Stainless Steel 347 Seamless Pipes & Tubes Manufacturer & Supplier
SS 347 (UNS S34700) is a niobium (columbium)-stabilized austenitic stainless steel providing superior resistance to intergranular corrosion at elevated temperatures. Preferred over 321 where intermittent heating is involved, as niobium provides more reliable stabilization than titanium.
UNS: S34700 | Category: Austenitic Stainless Steel | Werkstoff Nr: 1.4550 | EN Name: X6CrNiNb18-10
SS 347 — Also Known As
SS 347 is also commonly known as SS 347, 347 SS, Stainless Steel 347 Seamless Pipes & Tubes, S34700, UNS S34700, 1.4550, Werkstoff 1.4550, W.Nr 1.4550, X6CrNiNb18-10, 347 stainless steel, aisi 347, type 347, x6crninb1810.
SS 347 — Applicable Standards & Specifications
SS 347 is commonly supplied to ASTM A312, ASME SA312, ASTM A213, ASME SA213, ASME SA269, ASTM A511, ASME SA511, EN 10216-5, DIN 17456.
Size Range
Outer Diameter: 1/4" NPS to 10" NPS (6.35mm to 273.1mm OD)
Wall Thickness: SCH 5S to SCH 160
Chemical Composition (%)
| C | Mn | Si | Cr | Ni | Nb+Ta | P | S |
|---|---|---|---|---|---|---|---|
| 0.08 max | 2.00 max | 0.75 max | 17.0-19.0 | 9.0-13.0 | 10xC min | 0.045 max | 0.030 max |
Mechanical Properties
- Tensile Strength
- 515 MPa min
- Yield Strength
- 205 MPa min
- Elongation
- 35% min
- Hardness
- 92 HRB max
Physical Properties
- Density
- 7.96 g/cm3
- Melting Range
- 1400-1425 C
- Thermal Conductivity
- 16.1 W/m-K
- Electrical Resistivity
- 730 nOhm-m
- Specific Heat
- 500 J/kg-K
- Coeff. of Thermal Expansion
- 17.2 um/m-C
Corrosion Resistance
- Pitting Resistance (PREN)
- ~17.5
- Max Service Temp (Oxidizing)
- 900 C
- Intergranular Corrosion
- Resistant (Nb stabilized)
- Stress Corrosion Cracking
- Susceptible in chlorides >60C
- General Corrosion Rate
- <0.1 mm/yr in mild acids
- Seawater Resistance
- Limited
Applicable Standards
- ASTM A312 / ASME SA312
- ASTM A213 / ASME SA213
- ASTM A269
- DIN EN 10216-5
Applications
- High-temperature process piping
- Catalytic cracking units
- Fired heaters and furnace tubes
- Reformer piping
- Ammonia production plants
- Thermal cycling applications
Industries Served
- Petrochemical
- Refineries
- Power Generation
- Chemical Processing
- Fertilizer
Key Advantages
- More reliable stabilization than 321 for intermittent heating
- Excellent resistance to polythionic acid SCC
- Superior creep strength at 550-700C
- Better weldability than 321 in heavy sections
- Excellent thermal cycling resistance
Equivalent Grades
- ASTM
- TP347
- JIS
- SUS 347
- BS
- 347S31
- GOST
- 08Kh18N12B