Seamless Stainless Steel TP304L Pipe – Low-Carbon Austenitic Stainless Steel for Welded and Corrosion-Resistant Systems
A Seamless Stainless Steel TP304L Pipe is a corrosion-resistant industrial pipe manufactured from a solid stainless steel billet through hot extrusion or cold drawing processes. The seamless manufacturing method produces a pipe with no longitudinal weld seam, giving a uniform metallurgical structure and consistent mechanical properties. Pressure capability is established by wall-thickness calculation to the applicable design code, not by the manufacturing route alone.
Under the ASTM A312 / ASME SA312 specification,TP304L stainless steel is a low-carbon version of Type 304 austenitic stainless steel. Where a dual certification is required, the EN 1.4307 equivalent is stated on the material test certificate; the certification actually supplied is confirmed on the quotation and MTC.
The defining feature of 304L stainless steel is its reduced carbon content (maximum 0.035% per ASTM A312 Table 1), compared with 0.08% in standard 304 stainless steel. This lower carbon level reduces the risk of chromium carbide precipitation during welding, lowering the susceptibility to intergranular corrosion in the heat-affected zone (HAZ). Actual corrosion performance of a finished weldment depends on the welding procedure and service conditions.
Because of these characteristics, ASTM A312 TP304L seamless pipes are widely used in industries requiring extensive welding, high corrosion resistance, and long-term structural reliability.
Key Technical Advantages of TP304L Seamless Pipe
TP304L Seamless Stainless Steel Pipe is supplied for low-carbon weldability and reduced sensitization risk. The size range shown (OD 6–1016 mm; WT 0.5–65 mm) is the overall capability across this product family, not a per-grade commitment. Confirm the specific OD × WT × length combination for the ordered grade in the quotation. The governing specification must be stated on the purchase order: ASTM A312 / ASME SA312. Chemistry, mechanical properties, heat treatment, dimensional tolerance, NDT and certification must be reported against the ordered standard and material heat; do not treat typical values as guaranteed acceptance limits.
Resistance to Intergranular Corrosion
The low carbon composition lowers the tendency for chromium carbides to form at grain boundaries during exposure to temperatures between 425°C and 815°C, a phenomenon known as sensitization. This reduces, but does not eliminate, the risk of sensitization; performance after welding depends on the welding procedure, heat input and service environment.
Excellent Weldability
Because of its low carbon content, TP304L stainless steel is generally selected so that post-weld heat treatment can be avoided, which can reduce fabrication time and cost in large piping systems. Whether PWHT is required is determined by the project specification and the qualified welding procedure.
High Pressure Reliability
The seamless pipe structure has no longitudinal weld seam. Allowable working pressures are not set by the manufacturing route alone; they must be calculated per the applicable design code (for example ASME B31.3) using the ordered grade, wall thickness and design conditions.
Superior Formability and Fabrication Performance
TP304L stainless steel maintains excellent ductility and workability, allowing the pipe to be easily processed through bending, flanging, forming, and complex piping fabrication.
Excellent Low-Temperature Toughness
As an austenitic stainless steel, TP304L retains high impact toughness and mechanical stability at cryogenic temperatures, making it suitable for low-temperature applications.
Product Specifications and Data
To provide a comprehensive understanding of our Seamless Stainless steel 304L pipe, here are the detailed technical specifications and performance data.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| S30403 | 304L | 1.4307 | X2CrNi18-9 | SUS304L | 022Cr19Ni10 / 00Cr19Ni10 |
Grade correspondence does not make ASTM, ASME, EN, JIS and GB delivery requirements interchangeable. Confirm chemistry, heat treatment, mechanical properties, dimensions, testing and certification against the purchase specification. See the grade designation index.
Chemical Composition
The exceptional properties of 304L are a direct result of its specialized low-carbon chemical composition.
| Grade | C | Si | Mn | Cr | Ni | S | P |
|---|---|---|---|---|---|---|---|
| 304 | ≤ 0.08 | ≤1.00 | ≤2.00 | 18.00-20.00 | 8.00-11.00 | ≤0.03 | ≤0.045 |
| 304L | ≤0.035 | ≤1.00 | ≤2.00 | 18.00-20.00 | 8.00-13.00 | ≤0.03 | ≤0.045 |
| 304H | 0.04-0.10 | ≤1.00 | ≤2.00 | 18.00-20.00 | 8.00-11.00 | ≤0.03 | ≤0.045 |
Data source: ASTM A312-25 / ASME SA312 Table 1, TP304L row ≤ heat-analysis acceptance limits. Confirm the values against the ordered edition and the MTC.
Typical Mechanical Properties
Despite its lower carbon content, 304L maintains excellent mechanical properties.
| Material | Tensile Strength ksi(MPa) | Yield Strength ksi(MPa) | Elongation (%) | Hardness Brinell/Vickers | Hardness Rockwell |
|---|---|---|---|---|---|
| 304 | ≥75(515) | ≥30(205) | ≥ 35 | ≤192HBW/200HV | ≤90HRB |
| 304L | ≥70(485) | ≥25(170) | ≥ 35 | ≤192HBW/200HV | ≤90HRB |
| 304H | ≥75(515) | ≥30(205) | ≥ 35 | ≤192HBW/200HV | ≤90HRB |
Note: Typical values for reference only — not acceptance limits. Mechanical properties are reported on the MTC against the ordered standard, product form, condition and test temperature.
Typical Physical Properties
Here are some of the key physical properties of 304L that dictate its performance in various applications.
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.0 g/cm3 | 1400-1450 °C | 17.2 μm/m·°C | 16.2 W/m·K | 193 GPa | 0.72 × 10⁻⁶ Ω·m |
Note: Typical values for reference only — not acceptance limits. Physical and mechanical properties are reported on the MTC against the ordered standard, product form and condition.
Size Tolerance Chart (mm)
| NPS Designator (Inches) | Permissible Variations in Outside Diameter (Inches) |
| 1⁄8 to 1 1⁄2, inclusive | Over: 1⁄64 in. (0.015 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 1 1⁄2 to 4, inclusive | Over: 1⁄32 in. (0.031 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 4 to 8, inclusive | Over: 1⁄16 in. (0.062 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 8 to 18, inclusive | Over: 3⁄32 in. (0.093 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 18 to 26, inclusive | Over: 1⁄8 in. (0.125 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 26 to 34, inclusive | Over: 5⁄32 in. (0.156 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 34 to 48, inclusive | Over: 3⁄16 in. (0.187 in.) |
| Under: 1⁄32 in. (0.031 in.) |
Tolerance basis: permitted variations per the governing specification stated on this page and the applicable general-requirements standard (ASTM A999 / ASME SA999) for the ordered product form; the wall-thickness and length variations in this section follow the same basis.
The wall thickness tolerances are defined by the nominal wall thickness (t) and the outside diameter (D).
1. Minimum Wall Thickness
The minimum wall thickness at any point on the pipe shall not be more than {12.5%} under the nominal (specified) wall thickness.
2. Maximum Wall Thickness (Percentage Over Nominal)
The maximum allowable wall thickness variation depends on the size and the t/D ratio (ratio of nominal wall thickness to ordered outside diameter):
| NPS Designator (Inches) | t/D Ratio | Permissible Variation (Over Nominal WT) |
| 1/8 to 2, inclusive | All ratios | +20.0% |
| 3 to 18, inclusive | t/D ≤ 5% | +22.5% |
| 3 to 18, inclusive | t/D >5% | +15.0% |
| 20 and larger (Seamless) | t/D ≤ 5% | +22.5% |
| 20 and larger (Seamless) | t/D >5% | +15.0% |
| 20 and larger (Welded) | All ratios | +17.5% |
For pipe ordered to a Specific Cut Length, the standard tolerance is +1⁄8 in. [3.2 mm], -0 in. [0 mm].
