Hot rolled steel bulb angles Dimensions

IS 1252: Scope & Key Specifications for Bulb Angles

1. Scope (Clause 3.0)

• Defines bulb angle sections used in structural applications.
• Covers dimensions, sectional properties, mass, and tolerances.

2. Key Letter Symbols (Clause 4.1)

3. Sectional Properties and Dimensions (Clause 6.1)

• Nominal dimensions and mass values are tabulated in Table 1 (not shown here).
• Includes sectional area, moments of inertia, radii of gyration, and projection D.

4. Tolerances (Clause 6.2)

• Rolling and cutting tolerances as per IS 1852:1985.

Summary Formula

IS 1252 - Key References, Formulas & Tables Summary

Letter Symbols (Clause 4.1)

• a = Sectional area (cm²)
• m = Nominal mass (kg/m) = 0.785 × a
• D = Projection of bulb from inside face of web (mm)
• CIx, Cyy = Distances of centroid from flange/web back lines (cm)
• Ixx, Iyy = Moments of inertia about X-X and Y-Y axes (cm⁴)
• Iuu, Ivy = Moments of inertia about principal axes U-U (max) and V-V (min)
• exx, eyy = Extreme fibre distances from X-X and Y-Y axes (cm)
• Zx, Zy = Section moduli about X-X and Y-Y axes (cm³)
• rxx, ryy = Radii of gyration about X-X and Y-Y axes (cm)
• a = Angle between U-U and X-X axes

Key Formula:

[ m = 0.785 \times a ]

Table 1 (Clause 4.1 & 6.1) - Bulb Angles Properties

Includes:

• Designation (e.g., BA 100, BA 125*)
• Mass per metre (kg/m)
• Sectional area (cm²)
• Size (h × b in mm)
• Thickness of web (f) and flange (t) (mm)
• Radii at root, toe, bulb corners (mm)
• Centroid locations (cm)
• Moments of inertia (Ixx, Iyy, Iuu, Ivy) (cm⁴)
• Radii of gyration (cm)
• Moduli of section (Zx, Zy) (cm³)

Notes:

• Sections marked * or ** are heavier with wider flanges due to roll spreading.
• Mass should be specified when ordering these heavier sections.

BIS & Standard Mark:

• BIS ensures compliance via inspection, testing, and quality control.
• Indian Standards are periodically reviewed and amended.

flowchart LR
    A[Sectional Area (a)] --> B[Nominal Mass (m)]
    B --> C[m = 0.785 × a]
    D[Section Properties Table] --> E[Dimensions, Moments

IS 1252 - Definitions & Key Formulas for Bulb Angles (Clause 4.1 & 6.1)

Letter Symbols & Definitions

• a = Sectional area (cm²)
• m = Nominal mass per meter (kg/m), calculated as:
  [ m = 0.785 \times a ]
• D = Projection of the bulb from the inside face of the web (mm)
• CIx, Cyy = Distances of the centroid from back lines of flange and web (cm)
• Ixx, Iyy = Moments of inertia about X-X and Y-Y axes (cm⁴)
• Iuu, Ivy = Moments of inertia about principal axes U-U (max) and V-V (min) (cm⁴)
• exx, eyy = Distances to extreme fibers from X-X and Y-Y axes (cm)
• Zx, Zyy = Section moduli about X-X and Y-Y axes (cm³)
• rx, ry = Radii of gyration about X-X and Y-Y axes (cm)
• a = Angle between U-U and X-X axes

Important Notes

• Table 1 provides nominal dimensions, sectional properties, and mass per meter for various bulb angle designations (e.g., BA 100, BA 125, etc.).
• Heavier sections marked with * or ** have increased flange width due to roll spreading.
• Use the mass m formula for quick estimation of weight from sectional area.

Sample from Table 1 (Excerpt)

IS 1252: Dimensions and Sectional Properties of Hot Rolled Steel Bulb Angles

Key Specifications (Clause 6.1 & Table 1)

• Designation: BA + depth of longer leg in mm (e.g., BA100)
• Mass (m):
  [ m = 0.785 \times a \quad \text{(kg/m)} ] where (a) = sectional area in cm²

Important Symbols (Clause 4.1)

Typical Sectional Properties Table (Excerpt from Table 1)

IS 1252: Designation of Hot Rolled Steel Bulb Angles

Key Points:

• Designation Format:
  BA + depth of longer side (in mm)
  Example: BA 100 means bulb angle with 100 mm longer side depth.

• Heavier Sections:

  • Denoted by * and ** after the designation (e.g., BA 100*, BA 175**)
  • These have increased flange width due to roll spreading and higher mass.
  • Mass must be specified when ordering heavier sections.

Important Formulas & Symbols (Clause 4.1)

Sample Table Extract (from Table 1)

Notes:

• Mass per metre is calculated as

IS 1252: Tolerances for Bulb Angles (Referencing IS 1852:1985)

• Tolerances Standard:
  Rolling and cutting tolerances for bulb angles are governed by IS 1852:1985 (hot-rolled steel products).

