timber for use in coal mines

IS 4424: Scope & Key Specifications

• Scope: Covers manufacturing requirements and dimensions of props used in construction, allowing purchaser options per Clause 4.2.6.

Key Specifications:

Important Notes:

• Final test or analysis values must be rounded as per IS 2-1960 rules.
• Dimensions and definitions align with IS 707-1958.
• Purchasers may select sizes to suit their needs (Clause 4.2.6).

Rounding Off (IS 2-1960):

• Round off to the same number of significant figures as specified.
• Example: If specified value = 12.0, round test results to 3 significant figures.

flowchart TD
    A[Start: Prop Selection] --> B{Diameter 10-12 cm?}
    B -- Yes --> C{Length 100-500 cm?}
    B -- No --> D[Choose valid diameter]
    C -- Yes --> E[Use prop as per IS 4424]
    C -- No --> F[Choose valid length]

This ensures compliance with IS 4424 manufacturing and dimensional requirements.

IS 4424: Definitions and Related Specifications

• Clause 2.0: Definitions in IS 4424 refer to those in IS 707-1958 (Code for Structural Steel Sections).
• Clause 3.3: Abbreviations follow IS 1150-1966 (Code of Practice for Structural Steel).
• Clause 4.2: Specifies dimensions of members; these are standardized as per IS 707.
• Clause 4.2.6: Purchaser may select options to suit requirements.
• Rounding Off: Final test or calculation results must be rounded per IS 2-1960 rules, retaining the same number of significant figures as specified.

Key Reference Summary

Example: Rounding Off (IS 2-1960)

If you need specific member dimensions or abbreviations, refer to IS 707 and IS 1150 respectively.

IS 4424 - Timber Species Suitable for Coal Mining

Key Reference:

• Clause 3.1: Timber species suitable for coal mining are listed in Appendix A of IS 4424.

Typical Timber Species (from Appendix A):

• Sal (Shorea robusta)
• Teak (Tectona grandis)
• Eucalyptus
• Chir Pine
• Deodar
• Other locally available hardwoods with adequate strength and durability

Important Specifications:

• Timber must be sound, free from defects like knots, splits, or decay.
• Must have adequate strength, toughness, and resistance to fungal attack.
• Should be seasoned to moisture content typically below 15% for durability underground.

No direct formulas apply here, but timber selection is based on:

• Density
• Modulus of Elasticity (E)
• Compressive and bending strength

Summary Table (Indicative):

flowchart TD
    A[Timber Species Selection] --> B{Strength & Durability}
    B --> C[Sal, Teak, Eucalyptus]
    B --> D[Chir Pine, Deodar]
    A --> E[Moisture Content < 15%]
    A --> F[Free from Defects]

Note: Always refer to the latest IS 4424 Appendix A for detailed species and quality requirements.

IS 4424 - Manufacturing Requirements Summary

Key Specifications (Clause 4.2.1)

• Props Dimensions:
  • Diameter: 10 to 12 cm
  • Length: 100 to 500 cm

Additional Notes:

• Clause 4.2 allows dimensions of members to be as specified or as required by users.
• Clause 4.2.6 permits purchaser's option to select requirements suiting their needs.
• Final test or analysis values must be rounded off per IS 2-1960 rules, maintaining the same significant figures as specified.

Rounding Off (IS 2-1960)

• Round off the final values to the same decimal places as the specified values.
• Example: If specified value = 12.0, round test result to 1 decimal place.

Summary Table: Props Dimensions

This ensures props meet standard size ranges while allowing flexibility for user-specific needs.

IS 4424: Quality Requirements and Defects

Key Points from Clauses:

• Clause 5.2 (Defects Permitted to a Limited Extent):

  • Minor defects are allowed but within strict limits to ensure safety and performance.
  • Exact permissible defect types and limits depend on purchaser's option (Clause 4.2.6).

• Clause 4.2.6 (Purchaser's Option):

  • The purchaser may select specific quality requirements or defect tolerances suiting their needs.
  • This allows flexibility while adhering to the standard's minimum criteria.

• Rounding Off (Clause 0.6):

  • Test results must be rounded as per IS 2:1960 rules.
  • Number of significant figures retained should match those in the standard.

General Specifications:

Summary:

• Quality control involves limiting defects to acceptable levels.
• Purchaser can decide stricter or relaxed defect limits.
• Test results must be rounded correctly to maintain consistency.
• This approach balances standardization with flexibility.

flowchart TD
    A[Start: Manufacturing] --> B[Quality Inspection]
    B --> C{Defects Found?}
    C -- No --> D[Product Accepted]
    C -- Yes --> E{Defects Within Permissible Limits?}
    E -- Yes --> D
    E -- No --> F[Reject or Rework]
    D --> G[Final Rounding of Test Values as per IS 2]
    G --> H[Product Dispatch]

This diagram shows the quality check and defect control process per IS 4424.

IS 4424: Fire Resistance Treatment for Timber in Mines

Key Reference:

• Clause 6.1: Fire resistance treatments must comply with IS 401-1967 (Specification for Timber for Use in Coal Mines).

