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The main difference between A500 and A513 steel tubing is their intended use. ASTM A500 specifies structural tubing with minimum strength requirements for load-bearing applications. ASTM A513 covers electric-resistance-welded mechanical tubing, where dimensional accuracy, surface finish and fabrication performance are often more important.
Buyers comparing A513 and A500 steel tubing should choose A500 when structural calculations require certified strength. A513 is more suitable for machined, plated, telescoping or precision-fit components.
| Comparison | ASTM A500 | ASTM A513 |
| Primary purpose | Structural tubing | Mechanical tubing |
| Material | Carbon steel | Carbon and alloy steel |
| Manufacturing | Welded or seamless | Electric-resistance welded |
| Main priority | Certified strength | Dimensional accuracy |
| Common products | Columns, frames and supports | Machinery and automotive parts |
| Mechanical properties | Minimum values specified | Depend on grade, type and condition |
| Tolerances | Structural-grade tolerances | Generally tighter tolerances |
What Is ASTM A500 Structural Steel Tubing?
ASTM A500 covers cold-formed welded and seamless carbon steel structural tubing in round, square, rectangular and special shapes. Square and rectangular products are commonly known as hollow structural sections, or HSS.
The specification controls chemical composition, tensile strength, yield strength, elongation, dimensions and product inspection. These requirements allow engineers to use A500 tubing in structural calculations.
Grades B and C are the most common options. For square and rectangular tubing:
- Grade B has a minimum yield strength of 46 ksi, or 315 MPa.
- Grade C has a minimum yield strength of 50 ksi, or 345 MPa.
Round tubing has different minimum yield values, so figures for square and rectangular sections should not be applied automatically to round products.
Common A500 applications include:
- Columns and beams
- Building frames
- Roof trusses and braces
- Bridge components
- Equipment supports
- Solar mounting structures
- Architecturally exposed steelwork
Buyers sourcing ASTM A500 HSS can review BAOLAI’s square and rectangular steel pipes in different standards, grades, dimensions and surface finishes.
What Is ASTM A513 Mechanical Steel Tubing?
ASTM A513 covers electric-resistance-welded carbon and alloy steel mechanical tubing. It includes round, square, rectangular and special shapes made from hot-rolled or cold-rolled steel.
A513 is divided into several manufacturing types:
- Type 1a: Hot-rolled steel with mill scale
- Type 1b: Hot-rolled, pickled and oiled steel
- Type 2: Cold-rolled steel
- Type 3: Sink-drawn hot-rolled tubing
- Type 4: Sink-drawn cold-rolled tubing
- Type 5: Drawn-over-mandrel tubing
- Type 6: Special smooth inside diameter tubing
The type affects dimensional accuracy, surface condition and internal weld-bead control. Type 1 is suitable for general fabrication, while Type 2 provides a cleaner surface. Type 5 DOM offers better concentricity and dimensional consistency. Despite its name, DOM begins as welded tubing and is not seamless.
Common A513 applications include:
- Automotive components
- Machinery parts
- Furniture frames
- Fitness equipment
- Agricultural equipment
- Rollers and bushings
- Telescoping assemblies
- Precision welded components
What Are the Key Differences Between A500 and A513?
Strength Requirements
A500 defines minimum yield strength, tensile strength and elongation for each grade. These properties support structural design and material verification.
A513 does not provide one uniform minimum strength for every product. Its properties depend on the steel grade, tubing type, cold working and thermal condition.
This does not mean A513 cannot carry any load. It means the A513 designation alone does not provide the same structural guarantee as A500.
Materials and Manufacturing
A500 applies only to carbon steel and may be welded or seamless. Welded A500 tubing is normally produced through electric-resistance welding.
A513 covers both carbon and alloy steel but applies specifically to ERW mechanical tubing. Additional drawing or heat treatment may be used to improve tolerances, surface quality or residual stress.
Dimensional Tolerances
A513 generally provides tighter dimensional tolerances because mechanical components may need to fit inside bearings, sleeves or other parts.
A500 tolerances are suitable for structural fabrication but may be too broad for precision assembly. Important dimensions include:
- Outside diameter
- Wall thickness
- Ovality
- Straightness
- Corner radius
- Inside diameter
- Internal weld bead
Tolerance values depend on the shape, size and A513 type. A value stated for one round tube should not be applied to every square or rectangular section.
Surface Finish and Weld Bead
A500 commonly has a mill finish suitable for welding, painting or galvanizing.
A513 offers more surface options. Type 1b removes hot-rolled scale through pickling and oiling, while Type 2 starts with cold-rolled steel. DOM and smooth-ID products provide additional control where internal fit or surface quality matters.
The internal weld bead may be acceptable in a frame but interfere with a shaft or telescoping component. This requirement should be stated in the purchase order.
Testing and Documentation
A500 tubing is tested against the chemical and mechanical requirements of its grade. A mill test report can confirm strength, composition and traceability.
An A513 order should identify any required mechanical properties, hardness, heat treatment or testing. Requesting only “ASTM A513 tubing” may not define enough information for a critical component.
Cost
Neither standard is always more expensive.
Price depends on:
- Steel grade
- Shape and size
- Wall thickness
- Order quantity
- Tolerances
- Surface condition
- Heat treatment
- Testing requirements
A basic A513 tube may be competitively priced, while Type 5 DOM usually costs more because of its additional processing. A500 can be economical in common HSS sizes but less so when a special production run is required.
Can A513 Be Substituted for A500?
A513 should not automatically replace A500 when the drawing specifies a structural grade.
Substitution is normally unsuitable when:
- The tube is part of a building or bridge.
- The design specifies minimum yield strength.
- Structural calculations use A500 HSS properties.
- The project requires compliance with a building code.
- Certified structural documentation is required.
A513 may be considered for a non-critical frame if its actual properties satisfy the design. The decision should be supported by an MTR, material testing and engineering approval.
A500 should not automatically replace A513 either. It may provide sufficient strength but fail to meet the dimensional, surface or weld-bead requirements of a precision component.
How Should You Choose Between A500 and A513?
Use A500 when strength and structural compliance are the main requirements. Use A513 when fit, finish and further processing are more important.
| Application requirement | Recommended specification |
| Building column or beam | ASTM A500 |
| Structural frame or support | ASTM A500 |
| Component requiring certified yield strength | ASTM A500 |
| Precision-machined part | ASTM A513 |
| Telescoping assembly | ASTM A513 |
| Automotive or machinery component | ASTM A513 |
| Furniture or equipment frame | Depends on load and tolerances |
A complete request for quotation should include:
- ASTM standard and edition
- Grade or A513 type
- Shape and dimensions
- Wall thickness
- Required tolerances
- Thermal condition
- Surface finish
- Weld-bead requirements
- Length and quantity
- Testing and MTR requirements
How Do A500 and A513 Compare with EN Standards?
International buyers may encounter EN 10219 for cold-formed structural hollow sections and the EN 10305 series for precision steel tubes. These standards serve functions broadly comparable to A500 and A513, but they are not direct equivalents. Steel grades, mechanical properties, tolerances, delivery conditions and inspection documents must be compared before substitution.
BAOLAI Steel Tubing Solutions
BAOLAI supplies carbon steel tubing for structural fabrication, machinery and general engineering. Available options include custom dimensions, cutting, welding, galvanizing, painting and project-specific inspection.
For an accurate quotation, provide the required standard, grade or type, dimensions, wall thickness, quantity, surface condition and destination.
Conclusion
The A500 vs A513 decision depends on what the tubing must guarantee. Choose A500 for certified structural strength and A513 for tighter dimensions, controlled surfaces and mechanical fabrication.
The final choice should follow the drawing, load, tolerance and documentation requirements rather than price alone.
Frequently Asked Questions
Are A500 and A513 tubing sizes based on OD or nominal pipe size?
They are generally specified by actual outside dimensions rather than nominal pipe size. Buyers should confirm whether a drawing refers to pipe or tube because a two-inch nominal pipe does not have a two-inch outside diameter.
Can A500 and A513 tubing be galvanized?
Yes. Both can be galvanized when the steel and application are suitable. The added zinc thickness should be considered for holes, threads and close-fitting A513 components.
Which specification is better for low-temperature applications?
Neither designation alone guarantees low-temperature toughness. Projects exposed to severe cold should state the required impact-test temperature and use an appropriate grade or alternative standard.
Is ASTM A513 suitable for hydraulic pressure lines?
A513 is a mechanical tubing specification, not automatically a pressure-service standard. Hydraulic components must meet the applicable pressure design, material and testing requirements.
Can metric and inch-pound requirements be combined in one order?
They should not be mixed. A500/A500M and A513/A513M treat SI and inch-pound values as separate systems because converted figures may not be exact equivalents. One system should govern the order.
