What governs acceptance
A500 dimensional tolerances
A500 states permissible variations for outside dimensions, wall thickness, length, straightness, twist, and corner geometry. The purchased standard and your order govern acceptance — this page explains how to think about them.
On this page
The short answer
A500 defines permissible variations appropriate to a structural product: outside-dimension tolerances that scale with size, a wall-thickness tolerance applied to the specified nominal wall, length and straightness limits, and — for shaped sections — twist and corner provisions. The numeric limits are controlled content in the purchased standard and are reproduced here neither in full nor in part.
The practical headline: A500 tolerances are looser than mechanical-tubing expectations. If your application needs a tube to slide, press, seal, or be machined to a fit, you are usually in ASTM A513 territory, not A500.
The mass tolerance and design wall
A500 permits the delivered mass of a section to fall below the theoretical mass computed from nominal dimensions. This is why North American design practice applies a reduced design wall thickness to A500 HSS, and why calculated theoretical weight must never be used as an acceptance criterion. If the delivered-versus-nominal gap matters to your design, ASTM A1085 was written specifically to tighten it.
Applying tolerances in practice
Measure outside dimensions away from the weld and away from cut ends, following the measurement provisions of the standard. Remember that squareness of sides, corner radii, and twist interact on shaped sections: a stick that passes each individual check can still fight a fixture if the drawing assumed sharper corners than the product has.
If a requirement tighter than the standard's default matters to your assembly, negotiate it explicitly with the producer and put it on the order. The standard's defaults are what you get when you stay silent.
- Tolerances apply to the specified dimensions on the order, not to scaled drawing values
- Twist and straightness accumulate over length — state cut lengths where they matter
- Never accept or reject on calculated weight; use the standard's measurement provisions
Sources and limitations
- ASTM A500/A500M-23 — Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes — ASTM International. Controlling specification for grades, shapes, tolerances, testing, and ordering requirements. Purchase the current edition for all normative values.
- ASTM A1085/A1085M-22 — Standard Specification for Cold-Formed Welded Carbon Steel Hollow Structural Sections (HSS) — ASTM International. Controlling specification for the tighter HSS product, used for the A500-vs-A1085 comparison.
- AISC Steel Construction Manual and Specification for Structural Steel Buildings — American Institute of Steel Construction. Design-side reference for HSS section properties and the design wall thickness convention applied to A500 product.
These sources informed this page but do not substitute for the purchased standard. Numeric requirements — strengths, chemistry, and tolerance tables — are controlled ASTM content and are deliberately not reproduced on this site. The current official edition, your drawing, and your purchase order govern acceptance.