What Is ASTM A500 Rectangular Tube?

ASTM A500 rectangular tube is a type of cold-formed welded or seamless carbon steel structural tubing manufactured according to the ASTM A500 specification. It is widely used in building structures, industrial equipment, transportation systems, and general engineering applications due to its high strength, excellent weldability, and efficient structural design.

Unlike standard mechanical tubing, ASTM A500 rectangular tubing is specifically developed for structural applications where strength, dimensional consistency, and load-bearing performance are critical. Its hollow rectangular profile provides a favorable strength-to-weight ratio, making it an effective alternative to traditional solid steel sections.For detailed rectangular tube dimensions and standard sizes, refer to our Standard Rectangular Tube Size Table.

This guide explains the ASTM A500 specification, available grades, manufacturing methods, mechanical properties, and typical applications to help engineers and buyers select the right structural tubing solution.

What Is ASTM A500 Rectangular Tube?

Grades and Mechanical Properties

ASTM A500 includes four main carbon steel grades: Grade A, Grade B, Grade C, and Grade D. Each grade has different mechanical requirements, allowing engineers to select suitable tubing based on structural performance requirements.

Among them, ASTM A500 Grade B and Grade C are the most commonly used grades for rectangular tubing applications.

ASTM A500 Grade B Rectangular Tube

ASTM A500 Grade B is one of the most widely used structural tubing grades in North America.
Key characteristics include:
Minimum yield strength: 46,000 psi (317 MPa)
Good balance between strength and formability
Suitable for general structural applications

Grade B rectangular tubes are frequently used in construction frames, supports, and fabricated structures where reliable strength performance is required.

ASTM A500 Grade C Rectangular Tube

ASTM A500 Grade C provides higher mechanical strength compared with Grade B.
Main characteristics:
Minimum yield strength: 50,000 psi (345 MPa)
Higher tensile performance
Suitable for heavier structural requirements
Due to its increased strength, Grade C is often selected for applications requiring improved load capacity while maintaining a lightweight structure.

ASTM A500 Grade Comparison

Grade	Minimum Yield Strength	Typical Applications
Grade A	39,000 psi (269 MPa)	General structural applications
Grade B	46,000 psi (317 MPa)	Construction frames, supports, equipment structures
Grade C	50,000 psi (345 MPa)	Higher strength structural projects
Grade D	36,000 psi (250 MPa)	Special structural requirements

Tensile Properties of ASTM A500 Rectangular Tubes

ASTM A500 Rectangular Tube
Minimum stretch(Mpa)	310	400	427	400
Yield Strength (Mpa)	269	317	345	250
Minimum elongation per 50.8mm, %D	25A	13B	21C	23B

Applications of ASTM A500 Rectangular Tube

Thanks to its strength, formability, and versatility, ASTM A500 rectangular tubing is used across many sectors:

1. Construction Industry
It is commonly found in commercial buildings, warehouses, and residential structures. Its hollow shape reduces weight while maintaining structural performance.

2. Infrastructure Projects
Rectangular tubes are used in bridges, signposts, guardrails, and urban railings. Their reliability under dynamic stress is key to safety.

3. Equipment Framing
The tubes are ideal for creating frames in manufacturing equipment, farming machinery, and transportation systems.

4. Furniture and Design
Modern furniture makers use ASTM A500 tubes for aesthetic and practical reasons. Clean lines and strength make them a good choice for industrial designs.

Mechanical Properties of ASTM A500 Rectangular Tube

The mechanical properties of ASTM A500 rectangular tubing define its ability to withstand structural loads, deformation, and external forces. The specification establishes minimum requirements for yield strength, tensile strength, and elongation to ensure consistent performance in structural applications.
The mechanical requirements vary depending on the selected grade.

Grade	Minimum Yield Strength	Minimum Tensile Strength	Minimum Elongation
Grade A	39,000 psi (269 MPa)	45,000 psi (310 MPa)	25%
Grade B	46,000 psi (317 MPa)	58,000 psi (400 MPa)	23%
Grade C	50,000 psi (345 MPa)	62,000 psi (427 MPa)	21%
Grade D	36,000 psi (250 MPa)	58,000 psi (400 MPa)	23%

The higher strength levels of Grade B and Grade C make them suitable for structural applications requiring improved load resistance and durability.

ASTM A500 vs. Other Structural Tubing Standards

ASTM A500 is often compared with:
ASTM A513: Used for mechanical tubing, not structural.
ASTM A36: Standard for structural shapes like I-beams, not tubing.
EN 10210: European standard for hot-formed structural tubes.
ASTM A500 remains the preferred choice in North America for welded and seamless structural tubing.