What Is ASTM A513?
ASTM A513 covers electric-resistance-welded (ERW) carbon and alloy steel tubing for mechanical applications. Unlike pressure pipe, A513 tubing is ordered to dimensions and mechanical properties that suit machined components, structural members and fluid-transfer lines in machinery. The specification is divided into types that describe the manufacturing route, from simple cold drawing to mandrel-drawn tubing with a smooth internal surface, commonly known as DOM.
Grade System: SAE Numbers, Not Grade Letters
A513 orders tubing by SAE steel numbers rather than by letter grades. Common carbon grades include 1008, 1010, 1015, 1018, 1020 and 1026; alloy options include 4130, 4140 and 8620. The specification also recognizes MT grades such as MT1010 and MT1020, which carry guaranteed minimum mechanical properties for high-volume applications such as automotive components.
Mechanical Properties of Common Grades
Mechanical properties depend on the grade and the tubing type. The table below lists representative minimum requirements for hot-rolled, as-welded Type 5 tubing of the most common carbon grades:
| Grade | Yield Strength (min) | Tensile Strength (min) |
|---|---|---|
| 1010 | 172 MPa (25 ksi) | 345 MPa (50 ksi) |
| 1020 | 241 MPa (35 ksi) | 414 MPa (60 ksi) |
| 1026 | 276 MPa (40 ksi) | 483 MPa (70 ksi) |
Cold-drawn tubing (Type 1) typically shows higher yield and tensile values than the as-welded condition because of work hardening, so the ordering document must state the required type and any minimum property guarantees.
Manufacturing Types and Their Effect on Quality
| Type | Description | Typical Use |
|---|---|---|
| Type 1 | Cold drawn | Precision shafts and cylinders |
| Type 2 | Cold drawn, mandrel drawn | Uniform wall, machined parts |
| Type 3 | Cold drawn, special smooth inside (DOM) | Hydraulic cylinders |
| Type 4 | Hot rolled | Structural and general use |
| Type 5 | Hot rolled, pickled and oiled | Further forming and drawing |
| Type 6 | Hot rolled, pickled and limed | Wire and tube drawing stock |
For hydraulic cylinder barrels, DOM tubing is preferred because the internal flash is removed, giving a smooth bore that minimizes piston seal wear.
Dimensional and Surface Quality Parameters
Outside diameter tolerances for cold-drawn tubing are typically tighter than for hot-rolled, with common control of plus or minus 0.1 mm on small diameters.
Wall thickness is ordered by minimum wall or nominal wall; DOM tubing controls the internal surface finish to a specified roughness.
The weld seam is visible in as-welded product; after drawing, the seam remains sound but is less visible.
Lengths are commonly supplied in random lengths of 5 to 7 m, with cut-to-length service available.
Typical Applications
Hydraulic and pneumatic cylinder barrels.
Automotive components such as drive shafts, steering columns and suspension parts.
Furniture frames, exercise equipment and structural members.
Machinery rolls, spacers, bushings and fluid-transfer lines in equipment.
Common Misconceptions
"A513 pipe is seamless." It is electric-resistance-welded; for seamless mechanical tubing the correct standard is ASTM A519.
"A513 grades are A, B and C." A513 uses SAE steel numbers such as 1010, 1020 and 1026; the letter-grade system belongs to other standards such as A500.
"A513 can be used for pressure piping." A513 is a mechanical tubing standard without pressure ratings; use A106, A53 or A333 for pressure service.
FAQ
Q1: What does DOM mean in A513 tubing?
A: DOM stands for drawn-over-mandrel, a cold-drawing process that produces a smooth internal surface free of weld flash, ideal for hydraulic cylinder bores.
Q2: What is the difference between A513 and A500?
A: A513 is ERW mechanical tubing ordered by SAE grade and type; A500 is structural hollow structural sections ordered by letter grade with guaranteed structural properties.
Q3: Can A513 tubing be welded?
A: Yes. Carbon grades weld readily with standard processes; alloy grades such as 4130 require preheat and post-weld heat treatment for high-strength joints.
Q4: What is the typical yield strength of A513 1020 tubing?
A: For hot-rolled Type 5 tubing, the minimum yield is about 241 MPa and minimum tensile about 414 MPa; cold-drawn product is typically higher.
Q5: Is the weld seam of A513 tubing detectable after drawing?
A: The seam remains present but becomes much less visible after cold drawing; eddy-current testing can verify seam integrity when required.
Q6: What size range is A513 available in?
A: Common supply covers outside diameters from about 6 mm to 200 mm with wall thicknesses from 0.5 mm to 12 mm, depending on the manufacturer.