ISO 6362-6:2025

Overview

ISO 6362-6:2025 - Wrought aluminium and aluminium alloys - Extruded rods/bars, tubes and profiles - Part 6 - specifies tolerances on form and dimensions for extruded aluminium tubes with round, square, rectangular and hexagonal cross-sections. The standard applies to extruded round tubes with diameters from 13 mm to 450 mm and to square, rectangular and hexagonal tubes with a circumscribing circle up to 350 mm. Alloy designations follow the four‑digit system in the Registration of International Alloy Designations (the “Teal sheets”).

Key technical topics and requirements

• Scope and material groups: Divides commonly used wrought alloys into Group I and Group II with separate tolerances; different rules for seamless and porthole extruded tubes.
• Dimensional tolerances:
  • Round tube diameter tolerances by size and alloy group (examples from the standard: for D = 13–25 mm, maximum deviation at any point ±0.51 mm for Group I and ±0.76 mm for Group II).
  • Width/depth/width‑across‑flats tolerances for non‑round tubes with size bands and multipliers for very thin walls.
  • Rule: when outside diameter (DO), inside diameter (DI) and wall thickness (t) are specified, only two of these shall be stated on an order; standard tolerances apply to any two, not all three.
• Wall thickness and eccentricity: Tolerances on wall thickness for round and non‑round tubes, including separate provisions for wall‑thickness variation (eccentricity) for seamless and porthole tubes.
• Form tolerances: Straightness, convexity/concavity (square & rectangular), twist, angularity, corner and fillet radii, depth of dents for round tubes, and squareness of cut ends.
• Special conditions: Exceptions for tempers (e.g., O and T_510), agreement requirements for sizes outside the tables, and multipliers for wall thickness below 2.5% of the outside dimension.

Practical applications and users

ISO 6362-6:2025 is essential for:

• Extrusion manufacturers and process engineers - to set production tolerances and tooling.
• Quality inspectors and metrology labs - to verify compliance with dimensional and form tolerances.
• Purchasing and procurement teams - to prepare unambiguous orders (noting the two‑dimension rule).
• Designers and structural engineers - to ensure fit, assembly and performance when specifying extruded aluminium tubes for applications such as architectural framing, transport, heat exchangers and structural components.

Related standards

• ISO 6362 series (other parts cover inspection, mechanical properties and other profile types).
• ISO 6362-1 - Technical conditions for inspection and delivery (normative reference for Part 6).

Keywords: ISO 6362-6:2025, wrought aluminium, extruded tubes, tolerances, round tubes, square tubes, wall thickness, eccentricity, porthole tubes, seamless tubes, Teal sheets.