ASTM A500

ASTM A500 is a standard specification published by the American Society for Testing and Materials (ASTM) that covers cold-formed welded and seamless carbon steel structural tubing in round, square, rectangular, and “special” shapes. It is frequently used in construction projects, such as bridges and buildings, due to its high strength and low weight. The standard includes four grades of steel based on their strength. Generally, A500 tubes can be classified into round, square, or rectangular shapes. The most common grade of steel used in construction is Grade B, which has a minimum yield strength of 42000 psi. Grade C is also commonly used, with a minimum yield strength of 46000 psi. Also, heat treatment is required for Grade D. By meeting the requirements of the ASTM A500 standard, construction projects can ensure that they are using high-quality materials that will meet their needs.

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Steel Grades of ASTM A500

ASTM A500 Carbon Steel Material Component Properties

ASTM A500 carbon steel structural tube is only made from materials that meet the carbon steel requirements. A500 is mostly composed of iron, with additional carbon, manganese, phosphorus, sulfur, and copper. For accurate A500 carbon steel chemical characteristics, see the chart below.

ASTM A500 Carbon Steel Mechanical Properties

The amount of stretching tension that a material can endure before breaking or failing is referred to as its tensile strength. The ultimate tensile strength of A500 carbon steel is computed by dividing its area by the stress applied to it, which is represented in pounds or tons per square inch of material. Tensile strength is a critical indicator of ASTM A500’s capacity to perform in a given application. The tensile strength of A500 carbon steel is shown in the chart below.

Mechanical Properties of ASTM A500 Round Structural Tubing

Steel Grade	Tensile Strength		Yield Strength		Elongation in 50.8mm
Steel Grade	psi	Mpa	psi	Mpa	Min
Gr. A	45,000	310	33,000	228	25%
Gr. B	58,000	400	42,000	290	23%
Gr. C	62,000	427	46,000	317	21%
Gr. D	58,000	400	36,000	250	23%

Mechanical Properties of ASTM A500 Shaped Structural Tubing

Steel Grade	Tensile Strength		Yield Strength		Elongation in 50.8mm
Steel Grade	psi	Mpa	psi	Mpa	Min
Gr. A	45,000	310	39,000	269	25%
Gr. B	58,000	400	46,000	317	23%
Gr. C	62,000	427	50,000	345	21%
Gr. D	58,000	400	36,000	250	23%

ASTM A500 Carbon Steel Permissible Dimensional Variations for Outside Dimensions

Outside diameter measurements for the ASTM A500 carbon steel tube must be taken at least 2″ (50.8mm) from each end.

The outer diameter of round structural tubing having a nominal OD of 1.900″ (48.26mm) or less may vary no more than 0.5 percent of the specified size, rounded to the closest 0.005″ (0.13mm). Outside diameter may not vary more than 0.75 percent, rounded to the closest 0.005″, for nominal ODs of 2″ (50.8mm) and greater.

Square and rectangular structural tubes must be measured across the flats with an allowance for convexity or concavity. The dimensions specified must not exceed the plus/minus tolerances stated in the table below.

Outside Dimensional Tolerances for ASTM A500 Square & Rectangular Steel Tubing

There are multiple considerations that must be accounted for when determining the outside dimensional tolerances for square and rectangular steel tubing. The chart below and the following attributes describe the exact outside dimensional tolerances for A500 carbon steel.

Outside Large Flat Dimension	2½ in or under	Over 2½ to 3½ in	Over 3½ to 5½ in	Over 5½ in
Outside Large Flat Dimension	63.5mm or under	Over 63.5mm – 88.9mm	Over 88.9mm – 139.7mm	Over 139.7mm
Large Flat Dimension Tolerance	± 0.020 in	± 0.025 in	± 0.030 in	0.01 times large flat dimension
Large Flat Dimension Tolerance	± 0.51mm	± 0.64mm	± 0.76mm	0.01 times large flat dimension

Wall Thickness Requirement

Minimum wall thickness at any point of measurement shall not be less than 90% of specified nominal wall thickness. Maximum wall thickness, excluding weld seams, shall not be more than 110% of specified nominal wall thickness. Wall thickness of square structural tubing and rectangular structural tubing must be measured at the center of the flat.

Straightness Requirement

For a structural tube, the allowable variation in straightness is 1/8″ times the entire length in feet (or 10.4mm times the number of meters) divided by five.

Side Squareness Requirement

For square structural tubing and rectangular structural tubing, adjacent sides may deviate from 90° by no more than ±2°.

Applications of ASTM A500 Steel Structural Pipe

Depending on its size, A500 structural pipe is used in construction, heavy equipment, agricultural, machinery, fabrication, and general structural purposes. In construction, they are often used as support beams or columns. In heavy equipment manufacturing, they are used in the construction of machineries such as tractors and excavators. In agriculture, they are often used in the construction of irrigation systems. In fabrication, they are commonly used to create sections for steel beams and pillars. As a result, ASTM A500 structural pipes have a wide range of applications in many industries. ASTM A500 tubing comes in four grades: Grade A, Grade B, Grade C, and Grade D. Each grade has specific chemical requirements as well as different mechanical property requirements that must be met in order to be considered ASTM A500-compliant.

ASTM A500 Carbon Steel Structural Tubing Benefits

ASTM A500 Carbon Steel Structural Tubing has various advantages that make it a popular building material for structural load-bearing applications. Some of the most noticeable advantages that A500 Carbon Steel Structural Tubing offers are: