Criteria for Design of Steel Bins for Storage of Bulk Materials, Part 1: General Requirements and Assessment of Loads

IS 9178 Part 1 (1979) — Scope: Key Specifications & Tables

Scope:
IS 9178 Part 1 covers design parameters and material handling systems for bulk storage structures, focusing on bulk material characteristics, pressures, and handling.

Key Tables & Specifications:

1. Classification of Bulk Materials (Table 1, Clause 5.3)

2. Characteristics of Bulk Materials (Table 2, Clause 5.3)

Use these values for design pressures and flow analysis.

3. Design Pressure Calculation (Clause 6.3.1)

• Maximum design pressures for normal filling/emptying are computed as per Clause 6.2.
• Use bulk density and angle of internal friction from Tables 2 & 3.

Example Formula for Pressure (simplified):

[ P = W \times H \times K ]

• (P) = Pressure on structure (k

IS 9178 Part 1 (1979) - Key Definitions, Formulas & Tables

Key Notations (Clause 3.0)

• A = Horizontal cross-sectional area of stored material at depth z
• a, b = Sides of square/rectangular bin
• D = Internal diameter of circular bin
• h = Height of bin
• Pa = Air pressure for pneumatic emptying
• Ph, Pv, Pw = Horizontal, vertical pressure & wall friction load respectively
• S = Bottom diameter of insert
• U = Perimeter of cross-section at depth z
• W = Bulk density of stored material (kg/m³)
• z = Depth below max fill level
• δ = Wall friction angle
• ϕ = Internal friction angle (angle of repose)
• α = Hopper wall slope angle
• A, Mf, Me = Wall friction coefficients and pressure ratios during filling/emptying

Important Parameters (Clause 5.3)

• Bulk density W (kg/m³) and angle of internal friction ϕ (degrees) for various materials (see Table 2 excerpt below).

Sample from Table 2: Bulk Density & Internal Friction Angle

Wall Friction Coefficient

[ A = \tan \delta = \frac{P_w}{P_h} ]

Pressure Ratios

• ( A = \frac{P_{nl}}{P_v} )
• ( M_f = \frac{P_h}{P_v} ) (filling)
• (

IS 9178 Part 1 - Key Notations and Tables Summary

Key Notations (Clause 3.0)

Important Tables

1. Values of (1 - e^(-z/z0)) (Appendix A)

Used for pressure distribution calculations in bins.

(Values interpolate for design use)

2. Bulk Density and Angle of Internal Friction (Table 2)

Typical bulk densities (W) and minimum internal friction angles (φ) for common materials:

IS 9178 Part 1 - General Requirements Summary

1. Bulk Material Classification (Clause 5.3, Table 1)

• Classified by Size, Flowability, Abrasiveness, and Other Characteristics.
• Examples:
  • Size: Very fine (<100 mesh) to irregular/fibrous
  • Flowability: Very free flowing to sluggish
  • Abrasiveness: Non-abrasive to very abrasive

2. Bulk Material Properties (Clause 5.3, Table 2)

• Bulk Density (W) and Angle of Internal Friction (φ) are key parameters for design.
• Typical values (kg/m³ and degrees):

3. Design Pressure (Clause 6.3.1)

• Maximum design pressures for normal filling/emptying computed per Clause 6.2.
• Use design parameters from Tables 2 and 3 (not fully provided here).

4. Appendix A (Clause 6.2.1.3)

• Provides tabulated values for parameters like ( Z ) and related coefficients used in load calculations.

Typical Formula for Design Pressure ( P ):

[ P = W \times H \times K ]

• ( W ) = Bulk density (kg/m³)
• ( H ) = Height of material (m)
• ( K ) = Pressure coefficient (from tables or calculated using internal friction angle)

Visualization of Load Components on Steel Bin

graph TD
    A[Bulk Material] -->|Weight (W)| B[Vertical Load]
    B --> C[Bin Wall]
    A -->|Friction (φ)| D[Horizontal Load]
    D --> C
    C --> E[Structural

IS 9178 Part 1: Design Parameters Summary

1. Maximum Design Pressure (Clause 6.3.1)

• For normal filling/emptying, compute max design pressures as per Clause 6.2.
• Use design parameters from Tables 2 and 3.

