ASTM A554 SS 304 Square Pipe Corrosion Resistant Square Hollow Section
ASTM A554 is the American standard for welded stainless steel mechanical tubing in round, square, and rectangular shapes. It is specifically designed for mechanical and structural applications – not for pressure service (use ASTM A269 or A312 for pressure).
Square tubes under ASTM A554 are produced as cold-formed welded tubes from stainless steel strips, then heat-treated and finished to meet mechanical property requirements. The standard covers multiple stainless steel grades, with 304 and 316 being the most common.
| Quick Facts | Value |
|---|---|
| Standard | ASTM A554 |
| Shape | Square |
| Process | Cold-formed + welded + heat treated |
| Key Feature | Corrosion resistance + structural strength |
| Primary Use | Architectural, handrails, furniture, frames |
| Common Grades | 304, 304L, 316, 316L |
ASTM A554 references standard stainless steel compositions per ASTM A240. Below are the most common grades.
| Element | Grade 304 | Grade 304L | Grade 316 | Grade 316L |
|---|---|---|---|---|
| Carbon (C) | ≤ 0.08 | ≤ 0.035 | ≤ 0.08 | ≤ 0.035 |
| Chromium (Cr) | 18.0–20.0 | 18.0–20.0 | 16.0–18.0 | 16.0–18.0 |
| Nickel (Ni) | 8.0–10.5 | 8.0–12.0 | 10.0–14.0 | 10.0–14.0 |
| Molybdenum (Mo) | — | — | 2.00–3.00 | 2.00–3.00 |
| Manganese (Mn) | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 |
Grade Selection Guide:
| Grade | Key Feature | Typical Application |
|---|---|---|
| 304 | General-purpose, good corrosion resistance | Handrails, furniture, frames |
| 304L | Low carbon, better weldability | Welded structures, thin walls |
| 316 | Contains molybdenum, excellent corrosion resistance | Marine, coastal, chemical exposure |
| 316L | Low carbon + molybdenum | Marine welded structures |
ASTM A554 specifies mechanical property requirements based on the tube size (wall thickness) and heat treatment condition.
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 304 | ≥ 515 | ≥ 205 | ≥ 35 |
| 304L | ≥ 485 | ≥ 170 | ≥ 35 |
| 316 | ≥ 515 | ≥ 205 | ≥ 35 |
| 316L | ≥ 485 | ≥ 170 | ≥ 35 |
Elongation measured in 50 mm (2 inches). Values are minimum requirements per ASTM A554.
ASTM A554 tubes can be supplied in multiple conditions:
| Condition | Description | Application |
|---|---|---|
| As-welded | No heat treatment after welding | Non-critical, economy applications |
| Annealed | Full solution annealing | Maximum corrosion resistance and ductility |
| Stress-relieved | Low-temperature heat treatment | Reduced residual stress, good strength |
Recommended: For architectural and structural applications, annealed condition provides the best combination of corrosion resistance and mechanical properties.
| Parameter | Typical Tolerance |
|---|---|
| Outside dimensions | ± 0.4 mm to ± 0.8 mm (size dependent) |
| Wall thickness | ± 10% |
| Straightness | ≤ 1.0 mm per meter |
| Twist | ≤ 1° + 0.5° per meter |
| Corner radius | 1.5* to 2.5* wall thickness (typical) |
| Size (mm) | Common Wall Thickness (mm) |
|---|---|
| 10 * 10 | 0.8, 1.0, 1.2 |
| 20 * 20 | 1.0, 1.5, 2.0 |
| 25 * 25 | 1.5, 2.0, 2.5 |
| 30 * 30 | 1.5, 2.0, 2.5, 3.0 |
| 40 * 40 | 1.5, 2.0, 2.5, 3.0 |
| 50 * 50 | 2.0, 2.5, 3.0, 4.0 |
| 60 * 60 | 2.0, 2.5, 3.0, 4.0 |
| 80 * 80 | 2.5, 3.0, 4.0, 5.0 |
| 100 * 100 | 3.0, 4.0, 5.0, 6.0 |
Custom sizes and thicknesses available upon request.
Primary Use: Architectural and decorative structural applications
Other Applications:
- Handrails and guardrails
- Furniture frames (chairs, tables, shelves)
- Display racks and shelving
- Window and door frames
- Structural supports
- Food processing equipment
- Marine and coastal structures (316/316L)
- Medical equipment frames
- Gym and fitness equipment
Quick Pick:
| Need | Choose |
|---|---|
| General architectural/indoor | ASTM A554 304 |
| Welded structures (thin wall) | ASTM A554 304L |
| Marine / coastal/outdoor | ASTM A554 316 |
| Marine welded structures | ASTM A554 316L |
Every ASTM A554 square tube we supply is backed by comprehensive quality control.
| Test | Purpose |
|---|---|
| Chemical analysis | Verify composition per ASTM A240 |
| Tensile test | Confirm yield, tensile, elongation |
| Flattening test | Assess ductility and weld quality |
| Reverse flattening test | Check weld soundness |
| Hydrostatic test | (Upon request – not typically required for mechanical tubing) |
| Eddy current / Ultrasonic NDT | Detect surface and weld defects |
| Dimensional inspection | Verify size, wall thickness, straightness, twist |
| Visual inspection | Check surface finish and weld appearance |
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EN 10204 Type 3.1 – Mill test certificate (standard)
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EN 10204 Type 3.2 – Third-party verified (available on request)
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Full traceability – Heat number traceable to the mill
| Finish | Description | Application |
|---|---|---|
| Mill finish | As-welded, oxide present | Economy, will be painted/coated |
| Pickled | Acid cleaned, scale removed | Industrial, food equipment |
| Brushed (satin) | 180–240 grit, fine grain | Architectural, handrails |
| Polished | #4 polish, medium shine | Furniture, decorative |
| Mirror finish | #8 polish, highly reflective | High-end architectural showpieces |
| Advantage | Detail |
|---|---|
| Stock availability | Common sizes ready to ship |
| Custom cutting | Cut to exact lengths |
| Surface finishing | Brushing, polishing in-house |
| Fabrication services | Drilling, welding, and bending are available |
| Global shipping | Door-to-door delivery |
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