ASTM A500 is a standard specification published by ASTM International for cold-formed welded and seamless carbon steel structural tubing. It covers round, square, and rectangular hollow structural sections (HSS) used in construction and general structural applications.
When you see “ASTM A500 rectangular steel pipe,” it typically refers to rectangular HSS made to this standard.
1. Standard Overview
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Full Standard Name: ASTM A500 / A500M – Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes
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Shape Options: Round, square, and rectangular.
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Manufacturing Method:
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Cold-formed from steel strip.
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Electric-resistance welded (ERW) or seamless process.
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Coating: Usually bare (uncoated), but can be hot-dip galvanized or painted upon request.
2. Grades and Mechanical Properties
ASTM A500 defines four main grades (A, B, C, and D), each with different yield and tensile strengths. For rectangular tubing, Grades B and C are most common in structural work.
| Grade | Yield Strength (min) | Tensile Strength (min) | Elongation (min) | Common Use |
|---|---|---|---|---|
| A | 33 ksi (228 MPa) | 45 ksi (310 MPa) | 25% | Light-duty structures |
| B | 46 ksi (317 MPa) | 58 ksi (400 MPa) | 23% | General structural |
| C | 50 ksi (345 MPa) | 62 ksi (427 MPa) | 21% | Heavy structural |
| D* | 36 ksi (250 MPa) | 58 ksi (400 MPa) | 23% | Structural at low temperatures |
* Grade D is for cold-temperature applications (-50 °F / -45 °C).
3. Dimensional Tolerances (Rectangular Tubing)
Per ASTM A500:
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Outside Dimensions: ±0.75% of specified dimension, max ±0.75 mm.
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Wall Thickness: ±10% (not applicable to weld seam).
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Corner Radius: Max 3× wall thickness.
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Straightness: 1/8 inch per 10 feet (3 mm per 3 m).
4. Common Sizes
Rectangular tubing can be produced in a wide range of sizes. Examples:
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Width × Height: From 1.5″ × 1″ (38 × 25 mm) to 20″ × 12″ (508 × 305 mm)
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Wall Thickness: 0.065″ (1.65 mm) to 0.625″ (15.88 mm)
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Length: Standard 20 ft or 40 ft (6 m or 12 m), custom cutting available.
5. Manufacturing Process
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Slitting – Steel coil is slit to required strip width.
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Forming – The strip is cold-formed into a rectangular shape using rollers.
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Welding – Edges are welded using high-frequency electric resistance welding.
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Sizing – Tube passes through shaping stands to achieve precise dimensions.
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Cutting – Tubes are cut to specified length.
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Finishing – Ends deburred, surface cleaned, optional coating or galvanizing.
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Inspection & Testing – Dimensional checks, hydrostatic or non-destructive testing.
6. Applications of ASTM A500 Rectangular Pipe
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Construction: Columns, beams, frames, trusses.
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Industrial: Machinery frames, supports, racks.
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Transport: Truck beds, trailers, railings.
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Agriculture: Equipment frames, irrigation structures.
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Architectural: Decorative structures, canopies.
7. Advantages of ASTM A500 Rectangular Tubing
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High Strength-to-Weight Ratio – Offers structural integrity without excess weight.
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Uniformity – Cold-forming ensures consistent size and shape.
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Ease of Fabrication – Can be cut, welded, drilled, and bolted.
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Cost-Effective – Lighter than equivalent solid sections yet strong.
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Versatile – Fits a wide range of structural and mechanical uses.
8. ASTM A500 vs. Other Standards
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ASTM A53 – Covers round pipe for mechanical and pressure uses; not structural shapes.
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ASTM A847 – For weathering steel tubing with enhanced atmospheric corrosion resistance.
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EN 10219 – European standard for cold-formed welded structural hollow sections.
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JIS G3466 – Japanese standard for general structural rectangular tubing.
9. Buying Considerations
When sourcing ASTM A500 rectangular steel pipe:
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Confirm Grade – Grade B is standard; Grade C for higher loads.
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Specify Size & Wall Thickness – Match to structural design needs.
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Request Mill Test Reports (MTRs) – Verify compliance with ASTM A500.
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Check Surface Condition – Bare, primed, or galvanized.
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Order Quantity – Most mills have minimum orders (often 2–5 tons per size).
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Delivery Logistics – Coordinate for 20 ft/40 ft truck or container delivery.
10. Example Supplier Pricing (2025 Estimates)
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FOB China: $650–$850 per metric ton (Grade B, 6 m length, uncoated)
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FOB U.S. Midwest: $950–$1,200 per short ton
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Galvanized ASTM A500: +$100–$200 per ton depending on zinc coating weight
Pricing varies with:
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Global steel prices
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Wall thickness
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Coating/finish
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Order size
Conclusion
ASTM A500 rectangular steel pipe is a cornerstone material in construction, manufacturing, and engineering projects due to its strength, dimensional accuracy, and versatility. Whether you need it for load-bearing columns, machine frames, or decorative architectural elements, knowing the specifications, grades, and market prices helps you source the right product with confidence.
