347H Stainless Steel Pipe & Tube: High-Carbon Niobium-Tantalum Stabilized Extreme High-Temp Piping

What is 347H Stainless Steel Pipe & Tube?

347H is the high-carbon variant of 347, optimized for maximum high-temperature creep strength by combining high carbon content with niobium-tantalum stabilization, serving critical high-temperature, high-pressure piping systems.

Equivalent Grades (Horizontal)

UNS: S34709 | JIS: SUS347H | GB: 07Cr18Ni11Nb | EN: X7CrNiNb18-10 | W.Nr.: 1.4550

Chemical Composition (wt%, Horizontal)

C: 0.04-0.10 | Si: ≤1.00 | Mn: ≤2.00 | P: ≤0.045 | S: ≤0.030 | Cr: 17.00-19.00 | Ni: 9.00-13.00 | Nb+Ta: ≥10×C | Fe: Balance

Key Properties (20°C, Annealed, Horizontal)

Density: 7.93g/cm³ | Melting Point: 1400-1450°C | Tensile Strength: ≥515N/mm² | Yield Strength: ≥205N/mm² | Elongation: ≥40% | Hardness: ≤201HB

Core Characteristics

• High-carbon & Nb-Ta dual optimization: Delivers exceptional high-temperature creep strength at 600-900°C • Outstanding post-weld corrosion resistance: Ensures long-term reliability in high-temperature corrosive environments • Mandatory post-weld annealing: Optimizes high-temperature performance and structural uniformity • Critical component dedicated: Suitable for nuclear power plant piping and large boiler high-pressure high-temp components

347H vs 347 Stainless Steel Pipe (Horizontal)

Carbon Content: 347H (0.04-0.10%) | 347 (≤0.08%) | Creep Strength: 347H (Excellent) | 347 (Good) | Annealing: 347H (Mandatory) | 347 (Optional) | Application: 347H (Critical High-Stress) | 347 (General High-Temp)

Element	347	347H
Chromium	17.00 min.-19.00 max.	17.00 min.-19.00 max.
Nickel	9.00 min.-13.00 max.	9.00 min.-13.00 max.
Carbon	0.08	0.04 min.-0.10 max.
Manganese	2.00	2.00
Phosphorus	0.045	0.045
Sulfur	0.03	0.03
Silicon	0.75	0.75
Columbium & Tantalum	10 x (C + N) min.-1.00 max.	8 x (C + N) min.-1.00 max.
Iron	Balance	Balance

 

Stainless Steel Suppliers

If you have project requirements for stainless steel, we welcome your order. GNEE has a large inventory of popular products for you to choose from. It can be processed into various practical product forms, including plates, coils, tubes, bars, wires, etc. For detailed chemical composition information and free samples, please contact our factory immediately. We offer competitive prices and excellent service.Email: info@gneestainless.com

 

Testing and Documentation: Factory test certificate, EN 10204 3.1, chemical report, mechanical report, destructive testing report, non-destructive testing report, PMI test report, visual inspection report, third-party inspection report, NABL certified laboratory report.
Packaging: Wooden crate packaging, bubble wrap packaging, steel strapping, or packaging according to customer requirements.