TP304H is a high-carbon variant of the widely used TP304 stainless steel (austenitic stainless steel family), engineered to deliver enhanced high-temperature strength and structural stability—making it ideal for critical applications in extreme thermal environments. Below is a comprehensive breakdown of its parameters, performance, specifications, standards, equivalent grades, applications, and export packaging.
1. Core Chemical Composition (Parameters)
The high carbon content (0.04–0.10%) is the defining feature of TP304H, distinguishing it from standard TP304 (max 0.08% carbon) and enabling superior creep resistance at elevated temperatures. Its chemical composition adheres to ASTM A312/A312M and ASME SA312 standards:
| Element | Content Range (%) | Role |
| Carbon (C) | 0.04 – 0.10 | Enhances high-temperature strength and creep resistance |
| Chromium (Cr) | 18.00 – 20.00 | Forms a passive oxide layer for corrosion resistance |
| Nickel (Ni) | 8.00 – 11.00 | Stabilizes the austenitic structure and improves ductility |
| Manganese (Mn) | ≤ 2.00 | Boosts workability and tensile strength |
| Silicon (Si) | ≤ 0.75 | Aids in deoxidation during manufacturing |
| Phosphorus (P) | ≤ 0.045 | Controlled to avoid brittleness |
| Sulfur (S) | ≤ 0.030 | Minimized to prevent corrosion and improve weldability |
| Nitrogen (N) | ≤ 0.10 | Supplementary element to enhance strength without compromising ductility |
2. Mechanical & Physical Performance
TP304H balances corrosion resistance, high-temperature durability, and mechanical strength, making it suitable for long-term service in harsh conditions.
2.1 Mechanical Properties (As Delivered)
| Property | Specification (ASTM A312) | Test Standard |
| Tensile Strength (σb) | ≥ 515 MPa (75 ksi) | ASTM A370 |
| Yield Strength (σ0.2) | ≥ 205 MPa (30 ksi) | ASTM A370 |
| Elongation (in 50mm) | ≥ 35% | ASTM A370 |
| Hardness (Brinell) | ≤ 217 HB | ASTM E10 |
| Impact Toughness (Charpy V-notch) | ≥ 27 J at -196°C (-321°F) | ASTM A370/A673 |
2.2 Key Physical Properties
| Property | Value |
| Density | 7.93 g/cm³ (0.286 lb/in³) |
| Melting Point Range | 1398–1454°C (2548–2650°F) |
| Thermal Conductivity | 16.3 W/(m·K) at 100°C; 21.5 W/(m·K) at 500°C |
| Coefficient of Thermal Expansion | 17.2 × 10⁻⁶/°C (20–100°C); 19.0 × 10⁻⁶/°C (20–500°C) |
| Electrical Resistivity | 0.73 × 10⁻⁶ Ω·m at 20°C |
2.3 Special Performance Advantages
- High-Temperature Creep Resistance: The increased carbon content prevents grain boundary sliding at temperatures up to 870°C (1600°F), critical for long-term service in boilers or furnaces.
- Corrosion Resistance: Maintains TP304’s excellent resistance to atmospheric corrosion, mild acids (e.g., acetic acid), and organic compounds—suitable for both thermal and chemical environments.
- Weldability: Compatible with standard austenitic welding processes (TIG, MIG, SMAW) using matching filler metals (e.g., ER308H, E308H); post-weld heat treatment (PWHT) is not required for most applications.
3. Product Specifications (Seamless Tube)
This TP304H offering is a seamless stainless steel pipe (no welded joints, ensuring higher pressure resistance), with dimensions optimized for industrial versatility:
| Specification Item | Range/Details |
| Product Type | Seamless Stainless Steel Pipe/Tube |
| Outer Diameter (OD) | 10 mm – 406 mm (0.394 in – 16.0 in) |
| Inner Diameter (ID) | Varies by wall thickness; calculated as OD - 2×Wall Thickness |
| Wall Thickness (WT) | SCH 10, SCH 20, SCH 40, SCH 80, SCH 160, XXS (per ASME B36.19M) |
| Length | Standard: 6 meters (20 ft) or 12 meters (40 ft); Custom lengths available (max 18 meters) |
| Surface Finish | Annealed & Pickled (AP): Removes oxide scale, delivers a smooth, corrosion-resistant surface; Polished finish (2B, BA) optional for sanitary applications |
| Form | Straight lengths (standard); U-bends, coils, or custom shapes available on request |
4. Certifications & Standards
TP304H seamless pipes comply with global industry standards to ensure quality, traceability, and safety.
