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 TP304LN; also ASME SA312; EN 10216-5 1.4311; Equivalent to AISI 304LN
Usage of Seamless Stainless Steel Pipe: Pressure vessels and storage tanks (higher pressure rating – 20% higher allowable stress than 304L), heat exchanger shells and tubes (reduced wall thickness for better heat transfer), structural components in corrosive environments, chemical processing (higher pressure chloride service, non-marine), offshore platform topside piping (weight reduction), high-pressure water treatment systems (reverse osmosis feed lines), paper mill equipment (digester blow lines), brewery and dairy piping (higher operating pressures), hydraulic lines (higher burst pressure), pharmaceutical equipment (where higher strength allows thinner walls), pump and valve bodies, industrial structural tubing
Womic Steel offering high quality & competitive prices of ASTM A312 TP304LN seamless stainless steel pipe, nitrogen strengthened seamless tube, high strength SMLS stainless pipe, pressure vessel seamless pipe, cold drawn seamless tube. Mill certificate EN 10204 3.1/3.2, hydro test, UT/ET, solution annealed, beveled/plain ends, pickled/polished finish available. Factory direct supply for pressure vessel, structural, and industrial 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 stainless steel seamless tubular products. Our state-of-the-art seamless pipe production facility utilizes advanced hot-rolling and cold-drawing processes 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 and surface finish – critical for high-strength precision 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 pressure vessels and high-pressure 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 VIII, Div. 1) compliance
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 (180# to 320#)
ASTM A312 TP304LN: Material Composition & Performance Characteristics
ASTM A312 TP304LN is a low-carbon (≤ 0.03% C) nitrogen-strengthened (0.10-0.16% N) version of 304 stainless steel. The nitrogen addition provides solid solution strengthening, increasing yield strength by approximately 60% compared to 304L (170 MPa vs 275 MPa) while maintaining excellent ductility, toughness, and corrosion resistance. The low carbon content provides resistance to intergranular corrosion after welding. TP304LN is used where higher strength is needed but the additional corrosion resistance of molybdenum-bearing grades (316LN) is not required.
Chemical Composition (Ladle Analysis, % by mass):
| Element | TP304LN (ASTM A312) | TP304L (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 | 18.0 – 20.0 | 18.0 – 20.0 |
| Ni | 8.0 – 11.0 | 8.0 – 12.0 |
| N | 0.10 – 0.16 | ≤ 0.10 |
| Fe | Balance | Balance |
Mechanical Properties (Room Temperature, Solution Annealed):
| Property | TP304LN | TP304L |
| 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: 7.93 g/cm³
Modulus of Elasticity: 200 GPa (29 × 10⁶ psi)
Thermal Conductivity: 16.2 W/m·K at 100°C
Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/°C (20-100°C)
Corrosion Resistance:
Similar to 304L in most environments (good resistance to oxidizing acids, organic acids)
Slightly improved pitting resistance due to nitrogen (PREN ≈ 19-20 vs 18 for 304L)
Excellent resistance to intergranular corrosion after welding (low carbon)
Not suitable for chloride service above ambient temperature (use 316LN or duplex for chlorides)
Key Advantages over 304L:
60% higher yield strength (275 MPa vs 170 MPa) allows thinner walls for same pressure rating
20-25% higher allowable stress per ASME Section VIII for pressure vessels
Slightly better pitting resistance due to nitrogen
Comparable weldability and formability
Dimensional Range & Standards Compliance
| Item | Specification |
| Standard | ASTM A312 / ASME SA312 (also A213, A269, A999) |
| 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 |
| 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 TP304LN 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 | Hydraulic line |
| 3/4″ | 26.7 | 10S | 2.11 | 1.28 | CD | 6m | Instrument line |
| 1″ | 33.4 | 10S | 2.77 | 2.09 | CD | 6m | Pressure vessel |
| 1-1/2″ | 48.3 | 10S | 2.77 | 3.11 | CD | 6m | Process line |
| 2″ | 60.3 | 10S | 2.77 | 3.93 | CD | 6m / 12m | High pressure |
| 3″ | 88.9 | 10S | 3.05 | 6.46 | CD/HF | 6m / 12m | Heat exchanger |
| 4″ | 114.3 | 10S | 3.05 | 8.37 | CD/HF | 6m / 12m | Pressure vessel |
| 6″ | 168.3 | 10S | 3.40 | 13.8 | HF | 6m / 12m | Structural column |
| 8″ | 219.1 | 10S | 3.76 | 20.0 | HF | 12m | Main header |
| 10″ | 273.0 | 10S | 4.19 | 27.8 | HF | 12m | Chemical process |
| 12″ | 323.9 | 10S | 4.57 | 36.0 | HF | 12m | Structural support |
| 16″ | 406.4 | 10S | 4.78 | 47.4 | HF | 12m | Large diameter |
*Custom dimensions outside these ranges available. TP304LN allows 25-30% thinner walls than 304L for same pressure rating.*
Common Seamless High-Strength Stainless Steel Standards & Grades Manufactured by Womic Steel
| Standard | Steel Grades | Typical Application | Manufacturing Process |
| ASTM A312 | TP304LN, TP304L, TP316LN, TP316L | High strength corrosive service | CD/HF |
| ASTM A213 | TP304LN, TP316LN | Boiler, heat exchanger tubes | CD |
| ASTM A269 | TP304LN, TP316LN | General service tubing | CD |
| EN 10216-5 | 1.4311 (304LN), 1.4406 (316LN) | Pressure purposes, high strength | CD/HF |
Usage: Pressure vessels, heat exchangers (higher pressure rating), structural components, offshore piping, high-pressure water treatment, paper mill equipment.
Manufacturing Process – Seamless Stainless Steel Pipe (Cold Drawn / Hot Finished)
Womic Steel employs two primary seamless manufacturing processes for TP304LN production. Nitrogen retention in the finished pipe is critical.
Cold Drawn (CD) Process – Small to Medium Diameter (21.3–219.1mm OD):
Raw Material (Billet) Inspection: Billet verified for TP304LN composition (Cr 18-20%, Ni 8-11%, 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 retaining nitrogen in solution.
Straightening & Cut to Length
Pickling & Passivation
NDT: Eddy current (100%) + hydrostatic test.
Final Inspection & Marking
Hot 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 TP304LN:
Nitrogen content must be controlled to avoid nitride precipitation
Water quench mandatory to retain nitrogen in solid solution
Welding consumables should have matching nitrogen content (ER308L with N addition)
Quality Control & Testing Procedures for ASTM A312 TP304LN Seamless Stainless Steel Pipe
| Stage | Inspection Method | Purpose |
| Raw Material | Chemical Analysis (OES + Combustion for N) | Verify TP304LN (N 0.10-0.16%, Cr 18-20%, Ni 8-11%, C ≤ 0.03%) |
| Raw Material | Tensile Testing | Verify 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 | Confirm grade (Cr, Ni) |
| Finished Pipe | Intergranular Corrosion Test (A262 Practice E) | Detect sensitization (should pass) |
| Finished Pipe | Visual & Marking | Traceability |
Optional Tests:
Elevated temperature tensile test (if required for design)
Low-temperature Charpy impact for cryogenic service
G48 pitting test for chloride service qualification
Primary Applications – ASTM A312 TP304LN Seamless Stainless Steel Pipe
Pressure vessels and storage tanks: Higher allowable stress per ASME Section VIII allows thinner walls (25-30% weight savings) compared to 304L for the same pressure rating.
Heat exchanger shells and tubes: Shell side pressure can be increased without thickening shell. Tubes can have thinner walls for better heat transfer efficiency.
Structural components in corrosive environments: Building frames, pipe racks, equipment supports in chemical plants and offshore platforms. Higher strength reduces section size.
Chemical processing (higher pressure systems): Reactor inlet/outlet piping, high-pressure transfer lines where 304L is insufficient but 316LN is over-specified.
Offshore platform topside piping: Weight reduction is critical for offshore platforms. TP304LN allows thinner Schedule 10S or 5S instead of Schedule 40S.
High-pressure water treatment systems: Reverse osmosis feed lines and high-pressure pump discharge piping (higher pressure rating than 304L).
Paper mill equipment: Digester blow lines (higher strength to resist thermal and pressure cycling).
Brewery and dairy piping: CIP systems and product lines requiring higher operating pressures.
Hydraulic lines in industrial environments: Instrumentation and control lines requiring higher burst pressure.
Pharmaceutical equipment: Reactors and storage vessels where higher strength allows thinner walls and better heat transfer.
Packaging & Shipping – ASTM A312 TP304LN Seamless Stainless Steel Pipe Packaging:
Anti-corrosion protection: VCI paper or plastic wrap. For food/pharma, no oil residue.
End caps: Plastic caps for beveled ends.
Bundling (Small diameters): Bundles with steel straps and interleaving paper.
Individual packaging (Large diameters): Plastic film wrap.
Wooden crates for critical applications.
Shipping:
Containers for ≤ 610mm, break-bulk for larger diameters.
Documentation: MTC 3.1/3.2, hydrotest report, eddy current/UT reports, PMI report, IGC test report (if specified), dimensional report, packing list, COO. Optional nitrogen verification report upon request.
10. Womic Steel Advantages & FAQ – ASTM A312 TP304LN Seamless Stainless Steel Pipe
Why Partner with Womic Steel for TP304LN Seamless Pipe?
Complete Size Range: Cold Drawn 1/2″ – 8″, Hot Finished 4″ – 24″.
Full solution annealing (1040-1120°C, water quench).
Nitrogen content verified (0.10-0.16%) – guaranteed high strength (275 MPa yield min).
Higher strength allows thinner walls – weight savings of 25-30% over 304L.
Low carbon (≤ 0.03%) – excellent weldability and IGC resistance.
Competitive lead times: 25-35 days for CD, 35-50 days for HF.
Global Certification: ISO 9001, PED (CE), EN 10204 Type 3.2.
Frequently Asked Questions (FAQ) – ASTM A312 TP304LN Seamless Stainless Steel Pipe
Q: What is the advantage of TP304LN over standard 304L?
A: TP304LN has 60% higher yield strength (275 MPa vs 170 MPa) due to nitrogen addition, while maintaining similar corrosion resistance, ductility, and weldability. This allows designers to use thinner walls for pressure vessels and piping (25-30% weight reduction) for the same pressure rating. For structural applications, smaller section sizes can be used.
Q: Is TP304LN more expensive than 304L?
A: Slightly, due to nitrogen alloying and tighter composition control. However, the weight savings (25-30% thinner walls) often result in lower overall material cost for pressure-containing applications. For structural applications where strength is critical, the weight reduction may offset the higher unit price.
Q: Can TP304LN be used in seawater service?
A: No. TP304LN has similar pitting resistance to 304L (PREN ≈ 19-20). For seawater or high-chloride environments, use 316LN (with Mo) or duplex stainless steel. TP304LN is for non-chloride or low-chloride applications where higher strength is needed.
Q: Does TP304LN require solution annealing after processing?
A: ASTM A312 requires solution annealing for seamless pipe. For TP304LN, solution annealing at 1040-1120°C followed by water quench is necessary to dissolve any nitrides that may have formed during processing and to restore full corrosion resistance and mechanical properties. Womic performs solution annealing on all TP304LN seamless pipes.
Q: What is the typical allowable stress for TP304LN in ASME Section VIII?
A: At room temperature, allowable stress for TP304LN is approximately 138 MPa (20,000 psi) vs 115 MPa (16,700 psi) for 304L – about 20% higher. The actual values depend on temperature; refer to ASME Section II, Part D. Designers should use the correct allowable stress values for the specific grade.
Q: What is the typical lead time for TP304LN seamless pipe?
A: 25-35 days for CD (small to medium diameters), 35-50 days for HF (large diameters). TP304LN lead times are similar to 304L. Third-party inspection adds 7-14 days.
Q: Can TP304LN be used for high-temperature service (above 500°C)?
A: TP304LN’s high-temperature strength is better than 304L due to nitrogen solid solution strengthening. However, for sustained service above 550°C, grades with higher carbon (304H) or creep-resistant grades (321H, 347H) may be preferred due to better creep properties. TP304LN is best suited for moderate temperatures (< 450°C) where strength is needed.
Q: What welding filler metal is recommended for TP304LN?
A: AWS A5.9 ER308L (low carbon) is commonly used. For matching nitrogen content, ER308LN filler can be used, but ER308L is generally acceptable for most applications. The low carbon of ER308L prevents sensitization in the HAZ.
Project Reference – European Pressure Vessel Manufacturer (Germany)
Country: Germany (North Rhine-Westphalia)
Standard & Grade: ASTM A312 TP304LN (seamless) – ASME Section VIII compliant
Dimensions & Quantity:
OD 219.1mm (8″) × Schedule 10S (4.76mm WT) – 600 meters (approx. 28 tons) – Hot Finished
OD 273.0mm (10″) × Schedule 10S (4.19mm WT) – 400 meters (approx. 22 tons) – Hot Finished
OD 60.3mm (2″) × Schedule 40S (3.91mm WT) – 1,200 meters (approx. 10 tons) – Cold Drawn
OD 88.9mm (3″) × Schedule 40S (5.49mm WT) – 800 meters (approx. 12 tons) – Cold Drawn
Total: 3,000 meters, approx. 72 tons
Specifications: ASTM A312 TP304LN seamless, solution annealed and pickled, beveled ends for welding. Hydrostatic testing. Eddy current (CD) and UT (HF). PMI on every pipe. Mandatory tensile testing (yield ≥ 275 MPa, achieved 310-350 MPa; tensile ≥ 550 MPa, achieved 580-630 MPa). Charpy impact at 0°C (min 27J, achieved 100-160J). Intergranular corrosion test per ASTM A262 Practice E (pass). Third-party inspection by TÜV Germany.
Application: Pressure vessel shells and nozzle necks for a manufacturer of ASME-certified pressure vessels (air receivers, process vessels, gas accumulators). The vessels operate at pressures up to 3.5 MPa with non-corrosive gases and liquids. TP304LN was selected to reduce vessel weight (thinner walls) while maintaining the required pressure rating, reducing material cost and shipping weight.
Technical Challenges & Solutions:
Weight reduction using TP304LN – TP304LN’s higher allowable stress (20% higher than 304L per ASME Section VIII) allowed wall thickness reduction from 6.0mm to 4.8mm for the 8″ nozzles, saving 20% weight per vessel. For 20 vessels, total weight savings 4.5 tons. Client accepted design calculations from their engineering team.
Weldability for vessel fabrication – Pressure vessel fabrication requires reliable welding (SAW and GTAW). TP304LN with low carbon (0.015-0.020%) and nitrogen provided good weldability. Womic provided welding procedure qualification (WPQ) samples. Coupons passed tensile, bend, and Charpy tests at 0°C.
Intergranular corrosion resistance – Vessels may be exposed to sensitizing temperatures during post-weld heat treatment (if any). TP304LN with low carbon and nitrogen passed ASTM A262 Practice E with no intergranular attack.
Dimensional accuracy for nozzle fit-up – Nozzle necks require tight OD and WT tolerances for fit-up with flanges. Cold drawn pipes achieved OD tolerance ±0.1mm (ASME allows ±0.5% or 1.1mm for 8″). Client's fabrication team reported perfect fit-up.
Logistics to Germany – Pipes shipped from Shanghai to Hamburg port, then trucked to the manufacturer's facility. TÜV inspected at port. All 72 tons delivered in 3 shipments over 8 weeks. Documentation accepted.
Result: The pressure vessel manufacturer has switched from 304L to 304LN for all new vessel designs, reducing vessel weight by 20-25% and saving shipping costs. Womic Steel is now a preferred seamless pipe supplier for this manufacturer.
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 TP304LN seamless stainless steel pipes for pressure vessels, heat exchangers, structural components, and high-strength corrosive service applications worldwide.
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