304H Max Temperature Service Limits and Performance

304H Max Temperature: Service Limits and Performance

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 maximum temperature service limits and performance of 304H stainless steel for applications like boilers, heat exchangers, and SA 240 GR 304 pipe. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA240 Stainless sheet offerings.

Maximum Temperature Service Limits for 304H Stainless Steel

The maximum temperature service limits for 304H stainless steel, as specified by ASME BPVC Section II, Part D and ASTM A240, are:

• Continuous Service: Up to 1500°F (815°C). Ideal for long-term exposure in pressure vessels, boilers, and heat exchangers, where 304H maintains structural integrity with excellent creep resistance.
• Intermittent Service: Up to 1600°F (871°C). Suitable for short-term or cyclic exposure, such as during startup/shutdown cycles.
• Scaling Onset: Slight oxidation/scaling begins at ~1200°F (649°C), accelerating above 1500°F, which limits prolonged use beyond 1500°F.
• Sensitization Range: Avoid prolonged exposure to 797°F-1580°F (425°C-860°C) during service to prevent chromium carbide precipitation, which can reduce corrosion resistance.

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 applications, explore sa240 gr 321 or sa240 gr 310s.

Performance at High Temperatures

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

• Creep Resistance: The higher carbon content (0.04-0.10%) promotes finer grain structures (ASTM 5-8), increasing resistance to creep deformation at temperatures 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:
  • At 100°F (38°C): 25.0 ksi (172 MPa)
  • At 1000°F (538°C): 25.5 ksi (176 MPa)
  • At 1200°F (649°C): 13.7 ksi (94 MPa)
  • At 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), reflecting 304H’s suitability 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.
• Comparison: Outperforms 304L in high-temperature strength but is less resistant to chloride-induced pitting than sa240 gr 316l due to the absence of molybdenum.

For applications requiring chloride resistance, see sa240 gr 317l.

Chemical Composition Supporting High-Temperature Performance

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 key to 304H’s high-temperature performance. For comparison, see sa240 gr 304.

Mechanical Properties Supporting High-Temperature Performance

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.

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 Maximum Temperature Limits

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 Maximum Temperature

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

Up to 1500°F (815°C), where it maintains creep resistance and structural integrity, ideal for boilers and heat exchangers.

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

Up to 1600°F (871°C) for short-term exposure, suitable for cyclic operations like startup/shutdown in power plants.

How does 304H compare to 304L in maximum temperature performance?

304H supports 1500°F continuous service with 25.5 ksi allowable stress at 1000°F, while 304L is limited to ~800°F with 14.9 ksi, due to 304H’s higher carbon content.

Why is 304H suitable for high-temperature applications?

Higher carbon (0.04-0.10%) and fine grain size (ASTM 5-8) enhance creep resistance, ensuring durability up to 1500°F in pressure vessels.

What applications benefit from 304H’s maximum temperature limits?

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