ISO 12633-2:2011

Overview

ISO 12633-2:2011 - "Hot‑finished structural hollow sections of non‑alloy and fine grain steels - Part 2: Dimensions and sectional properties" specifies the dimensional tolerances, measurement methods and sectional properties for hot‑finished circular, square and rectangular structural hollow sections. The standard complements ISO 12633‑1 (technical delivery conditions) and provides nominal dimensions and calculated sectional properties for a range of standard sizes.

Key topics and technical requirements

• Tolerances on geometry and mass: outside dimensions ±1% (minimum ±0.5 mm, maximum ±10 mm); thickness tolerance −10%; mass per unit length ±6% (special note for seamless sections).
• Shape controls: out‑of‑roundness for circular sections ≤ 2% where D/t ≤ 100; concavity/convexity for square/rectangular sides ≤ 1%; squareness 90° ± 1°.
• Other limits: external corner profile length up to 3T at each corner; twist limited to 2 mm + 0.5 mm/m length; straightness limited to 0.2% of total length.
• Length tolerances: random, approximate and exact length options are defined (e.g., approximate length ±500 mm by default; exact lengths have tight positive tolerances). Option to tighten approximate length is available.
• Weld bead height: for submerged‑arc‑welded sections maximum internal/external bead heights are specified (≤ 3.5 mm for T ≤ 14.2 mm; ≤ 4.8 mm for T > 14.2 mm).
• Measurement and calculation: measurement positions and procedures are defined (measure outside dimensions at ≥ D/B/H from the end, thickness at ≥ 2T from weld). Out‑of‑roundness is calculated as (Dmax − Dmin)/D × 100. Annex A provides formulae for sectional properties (area, second moment of area, section moduli, torsional constants).

Applications and who uses this standard

• Manufacturers and mill quality control: to set production tolerances, inspect finished hollow sections and verify conformity.
• Structural and civil engineers: to select appropriate hollow section sizes and use reliable sectional properties in structural analysis and design.
• Fabricators and detailers: for estimating cuts, fits and weld preparation knowing corner radii, wall thickness limits and straightness.
• Procurement/specifiers and inspectors: to prepare purchase orders (mandatory purchaser information is defined) and to accept/reject deliveries according to tolerances.

Related standards

• ISO 12633‑1: Technical delivery conditions for hot‑finished structural hollow sections - required for material and delivery requirements.
• Other regional or product standards may reference ISO 12633‑2 for dimensions and sectional data.

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