Hot-rolled steel L-sections for shipbuilding

IS 1864: Scope & Key Specifications for 'L' Sections

• Scope: Covers dimensions and sectional properties of 'L' (angle) sections, including standard and supplementary sizes (Table 1 and Table 1A).
• Dimensions: As per Clause 4.1, dimensions must conform to Tables 1 and 1A.
• Material: Specified in Clause 4.1.

Key Tables Summary

Sample from Table 1A (Supplementary 'L' Sections)

Sample from Table 1 (Standard 'L' Sections)

IS 1864 - Designation of L-Sections (Angles)

Key Points from IS 1864:

• Designation format (Clause 3.1):
  L H × B × t × T
  where,
  • L = Angle section
  • H = Height of web (mm)
  • B = Width of flange (mm)
  • t = Thickness of web (mm)
  • T = Thickness of flange (mm)
    Example: L 250 × 90 × 9 × 13

Typical Dimensions & Sectional Properties (from Table 1A & Table 1):

Notes:

• Radius (R) is the root radius of the angle.
• Centroid is measured from the web edge.
• Ix is the moment of inertia about the centroidal x-axis.

Summary Diagram of L-Section Dimensions:

graph LR
A[Height (H)] --> Web[Web thickness (t)]
B[Width (B)] --> Flange[Flange thickness (T)]
Web -->|Root radius (

IS 1864 - Dimensions & Sectional Properties of 'L' Sections

Key Dimensions & Properties (from Table 1 & 1A):

Notations:

• H = Height of the longer leg
• B = Width of the shorter leg
• t = Thickness of the longer leg
• T = Thickness of the shorter leg
• r = Radius of fillet
• Ix, Iy = Moment of inertia about x and y axes respectively

Important Notes:

• Table 1A lists supplementary 'L' sections available on mutual agreement.
• Dimensions are in mm; sectional properties in cm³ (section modulus), cm⁴ (moment of inertia).
• Use these properties for structural analysis and design calculations as per IS 800.

flowchart LR
    A[L Section] --> B[Dimensions: H, B, t, T, r]
    B --> C[Calculate Area]
    B --> D[Calculate Ix, Iy]
    C & D

IS 1864: Material Requirements for 'L' Sections (Clause 4.1)

Key Specifications:

• Dimensions and sectional properties of 'L' sections are given in Tables 1 and 1A.
• Tables cover size, mass, thickness, radii, centroid, moment of inertia, and section modulus.

Important Parameters from Tables 1 & 1A:

Example Extract from Table 1:

Usage Notes:

• Use these tables to select 'L' sections based on structural requirements.
• Dimensions must conform exactly to the tables for standardization.
• For sizes not listed, mutual agreement with suppliers is required (Clause 0.3).

flowchart LR
    A

IS 1864: Key Tolerances for Structural Steel Sections

1. Flange Thickness (T) Tolerance (Clause 5.3, Table 2)

2. Height of Web (H) and Width of Flange (B) Tolerance (Clause 5.1)

3. Web Thickness (t) Tolerance (Clause 5.2)

• Web thickness tolerance is specified but exact values are not in the provided context. Typically, it is similar or slightly tighter than flange thickness tolerances.

4. Mass Tolerance (Clause 5.8)

• Mass tolerance = ±2.5% of the mass per unit length (from Tables 1 and IA).

Summary Diagram:

graph TD
    A[Flange Thickness Tolerance] -->|Up to 20 mm| B(+2.0 / -0.4 mm)
    A -->|20-30 mm| C(+2.0 / -0.5 mm)
    A -->|30-35 mm| D(+2.5 / -0.6 mm)
    E[Height of Web (H) & Width of Flange (B)] -->|≤ 200 mm| F(±3 mm)
    E -->|> 200 mm| G(±4 mm)
    H[Mass Tolerance] --> I(±2.5%)

Use these tolerances for quality control and fabrication checks as per IS 1864.

IS 1864: Measurement Methods for L Sections

Key Specifications from Clause 4.1 & Table 1

• Dimensions and sectional properties for L (angle) sections are standardized.
• Mass per unit length tolerance: ±2.5% (Clause 5.8).
• Dimensions include:
  • Length (L): e.g., 200 mm to 500 mm
  • Width (b): e.g., 90 mm to 120 mm
  • Thickness (t1, t2): varies from 9 mm to 35 mm
  • Radius (r): e.g., 7.5 mm to 20 mm

Important Sectional Properties

Example (L 250 x 90 x 9 x 13)

• Mass: 26.2 kg/m
• Length: 250 mm
• Width: 90 mm
• Thickness: 9 mm & 13 mm
• Radius: 7.5 mm
• Moment of Inertia Ix: 33.4 cm⁴
• Sectional Area: 8.64 cm²

Rounding Off (Clause 0.4)

• Final values must be rounded as per IS 2-1960.
• Number of significant digits retained = number in the standard.

