rolled steel bulb flats

IS 1863 Scope - Key Specifications & Tables

IS 1863 covers hot rolled steel bulb flats used in structural engineering.

Key Points:

• Dimensions & Sectional Properties (Clause 4.1, Table 4):
  Includes mass (kg/m), sectional area (cm²), width (b), thickness (t), centroid location, moment of inertia (Ix), and section modulus (Zx).
  Example for 120 × 6 bulb flat:

  • Mass = 7.83 kg/m
  • Sectional area = 9.3 cm²
  • Width (b) = 120 mm
  • Thickness (t) = 6 mm
  • Moment of inertia (Ix) = 133 × 10³ mm⁴
  • Section modulus (Zx) = 18.4 × 10³ mm³

• Tolerances (Clause 5.1 & 5.5):

  • Width and thickness tolerances vary by size (see Table 2).
  • Weight tolerance ±2.5% of mass per unit length.

Tolerance Table Snapshot (Width b / Thickness t):

Units:

• Mass in kg/m
• Area in cm² or 10³ mm²
• Lengths in mm
• Moments of inertia in cm⁴ or 10⁴ mm⁴
• Section modulus in cm³ or 10³ mm³

Summary Diagram: Sectional Properties Relation

IS 1863 Key References: Dimensions, Tolerances & Sectional Properties

1. Dimensions & Sectional Properties (Clause 4.1, Table 4)

• Sections like 120×6, 140×10, 160×10 etc. are tabulated with:
  • Mass (kg/m)
  • Sectional Area (cm²)
  • Width (b, mm)
  • Thickness (t, mm)
  • Centroid location (mm)
  • Moment of inertia (cm⁴)
  • Section modulus (cm³)

Example (120×6):

2. Tolerances (Clause 5.5)

• Weight tolerance: ±2.5% of mass per unit length (from Table 1).
• Width and Thickness tolerances (Table 2):

3. Related Indian Standards

• IS 808 (hot rolled steel sections)
• IS 811 (cold formed sections)
• IS 1173 (steel tee bars)
• IS 1863 (rolling & cutting tolerances)
• IS 1730 series

IS 1863: Designation of Rolled Steel Bulb Flats

The designation format is typically:
[Width] × [Thickness] (in mm)
e.g., 120 × 6 means 120 mm width and 6 mm thickness.

Key Parameters from IS 1863 Table 4.1 & 5.5:

Important Notes:

• Mass tolerance: ±2.5% of the mass per unit length (Clause 5.5).
• Centroid and sectional properties are about the XX axis.
• Supplementary sizes (Table 1A) are not covered by ISO/DIS 4974 and may be obtained by mutual arrangement.
• Dimensions include width (b), thickness (t), and radius (r) for curved edges.

Typical Use:

• Designation helps select bulb flats based on structural requirements.
• Sectional properties (Ix, Zx) are critical for bending and strength calculations.

Formula for Section Modulus (Z

IS 1863 - Key Formulas and Tables for Bulb Flats Dimensions & Sectional Properties

Dimensions (Typical from Table 1 & 1A)

Key Specifications:

• Mass tolerance: ±2.5% of mass per unit length (Clause 5.5)
• Centroid (c): Distance from base to centroid in mm
• Section Modulus (Zx): Used for bending design, in cm³
• Moment of Inertia (Ix): Resistance to bending, in cm⁴

Formulas:

• Section Modulus:
  [ Z_x = \frac{I_x}{y_{\max}} ] where (I_x) = moment of inertia about neutral axis, (y_{\max}) = max distance to extreme fiber.

• Moment of Inertia (approx.):
  For bulb flats

IS 1863: Key Tolerances for Hot Rolled Steel Sections

1. Tolerances on Width and Thickness (Clause 5.1, Table 2)

2. Radius at Corners (Clause 5.2, Table 3)

3. Weight Tolerance (Clause 5.5)

• ± 2.5% of the mass per unit length as per Table 1.

