Aluminium channels
1985 Edition

Scope and Principal Specifications for Aluminium Channels as per IS 3921

Scope (Clause 2.0)

• Defines the aluminium channel profiles covered by this standard.
• Establishes standard dimensions, sectional properties, and marking criteria for aluminium channels used in structural contexts.

Principal Specifications (Clause 6.1 & Table 1)

• Channel designations (e.g., ALC 40x20-0.44) include:
  • Weight per unit length (kg/m)
  • Cross-sectional area (cm²)
  • Section depth (h) and flange width (b) (mm)
  • Thickness of web (tw) and flange (tf) (mm)
  • Root radius (mm)
  • Centroid location (Cy, cm)
  • Moments of inertia (Ix, Iy, cm⁴)
  • Radii of gyration (rx, ry, cm)
  • Section modulus (Zx, Zy, cm³)

Dimensional Allowances (Clause 6.2)

• Tolerances as prescribed in IS 3965-1981 for aluminium profiles.

Rounding Protocol (Clause 0.7)

• Results from testing or calculations should be rounded following IS 2-1960 to match the significant figures of the specified parameters.

Sample Specification Extract (ALC 40x20-0.44)

The standard offers detailed sectional data to support design and quality assurance.

IS 3921 - Terminology and Abbreviations (Clauses 2.0, 3.1, 6.1)

Principal Symbol Definitions:

Key Formulas:

• Section Modulus: [ Z_x = \frac{I_x}{C_x}, \quad Z_y = \frac{I_y}{C_y} ]
• Radius of Gyration: [ r_x = \sqrt{\frac{I_x}{a}}, \quad r_y = \sqrt{\frac{I_y}{a}} ]

Sample from Table 1 (Aluminium Channels):

Materials and Aluminium Alloys as per IS 3921

1. Alloy and Temper Standards (Clause 5.1.1)

• Aluminium alloys must adhere to IS: 733-1983.
• Typical alloys include: 19000, 24345, 24534, 52000, 53000, 63400, 64423, 64430, 65032, 74530.
• Temper conditions defined by IS: 733 ensure adequate strength and ductility.

2. Dimensional and Sectional Parameters (Clause 6.1 & Table 1)

• Channel sections are characterized by designation, mass per meter, sectional area, depth (h), width (b), thickness of web (tw) and flange (tf), root radius (r), centroid location (Cy), moments of inertia (Ix, Iy), radii of gyration (Tx, Ty), and section modulus (Zx, Zy).

3. Illustrative Example (ALC 50x30-1.14)

• Mass per meter: 1.14 kg
• Sectional area: 4.23 cm²
• Depth (h): 50 mm
• Width (b): 30 mm
• Thickness (tw, tf): 4 mm
• Root radius: 6 mm
• Moments of inertia: Ix = 15.80 cm⁴, Iy = 3.52 cm⁴
• Section modulus: Zx = 6.32 cm³, Zy = 1.72 cm³

Summary:

• Aluminium alloys must comply with IS: 733-1983.
• Selection of alloy and temper depends on application requirements.

Dimensional and Sectional Properties of Aluminium Channels under IS 3921

Highlights from Clause 6 (Table 1 Overview)

Sample Dimensions and Properties (ALC 60x30-1.55)

Additional Information:

• Dimensional tolerances are established by IS 3965-1981.
• Aluminium alloy requirements conform to IS 733-1983.
• Sectional properties support structural calculations such as bending and shear.

Manufacturing Guidelines for Aluminium Channels as per IS 3921

Essential Points from Clause 6.1.1 and Table 1:

• Aluminium channels with dimensions not listed in Table 1 may be produced subject to mutual consent between purchaser and manufacturer.
• Alloys and tempers must comply with IS 733-1983 (Clause 5.1.1).
• Table 1 contains comprehensive sectional properties for standard aluminium channels.

Key Parameters Defined in Table 1:

Sample Data (ALC 50x30-1.14):

• Mass per meter: 1.14 kg
• Sectional area: 4.23 cm²
• Depth: 50 mm
• Flange width: 30 mm
• Thickness web and flange: 4 mm
• Root radius: 6 mm
• Moment of inertia Ix: 15.80 cm⁴, Iy: 3.52 cm⁴
• Section modulus Zx: 6.32 cm³, Zy: 1.72 cm³

Summary:

• Standard dimensions and sectional properties are detailed in Table 1.
• Custom sizes are permissible with purchaser-manufacturer agreement.
• Alloy and temper conformity to IS 733-1983 is mandatory.
• Sectional data facilitates structural analysis for strength and stability.

flowchart TD
    A[Select Aluminium Channel] --> B{Is it a Standard Size?}
    B -- Yes --> C[Use Table 1 Data]
    B -- No --> D[Custom Size with Agreement]
    C & D --> E[Manufacture as per IS 3921]

Marking and Packaging Guidelines According to IS 3921

Marking (Clause 8.1):

• Aluminium channels must bear clear markings indicating:
  • Channel designation
  • Alloy and temper designation
  • Manufacturer’s name or trademark
  • Batch number or manufacturing year

ISI Certification Mark (Clause 8.2):

• Channels may display the ISI mark indicating compliance.
• Usage of the ISI mark is regulated under the Indian Standards Institution (Certification Marks) Act.
• The ISI mark certifies adherence to IS 3921 with ongoing inspection and quality assurance.