Summary

• Use Table 1 for dimensions and sectional properties.
• Allow ±2.5% tolerance on mass per unit length.
• Round off values per IS 2-1960.
• Section properties critical for design calculations (moment of inertia, sectional area).

flowchart TD
    A[Select L Section] --> B[Refer Table 1 for Dimensions]
    B --> C[Check Mass per unit length ±2.5%]
    C --> D[Use Section Properties (Ix, A) for design]
    D

IS 1864: Marking and Identification - Key Points

• Dimensions & Mass:

  • Dimensions for L sections are per Tables 1 and 1A (Clause 4.1).
  • Mass tolerance is ±2.5% of the mass per unit length listed in these tables (Clause 5.8).

• Identification:

  • Each section should be clearly marked with size and mass for traceability.
  • Marking usually includes:
    • Section designation (e.g., L 400 x 120 x 12.5 x 25)
    • Manufacturer’s identification
    • Heat number or batch number for quality control

• Typical Section Designation Format:
  L [Leg length] x [Other leg length] x [Thickness] x [Mass per meter]

• Example:

  Section	Dimensions (mm)	Mass (kg/m)
  L 400 x 120 x 12.5 x 25	400 x 120 x 12.5	25
  L 425 x 120 x 12.5 x 26	425 x 120 x 12.5	26

• Tolerance on Mass:
  [ \text{Mass tolerance} = \pm 2.5% \times \text{Mass per unit length} ]

Summary Diagram (Marking Flow)

flowchart LR
    A[Manufactured Section] --> B[Mark Section Size & Mass]
    B --> C[Add Manufacturer ID]
    C --> D[Add Batch/Heat Number]
    D --> E[Ready for Dispatch]

This ensures traceability and compliance with IS 1864 standards.

IS 1864 Supplementary Sizes for 'L' Sections

Key Notes:

• Supplementary sizes are listed in Table 1A (Clause 0.3 & 4.1).
• Dimensions and sectional properties must follow Tables 1 and 1A.
• These sections are available by mutual arrangement with suppliers.

Table 1A: Selected Supplementary 'L' Sections

IS 1864: Compliance and Testing Key Points

• Rounding Off (Clause 0.4):
  Final test or analysis results must be rounded per IS 2-1960.

  • Retain the same number of significant figures as in the specified value.

• Dimensions (Clause 4.1):
  Use Tables 1 and 1A for dimensions of sections.

  • Table 1A covers supplementary 'L' sections available on mutual agreement.

• Mass Tolerance (Clause 5.8):
  Mass per unit length tolerance: ±2.5% of values in Tables 1 and 1A.

Summary Table for Mass Tolerance

Notes:

• Always verify dimensions and mass from Tables 1 and 1A before acceptance.
• Testing results must strictly follow rounding rules for compliance.

flowchart TD
    A[Test/Analysis Result] --> B[Rounding as per IS 2-1960]
    B --> C[Compare with Specified Value]
    C --> D{Within Tolerance?}
    D -- Yes --> E[Complies]
    D -- No --> F[Reject/Retest]

This ensures consistent, standardized evaluation of structural steel sections per IS 1864.

IS 1864 - Hot Rolled Steel 'L' Sections for Shipbuilding

Key Specifications:

• Scope: Covers dimensions, sectional properties, and tolerances of hot rolled steel 'L' sections used in shipbuilding.
• Material: Steel conforming to shipbuilding grade with adequate strength and toughness.
• Dimensions: Standard leg lengths and thicknesses specified for uniformity.
• Tolerances: Limits on deviations in leg lengths, thickness, and angles to ensure fit and structural integrity.

Important Sectional Properties:

Application Notes:

• 'L' sections provide corner stiffening and framing in ship hulls.
• Used in structural members subjected to bending and axial loads.
• Ensure compliance with dimensional tolerances for proper assembly.

Typical Formula for Section Modulus (Z):

[ Z = \frac{I}{y} ]

Where:

• (I) = Moment of inertia about the neutral axis
• (y) = Distance from neutral axis to extreme fiber

graph LR
A[Hot Rolled Steel 'L' Section] --> B[Dimensions: a, b, t]
A --> C[Sectional Properties: A, Ix, Iy]
A --> D[Applications: Ship Hull Framing]
B --> E[Tolerances]
C --> F[Strength & Stability]

For detailed tables and exact dimensions, refer to the full IS 1864 document.