Pipe is typically supplied in Single Random Lengths (17 to 24 ft) or Double Random Lengths (38 to 40 ft), unless otherwise specified.
Disclaimer: These tolerances are based on ASTM A999/A999M general dimensional requirements commonly referenced by ASTM A312 and ASTM A790. The full and most current specification document must always be consulted for official design and procurement purposes.
Typical Applications of ASTM A312 TP304L Seamless Pipe
Due to its corrosion resistance and excellent weldability, TP304L seamless stainless steel pipe is widely used in industries that require extensive welding and high structural reliability.
Petrochemical and Oil Refining
- Process piping systems
- Heat exchanger tubing
- Corrosion-resistant pipelines
- Field-welded piping installations
Nuclear and Power Generation
- Cooling water systems
- Structural containment components
- Corrosion-resistant piping for high-reliability systems
Chemical Processing Industry
TP304L pipes are commonly used for handling:
- Nitric acid
- Oxidizing chemicals
- Industrial solvents
- Corrosive process fluids
High-Purity Processing Industries
Because of its smooth internal surface and hygienic properties, TP304L is widely used in:
- Food and beverage processing
- Pharmaceutical manufacturing
- Biotechnology production systems
- CIP (Clean-in-Place) sanitary piping systems
Quality Assurance and Compliance Standards
To ensure reliability and full traceability, all Seamless Stainless Steel TP304L Pipes are supplied with comprehensive testing and certification documentation in compliance with ASTM A312 / ASME SA312 standards.
Certification & Test | Technical Description |
Material Test Certificates | Supplied to EN 10204 3.1 as standard; 3.2 by arrangement when specified on the purchase order. |
Alloy Verification | Positive Material Identification (PMI) to confirm chemical composition, performed when specified on the purchase order. |
Non-Destructive Testing | Ultrasonic Testing (UT) or Eddy Current Testing (ECT) — the applicable method and acceptance level are agreed on the purchase order (the two methods are alternatives, not a combined default). |
Pressure Testing | Hydrostatic pressure testing to verify pipe integrity |
Dimensional Inspection | Precision measurement of OD, wall thickness (WT), and surface roughness (Ra) |
Heat Treatment Records | Solution annealing documentation and metallurgical grain size analysis |
Frequently Asked Questions
What sizes are available for TP304L seamless pipe?
The overall range is OD 6–1016 mm; WT 0.5–65 mm. Requirements outside this range are reviewed against mill capability on request.
Which specification governs TP304L seamless pipe?
ASTM A312 / ASME SA312 is the governing specification for TP304L seamless pipe. The edition in force at order time is stated on the quotation and purchase order; chemistry, mechanical properties, heat treatment, dimensions and testing are reported against the ordered standard and material heat.
What inspection documents are provided?
Each order is documented with a mill test certificate stating heat chemistry and mechanical test results. EN 10204 3.1 certification, hydrostatic testing, eddy-current or ultrasonic inspection and PMI are performed when specified in the purchase order.
Technical review: page data reviewed by the Xinzhe technical desk on 2026-09-27. Chemistry acceptance limits are compiled from the governing ASTM/ASME specification stated on this page; mechanical and physical values are typical reference data and are not acceptance guarantees. Values must be confirmed against the standard edition in force at order time and the material test certificate.
Ready to Request a Quotation?
Send the NPS and schedule (or actual OD and wall), quantity, length, end finish and the inspection items you need as acceptance criteria — you will get a written quotation stating the specification and edition, delivery condition, documents included and lead time.
For the same grade in tube form, see the TP304L seamless tube. To compare other grades and size combinations, browse the Stainless Steel Seamless Tube category. Minimum order quantity and lead time are confirmed on enquiry against the ordered grade, size and quantity.