Production Details from Table 1 (Clause 6.1):

Example: Aluminium Channel ALC 100x50-4.09

Quality Control and Testing Under IS 3921

1. Rounding Off Results (Clause 0.7)

• Test outcomes must be rounded according to IS 2:1960.
• The number of significant digits in reported results should correspond to those of the specified values.

2. Marking and Identification (Clauses 2.7 & 6.1)

• Channels are marked assuming aluminium density of 2.7 g/cm³.
• Table 1 lists detailed sectional data including:
  • Mass per metre (kg/m)
  • Cross-sectional area (cm²)
  • Depth, width, thicknesses (mm)
  • Root radius (mm)
  • Centroid position (cm)
  • Moments of inertia (Ix, Iy in cm⁴)
  • Radii of gyration (Tx, Ty in cm)
  • Section moduli (Zx, Zy in cm³)

3. Testing Requirements

• Dimensional verification must confirm tolerances.
• Mechanical properties should be validated through tests compliant with relevant standards.
• Sectional properties from Table 1 should be used for structural design verification.

Sample Data Extract (ALC 50x30-1.14)

Overview Diagram of Sectional Parameters

flowchart LR
    A[Aluminium Channel Profile] --> B[Section Dimensions]
    A --> C[Mechanical Properties]
    B --> D[Mass, Area, Depth, Width]
    C --> E[Inertia, Modulus, Radius of Gyration]

Guidelines for Use of ISI Mark on Aluminium Channels per IS 3921

Clause 8.2 Overview:

• Wrought aluminium and aluminium alloy channels may bear the ISI Certification Mark.
• The ISI symbol certifies conformance with the standard through a rigorous regime of inspection, testing, and quality oversight by ISI.
• Licensing for use of the ISI mark is governed by the Indian Standards Institution (Certification Marks) Act.
• Manufacturers must obtain appropriate licenses from ISI to apply the mark legally.

Key Aspects of ISI Mark Usage

Additional Information

• The ISI mark represents verified product quality and standard adherence.
• Manufacturers must maintain ISI-approved quality control systems.
• ISI conducts periodic audits and random product sampling to ensure continued compliance.

flowchart LR
    A[Manufacturer Applies for ISI License] --> B{License Granted?}
    B -- Yes --> C[Produce ISI Marked Products]
    B -- No --> D[Cannot Use ISI Mark]
    C --> E[Continuous ISI Surveillance & Testing]
    E -- Compliant --> F[Market Products]
    E -- Non-compliant --> G[License Suspension or Revocation]

Rounding Off Numerical Data as Specified in IS 3921

• Reference Standard: IS 2-1960 governs rounding practices.
• Procedure: Final test or calculated figures must be rounded to the same number of significant digits as the values specified in the standard.
• This ensures consistency and standard compliance in data reporting.

Rounding Rules Summary (IS 2-1960):

• Maintain the decimal places or significant figures as per the original specification.
• Example: For a specified value of 3.55 (two decimal places), 3.546 rounds to 3.55, while 3.544 rounds to 3.54.

Additional Notes from IS 3921:

• Dimensional tolerances for aluminium sections follow IS 3965-1981.
• Sectional property values in Table 1 are rounded according to these rules.

flowchart TD
    A[Measured/Calculated Value] --> B{Number of Significant Figures}
    B -->|Matches Specified| C[Round According to IS 2-1960]
    C --> D[Final Rounded Number]
    D --> E[Compliance Verification]

Essential Tables, Symbols, and Formulas in IS 3921 for Aluminium Channels

Table 1: Aluminium Channel Dimensions and Properties

• Lists detailed dimensions, weight, and sectional properties for various aluminium channel designations (e.g., ALC 40x20-0.44).
• Properties include:
  • Weight per metre (kg/m)
  • Cross-sectional area (cm²)
  • Depth (h), Flange width (b), Web and flange thickness (tw, tf) (mm)
  • Root radius (mm)
  • Centroid location (Cy, cm)
  • Moments of inertia (Ix, Iy, cm⁴)
  • Radii of gyration (rx, ry, cm)
  • Section modulus (Zx, Zy, cm³)

Common Symbols (Clause 3.1):

Notes:

• Mass per metre calculations assume aluminium density of 2.7 g/cm³ (Clause 2.7).
• Table 1 provides essential data for design and analysis by referencing sectional properties.

Sample Extract from Table 1: