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ASTM A358 347H EFW Stainless Steel Pipe Class 1 Niobium Stabilized High Carbon for High Temperature Creep Service
| MOQ: | 5Ton |
| Price: | Based on grade, size, surface, processing, quantity and current raw material market price. |
| Standard Packaging: | Standard seaworthy export packing with bundles, waterproof wrapping, pallets or wooden cases. |
| Delivery Period: | 7-15 |
| Payment Method: | L/C,D/A,D/P,T/T,Western Union |
| Supply Capacity: | Stock supply, regular production and custom manufacturing available. |
Shaanxi Shangyou Stainless Steel Co., Ltd. supplies ASTM A358 347H EFW stainless steel pipe for global EPC contractors, refinery engineers, power plant fabricators, and petrochemical processors requiring niobium-stabilized, high-carbon austenitic piping with optimized creep resistance at elevated temperatures. Produced to ASTM A358/A358M, this specification covers electric-fusion-welded austenitic stainless steel pipe formed from plate or sheet with filler metal added during the welding process .
ASTM A358 is the standard specification for large-diameter EFW stainless steel pipe, covering sizes from NPS 8 to NPS 110 . Class 1 requires double welding with filler metal in all passes and 100% radiography, making it the standard for critical high-temperature process piping in refineries and power plants . 347H (UNS S34709) is the high-carbon, niobium-stabilized variant of 347 (C 0.04-0.10%, Nb ≥10×C%) . Niobium stabilization prevents sensitization in the heat-affected zone during welding, preserving intergranular corrosion resistance without post-weld heat treatment . 347H is specifically engineered for service at temperatures where creep and stress rupture properties are important .
| Dimension | Specification |
|---|---|
| Product Name | ASTM A358 347H EFW Stainless Steel Pipe |
| Product Alias | 347H EFW Pipe / A358 Class 1 Pipe / Niobium Stabilized High Temp Pipe / Superheater Pipe |
| Material Type | Niobium-Stabilized Austenitic Stainless Steel (EFW with Filler Metal, High Carbon) |
| Key Feature | Nb stabilization prevents sensitization; 0.04-0.10% C for creep strength; Class 1 double-welded with filler; 100% RT; NPS 8-110; service to 850°C |
| Chemical Composition | Cr 17.0-19.0% / Ni 9.0-13.0% / C 0.04-0.10% / Nb ≥10×C% (max 1.0%) / Mn ≤2.0% / Si ≤1.0% / Fe Balance |
| Mechanical Properties | Tensile ≥515 MPa / Yield ≥205 MPa / Elongation ≥40% |
| Physical Properties | Density ~8.0 g/cm3 / Elastic Modulus 190-215 GPa |
| Heat Treatment | Solution annealed at 1900°F (1040°C) + water quench or rapid cool |
| Recommended Filler Metal | ER347 (AWS A5.9) with minimum 0.04% carbon content |
| Primary Applications | Petroleum Refining / Power Generation / Superheaters / Chemical Processing / Thermal Energy Storage / Petrochemical Plants |
| Parameter | Available Options |
|---|---|
| Product Standard | ASTM A358/A358M, ASME SA-358 |
| UNS Equivalent | UNS S34709 |
| Nominal Pipe Size (NPS) | NPS 8 to NPS 110 (DN200 to DN2750) |
| Wall Thickness | Schedule 5S, 10S, 40S, 80S per ASME B36.19; custom up to 100mm |
| Length | Single random, double random, or cut-to-length |
| Pipe End | Plain End (PE) / Beveled End (BE) |
| Class | Class 1 (Double-welded, 100% RT) / Class 3 (Single-welded, 100% RT) / Class 5 (Double-welded, spot RT) |
| Recommended Filler Metal | ER347 (AWS A5.9/A5.9M), E347T, IN348 |
| Inspection | 100% Radiography (Class 1) / Hydrostatic Test / Transverse Tension / Guided-Bend Weld Test / PMI |
| Documents | MTC 3.1 / Inspection Reports / Packing List / Heat Number Traceability |
ASTM A358 347H EFW pipe is specified for large-diameter, high-temperature piping systems requiring creep resistance and intergranular corrosion stability in the 425-850°C service range.
Typical applications include :
- Petroleum refining: catalytic crackers ("cat crackers"), fired heater tubes, transfer lines
- Power generation: superheater manifolds, boiler external piping, steam lines
- Chemical and petrochemical processing: furnace components, reactor vessels
- Gas and steam turbine components
- Thermal energy storage systems
Key selection considerations: Choose 347H over 321H when the service environment involves strongly oxidizing media or polythionic acid stress corrosion cracking—347H offers slightly improved corrosion resistance in these conditions . Niobium stabilization (minimum 10× carbon content) provides superior structural stability compared to titanium stabilization, particularly for long-term thermal exposure. The higher, controlled carbon range (0.04-0.10%) maximizes creep rupture strength . Select Class 1 for critical process piping requiring maximum weld seam integrity—double-welded construction with 100% RT is standard for refineries and power plants . Recommended filler metal is ER347, which must have minimum 0.04% carbon to match the H-grade properties . The required solution annealing temperature is 1040°C with water quench or rapid cool .
Shangyou Stainless Steel provides value-added processing including custom cutting, beveling, and end protection for large-diameter EFW pipes.
All pipes are packed with export-standard protection including protective end caps, steel strapping, waterproof wrapping, and steel frames or wooden pallets.
Quality documents include MTC 3.1, inspection reports, packing list, and heat number traceability. Third-party inspection (SGS, TUV, BV) can be arranged upon request.
- 1. What is ASTM A358?
- ASTM A358 is the standard specification for electric-fusion-welded austenitic stainless steel pipe for high-temperature and general corrosive service .
- 2. What is the difference between 347 and 347H?
- 347 has max 0.08% carbon; 347H has 0.04-0.10% carbon. The H-grade is specifically intended for service where creep and stress rupture properties are important .
- 3. What is the UNS number for 347H?
- UNS S34709 .
- 4. What is Class 1 under ASTM A358?
- Class 1 requires double welding with filler metal in all passes and 100% radiography—the highest weld quality level in the specification .
- 5. What is the solution annealing temperature for 347H?
- 1900°F (1040°C) with water quench or rapid cool .
- 6. Is filler metal required for Class 1?
- Yes, Class 1 requires filler metal in all passes. Recommended filler metal is ER347 with minimum 0.04% carbon content .
- 7. What is the maximum service temperature for 347H?
- Good oxidation resistance up to approximately 850°C .
- 8. Why is niobium added to 347H?
- Niobium stabilizes the alloy by binding carbon, preventing chromium carbide precipitation (sensitization) in the heat-affected zone during welding, even under demanding operating conditions .
- 9. What size range does ASTM A358 cover?
- NPS 8 to NPS 110 (DN200 to DN2750) .
- 10. What are typical applications for A358 347H pipe?
- Petroleum refining (cat crackers), power generation (superheaters), chemical processing, and high-temperature furnace equipment .
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