2. Bulk Material Classification & Properties (Clause 5.3)

Table 1: Material Classification by Size, Flowability, Abrasiveness, etc.

• Size classes:
  • A: Very fine (<100 mesh)
  • B: Fine (<3 mm)
  • C: Granular (<12 mm)
  • D: Lumpy (>12 mm)
  • H: Irregular/fibrous
• Flowability: 1 (Very free flowing) to 3 (Sluggish)
• Abrasiveness: 6 (Non), 7 (Mild), 8 (Very)
• Other: Corrosive, explosive, dusty, etc.

3. Table 2: Bulk Density & Angle of Internal Friction (Key Examples)

4. Appendix A (Clause 6.2.1.3) - Values for Material Handling System Parameters

• Table with values of parameters like Z/Z₀ for flow calculations, e.g.:

IS 9178 Part 1: Assessment of Loads - Key Points

1. Governing Loading Conditions (Clause 6.1.4 & Table 4)

• For granular materials, horizontal pressure governs during emptying.
• For powdery materials, filling and emptying pressures are considered equal.
• Arching and piping effects may increase loads; remedial measures should be applied.

2. Pressure Ratio (Clause 6.1.1 & Table 3)

• Horizontal to vertical pressure ratio (K) is provided in Table 3 (not fully shown here).
• Typical assumption:
  [ K = \frac{P_h}{P_v} ]
• Values depend on material properties and state (filling or emptying).

3. Experimental Determination (Clause 5.4.1)

• Wall friction angle ((\delta)) and internal friction angle ((\phi)) should be experimentally determined if moisture or consolidation affects them.

4. Material Handling System Parameters (Clause 6.2.1.3 & Appendix A)

• Table 8 and Appendix A provide values of dimensionless parameters related to load distribution.
• Parameters like (Z/Z_0) and related coefficients are tabulated for design.

Summary Table for Load Cases (from Table 4):

Additional Notes:

• Consider arching effects which may increase pressures locally.
• Use experimental data for friction angles when moisture or consolidation is significant.
• Refer to IS 9178 Part 1 for detailed tables of pressure ratios and coefficients.

flowchart TD
    A[Material Type] --> B{Granular}
    A --> C{Powdery}
    B --> D[Filling

IS 9178 Part 1: Flow Correction and Emptying Devices

Key Points from Clauses:

• 7.1: Flow correcting devices ensure continuous flow and reduce excess emptying pressure.
• 6.7.2: Special unloading devices withdrawing only topmost material avoid excess pressure considerations.
• 6.3.1: Maximum design pressures for normal filling/emptying use parameters from Tables 2 & 3.
• 7.2.1: Insert type flow correctors:
  • Large insert near bin-hopper transition → promotes mass flow.
  • Small insert near hopper outlet → prevents piping (rat-holing) & arching.

Typical Design Parameters (from Tables 2 & 3, IS 9178 Part 1):

Flow Correction Device Guidelines:

• Large Inserts: Installed at bin-hopper junction to ensure mass flow (all material moves).
• Small Inserts: Near hopper outlet to prevent rat-holing (material stagnant zones) and arching (flow blockages).

Formula for Excess Pressure during Emptying:

[ P_e = \gamma \cdot H \cdot k ]

• ( P_e ) = Excess pressure
• ( \gamma ) = Bulk density
• ( H ) = Height of material
• ( k ) = Flow correction factor (from inserts)

Diagram: Insert Placement Locations

flowchart TD
    A[Bin] -->|Large Insert| B[Transition Zone]
    B --> C[Hopper]
    C -->|Small Insert| D[Hopper Outlet]

Summary: Use inserts to control flow pattern and reduce excess pressure. Refer to IS 9178 Tables 2 & 3 for design parameters and apply correction factors in pressure calculations. Special unloading devices negate excess pressure concerns by layer

IS 9178 Part 1 - Material Handling System: Key Points

1. Material Handling Equipments (Clause 8.1, Appendix B)

• Main equipment for filling/emptying bins:
  • Belt conveyor
  • Bucket elevator
  • Screw conveyor
  • Pneumatic elevator (pumping)
• Bunker covers often have openings for these; design must consider additional loads.
• Bins require bunker columns and discharge devices (e.g., sliding doors, rotary valves).
• Load from these devices must be included in bin/support design.

