304H Temperature Range Operating Limits for Applications

304H Temperature Range: Operating Limits for Applications

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply premium 304H stainless steel plates compliant with ASME SA 240 and ASTM A240 standards. 304H stainless steel, also known as AISI 304H, UNS S30409, or EN 1.4948, is a high-carbon austenitic stainless steel optimized for high-temperature strength and creep resistance.

This guide details the temperature range and operating limits of 304H stainless steel for applications like boilers, heat exchangers, and SA 240 GR 304 pipe, ensuring optimal performance in demanding environments. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA240 Stainless sheet offerings.

Temperature Range of 304H Stainless Steel

The temperature range for 304H stainless steel, as specified by ASME BPVC Section II, Part D and ASTM A240, is designed for high-temperature service:

• Continuous Service Temperature: Up to 1500°F (815°C). This is the maximum recommended temperature for long-term exposure in pressure vessels, boilers, and heat exchangers, where 304H maintains structural integrity with excellent creep resistance.
• Intermittent Service Temperature: Up to 1600°F (871°C). Suitable for short-term or cyclic exposure, such as during startup/shutdown cycles in power generation systems.
• Scaling/oxidation Onset: Slight oxidation begins at ~1200°F (649°C), accelerating above 1500°F, limiting prolonged use beyond this threshold.
• Sensitization Range: Avoid prolonged exposure to 797°F-1580°F (425°C-860°C) during service or welding to prevent chromium carbide precipitation, which can reduce corrosion resistance.
• Heat Treatment Range: Solution annealing at 1870°F-2100°F (1020°C-1149°C) with rapid cooling to restore corrosion resistance and optimize grain structure for creep performance.

These limits are driven by the high carbon content (0.04-0.10%), which enhances creep and stress rupture strength compared to 304 (≤0.08% C) and 304L (≤0.03% C). For higher-temperature or chloride-resistant applications, explore sa240 gr 321 or sa240 gr 316l.

Operating Limits and Performance

304H stainless steelexcels in high-temperature environments due to its enhanced creep and stress rupture properties:

• Creep Resistance: The higher carbon content promotes finer grain structures (ASTM 5-8), increasing resistance to creep deformation above 800°F (427°C). This ensures long-term durability in applications like boilers and heat exchangers.
• Allowable Stress: Per ASME BPVC Section II, Part D, allowable stress values demonstrate superior performance:
  • 100°F (38°C): 25.0 ksi (172 MPa)
  • 1000°F (538°C): 25.5 ksi (176 MPa)
  • 1200°F (649°C): 13.7 ksi (94 MPa)
  • 1500°F (816°C): 4.8 ksi (33 MPa)
    These values are higher than 304 (18.6 ksi at 1000°F) and 304L (14.9 ksi at 1000°F), making 304H ideal for high-temperature structural loads.
• Oxidation Resistance: The 18-20% chromium content forms a protective oxide layer, resisting scaling up to 1200°F. Beyond 1500°F, scaling accelerates, limiting continuous use.
• Sensitization Considerations: Prolonged exposure in the 797°F-1580°F range risks sensitization, reducing corrosion resistance unless annealed. Post-weld annealing at 1870-2050°F mitigates this risk.
• Comparison: 304H outperforms 304L (limited to ~800°F) in high-temperature strength but is less resistant to chloride-induced pitting than sa240 gr 317l due to the absence of molybdenum.

Chemical Composition Supporting Temperature Range

The chemical composition of 304H stainless steel supports its high-temperature capabilities:

Higher carbon content compared to 304 (≤0.08%) and 304L (≤0.03%) is critical for creep resistance. For comparison, see sa240 gr 304.

Mechanical Properties Supporting Temperature Range

The mechanical properties of 304H stainless steel for annealed plates (8-75 mm thick) complement its temperature limits:

These properties, combined with fine grain size (ASTM 5-8), ensure creep resistance and structural integrity at 1500°F, ideal for applications like plat SS 304 3mm or plate 2 mm SUS 304.

Physical Properties

• Density: 8.00 g/cm³, ideal for lightweight designs (e.g., a 1m x 1m x 3mm plate weighs ~24 kg).
• Melting Point: 1400-1450°C, suitable for high-temperature processing.
• Thermal Conductivity: 16.2 W/m·K at 100°C.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K (20-100°C).
• Electrical Resistivity: 0.72 × 10⁻⁶ Ω·m.

These properties support performance at high temperatures, unlike ferritic grades like sa240 gr 430.

Corrosion Resistance

304H stainless steeloffers excellent corrosion resistance in:

• Atmospheric conditions, freshwater, and mild acids (food-grade).
• General environments, outperforming SS204 vs SS 304 due to higher nickel (8-10.5%).

Higher carbon (0.04-0.10%) increases sensitization risk in weld zones (797°F-1580°F), requiring annealing. For chloride-heavy environments, see sa240 gr 316ln.

Weldability

Weldability is fair using ER308H fillers. Higher carbon risks sensitization, necessitating low heat input (<2.0 kJ/mm) or post-weld annealing (1870-2100°F). For better weldability, see sa240 gr 304l.

Applications Leveraging Temperature Range

304H stainless steelis used in:

• Boilers and pressure vessels (steam drums, headers).
• Heat exchangers (tubes, shells).
• Power generation (superheaters, reheaters).
• Chemical processing (vessels, SA 240 GR 304 pipe).
• High-temperature piping and fittings.

For cost-effective alternatives, see sa240 gr 201.

Pricing and Availability

As of October 19, 2025, 304H stainless steel plate prices (2B finish, 3-6mm) range from $1.60-$3.50/kg. Gangsteel offers $1.60/kg FOB (MOQ 1 ton) for sa240 gr 304h. Contact admin@gangsteel.com or visit astm a 240 stainless plate.

FAQ on 304H Stainless Steel Temperature Range

What is the maximum continuous service temperature for 304H stainless steel?

Up to 1500°F (815°C), ideal for long-term use in boilers and heat exchangers, with excellent creep resistance (25.5 ksi at 1000°F).

What is the intermittent service temperature for 304H stainless steel?

Up to 1600°F (871°C) for short-term exposure, suitable for cyclic operations in power generation systems.

How does 304H compare to 304L in temperature range?

304H supports continuous service up to 1500°F with higher creep strength, while 304L is limited to ~800°F but offers better weldability.

Why is 304H suitable for high-temperature applications?

High carbon (0.04-0.10%) and fine grain size (ASTM 5-8) enhance creep resistance, ensuring durability at 1500°F for structural applications.

What applications benefit from 304H’s temperature range?

Boilers, heat exchangers, superheaters, and SA 240 GR 304 pipe leverage 304H’s high-temperature strength for reliable performance.