ASTM A252 Grade 3 is the highest performance grade among the three A252 steel pipe grades, widely used for heavy-load structures and projects in complex geologic conditions. Common applications include large commercial buildings, large bridges, offshore platforms, and other demanding construction projects.
ASTM A252 Grades Overview
| Grade | Tensile Strength | Yield Strength | Elongation (2 in.) |
|---|---|---|---|
| Grade 1 | 345 MPa (50,000 psi) | 205 MPa (30,000 psi) | 30% |
| Grade 2 | 415 MPa (60,000 psi) | 240 MPa (35,000 psi) | 25% |
| Grade 3 | 455 MPa (66,000 psi) | 310 MPa (45,000 psi) | 20% |
Chemical requirement: Phosphorus ≤ 0.050% for all grades
Performance: Higher grade number = higher mechanical performance
Manufacturing & Material Process
Raw Material Production: Open-hearth, basic-oxygen, or electric furnace steel
Pipe Types: Seamless, LSAW, SSAW, EFW, ERW, or other welded pipes
Seam Orientation: Longitudinal, helical-butt, or helical-lap
Mechanical Properties – ASTM A252 Grade 3
| Property | Value |
|---|---|
| Tensile Strength | 66,000 psi (455 MPa) min |
| Yield Strength | 45,000 psi (310 MPa) min |
| Elongation (≥5/16 in. wall) | 20% |
| Elongation (<5/16 in. wall) | Deduction 1.0% per 1/32 in. wall decrease |
Nominal Wall Thickness vs Elongation:
| Wall Thickness | Elongation (2 in.) |
|---|---|
| 5/16 in (7.9 mm) | 20% |
| 9/32 in (7.1 mm) | 19% |
| 1/4 in (6.4 mm) | 18% |
| 7/32 in (5.6 mm) | 17% |
| 3/16 in (4.8 mm) | 16% |
| 11/64 in (4.4 mm) | 15.5% |
| 5/32 in (4.0 mm) | 15% |
| 9/64 in (3.6 mm) | 14.5% |
| 1/8 in (3.2 mm) | 14% |
| 7/64 in (2.8 mm) | 13.5% |
Elongation formula (intermediate thicknesses):
E=32t+10orE=1.25t+10E = 32t + 10 \quad \text{or} \quad E = 1.25t + 10E=32t+10orE=1.25t+10
Where E = elongation (%) and t = wall thickness (in mm).
Pipe Ends & Appearance
Pipe Ends: Plain-ended; bevel angle 30°–35° if required
Cutting: Flame-cut or machine-cut, burrs removed
Surface Quality:
Surface defects ≤ 12.5% wall thickness acceptable
Defects 12.5–33% wall thickness can be repaired by welding
Straightness: Pipes shall be reasonably straight and free from defects affecting usability
Dimensions
Seamless Piles: Ø 13.7 mm – 1200 mm
Welded Piles: Ø 21.3 mm – 3500 mm
Other Requirements: Dimensional tolerances and pipe weight tables follow ASTM A252 specifications
ASTM A252 Grade 2 vs Grade 3
| Feature | Grade 2 | Grade 3 |
|---|---|---|
| Phosphorus content | ≤0.050% | ≤0.050% |
| Tensile Strength | 415 MPa | 455 MPa |
| Yield Strength | 240 MPa | 310 MPa |
| Elongation (2 in.) | 25% | 20% |
Grade 3 steel pipes are chosen for high-load, complex, and critical engineering conditions. Alternative materials such as API 5L X52, ASTM A500 Grade C, EN 10210 S355J2H, AS 1163 C350, JIS G 3444 STK 490 may also be used depending on project requirements.
