ISO 6362-6:2012

Overview

ISO 6362-6:2012 is an international standard that defines tolerances on shape and dimensions for extruded wrought aluminium and aluminium-alloy tubes and bars. It covers extruded round tubes/bars (diameters 8 mm to 350 mm) and extruded square and hexagonal tubes/bars (widths across flats 10 mm to 220 mm). The document specifies measurement rules, allowable deviations and grouping of common alloys by manufacturing difficulty.

Key phrases: ISO 6362-6, aluminium extruded tubes tolerances, extruded aluminium tolerances, round square hexagonal tubes.

Key topics and technical requirements

• Scope and material grouping: Alloys are divided into Group I and Group II with example alloy lists; grouping affects allowable tolerances.
• Dimension tolerances: Tabulated tolerances for outside/inside diameter and width/width-across-flats across size ranges (see Tables 3–5). The standard instructs purchasers to specify only two of OD, ID and wall thickness when all three are relevant.
• Wall thickness tolerances: Detailed limits for round and non‑round (seamless and porthole) tubes by nominal thickness and circumscribed diameter (Tables 6–8).
• Form and shape tolerances: Limits and definitions for straightness, eccentricity (wall thickness variation), convexity/concavity, twist, angularity, corner and fillet radii, squareness of cut ends and depth of dents. Annex A gives guidance on eccentricity.
• Special cases: Rules for thin-wall sections (wall thickness < 2.5 % of outside dimension) where tolerances are multiplied; special tempers (e.g., O and Tx510) require agreement between purchaser and supplier.
• Measurement conventions: Mean diameter/wall thickness are defined (average of two orthogonal measurements) and tolerances may be expressed as maximum deviation at any point or mean deviation.

Practical applications and typical users

Who uses ISO 6362-6:

• Extrusion mills and aluminium tube manufacturers for production control and quality assurance
• Purchasing/specification engineers who write procurement orders for extruded tubes and profiles
• Quality inspectors and test laboratories performing dimensional checks
• Designers and product engineers who must account for manufacturing tolerances in assemblies

Typical applications:

• Structural and mechanical components where dimensional accuracy matters (frames, supports, chassis)
• Tubes used in thermal or fluid systems where wall thickness and concentricity are critical
• Architectural and transportation extrusions requiring consistent form and finish

Related standards

• ISO 6362-1: Technical conditions for inspection and delivery
• ISO 6362-2: Mechanical properties
• ISO 6362-3, -4, -5, -7: Other parts covering rectangular bars, profiles, bars tolerances and chemical composition

Use ISO 6362-6 to ensure consistent dimensional quality and clear contractual specifications when ordering or producing extruded aluminium tubes and bars.