Womic Steel is a leading manufacturer of premium stainless steel pipe products, including S321 and S347 stainless steel pipes. These stabilized austenitic stainless steels comply with international standards such as ASTM A312, ASTM A213, and EN 10216-5, offering superior high-temperature strength, corrosion resistance, and weldability. Below is a comprehensive technical comparison and application guide between these two materials.
1. Product Standards
- S321 Stainless Steel: UNS S32100 / TP321 / 1Cr18Ni9Ti
- S347 Stainless Steel: UNS S34700 / TP347 / 0Cr18Ni11Nb
- Common Standards: ASTM A312 (welded/seamless pipe), ASTM A213 (boiler/tube), EN 10216-5
2. Dimensional Capabilities
Womic Steel provides both seamless and welded stainless steel pipes in the following ranges:
- Outer Diameter: 6 mm – 1016 mm
- Wall Thickness: 1 mm – 50 mm
- Length: Up to 12.2 meters (fixed/random lengths)
- Pipe Type: Seamless (SMLS), ERW, TIG welded, LSAW
Custom diameters and tolerances available on request.
3. Chemical Composition
S321 uses Titanium (Ti) for stabilization, while S347 uses Niobium (Nb) to improve intergranular corrosion resistance, especially after welding.
4. Mechanical Properties (Typical)
S321 Stainless Steel Pipe:
- Tensile Strength (Rm): ≥ 520 MPa
- Yield Strength (Rp0.2): ≥ 205 MPa
- Elongation (A): ≥ 40%
- Hardness: ≤ 187 HB / ≤ 90 HRB / ≤ 200 HV
- Impact Resistance: Suitable for room-temperature use, fair at low temperatures
S347 Stainless Steel Pipe:
- Tensile Strength (Rm): ≥ 520 MPa
- Yield Strength (Rp0.2): ≥ 206 MPa
- Elongation (A): ≥ 40%
- Hardness: ≤ 187 HB
- Excellent stress rupture and creep resistance at high temperature
5. Heat Treatment
S321 is solution annealed at 920–1150°C, with optional stabilization at 850–930°C.
S347 is solution treated at 1000–1100°C and requires no additional stabilization due to Nb content.
Womic Steel ensures uniform grain refinement through precise furnace control.
6. Welding & Fabrication
Both grades exhibit good weldability. S347 provides better post-weld corrosion resistance. ER347 filler wire is recommended for both grades to preserve corrosion resistance and mechanical strength.
7. Testing & Quality Control
- Hydrostatic Testing
- Ultrasonic Testing (UT), Radiographic Testing (RT)
- Intergranular Corrosion Test (ASTM A262 Practice E)
- Mechanical Tests: Tensile, Flaring, Flattening, Hardness
- Optional Charpy Impact Testing: at -46°C or -196°C
Each pipe includes full traceability and EN 10204 3.1 or 3.2 certification.
8. Applications & Material Selection
S347 is recommended for boilers, reheaters, and high-temperature welding applications.
S321 is ideal for cost-sensitive and moderate-temperature uses like exhaust ducts and general industrial piping.
9. Certifications & Compliance
- ISO 9001:2015, ISO 14001:2015, ISO 45001:2018
- PED 2014/68/EU, AD2000 W0 (Pressure Equipment)
- ASTM/EN/ASME compliant
- Third-party inspection by SGS, DNV, BV, TÜV
10. Production Capacity & Delivery
- Monthly Output: 8,000+ tons
- Lead Time: 10–25 working days
- Stable raw material from TISCO, POSCO, LISCO
11. Packaging & Logistics
- Bundled with steel straps, capped ends, film wrap
- Export packaging with wooden cases or steel crates
- Pipe Marking: Grade, OD, Wall, Heat No., Batch No., Barcoding
12. Processing Capabilities
- Bending, Beveling, Threading, Slotting
- Pickling, Passivation, Electro/Mechanical Polishing
- FBE/3LPE/3LPP Coating
- CNC Machining, Pipe Spool Fabrication
Why Choose Womic Steel
Womic Steel offers complete control over production from forming to coating, ensuring reliable quality, fast lead times, and excellent technical support for stainless steel pipe solutions worldwide.
Website: www.womicsteel.com
Email: sales@womicsteel.com
Tel/WhatsApp/WeChat: Victor: +86-15575100681 or Jack: +86-18390957568
Post time: Nov-05-2026