Welded stainless steel round pipe is manufactured by forming a flat stainless steel strip or sheet into a cylindrical shape and welding the longitudinal seam. This process creates a cost-effective, dimensionally consistent pipe suitable for a wide range of industrial, commercial, and architectural applications.
While seamless pipes are preferred for extremely high-pressure environments, welded pipes offer exceptional value for general-purpose applications where pressure ratings are moderate, but cost efficiency, size availability, and dimensional accuracy are priorities.
Modern welding technologies — including Tungsten Inert Gas (TIG), Laser, and Electric Resistance Welding (ERW) — produce weld seams that are virtually indistinguishable from the base metal, with many welded pipes capable of meeting or exceeding the same pressure ratings as seamless alternatives.
Specifications at a Glance
| Parameter |
Details |
| Product Name |
Welded Stainless Steel Round Pipe |
| Standards |
ASTM A312, A358, A778, A269, EN 10217-7, JIS G3459, GB/T 12771 |
| Grades |
304, 304L, 316, 316L, 316Ti, 321, 310S, 317L, 904L, Duplex 2205 |
| Dimensions |
1/2″ – 48″+ OD (12.7mm – 1219mm+) |
| Wall Thickness |
Schedule 5S, 10S, 20, 40, 80 (0.5mm – 20mm) |
| Length |
3m – 12m (random, fixed, or custom lengths) |
| Weld Types |
ERW (Electric Resistance Welded), EFW (Electric Fusion Welded), TIG |
| Surface Finish |
Mill Finish, Pickled, Polished (Mirror), Brushed (Hairline) |
| Manufacturing Process |
Cold Rolled / Hot Rolled strip → Forming → Welding → Heat Treatment → Sizing |
Available Grades & Standards
| Grade |
Standard |
Key Characteristics |
Typical Applications |
| 304 |
ASTM A312 |
General-purpose, good corrosion resistance |
Food processing, dairy, beverage lines |
| 304L |
ASTM A312 |
Low carbon, better weldability |
Chemical tanks, welded equipment |
| 316 |
ASTM A312 |
Molybdenum added, chloride resistance |
Marine, pharmaceutical, coastal |
| 316L |
ASTM A312 |
Low-carbon version of 316 |
High chloride environments |
| 316Ti |
ASTM A249 |
Titanium stabilized, high temperature |
Exhaust systems, heat exchangers |
| 321 |
ASTM A249 |
Titanium stabilized, 800-1500°F service |
Aircraft, exhaust stacks |
| 310S |
ASTM A312 |
High temperature up to 2000°F |
Furnace parts, heat treatment |
| 317L |
ASTM A312 |
Higher molybdenum than 316 |
Pulp & paper, chemical processing |
| 904L |
ASTM A312 |
Super austenitic, severe corrosion |
Sulfuric acid, seawater |
| 2205 |
ASTM A358 |
Duplex, high strength + SCC resistance |
Offshore, desalination |
Chemical Composition (%)
| Grade |
C |
Mn |
Si |
Cr |
Ni |
Mo |
Others |
| 304 |
≤0.08 |
≤2.00 |
≤1.00 |
18.0-20.0 |
8.0-11.0 |
– |
– |
| 304L |
≤0.030 |
≤2.00 |
≤1.00 |
18.0-20.0 |
8.0-12.0 |
– |
– |
| 316 |
≤0.08 |
≤2.00 |
≤1.00 |
16.0-18.0 |
10.0-14.0 |
2.0-3.0 |
– |
| 316L |
≤0.030 |
≤2.00 |
≤1.00 |
16.0-18.0 |
10.0-14.0 |
2.0-3.0 |
– |
| 310S |
≤0.08 |
≤2.00 |
≤1.50 |
24.0-26.0 |
19.0-22.0 |
– |
– |
| 2205 |
≤0.030 |
≤2.00 |
≤1.00 |
22.0-23.0 |
4.5-6.5 |
3.0-3.5 |
N 0.14-0.20 |
Mechanical Properties (Typical)
| Grade |
Tensile Strength (MPa) |
Yield Strength (MPa) |
Elongation (%) |
Hardness (HB max) |
| 304 |
≥515 |
≥205 |
≥40 |
≤201 |
| 304L |
≥485 |