Summary:

• Width and Thickness tolerances depend on size ranges.
• Corner radius ensures smooth edges to avoid stress concentrations.
• Weight tolerance controls mass variation for quality assurance.

flowchart TD
    A[Steel Section] --> B[Width & Thickness Check]
    B --> C{Within Tolerance?}
    C -->|Yes| D[Accept Section]
    C -->|No| E[Reject or Rework]
    A --> F[Corner Radius Check]
    F --> G{Radius ≤ Max?}
    G -->|Yes| D
    G -->|No| E
    A --> H[Weight Check

IS 1863: Key Formulas, Tables, and Specifications for Materials

1. Sectional Properties & Dimensions (Clause 4.1):

Refer to Clause 4.1 Table for full details.

2. Tolerances (Clause 5.5):

• Weight tolerance: ±2.5% of mass per unit length (Table 1 values).
• Width and Thickness Tolerances (Table 2):

IS 1863: Manufacturing Requirements - Key Formulas, Tables & Specs

1. Dimensions & Sectional Properties (Clause 4.1, Table 4)

Refer to full Table 4 in IS 1863 for complete sizes.

2. Tolerances on Width and Thickness (Clause 5.1, Table 2)

3. Radius at Corner (Clause 5.2, Table 3)

IS 1863: Inspection and Testing - Key Specifications

1. Weight Tolerance (Clause 5.5)

• ± 2.5% of the mass per unit length (from Table 1).

2. Dimensional Tolerances (Clause 5.1, Table 2)

3. Radius at Corners (Clause 5.2, Table 3)

Additional Notes:

• Mass per unit length and sectional properties are detailed in Table 1 (e.g., 120×6 mm section mass = 7.83 kg/m).
• Inspection includes verifying dimensional tolerances, weight, and corner radii.
• Testing typically involves verifying mechanical properties per relevant IS standards.

flowchart TD
    A[Start: Steel Section] --> B[Measure Width & Thickness]
    B --> C{Within Tolerances?}
    C -- Yes --> D[Check Weight ±2.5%]
    C -- No --> E[Reject or Rework]
    D --> F[Check Radius at Corners]
    F --> G{Within

IS 1863: Marking - Key Specifications & Tables

1. Dimensions & Sectional Properties (Clause 4.1)

• Sections specified by width (b), thickness (t), and other dimensions.
• Mass, sectional area, surface area, centroid, and moment of resistance (Zx) are tabulated.
• Example from Table 4:

2. Tolerances (Clause 5.1 & 5.5)

• Width and Thickness Tolerances (Table 2):

• Weight Tolerance (Clause 5.5): ±2.5% of mass per unit length.

3. Radius at Corners (Clause 5.2, Table 3)

IS 1863: Supplementary Sizes for Bulb Flats

Key Dimensions & Sectional Properties (Selected Sizes)

Tolerances on Width and Thickness (Clause 5.1)

IS 1863 Application Notes - Key Formulas, Tables & Specifications

1. Dimensions & Sectional Properties (Clause 4.1, Table 4)

• Sections like bulb flats have specified dimensions (width b, thickness t, length l) and properties:
  • Mass (kg/m)
  • Sectional Area (cm²)
  • Centroid (Cₓ in mm)
  • Moment of Inertia (Iₓ in cm⁴)
  • Section Modulus (Zₓ in cm³)

2. Tolerances (Clause 5.5, Table 5)

• Weight tolerance: ±2.5% of mass per unit length.
• Width & Thickness tolerances (Clause 5.1, Table 2):

IS 1863: Rounding Off Rules & Key Specifications

1. Rounding Off Rules (Clause 0.4)

• Final values (test or analysis results) must be rounded as per IS 2-1960.
• Number of significant figures in rounded value = number in the specified value.
• Ensures consistency and compliance in reporting.

2. Tolerances (Clause 5)

a) Radius at Corner (Clause 5.2, Table 3)

b) Width and Thickness Tolerances (Clause 5.1, Table 2)

c) Weight Tolerance (Clause 5.5)

• ±2.5% of the mass per unit length (from Table 1).

Summary Diagram: Rounding & Tolerance Flow

flowchart TD
    A[Measured/Calculated Value] --> B[Rounded as per IS 2-1960]
    B --> C[Retain same significant figures as Specified Value]
    C --> D{Check Tolerances}
    D -->|Radius at Corner| E[Refer Table 3