4.1 Main Manufacturing & Material Standards
- ASTM A312/A312M: Standard for seamless, welded, and heavily cold-worked austenitic stainless steel pipes for general service.
- ASME SA312: Boiler and pressure vessel code (BPVC) standard (equivalent to ASTM A312) for high-pressure, high-temperature applications.
- EN 10216-5: European standard for seamless stainless steel tubes for pressure purposes (austenitic grades).
4.2 Quality Certificate: EN 10204-3.1
The product is accompanied by an EN 10204-3.1 certificate—a third-party verified document that confirms:
- Compliance with specified chemical composition and mechanical properties.
- Traceability of raw materials (from melt to finished product).
- Non-destructive testing (NDT) results (e.g., ultrasonic testing for internal defects, eddy current testing for surface flaws).
- Manufacturing process validation (e.g., annealing temperature, seamless extrusion parameters).
5. Equivalent Grades
TP304H has established equivalents across major regional standards, facilitating global procurement and design compatibility:
| Regional Standard | Equivalent Grade | Key Difference (If Any) |
| ASTM/ASME (USA) | TP304H / SA304H | Baseline grade (defining standard) |
| EN (Europe) | X5CrNi18-10 H | Complies with EN 10088-1; carbon range 0.04–0.10% |
| JIS (Japan) | SUS304H | JIS G3459 (seamless pipes); carbon ≤ 0.10% |
| GB (China) | 06Cr19Ni10H | GB/T 14976; carbon 0.04–0.10% |
| DIN (Germany) | 1.4307 | DIN EN 10088-1; austenitic grade with high carbon |
6. Typical Applications
TP304H’s high-temperature strength and corrosion resistance make it a top choice for industries requiring reliable performance in extreme thermal conditions:
- Power Generation: Boiler tubes, superheater tubes, and steam pipelines (resists creep under high pressure/temperature).
- Petrochemical & Refining: Heat exchanger tubes, reactor internals, and process pipelines (handles organic solvents and high-temperature hydrocarbons).
- Chemical Processing: Pipes for transporting mild acids (e.g., sulfuric acid < 50%), alkalis, and chemical intermediates.
- Oil & Gas: Downhole tubes (for high-temperature wells) and surface pipelines (resists atmospheric and soil corrosion).
- Food & Beverage: Sanitary pipes for high-temperature processing (e.g., pasteurization, sterilization) – when polished finish is specified.
- Aerospace & Automotive: Exhaust system components and heat shields (for high-temperature engine environments).
7. Export Packaging
To ensure product integrity during international shipping (sea/air/land), TP304H seamless pipes are packaged in compliance with global logistics standards:
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Inner Protection:
- Each pipe is wrapped in PE film (polyethylene) to prevent scratches, moisture, and oxidation.
- For polished or high-precision pipes, additional kraft paper or PVC sleeves are used to avoid surface damage.
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Outer Packaging (Options):
- Wooden Crates/Boxes: For small-diameter pipes (OD < 50 mm) or custom lengths; crates are heat-treated (ISPM 15 compliant) to meet international phytosanitary requirements (avoids pest infestation).
- Steel Bundles: For standard-length pipes (6m/12m); pipes are bundled with steel straps (50–100 pipes per bundle) and secured on wooden pallets (ISPM 15) for stability.
- Bulk Containers: For large-diameter pipes (OD > 200 mm); loaded into 20ft/40ft shipping containers with foam padding between pipes to prevent collision damage.
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Marking & Labeling:
- Each pipe/bundle is labeled with: Product grade (TP304H), OD/WT/length, heat number, certificate number (EN 10204-3.1), manufacturer name, and destination port.
- Shipping documents (commercial invoice, packing list, certificate of origin, EN 10204-3.1 certificate) are enclosed in a waterproof envelope attached to the packaging.
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Special Requirements:
- Anti-rust oil coating: Optional for long-term storage (prevents oxidation in humid environments).
- Waterproof covers: Used for open-top containers or sea shipping to protect against rain/salt spray.
