The 347H Blind Flange (UNS S34709, EN 1.4961), with high-carbon, niobium-stabilized austenitic stainless steel blind flange designed for extreme high-temperature and high-pressure industrial piping systems. As a critical closure component, it completely blocks the end of a pipeline to isolate media, prevent leakage, and facilitate maintenance. HT PIPE supply all different types and scales of flanges. Please feel free to contact us for further product information and pricing.
UNS S34709 Material Composition
| Element | Content |
|---|---|
| Carbon (C) | 0.04–0.10 |
| Chromium (Cr) | 17.00–19.00 |
| Nickel (Ni) | 9.00–13.00 |
| Niobium (Cb) | ≥8×C% |
| Manganese (Mn) | ≤2.00 |
| Silicon (Si) | ≤1.00 |
| Phosphorus (P) | ≤0.045 |
| Sulfur (S) | ≤0.030 |
| Iron (Fe) | Balance |
UNS S34709 s347h flange Standard Dimensions & Pressure Ratings
Compliance Standards: ASTM A182/ASME SA182 (material), ASME B16.5/B16.47 (dimensions), DIN 2527, JIS B2220, EN 1092
Size Range: 1/2" (15 NB) to 48" (1200 NB) (customizable up to 60" for large-diameter projects)
Pressure Classifications: 150#–2500# (ANSI), PN6–PN64 (DIN/EN)
Face Types: Flat Face (FF), Raised Face (RF), Ring Type Joint (RTJ) (for high-pressure sealing)
s347h flange material Mechanical Properties
Density: 8.0 g/cm³
Melting Point: 1454°C (2650°F)
Tensile Strength: ≥75,000 psi (515 MPa)
Yield Strength (0.2% Offset): ≥30,000 psi (205 MPa)
Elongation: ≥35%
Max Service Temperature: Up to 650°C (1200°F) (long-term stable operation)
347H Blind Flange Key Advantages
s347h flange High-Temperature Performance
Enhanced Creep Resistance: Maintains structural integrity under prolonged stress at elevated temperatures, critical for power plant boilers, petrochemical cracking units, and high-temperature steam pipelines.
Thermal Stability: Minimal deformation during rapid heating/cooling cycles, reducing seal failure risks.
ss347h Corrosion & Oxidation Resistance
Intergranular Corrosion Resistance: Niobium carbides prevent chromium depletion at grain boundaries, avoiding corrosion during welding and high-temperature service.
Chloride & Acid Corrosion Resistance: 50% higher resistance to chloride stress corrosion than 304, suitable for seawater desalination, chemical processing, and pulp/paper industries.
Oxidation Resistance: Maintains protective oxide layers at temperatures up to 800°C, ideal for high-temperature exhaust systems and thermal equipment.
stainless steel 347h flange Welding & Machining Compatibility
Weld-Friendly: No post-weld annealing required, reducing construction time and costs while ensuring weld integrity.
Machinability: Machinability for custom drilling, facing, and threading to meet project-specific requirements.
Wide Compatibility: Compatible with 347/321 stainless steel pipes and fittings, simplifying system integration.
