304H Austenitic Stainless Steel Coil Tube for High-Temperature Applications
Product Overview
The 304H Stainless Steel Coil Tube is a premium-grade austenitic stainless steel tubing product engineered specifically for demanding high-temperature service environments. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this coil tube is distinguished by its elevated carbon content (C ≥ 0.04%), which confers superior high-temperature creep strength and stress rupture resistance compared to conventional 304 and 304L grades. Designed for continuous service in aggressive thermal conditions, this product represents a critical material solution for power generation, petrochemical, and process engineering industries where long-term structural integrity under sustained high-temperature loads is paramount.
Material & Properties
The 304H grade belongs to the austenitic stainless steel family (UNS S30409 / EN 1.4954), offering an excellent combination of corrosion resistance, thermal stability, and mechanical strength at elevated temperatures. The deliberately increased carbon content — maintained at or above 0.04% — is the defining characteristic that differentiates 304H from its lower-carbon counterparts. This microstructural refinement results in significantly enhanced precipitation hardening and carbide strengthening at temperatures exceeding 600°C, making it the preferred alloy for applications involving prolonged exposure to high-temperature creep conditions.
Key Material Characteristics:
- Carbon Content: ≥ 0.04% — optimized for high-temperature creep and stress rupture resistance
- Corrosion Resistance: Excellent resistance to atmospheric, chemical, and aqueous corrosion environments
- Thermal Stability: Maintains mechanical integrity at temperatures up to 900°C in non-oxidizing atmospheres
- Creep Strength: Superior to 304 and 304L grades at temperatures above 600°C
- Weldability: Good weldability with standard austenitic stainless steel welding practices
- Formability: Excellent cold and hot forming characteristics
- Non-magnetic: Inherent austenitic structure provides non-magnetic properties
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | 304H (UNS S30409 / EN 1.4954) |
| Product Form | Coil Tube (Continuous Coil) |
| Carbon Content | ≥ 0.04% |
| Chromium Content | 18.0% – 20.0% |
| Nickel Content | 8.0% – 10.5% |
| Manganese | ≤ 2.0% |
| Silicon | ≤ 1.0% |
| Sulfur | ≤ 0.030% |
| Phosphorus | ≤ 0.045% |
| Outer Diameter Range | Customizable per customer requirements |
| Wall Thickness Range | Customizable per customer requirements |
| Standard Compliance | ASTM A213 / ASME SA-213 / EN 10216-5 |
| Maximum Service Temperature | Up to 900°C (non-oxidizing atmosphere) |
| Surface Finish | Pickled & Passivated / Bright Annealed |
| Heat Treatment | Solution Annealed (1050°C – 1150°C), Water or Air Cooled |
Manufacturing Process
The production of 304H stainless steel coil tube at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorously controlled multi-stage manufacturing process to ensure consistent quality and performance:
- Raw Material Selection: Premium-grade 304H stainless steel strip is sourced from certified mills, with strict incoming inspection of chemical composition and mechanical properties.
- Coiling & Forming: High-precision CNC roll-forming machines shape the flat strip into the desired coil tube geometry with tight dimensional tolerances.
- Welding: Longitudinal weld seams are formed using TIG (GTAW) or MIG (GMAW) processes with inert gas shielding (argon or argon-helium mixtures) to prevent oxidation and ensure sound weld integrity.
- Heat Treatment: The formed tubes undergo solution annealing at 1050°C – 1150°C followed by controlled cooling to achieve the desired austenitic microstructure and optimal mechanical properties.
- Pickling & Passivation: Surface treatment removes oxide scale and forms a protective chromium oxide passive layer for enhanced corrosion resistance.
- Quality Inspection: Every coil undergoes comprehensive testing including dimensional verification, hydrostatic pressure testing, and chemical composition analysis.
Applications
The 304H Stainless Steel Coil Tube is specifically engineered for high-temperature industrial applications where conventional 304 or 304L grades would exhibit unacceptable creep deformation or premature failure. Primary application areas include:
- Boiler Superheaters: Primary application — the enhanced creep strength at elevated temperatures makes 304H the ideal choice for superheater tubes in utility boilers, where sustained exposure to temperatures above 600°C is routine.
- High-Temperature Steam Piping: Used in steam distribution systems for power plants, refineries, and chemical processing facilities operating at elevated pressures and temperatures.
- Heat Exchangers: Suitable for high-temperature heat exchanger tubes where thermal cycling and sustained high-temperature loads are present.
- Furnace Components: Tubular components in industrial furnaces and kilns requiring corrosion-resistant, high-temperature structural elements.
- Petrochemical Processing: High-temperature process piping in refineries, petrochemical plants, and polymer production facilities.
- Power Generation: Turbine exhaust ducts, waste heat recovery systems, and auxiliary heat transfer circuits in thermal power stations.
Quality Certifications & Standards
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system ensuring that every 304H coil tube product meets or exceeds international standards:
- Material Standards: ASTM A213 / ASME SA-213 Type 304H, EN 10216-5, GB/T 5310
- Quality Management: ISO 9001 certified manufacturing processes
- Testing & Inspection: 100% hydrostatic pressure testing, ultrasonic flaw detection, and spectrographic chemical analysis on every production lot
- Mill Test Certificates (MTC): Full EN 10204 Type 3.1 certificates provided with each shipment
- Third-Party Inspection: Available upon customer request (BV, SGS, or equivalent)
- Traceability: Complete heat-number traceability from raw material through final product delivery
Unique Selling Points
The 304H grade represents a purpose-engineered solution where high-temperature creep resistance is non-negotiable. While 304 and 304L offer excellent general-purpose corrosion resistance, their low carbon content limits performance under sustained high-temperature mechanical loads. The 304H coil tube bridges this gap by maintaining the same corrosion resistance and formability while delivering significantly superior creep strength and stress rupture life at temperatures above 600°C — making it the material of choice for boiler superheaters and high-temperature steam systems where failure is not an option.
- Enhanced High-Temperature Performance: Carbon content ≥ 0.04% provides measurable creep strength advantage over 304/304L at temperatures exceeding 600°C
- Coil Format Advantage: Continuous coil delivery enables efficient downstream processing, reduced waste, and seamless integration into automated tube fabrication lines
- Proven Track Record: Widely specified and deployed in global power generation and petrochemical industries
- Comprehensive Quality Assurance: End-to-end traceability and multi-stage inspection ensure consistent, reliable performance
- Customization Capability: Flexible diameter, wall thickness, and coil length options tailored to specific project requirements