ASTM A376 TP347H Austenitic Seamless Steel Tubes for High-Temperature Environments in Power Plants
ASTM A376 TP347H Austenitic Seamless Steel Tubes for High-Temperature Environments in Power Plants
ASTM A376 TP347H is a seamless austenitic stainless steel tube suitable for high-temperature power plant applications, such as superheaters and reheaters. It employs niobium (Niobium) stabilization and a high-carbon content process, resulting in excellent resistance to creep, oxidation, and intergranular corrosion, thus making it specifically designed for high-temperature environments. This material must undergo heat treatment and various tests (tensile testing, hydrostatic testing, etc.), and can be hot-finished or cold-finished.
What is the difference between SS 347 and SS 347H?
SS 347 is an austenitic stainless steel containing chromium, nickel, and niobium. SS 347H is also an austenitic stainless steel containing chromium, nickel, and niobium, but its carbon content is higher than that of SS 347. Both SS 347 and SS 347H are heat-resistant and can be used in high-temperature environments.
ASTM A376 TP347H stainless steel high-temperature tubes are seamless austenitic stainless steel tubes designed specifically for high-temperature applications. Due to their excellent creep resistance and resistance to intergranular corrosion at high temperatures, they are particularly suitable for power generation, petrochemicals, and other harsh industrial applications. This niobium-stabilized steel has a higher carbon content than standard 347 steel, preventing chromium carbide precipitation and making it more suitable for continuous use in extreme temperature and corrosive environments.
Our ASTM A376 347/347H seamless stainless steel tubes are manufactured using cold working processes and undergo heat treatment, pickling, and passivation. Ends are available in bevel or flush. Outer diameter (OD) ranges from 1/2 inch to 30 inches, and wall thickness grades are available in SCH5S, 10S, 40S, and 80S, with custom average wall thicknesses also available upon request.
Chemical Composition of TP347H Tubes (UNS S34709)
| Element | Requirement (%) | Notes |
| Carbon (C) | 0.04–0.10 | Controlled for high-temperature stability |
| Manganese (Mn) | 2.00 max | |
| Phosphorus (P) | 0.045 max | |
| Sulfur (S) | 0.030 max | |
| Silicon (Si) | 1.00 max | |
| Nickel (Ni) | 9.0–13.0 | Austenite stabilizer |
| Chromium (Cr) | 17.0–19.0 | Oxidation resistance |
Mechanical Properties of TP347H Tubes (UNS S34709)
| Property | Requirement |
| Grade | TP347H |
| UNS Designation | S34709 |
| Tensile Strength, min | 75 ksi [515 MPa] |
| Yield Strength, min | 30 ksi [205 MPa] |
| Elongation in 2 in.., min | 35% (Longitudinal) |
TP347H Tubes Testing Requirements Summary
| Category | Test Type | Key Requirements |
| Pressure/NDE | Hydrostatic Test | Each pipe tested per A999/A999M (except NPS≥24 with NH marking) |
| NDE (UT/ET) | Mandatory for all pipes (manufacturer's method selection) | |
| Mechanical | Tensile Test | 1 test per lot (≤100 pipes); 2 tests for >100 pipes |
| Flattening Test | 5% of batch furnace pipes; min. 2 pipes for continuous process | |
| Chemical | Product Analysis | Required for each pipe length (individual rejection) |
| Special Tests | Transverse Tension | Mandatory for NPS≥8 pipes (each end) |
| Etching Test | Checks homogeneity per Method E381 | |
| Ultrasonic Test | Full-length scanning with calibration notches | |
| Intergranular Corrosion | Practice A262 (as-shipped/sensitized condition) |
Why Choose Gnee Steel (Supplier Example)?
✅ Large stock of 347H stainless steel strip/coil, fast shipping.
✅ Factory direct sales, highly competitive prices, excellent value for money.
✅ Comprehensive quality assurance: Material Testing Certificate (MTC), Chemical Composition Certificate, and Mechanical Properties Certificate.
✅ Value-added services: Slitting, cutting, polishing, surface treatment.
✅ Worldwide shipping, secure and reliable packaging, and provision of export-required documentation.
Email: ru@gneesteelgroup.com
If you have a project requiring ASTM A376 TP347H seamless steel pipes, please feel free to place an order. GNEE maintains a large inventory of commonly used products for your selection. These products can be processed into various practical product forms. For detailed chemical composition information and to request free samples, please contact our factory immediately. We offer highly competitive prices and excellent service.
Gnee Steel specializes in the production of a wide range of stainless steel products. Gnee Steel's product packaging includes: Steel Strapping: Pipes with an outer diameter of 3 inches or less are typically strapped together with polypropylene film to prevent rust during ocean shipping, and then secured with steel strapping. Wooden Cases/Crates: Pipes are typically packaged in wooden cases or crates to protect the pipes during transportation, especially those that are longer or have larger diameters. Seaworthy Export Packaging: Suppliers typically use standard seaworthy export packaging methods, which may include a variety of materials and techniques to protect the pipes during transportation. Tarpaulin Packaging: This prevents rain, seawater, and other external factors from penetrating the export crates during transportation. Gnee Steel specializes in the production and sale of alloy materials. Gnee Steel's products are widely used in the aerospace, chemical, power, automotive, and nuclear energy sectors, and we can provide customized alloy material solutions based on customer needs. For alloy material pricing or customized alloy material solutions, please contact us for a quote: ru@gneesteelgroup.com