• Key Dimensions & Symbols (Clause 4.1):

  • ( a ) = Sectional area (cm²)
  • ( m ) = Nominal mass (kg/m) = 0.785 × ( a )
  • ( D ) = Projection of bulb from inside face of web
  • ( C_{Ix}, C_{yy} ) = Centroid distances from flange/web back lines
  • ( I_{xx}, I_{yy} ) = Moments of inertia about X-X and Y-Y axes
  • ( Z_x, Z_y ) = Section modulus about X-X and Y-Y axes
  • ( r_x, r_y ) = Radius of gyration about X-X and Y-Y axes
  • ( \alpha ) = Angle between principal axes U-U and X-X

• Nominal Dimensions & Mass:
  Given in Table 1 of IS 1252, including sectional properties for design.

Typical Tolerances (from IS 1852:1985 for Hot-Rolled Products)

Note: Exact tolerances vary by product size and are detailed in IS 1852 tables.

Important Formula for Mass

[ m = 0.785 \times a \quad \text{(kg/m)} ]

flowchart LR
    A[IS 1252 Bulb Angles] --> B[Refer IS 1852:1985 for Tolerances]
    B --> C[Thickness, Width, Length, Mass tolerances]
    A --> D[Sectional Properties]
    D --> E[a, m, D, C_{

Rounding Off Rules - IS 1252 (Related to IS 1852:1985)

IS 1252 refers to IS 1852:1985 for rolling and cutting tolerances of bulb angles, which implicitly governs rounding off rules for dimensions and mass.

Key Points on Rounding Off (from IS 1852 & IS 1252 context):

• Mass per metre (m) and sectional area (a) are related by: [ m = 0.785 \times a ] where:

  • ( m ) = nominal mass in kg/m
  • ( a ) = sectional area in cm²

• Dimensions such as thickness, radius at root, toe, and bulb corners are specified with tolerances per IS 1852.

• Tolerances are applied to rolling and cutting dimensions, and final values are rounded off to the nearest practical value as per manufacturing precision.

Typical Rounding Off Guidelines (General Engineering Practice):

Summary Table Extract (Example for Bulb Angles):

Notes:

• Sections marked with

IS 1252: Marking and Quality Assurance - Key Points

Marking & Quality Assurance:

• The Standard Mark on steel products signifies compliance with IS 1252 under BIS supervision.
• It assures production under a strict system of inspection, testing, and quality control.
• The BIS continuously monitors standard-marked products for conformity.
• Licence for Standard Mark use is granted under the Bureau of Indian Standards Act, 1986.
• Manufacturers must specify mass when ordering heavier sections (marked *, **) due to flange width changes.
• Users should ensure they have the latest standard edition or amendments.

Key Formulas & Symbols (Clause 4.1)

Table Snapshot: Bulb Angle Example (BA 100)

Summary

• Use Table 1 in IS 1252 for bulb angle dimensions and properties.

IS 1252 — Application Notes: Key Formulas, Tables & Specifications

1. Letter Symbols (Clause 4.1)

• a = Sectional area (cm²)
• m = Nominal mass (kg/m), ( m = 0.785 \times a )
• D = Projection of bulb from inside face of web (mm)
• CIx, Cyy = Distances of centroid from flange/web back line (cm)
• Ixx, Iyy = Moments of inertia about principal axes (cm⁴)
• Iuu, Ivy = Moments of inertia about principal axes U-U (max) and V-V (min)
• exx, eyy = Distance of extreme fiber from X-X and Y-Y axes (cm)
• Zx, Zyy = Section modulus about X-X and Y-Y axes (cm³)
• rxx, ryy = Radius of gyration about X-X and Y-Y axes (cm)
• a = Angle between U-U and X-X axes

2. Nominal Dimensions & Properties (Clause 6.1 & Table 1)

• Bulb angles are specified by size (h × b), web thickness (f), flange thickness (t), radii (root, toe, bulb corners).
• Mass per metre and sectional properties (area, moments of inertia, radii of gyration, moduli) are tabulated for standard sizes.

3. Important Formula

[ m = 0.785 \times a ] where:

• (m) = mass per metre (kg/m)
• (a) = sectional area (cm²)

4. Usage Notes

• Sections marked * or ** indicate heavier variants with increased flange width.
• Specify mass when ordering heavier sections.
• Dimensions and properties ensure compatibility and design safety.

Sample Table Extract (for BA 100):

Ordering Instructions for Bulb Angles as per IS 1252

• Designation & Mass: Specify exact designation (e.g., BA 150, BA 150*) and mass per metre (m) in kg. Heavier sections marked with * or ** must mention mass explicitly due to flange width variation.

• Dimensions: Include nominal size (h × b in mm), web thickness (f), flange thickness (11), and radii (root r, toe F1, bulb corners s).

• Sectional Properties: Refer to Table 1 for sectional area (a), moments of inertia (Ixx, Iyy, Iuu, Ivy), radii of gyration (rxx, ryy, ruu, rvy), moduli of section (Zx, Zy), and center of gravity distances (CIx, CIy).

• Formula for Mass per Metre: [ m = 0.785 \times a \quad (\text{kg/m}) ] where (a) = sectional area in cm².

• Reference for Tolerances: Follow IS 1852:1985 for rolling and cutting tolerances.

• Note: Use the Standard Mark only if production complies with BIS quality control.

Example Table Extract (Partial)

For detailed dimensions and properties, always refer to Table 1 of IS 1252.