Super 304H (UNS S30432) is a high strength austenitic copper-bearing stainless steel, designed to meet the requirements for superheater/reheater sections of supercritical and ultra-supercritical boilers. The Super 304H is basically a modified version of the conventional TP304H on the matrix of 18Cr-9Ni, and forms the copper-rich phase and Niobium carbonitrides during service thus giving it greater creep strength than the conventional 304H.
This results in a materially greater allowable stress over the creep range, superior steam oxidation resistance and a materially lower cost than the 25Cr grades. It is delivered in solution-treated condition to meet ASTM A213/ASME SA-213 to a minimum tensile strength of 590 MPa and minimum yield of 235 MPa. USA Piping Solution can provide Super 304H with an EN 10204 3.1 mill test certificate, solution treatment records, and third-party inspection as requested.
Specifications of S30432 Super 304H Pipes & Tubes
| Specification | Details |
|---|---|
| Product Name | S30432 (Super 304H) Seamless Boiler & Superheater Tubes |
| Material Grade | S30432 / Super 304H (UNS S30432, 18Cr-9Ni-3Cu-Nb-N) |
| Governing Standards | ASTM: A213 / A213M ASME: SA-213 / SA-213M |
| Manufacturing Type | Seamless (Cold Drawn, Hot Finished) |
| Product Forms | Seamless Boiler Tube, Superheater Tube, Reheater Tube, Heat Exchanger Tube |
| Available Forms | Round, U-bend |
| Outside Diameter (OD) | 15.88 mm to 101.6 mm (5/8" OD to 4" OD) (Confirm exact mill capability with client) |
| Wall Thickness | Minimum Wall Thickness (MWT) or Average Wall Thickness as ordered per ASTM A213 |
| Sizing Convention | Tube is ordered by Outside Diameter (OD) and Wall Thickness, not by Nominal Bore (NB) or Pipe Schedule |
| Length | Single Random, Double Random, Fixed Cut Lengths (up to 12 Meters) |
| Maximum Service Temperature | Maximum metal temperature: approximately 650 °C for continuous service. Steam oxidation resistance and creep strength both fall away above that, and the grade is normally specified for the lower stages of a USC superheater with a 25Cr grade above it. |
| End Finish | Plain end (PE), bevelled end (BE) |
| Surface Finish | Solution Annealed & Pickled (AP), Bright Annealed (BA) |
| Testing & Quality | PMI Testing, Hydrostatic Test, Flattening Test, Flaring Test, Eddy Current Test / Ultrasonic Test (UT), Intergranular Corrosion (IGC) Test (ASTM A262 Practice E), Grain Size Measurement (ASTM E112 ≥ No. 7), Mechanical Testing |
| Certifications | EN 10204 3.1 Mill Test Certificate (MTC), Third-Party Inspection (TPI) |
| Marking | Grade (S30432 / Super 304H), Heat Number, Size, Standard (ASTM A213), Manufacturer's Mark |
| Packaging | Wrapped Bundles with Plastic End Caps, Export-Worthy Wooden Crates / Boxes |
Applications Uses of S30432 Super 304H Pipes & Tubes
- Ultra-Supercritical Power Plants
- High-Pressure Boiler Systems
- Superheaters and Reheaters
- Heat Exchangers
- Petrochemical Processing Plants
- Oil & Gas Refineries
- Chemical Processing Industries
- Industrial Furnaces and Thermal Equipment
Frequently Asked Questions
1. What are S30432 Super 304H Pipes & Tubes?
S30432 Super 304H Pipes & Tubes are high-temperature austenitic stainless steel products designed for boilers, superheaters, reheaters, and heat exchangers. They offer excellent creep strength and oxidation resistance.
2. Where are S30432 Super 304H Pipes & Tubes used?
They are widely used in power plants, high-pressure boilers, petrochemical plants, oil refineries, heat exchangers, and chemical processing industries.
3. Are S30432 Super 304H Pipes & Tubes suitable for boiler applications?
Yes. They are specifically developed for supercritical and ultra-supercritical boilers operating at high temperatures and pressures.
4. Is Super 304H resistant to high-temperature oxidation?
Yes. Super 304H has excellent resistance to high-temperature oxidation and steam corrosion, making it suitable for continuous service at elevated temperatures.
5. Can S30432 Super 304H Pipes & Tubes be welded?
Yes. S30432 Super 304H Pipes & Tubes have good weldability and can be welded using suitable stainless steel welding procedures and filler materials.
6. What is the difference between Super 304H and TP310HCbN?
Both are austenitic grades for ultra-supercritical boilers. Super 304H contains about 18% Cr, 9% Ni, and 3% Cu and is commonly used in lower and middle superheater stages. TP310HCbN contains about 25% Cr and 20% Ni with Nb and N, providing better steam oxidation resistance for higher-temperature service.
7. Why does Super 304H contain copper?
Copper forms fine copper-rich precipitates during high-temperature service, which improve creep strength by restricting dislocation movement. This strengthens Super 304H beyond conventional TP304H in long-term high-temperature applications.