304H stainless steel pipe vs. 304 stainless steel pipe
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When choosing stainless steel piping for industrial or high-temperature applications, it's critical to understand the difference between 304H stainless steel pipe and 304 stainless steel pipe.
In this guide, we'll compare 304H and 304 stainless steel pipe in terms of chemical composition, high-temperature strength, corrosion resistance, standards, and applications so you can make the right choice for your project.
difference between 304 and 304H stainless steel pipe
| Property | 304 Stainless Steel | 304H Stainless Steel |
|---|---|---|
| Carbon Content | ≤ 0.08% | 0.04 – 0.10% |
| Chromium / Nickel Content | 18–20% Cr / 8–10.5% Ni | 18–20% Cr / 8–10.5% Ni |
| Microstructure | Single-phase austenite | Austenite + trace carbide precipitates (strengthened under high temperatures) |
| Heat Treatment Response | Solution annealing at 950–1150°C | Solution annealing at 1010–1150°C (suitable for high-temperature creep applications) |
304 vs 304H Stainless Steel round Pipe：Chemical Composition
| Element | 304 (TP304) | 304H (TP304H) |
|---|---|---|
| Carbon (C) | ≤ 0.08% | 0.04% – 0.10% |
| Manganese (Mn) | ≤ 2.00% | ≤ 2.00% |
| Phosphorus (P) | ≤ 0.045% | ≤ 0.045% |
| Sulfur (S) | ≤ 0.030% | ≤ 0.030% |
| Silicon (Si) | ≤ 1.00% | ≤ 1.00% |
| Chromium (Cr) | 18.0 – 20.0% | 18.0 – 20.0% |
| Nickel (Ni) | 8.0 – 11.0% | 8.0 – 11.0% |
| Nitrogen (N) | ≤ 0.10% | ≤ 0.10% |
| Iron (Fe) | Balance | Balance |
Corrosion resistance: In a Cl⁻-containing environment, the pitting potential of 304H is about 50mV lower than that of 304, which means that it is more susceptible to localized corrosion. For example, in a petrochemical plant seawater cooling system, 304H pipes were perforated after 2 years of use at a Cl⁻ concentration of 180ppm, while 304 pipes had a lifespan of up to 5 years under the same conditions.
304 vs 304H Stainless seamless Steel Pipe ：Mechanical Properties
| Property | 304 (TP304) | 304H (TP304H) |
|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 585 |
| Yield Strength (0.2%, MPa) | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 35 | ≥ 35 |
| Hardness (HRB) | ≤ 90 | ≤ 95 |
| Operating Temp. (Max) | ~870°C (short-term) | Continuous ≥ 525°C |
Case: In the 650℃ boiler superheater pipe, the creep rupture strength of 304H is about 30% higher than that of 304, and it can withstand higher steam pressure (such as the 30MPa working condition of ultra-supercritical units). The high elongation of 304 makes it less likely to crack during cold bending of building curtain walls.
304 vs. 304H Stainless Steel welded pipe：Processing and Welding Comparison
| Process Step | 304 Stainless Steel | 304H Stainless Steel |
|---|---|---|
| Cold Working | Suitable for deep drawing (e.g., sinks and cookware) | Requires more robust equipment (e.g., high-pressure piping components) |
| Hot Working | Heating temperature: 900–1150°C | Heating temperature: 950–1180°C |
| Welding Filler Metal | ER308 welding wire | ER308H welding wire (carbon content 0.04–0.08%) |
| Post-weld Heat Treatment | Recommended stress relief annealing at 600–800°C | Mandatory stabilization annealing at 850–900°C |
Case: The welding cost of 304H is about 25% higher than that of 304, mainly due to the need to use high-carbon welding wire and additional annealing process. For example, in a chemical project, the total cost of 304H pipeline welding is 180,000 yuan/km higher than that of 304.
Choosing the Right Stainless Steel Pipe for Your Project
At Gnee Stainless Steel, we offer both 304 and 304H stainless steel pipes in seamless and welded forms, with a wide range of diameters, wall thicknesses, and mill certifications (EN 10204 3.1 / 3.2 available).
1. Custom cutting, beveling, pickling, and export packaging available
2. ISO 9001 & PED certified mill sources