2. Bulk Material Characteristics (Clause 5.3, Tables 1 & 2)

• Classification by size, flowability, abrasiveness, and other properties.
• Key parameters for design:
  • Bulk density (W) in kg/m³
  • Angle of internal friction (φ) in degrees

3. Design Implications

• Use bulk density for load calculations on bins.
• Use angle of internal friction to estimate lateral earth pressure on bin walls.
• Consider equipment load on bin covers/supports.

Typical Load Calculation Formula:

[ P = W \times H \times K_a ] Where:

• (P) = lateral pressure on bin wall
• (W) = bulk density (kg/m³)
• (H) = height of material (m)
• (K_a = \tan^2(45^\circ - \phi/2)) = active earth pressure coefficient

flowchart TD
    A[Material Handling System] --> B[Belt Conveyor]
    A --> C[Bucket Elevator]
    A --> D[Screw Conveyor]
    A --> E[Pneumatic Elevator]
    B --> F[Load on Bin Cover]
    C -->

Pressure Variation Along Bin Depth (IS 9178 Part 1, Clause 6.2.1.3)

The pressure at any depth ( z ) in the bin is given by:

[ P_i(z) = (P_i)_{\max} \left( 1 - 2^{-\frac{z}{Z_i}} \right) ]

• ( P_i ): Pressure (subscripts ( w, h, v ) for wall, horizontal, vertical)
• ( (P_i)_{\max} ): Maximum pressure at the base
• ( z ): Depth from the top
• ( Z_i ): Characteristic depth parameter, varies for filling and emptying

Characteristic Depth ( Z_i ):

(Refer to Appendix A for values of ( 1 - 2^{-z/Z_i} ) and use linear interpolation for intermediate values.)

Additional Specifications:

• Bin Bottom Pressure Reduction (Clause 6.7.1):
  Horizontal pressure during emptying reduces linearly from emptying pressure at height ( \min(1.2d, 0.75h) ) above bin bottom to filling pressure at bin bottom.

• Horizontal Pressure Increase due to Air Inlets (Clause 6.6.3.1):
  Increase horizontal pressure by inlet air pressure over the height of air inlets; taper linearly to zero at bin top.

• Homogenization (Clause 6.3.2):
  For powdery materials mixed by compressed air, lateral and vertical pressures depend on the void volume (~40% of bin volume). Use the above formula but pressure should not be less than that calculated by Clause 6.2.1.

Visual Summary (Fig. 3):

graph LR
A[Top of Bin] -->|Pressure decreases| B[Depth z]
B -->|Pressure max at base| C[Bin Bottom]
C -->|Pressure reduction| D[Height min(1.2d,0.75h)]

**Use this formula and guidelines to calculate pressure variation accurately along bin

IS 9178 Part 1: Material Handling Equipment & Layout - Key Points

1. Material Handling Equipment (Clause 8.1, Appendix B)

• Equipment used for filling/emptying bins:
  • Belt conveyor
  • Bucket elevator
  • Screw conveyor
  • Pneumatic elevator (pumping)
• Support for equipment often requires openings on bunker covers.
• Additional loads from equipment/supports must be considered in bunker design.
• Bins should have bunker columns for proper discharge.
• Discharge devices include:
  • Sliding doors (manual/powered)
  • Rotary valves
  • Discharge gates
  • Pneumatic methods
• Loads from these devices and connections must be accounted for in structural design.

2. Layout & Design Considerations (Clause 4.2)

• Optimum dimensions, shape, and layout must consider:
  • Economic factors
  • Material handling system requirements (Clause 4.2)
• Material handling affects bin design and layout.

3. Appendix A - Values Table (Clause 6.2.1.3)

• Contains tabulated values of parameters (e.g., Z, Z₀) relevant for design calculations.
• Use these for structural analysis and design of bins with handling systems.

Summary Table: Equipment & Design Impact

flowchart LR
    A[Material Handling Equipment] --> B[Belt Conveyor]
    A --> C[Bucket Elevator]
    A --> D[Screw Conveyor]
    A --> E[Pneumatic Elevator]
    B & C & D & E --> F[Load on Bunker Structure]
    F --> G[Design Considerations]
    G --> H[Openings on Cover]
    G --> I[Support Beams]
    G --> J[Bunker Columns]

Note: Always refer to Appendix B