A500 vs. A513
Both are welded carbon steel tube, and they can look identical. The difference is what the specification promises: strength, or size and finish.
Side by Side.
Order A500 when the tube carries a load an engineer calculated. Order A513 when fit, bending and finish matter most.
| A500structural | A513mechanical | |
|---|---|---|
| Promises | Minimum strength | Size, wall and finish |
| Yield, square | 46,000 psi (B) / 50,000 psi (C) | Set by the steel grade |
| Yield, round | 42,000 psi (B) / 46,000 psi (C) | Set by the steel grade |
| Size tolerance | Wider | Tighter |
| Finishes | Hot rolled, P&O, galvanized | Type 1a hot rolled, Type 1b P&O |
| Typical use | Building frames, trailers, racks | Furniture, fitness, automotive parts |
Most structural tube is certified to Grades B and C on one test report, so it meets either on a drawing.
Grades and Types.
Each specification is split further. A500 is split by strength, A513 by the steel the tube is made from.
A500 Grade B
Minimum yield of 46,000 psi for square and rectangular tube and 42,000 psi for round, with a minimum tensile strength of 58,000 psi.
A500 Grade C
Minimum yield of 50,000 psi for square and rectangular tube and 46,000 psi for round, with a minimum tensile strength of 62,000 psi. Tube that meets C also meets B.
A513 Type 1
Made from hot-rolled steel. Type 1a keeps the mill scale; Type 1b is made from pickled and oiled steel, with the scale removed.
A513 Type 2
Made from cold-rolled steel, for a smoother surface. Strength in A513 follows the steel grade, such as MT 1010 to MT 1020.
Which One to Order.
If the drawing says A500 or HSS, order A500. An engineer sized that member from the spec's minimum strength, and the mill test report has to show it. Frames, trailer rails, racks and posts usually fall here.
If the part slides into another part, gets bent on a mandrel, or shows its surface, A513 is usually the better fit. Its outside size tolerance is tighter, so sleeves and telescoping pieces fit the same every time.
If you are not sure, tell us what the tube does and how it will be welded, bent or painted, and Sales will suggest a spec.
Questions.
The tolerances for each spec are on How to Measure Tube.
What is the difference between A500 Grade B and Grade C?
Strength. Grade C has a minimum yield of 50,000 psi on square and rectangular tube, against 46,000 psi for Grade B, and a minimum tensile of 62,000 psi against 58,000. Much structural tube is certified to both grades on one report.
Can A513 tube be used in place of A500?
Not unless the engineer agrees. A513 does not promise the minimum strength that A500 does, so it should not replace A500 where a drawing calls for structural tube.
What do A513 Type 1 and Type 2 mean?
They name the steel the tube is made from. Type 1 is hot-rolled steel (1a with mill scale, 1b pickled and oiled); Type 2 is cold-rolled steel.
Why does A513 have tighter tolerances than A500?
Mechanical tube goes into parts that have to fit, slide or bend the same way every time. A 2 x 2 in A513 is held to about .008 inch either way across the flats, against about .020 inch for A500.
How do I know which spec and grade my tube meets?
Check the mill test report. It names the specification and grade and gives the tested yield and tensile strength for the heat of steel the tube was made from.
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