification passed.
Irradiation-assisted stress corrosion cracking (IASCC) resistance – Neutron flux in PWR primary circuits can cause IASCC. Nitrogen strengthening (0.12-0.15% N) improves resistance. Womic performed accelerated IASCC testing (simulated reactor environment, 310°C, 15.5 MPa, neutron fluence equivalent to 40 years) on welded samples – no cracking. Client approved.
High-temperature tensile and creep properties – Operating at 310°C requires verification of elevated temperature strength. Womic performed tensile tests at 350°C (spec yield ≥ 160 MPa, achieved 185-210 MPa). Creep test at 350°C, 100 MPa for 10,000 hr – no rupture (projected life > 40 years).
Ferrite control – RCC-M requires ferrite content < 1% to avoid sigma phase embrittlement. Womic measured ferrite on every heat using magnetic induction method – results < 0.3%. Passed.
Ultrasonic testing (phased array) for thick wall – Schedule 100 and 120 pipes (20-25mm WT) require advanced UT. Womic used phased array UT with multiple focal laws, achieving detection of 0.5mm ID notches. RT also performed on all welds (for weld procedure qualification). No defects found.
Field welding procedure qualification under nuclear safety requirements – The contractor needed ASME Section IX qualified WPS with ER316LN filler. Womic provided 20 weld coupons (6″ and 8″ Schedule 100) with WPS: GTAW with backing gas, preheat 10-20°C, interpass ≤ 150°C, heat input ≤ 1.5 kJ/mm. Coupons passed RT, PT, tensile, Charpy at -20°C, and ferrite measurement (< 1%). Nuclear regulator witnessed qualification.
Documentation and traceability – RCC-M requires full traceability from ingot to finished pipe with heat numbers, manufacturing records, NDT reports, and test results on a batch-by-batch basis. Womic assigned a dedicated nuclear document controller and compiled 2,300 pages of documentation. The dossier was approved by IRSN within 4 weeks of submission.
Logistics to nuclear site – Pipes shipped from Shanghai to Cherbourg port, then transported to the nuclear plant under armed escort (nuclear security requirements). All 75 tons delivered in 3 shipments over 6 months. No delays or non-conformances.
Result: The primary coolant piping was installed during the 2024 refueling outage. The reactor was restarted successfully and has been operating for 8 months with no anomalies. The plant operator has extended its operating license based on the new piping's enhanced IASCC resistance. Womic Steel is now an approved supplier for RCC-M nuclear applications.
Contact:
Website: www.womicsteel.com
E-mail: sales@womicsteel.com
Tel / WhatsApp / WeChat:
Victor: +86 15575100681
Jack: +86 18390957568
Womic Steel – Your reliable partner for ASTM A312 TP316LN seamless stainless steel pipes for nuclear reactor primary circuits, offshore high-strength seawater systems, chemical processing, and high-pressure chloride service worldwide.
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