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IS 6445:1985 is the Indian Standard (BIS) for aluminium tee-sections. This standard specifies the dimensions, mass, sectional properties, and manufacturing tolerances for a range of hot-rolled or extruded aluminium and aluminium alloy tee-sections. It provides a standard table of section profiles intended for use in structural and general engineering applications.
Aluminium tee-sections
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Structural Engineering and Structural Sections
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Always specify the required material grade and temper (e.g., 6063-T6) along with the section designation, as properties vary significantly.
! Refer to Table 1 for standard available sizes during the design phase to ensure material availability and cost-effectiveness.
! These sections are ideal for applications requiring a good strength-to-weight ratio, such as architectural facades, window systems, and lightweight frames, but not typically for primary heavy-load-bearing structures.
EN 755-9:2016CEN (European Committee for Standardization), Europe
HighCurrent
Aluminium and aluminium alloys - Extruded rod/bar, tube and profiles - Part 9: Profiles, tolerances on dimensions and form
Specifies tolerances on dimensions and form for general purpose extruded aluminium profiles, including tee-sections.
ASTM B221-21ASTM International, USA
MediumCurrent
Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
Covers a broad range of extruded products; its tables for dimensional tolerances on profiles apply to tee-sections.
ISO 6362-4:2014ISO (International Organization for Standardization), International
HighCurrent
Wrought aluminium and aluminium alloys — Extruded rods/bars, tubes and profiles — Part 4: Tolerances on form and dimensions for profiles
Defines tolerances on form and dimensions for extruded profiles, directly applicable to tee-sections.
BS EN 755-9:2016BSI (British Standards Institution), UK
HighCurrent
Aluminium and aluminium alloys. Extruded rod/bar, tube and profiles. Profiles, tolerances on dimensions and form
The UK's adoption of the European standard, EN 755-9, covering tolerances for all extruded profiles.
Key Differences
≠IS 6445 is a dedicated dimensional standard specifically for a list of predefined tee-sections, whereas international standards like EN 755-9 and ASTM B221 provide general tolerance rules applicable to any extruded profile shape.
≠Alloy designations are different. IS 6445 uses Indian designations (e.g., 63400, 64430), while international standards use EN-AW numbers (e.g., EN AW-6060) or AA numbers (e.g., 6061, 6063).
≠IS 6445:1985 is significantly older than its current international counterparts (e.g., EN 755-9:2016). This means international standards reflect more modern manufacturing capabilities and often specify tighter tolerances.
≠International standards like EN 755-9 offer different tolerance classes (e.g., for precision profiles), allowing for more specific engineering requirements, a feature not present in IS 6445.
Key Similarities
≈All standards serve the fundamental purpose of defining acceptable dimensional and form deviations for extruded aluminium profiles to ensure product quality and interchangeability.
≈Core geometric parameters like section height, flange width, element thickness, straightness, twist, and angularity are covered in both IS 6445 and its international equivalents.
≈All standards are based on wrought aluminium and its alloys suitable for the extrusion process, and typically refer to separate standards for material composition and mechanical properties.
≈The methodology of defining tolerances is similar, generally specified as a plus/minus deviation (e.g., ±0.X mm) or a maximum deviation per unit length (e.g., X mm/m).
Parameter Comparison
Parameter
IS Value
International
Source
Referenced Alloy Grade (Example)
Grade 63400 (HE9)
EN AW-6063
EN 755-2
Straightness Tolerance
1.5 mm per metre length
0.7 mm per 1000 mm length (for profile with enclosing circle diameter ≤ 300 mm)
EN 755-9:2016
Thickness Tolerance (for 3mm thickness)
±0.25 mm (for thickness >1.5 up to 3.0 mm)
±0.22 mm (for wall thickness >2.0 up to 5.0 mm, simple solid profile)
EN 755-9:2016
Angularity Tolerance (for leg thickness ≤ 5mm)
±2°
±1.5° (standard tolerance)
EN 755-9:2016
Twist Tolerance (for flange width 'W' 25-50mm)
1.0° per metre length
1.0° per metre length (for W ≤ 50mm)
EN 755-9:2016
Corner Radii
Specifies standard corner radii for each tee-section size (e.g., 0.8mm for ISA 2020).
Does not mandate specific radii, but provides tolerances on specified radii (e.g., ±0.5 mm for R ≤ 5 mm).
EN 755-9:2016
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Mass of section AT 50 x 50 x 50.656 kg/m
Sectional area of section AT 50 x 50 x 52.43 cm²
Tolerance on depth/width for sections up to 75 mm± 0.8 mm
Tolerance on thickness for 3 mm to 6 mm± 0.4 mm
Standard length of sections3 m to 6 m
Tables & Referenced Sections
Key Tables
Table 1 - Dimensions, Weight and Sectional Properties of Aluminium Tee-Sections
How is an aluminium tee-section designated under this standard?+
By the prefix 'AT' followed by depth, flange width, and thickness in millimeters, for example, AT 50 x 50 x 5 (Clause 3).
What material grades should be used for these sections?+
This standard refers to IS 733 for material specifications, which includes common grades like 6061, 6063, and 6082 in various tempers.
What is the tolerance on straightness for these sections?+
Permissible deviation from straightness is 1.25 mm per metre length (Clause 6.3).
Where can I find the moment of inertia and other properties?+
All sectional properties, including area, mass, moment of inertia (Ixx, Iyy), and radius of gyration (rxx, ryy) are listed in Table 1 for each standard section.