ASTM A500/A500M: Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes

1. Scope  

- Covers cold-formed welded and seamless carbon steel tubing used in structural applications (e.g., construction, bridges, machinery).  

- Includes round, square, rectangular, and other shapes.  

- Available in metric (A500M) and inch-pound (A500) versions.  

 2. Ordering Information  

Buyers must specify:  

- ASTM designation (A500 or A500M)  

- Shape (round, square, rectangular, etc.)  

- Dimensions (outer diameter, side lengths, wall thickness)  

- Grade (A, B, C, or D)  

- Length (random or exact)  

- Additional requirements (testing, coating, certification)  

 3. Main Steel Grades & Mechanical Properties  

| Grade | Yield Strength (min) | Tensile Strength (min) | Elongation (%) |   

| A     | 39 ksi (270 MPa)         | 45 ksi (310 MPa)           | 25 (2")            |  

| B     | 46 ksi (320 MPa)         | 58 ksi (400 MPa)           | 23 (2")            |  

| C     | 50 ksi (345 MPa)         | 62 ksi (425 MPa)           | 21 (2")            |  

| D (Rectangular/Square only) | 36 ksi (250 MPa) | 58 ksi (400 MPa) | 23 (2") |  

 4. Chemical Composition (Max %)  

| Element | Grade A | Grade B | Grade C | Grade D |  

| C       | 0.26       | 0.26       | 0.23       | 0.20       |  

| Mn      | -          | 1.35       | 1.35       | 1.35       |  

| P       | 0.035      | 0.035      | 0.035      | 0.035      |  

| S       | 0.035      | 0.035      | 0.035      | 0.035      |  

 5. Inspection & Testing Requirements  

- Tensile Test: Required for each heat/lot.  

- Flattening Test (Welded Tubing): Mandatory for Grades A, B, C (except seamless).  

- Bend Test (Grade D Rectangular/Square): Required.  

- Hydrostatic or NDT (Optional): If specified, tubes must be leak-tested (hydrostatic) or examined via eddy current or ultrasonic testing.  

- Visual Inspection: Surface must be free of cracks, seams, or excessive imperfections.  

 6. Dimensional Tolerances  

- Outside Dimensions: ±0.5% (round) or ±0.75% (shapes).  

- Wall Thickness: Varies by manufacturing method (seamless: ±12.5%; welded: ±10%).  

- Straightness: Max deviation of 0.125% of length.  

 7. Marking & Certification  

- Marking: Must include ASTM A500/A500M, grade, size, manufacturer’s name, and heat number.  

- Certification: Mill Test Report (MTR) with chemical/mechanical test data.  

 Key Revisions in Latest Edition  

- Tighter tolerances for wall thickness in welded tubing.  

- Clarified bend test requirements for Grade D.  

- Updated referencing standards for testing methods.  

 Comparison with Similar Standards  

- ASTM A501: Hot-formed tubing (higher strength, less precise tolerances).  

- ASTM A1085: Improved structural properties and toughness.  

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