≥170 |
≥40 |
≤201 |
| 316 |
≥515 |
≥205 |
≥40 |
≤217 |
| 316L |
≥485 |
≥170 |
≥40 |
≤217 |
| 310S |
≥515 |
≥205 |
≥40 |
≤217 |
| 2205 |
≥620 |
≥450 |
≥25 |
≤293 |
Physical Properties
| Property |
304/304L |
316/316L |
2205 |
| Density (g/cm³) |
7.93 |
7.98 |
7.80 |
| Modulus of Elasticity (GPa) |
193 |
193 |
190 |
| Thermal Conductivity (W/m·K) |
16.2 |
16.3 |
19.0 |
| Coefficient of Thermal Expansion (10⁻⁶/°C) |
17.2 |
17.2 |
13.7 |
| Electrical Resistivity (μΩ·cm) |
72 |
74 |
80 |
Welded stainless steel round pipe Dimensions & Schedule Chart
Standard Pipe Sizes (ANSI B36.19) – Welded
| NPS (inch) |
OD (mm) |
Schedule 5S (mm) |
Schedule 10S (mm) |
Schedule 40S (mm) |
Schedule 80S (mm) |
| 1/2″ |
21.3 |
1.65 |
2.11 |
2.77 |
3.73 |
| 3/4″ |
26.7 |
1.65 |
2.11 |
2.87 |
3.91 |
| 1″ |
33.4 |
1.65 |
2.77 |
3.38 |
4.55 |
| 1-1/2″ |
48.3 |
1.65 |
2.77 |
3.68 |
5.08 |
| 2″ |
60.3 |
1.65 |
2.77 |
3.91 |
5.54 |
| 3″ |
88.9 |
2.11 |
3.05 |
5.49 |
7.62 |
| 4″ |
114.3 |
2.11 |
3.05 |
6.02 |
8.56 |
| 6″ |
168.3 |
2.77 |
3.40 |
7.11 |
10.97 |
| 8″ |
219.1 |
2.77 |
3.76 |
8.18 |
12.70 |
| 10″ |
273.1 |
3.40 |
4.19 |
9.27 |
15.09 |
| 12″ |
323.9 |
3.40 |
4.57 |
10.31 |
17.48 |
| 14″ |
355.6 |
3.96 |
4.78 |
11.13 |
19.05 |
| 16″ |
406.4 |
4.19 |
4.78 |
12.70 |
21.44 |
| 18″ |
457.2 |
4.19 |
4.78 |
14.27 |
23.83 |
| 20″ |
508.0 |
4.78 |
5.54 |
15.09 |
26.19 |
| 24″ |
609.6 |
5.54 |
6.35 |
17.48 |
30.96 |
Larger diameters up to 48″ available upon request
Dimensional Tolerances (ASTM A312)
| Parameter |
Tolerance |
| OD (≤48″) |
±0.5% |
| OD (>48″) |
±1.0% |
| Wall Thickness |
±10% |
| Length (fixed) |
+3mm / -0mm |
| Straightness |
≤1.5mm per meter |
| Out-of-Roundness |
Within OD tolerance |
Key Process Steps Explained:
| Step |
Description |
| Coil Preparation |
High-quality stainless steel coil is inspected and slit to the required width |
| Forming |
The strip is progressively roll-formed into a cylindrical shape |
| Welding |
Longitudinal seam is welded using TIG, ERW, or Laser (no filler metal for autogenous welding) |
| Weld Bead Trimming |
Internal and external weld beads are trimmed for a smooth surface |
| Heat Treatment |
Solution annealing at 1040-1120°C to restore corrosion resistance |
| Sizing |
Pipe passes through sizing rolls to achieve precise OD |
| Pickling/Polishing |
Removal of oxide scale and surface finishing |
Welded vs. Seamless – Which to Choose?
| Feature |
Welded Pipe |
Seamless Pipe |
| Cost |
20-30% lower |
Higher |
| Lead Time |
Shorter |
Longer |
| Size Range |
1/2″ to 48″+ |
1/2″ to 24″ |
| Wall Thickness Consistency |
Excellent |
Good |
| Weld Seam |
Present (but high quality) |
None |
| Pressure Rating |
High (meets ASTM standards) |
Very High |
| Corrosion Resistance |
Excellent (with proper HT) |
Excellent |
| Best For |
General industrial, large diameters, cost-sensitive projects |
Extreme high pressure, critical safety applications |
Key Insight: Modern welded pipes — especially those that are solution annealed and full-penetration welded — perform nearly identically to seamless pipes for the vast majority of applications. Many ASTM standards treat welded and seamless as interchangeable for pressure ratings.
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