ASTM A500 Grade B is a standard specification for cold-formed welded and seamless carbon steel structural tubing. Unlike hot-rolled steel, the cold-forming process gives this rectangular tubing (also known as RHS - Rectangular Hollow Section) a superior surface finish, higher strength-to-weight ratio, and much tighter dimensional tolerances.
Grade B is the "Sweet Spot": It is the most common structural grade because it offers a significant increase in yield strength (46,000 psi) compared to Grade A (33,000 psi) while remaining highly weldable and cost-effective.
Structural Integrity: Its closed-loop shape provides excellent resistance to torsion (twisting) and multi-directional loading, making it ideal for columns and frames.
Specifications of ASTM A500 Gr.B Rectangular Tube
| Feature | Technical Details |
| Standard | ASTM A500 / A500M |
| Grade | Grade B (The industry standard for construction) |
| Manufacturing | ERW (Electric Resistance Welded) or Seamless |
| Shape | Rectangular Hollow Section (RHS) |
| Wall Thickness | Up to 0.625" (15.88 mm) |
| Max Perimeter | 64 inches (1626 mm) |
| Standard Lengths | 20ft (6m), 40ft (12m), or custom lengths |
| Finishes | Bare, Lightly Oiled, Hot-Dip Galvanized, or Red/Gray Primer |
Chemical & Mechanical Information
ASTM A500 Grade B is engineered for structural stability. Below are the data-backed requirements for Welded Tubing (the most common type).
Chemical Composition (Max %)
| Carbon (C) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Copper (Cu)* |
| 0.26% | 1.35% | 0.035% | 0.035% | 0.20% |
| *Copper is optional; included only if copper-bearing steel is specified for corrosion resistance. |
Mechanical Properties (Minimum Requirements)
| Property | Value (Imperial) | Value (Metric) |
| Tensile Strength | 58,000 psi | 400 MPa |
| Yield Strength | 46,000 psi | 315 MPa |
| Elongation (in 2") | 23% | 23% |
Sizes of ASTM A500 Gr.B Rectangular Tube
Rectangular tubing sizes are defined by Width x Height x Wall Thickness. Below are common industry-standard sizes.
| Nominal Size (Inches) | Metric Equivalent (mm) | Wall Thickness Options (Inches) |
| 2" x 1" | 50.8 x 25.4 | 0.120", 0.188" |
| 3" x 2" | 76.2 x 50.8 | 0.120", 0.188", 0.250" |
| 4" x 2" | 101.6 x 50.8 | 0.120", 0.188", 0.250", 0.313" |
| 6" x 4" | 152.4 x 101.6 | 0.188", 0.250", 0.313", 0.375", 0.500" |
| 8" x 4" | 203.2 x 101.6 | 0.250", 0.313", 0.375", 0.500" |
| 10" x 6" | 254.0 x 152.4 | 0.250", 0.313", 0.375", 0.500", 0.625" |
| 12" x 8" | 304.8 x 203.2 | 0.313", 0.375", 0.500", 0.625" |
Application of ASTM A500 Gr.B Rectangular Tube
Due to its aesthetic appeal (flat sides) and high structural strength, it is used across multiple industries:
Construction & Architecture:
Support columns and beams for buildings.
Exposed structural steelwork (canopies, entrances).
Pedestrian bridges and highway railings.
Industrial Machinery:
Frames for heavy equipment and conveyor systems.
Material handling racks and industrial shelving.
Transportation:
Trailer chassis and frames.
Agricultural equipment components (tractors, plows).
Infrastructure:
Sign supports and light poles.
Protective bollards and security fencing.
General Fabrication:
Mezzanine floors.
Custom workstations and steel furniture.
GNEE ASTM 500 GRB SHS Tube factory
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GNEE A500 GRB SHS Tube certificate
FAQ
Q: What are the main differences between Grade A, Grade B, and Grade C?
A:
Grade B is the most common and widely stocked structural grade, offering a minimum yield strength of 46,000 psi.
Grade A has lower strength (33,000 psi) and is used for lighter applications.
Grade C offers the highest strength (50,000 psi) but is slightly less ductile and less commonly stocked. Grade B is the industry "standard" for construction.
Q: What are the wall thickness tolerances for A500 Grade B?
A: According to ASTM A500, the wall thickness tolerance is typically ±10% of the nominal wall thickness. Our high-precision cold-forming process often allows us to maintain even tighter tolerances to ensure seamless assembly in precision fabrication.
Q: What surface protection options do you provide for export?
A: We offer several finishes depending on your environment:
Hot-Dip Galvanized: Best for outdoor/corrosive environments (North America/Coastal regions).
Zinc-rich Primer: Grey or Red primer for immediate fabrication and paint prep.
Lightly Oiled / Bare: For indoor use or customers performing their own coating.
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