Overview
ISO 6363-6:2022 specifies tolerances on form and dimensions for wrought aluminium / aluminum cold-drawn round tubes (both seamless and porthole). The standard applies to cold-drawn round tubes and defines how to inspect and accept dimensional variations such as outside diameter (OD), inside diameter (ID), wall thickness, fixed lengths, squareness of cut ends and straightness. Alloy grouping (Group I and Group II) used for tolerance selection is also included.
Key topics and requirements
- Scope: Tolerances apply to cold-drawn round tubes (seamless and porthole). Temper O, coiled tubes and very thin walls have specific notes/exceptions.
- Alloy groups: Tubes are classified into Alloy Group I and Alloy Group II (see Tables 1–2) - different tolerance limits apply by group.
- Dimension selection rule: When OD, ID and wall thickness are all specified, standard tolerances apply to any two of these; purchasers should specify only two nominal dimensions.
- Diameter tolerances (Table 3): Maximum allowable deviation at any point and for mean diameter are provided by OD/ID ranges and alloy group. Values are given per diameter bands (e.g., 4–12 mm, 12–25 mm, etc.).
- Wall thickness tolerances (Table 4): Limits for maximum deviation at any point and mean wall thickness are set by wall thickness ranges; special rules for coiled tubes and thin walls (percentage-based minima) are included.
- Fixed-length tolerances (Tables 5–6): Permitted deviations for straight and coiled tubes depend on OD and length bands; coiled tube length tolerances are expressed as percentages.
- Squareness of cut ends: Defined as within half of the fixed-length tolerance range.
- Straightness (Table 7): Maximum allowable deviation for any 300 mm length and for total length, with measurement method described (tube on flat surface). Exceptions apply for temper grade O.
- Normative references and materials: Uses ISO 6363-1 terms/definitions and references alloy listings in ISO 6362-7 and the Aluminum Association “Teal sheets”.
Applications and who uses it
- Manufacturers and mill operators of cold-drawn aluminium tubing for mechanical, heat exchanger, automotive, aerospace and construction applications.
- Quality engineers, inspection laboratories and purchasing/specification teams who need standardized tolerances for drawn round tubes.
- Designers and OEMs requiring consistent tube geometry for assembly, fitting, pressure performance, or finishing operations.
Related standards
- ISO 6363-1 - Technical conditions for inspection and delivery (terms and general rules).
- ISO 6362-7 and Aluminum Association “Teal sheets” - alloy chemical composition and designation references.
Keywords: ISO 6363-6:2022, tolerances, aluminium tubes, cold-drawn round tubes, drawn round tubes, outside diameter, wall thickness, straightness, squareness, alloy groups.