USA Piping Solution manufactures and supplies Stainless Steel 431 Welded Tubes for a wide spectrum of structural, chemical, and industrial applications throughout the United States and worldwide. SS 431 Welded Tubes (UNS S43100 / DIN 1.4057 / AISI 431) are produced by forming flat-rolled martensitic stainless steel strip and welding the longitudinal seam by ERW or EFW methods. Post-weld annealing and normalizing treatments restore the microstructure of the weld-affected zone, ensuring the tube meets specified mechanical properties. USA Piping Solution stocks SS 431 Welded Tubes in round, square, and rectangular cross-sections with bright annealed, 2B, polished, and satin surface options. All products are supplied with full traceability documentation and third-party inspection certificates on request.
SS 431 Welded Tube Specifications
Parameter | Details |
|---|---|
Grade | SS 431 Welded Tube, AISI 431, UNS S43100, DIN 1.4057, W.Nr. 1.4057 |
Manufacturing Method | ERW (Electric Resistance Welding); EFW (Electric Fusion Welding) |
Applicable Standards | ASTM A268 / ASME SA268, ASTM A554 (Mechanical / Ornamental Tubing) |
OD Range | 25 mm to 406 mm (ERW); 200 mm to 2500 mm (EFW) |
Wall Thickness | 1.0 mm to 20 mm (ERW); up to 40 mm (EFW) |
Length | Single Random (4 m to 7 m); Double Random (8 m to 12 m); Cut Length |
Shape | Round, Square, Rectangular |
Post-weld Treatment | Annealed / Normalized; Pickled or Bright Annealed |
Surface Finish | 2B, BA, No.4, No.8 Mirror, Satin, Electropolished |
Certification | EN 10204 3.1 / 3.2; SGS, TUV, DNV on request |
Chemical Composition
Grade | C (max) | Mn (max) | Si (max) | P (max) | S (max) | Cr | Ni |
|---|---|---|---|---|---|---|---|
431 (Welded) | 0.20 | 1.00 | 1.00 | 0.04 | 0.03 | 15.0 to 17.0 | 1.25 to 2.50 |
Physical Properties
Property | Value |
|---|---|
Density | 7800 kg/m3 |
Thermal Conductivity at 100 C | 20.2 W/m.K |
Electrical Resistivity | 720 nOhm.m |
Specific Heat (0-100 C) | 460 J/kg.K |
Thermal Expansion (0-100 C) | 12.1 mm/m/C |
Types of Stainless Steel 431 Welded Tubes
- SS 431 ERW Round Welded Tubes
- SS 431 ERW Square Welded Tubes
- SS 431 ERW Rectangular Welded Tubes
- SS 431 EFW Large Diameter Welded Tubes
- SS 431 Decorative / Ornamental Welded Tubes (ASTM A554)
Testing and Inspection
- Flattening Test (seam at 90 degrees to force)
- Flare Test on weld zone
- Eddy Current Non-Destructive Testing (NDT)
- Hydrostatic Pressure Test
- Visual and Dimensional Inspection
- Tensile and Yield Strength Verification per heat batch
Applications of SS 431 Welded Tubes
- Structural and architectural tubing where martensitic strength is needed
- Decorative exterior cladding and handrail systems
- Light-duty chemical process tubing
- Food processing equipment handles and structural supports
- Marine exterior fittings (non-critical pressure service)
- General fabrication and machined component blanks
Frequently Asked Questions (FAQs)
Q1: We need SS 431 welded rectangular tubes for structural chassis members in a marine vessel. Does post-weld annealing fully restore the base metal corrosion resistance at the seam?
A: Yes. Full solution annealing after welding restores the microstructure and corrosion resistance at the weld seam to near-base-metal levels. We supply all SS 431 welded tubes in the annealed condition with heat treatment records confirming the thermal cycle applied.
Q2: Can SS 431 welded tubes be re-hardened by our fabricator after we have completed structural welding on-site?
A: Yes. SS 431 welded tubes can be through-hardened after fabrication welding by heating to 950 to 1000 C followed by oil or air quenching, then tempering. Post-fabrication hardening requires careful temperature control. We can provide the heat treatment procedure with your order.
Q3: For a railing system in a coastal hotel, are SS 431 welded tubes in mirror finish a better choice than SS 316L for long-term appearance?
A: SS 316L is recommended over SS 431 for direct coastal exposure due to superior pitting resistance in chloride environments. For sheltered coastal installations, SS 431 mirror finish tubes are acceptable and more cost-effective. We can supply both grades for your evaluation.
Q4: We are buying SS 431 welded tubes to machine into shaft coupling blanks. What wall thickness is typically needed for a 50 mm OD blank with 15 mm final bore?
A: For a 50 mm OD coupling blank with 15 mm final bore, a wall thickness of at least 18 to 20 mm is recommended to allow machining allowance. We supply thick-wall SS 431 welded tubes and can discuss hollow bar alternatives for tighter machining tolerances.
Q5: Do you supply ASTM A554 SS 431 welded ornamental tubes with polished surface for interior furniture fabrication, and what is the standard delivery time from your US warehouse?
A: Yes. ASTM A554 SS 431 ornamental welded tubes in No.4, satin, and mirror finishes are available. Standard delivery from US warehouse is 5 to 7 business days for stocked sizes. Custom polished finishes are produced in 2 to 3 weeks. Contact us with dimensions.
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SS 431 Welded Tubes Available in ERW, EFW, Square & Rectangular
Post-weld annealed, dimensionally inspected, and supplied with full EN 10204 3.1 certification. Polished architectural and industrial grades both in stock. Contact USA Piping Solution.
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