Important Points from IS 401-1967 (related to fire resistance):

• Fire Retardant Treatments:

  • Timber should be treated with approved fire retardant chemicals.
  • Common chemicals: Borates, ammonium phosphate, or proprietary fire retardants.

• Treatment Methods:

  • Pressure impregnation or vacuum-pressure processes for deep penetration.
  • Surface coating with fire resistant paints or varnishes may be used for additional protection.

• Performance Criteria:

  • Treated timber should resist ignition and reduce flame spread.
  • Maintain structural integrity for a minimum duration under fire exposure (typically 30-60 minutes depending on application).

Typical Fire Resistance Parameters:

Summary:

• Follow IS 401-1967 for detailed chemical specifications and treatment procedures.
• Use pressure impregnation for durability.
• Ensure treated timber meets minimum fire resistance duration.
• Select timber species as per Clause 2.00 of IS 4424 for suitability in mines.

flowchart LR
    A[Raw Timber] --> B[Fire Retardant Treatment]
    B --> C{Treatment Method}
    C -->|Pressure Impregnation| D[Treated Timber]
    C -->|Surface Coating| D
    D --> E[Fire Resistance Testing]
    E --> F{Meets IS 401-1967?}
    F -->|Yes| G[Approved for Use in Mines]
    F -->|No| H[Retreatment or Reject]

For detailed chemical compositions and test methods, refer directly to IS 401-1967.

IS 4424: Design & Dimensions of Timber Members (Mining Timber)

Key Specifications:

• Clause 4.1:

  • Timber must be sawn square.
  • Bark completely removed; branches dressed flush with stem.
  • Ends (top & bottom) are cut parallel and perpendicular to the prop axis.

• Clause 4.2:

  • Specifies dimensions of timber members (props, bars, etc.).
  • Exact dimensions depend on use, but typical mining props are square or rectangular sections.

Typical Dimensions (per IS 4424 and mining practice):

Design Considerations:

• Use species recommended in Clause 2.00 (e.g., Sal, Teak, Shorea) for strength and durability.
• Ensure square cross-section for uniform load distribution.
• Ends cut flat and perpendicular to axis to avoid eccentric loading.

Summary Diagram of Timber Prop Dimensions

graph TD
A[Timber Prop] --> B[Square Cross-section]
B --> C[75mm to 100mm sides]
A --> D[Length]
D --> E[1.5m to 2.0m]
A --> F[Ends Cut]
F --> G[Parallel & Perpendicular to Axis]

Note: For detailed strength values, refer to IS 883 (Code of Practice for Timber Structures) and IS 11223 (Timber for Mining).

IS 4424: Measurement and Inspection Key Points

1. Measurement (Clause 4.3)

• Measurements must be precise and conform to specified dimensions.
• Final values (observed or calculated) must be rounded off per IS 2:1960 rules.
• The number of significant digits in rounded values should match those in the standard's specified values.

2. Purchaser's Option (Clause 4.2.6)

• The purchaser may select options to suit specific requirements.
• This flexibility allows adaptation to project needs without compromising standard compliance.

3. Dimensions (Clause 4.2)

• Dimensions of timber members and other components must adhere strictly to the values given in the standard tables.
• Use recommended species of timber (Clause 2.00 table) for mine supports.

4. Rounding Off Rules (IS 2:1960)

• If the digit to be dropped is less than 5, the preceding digit remains unchanged.
• If the digit is 5 or greater, the preceding digit is increased by one.

Example: Rounding off to 2 decimal places

Summary Table: Timber Species for Mines (Clause 2.00)

flowchart TD
    A[Measurement] --> B[Observe/Calculate values]
    B --> C[Round off per IS 2:1960]
    C --> D[Compare with standard specified values]
    D --> E{Compliant?}
    E -->|Yes| F[Accept]
    E -->|No| G[Reject/Retest]

In brief: Follow IS 2:1960 for rounding, adhere to specified dimensions, and use recommended timber species for compliance with IS 4424 measurement and inspection requirements.

IS 4424 - Marking and Identification of Timber

Key Specifications (Clause 8.1 & 8.1.1):

• Manufacturer's Identification:
  Each timber piece must be marked with the manufacturer's identification mark or initials in a suitable manner (e.g., branding, stamping).

• ISI Certification Mark (Optional):
  Timber may also be marked with the ISI Certification Mark to indicate compliance with Indian Standards.

  • This mark ensures production under strict inspection, testing, and quality control.
  • Use governed by Indian Standards Institution (Certification Marks) Act.

Important Notes:

• Marking ensures traceability and quality assurance.
• Marking methods should not damage timber or reduce its structural integrity.
• Refer to IS 1150-1966 for abbreviations and further marking conventions.

Summary Table:

flowchart LR
    A[Timber Piece] --> B[Mark Manufacturer's ID]
    B --> C{Use ISI Mark?}
    C -- Yes --> D[Apply ISI Certification Mark]
    C -- No --> E[Only Manufacturer's Mark]
    D & E --> F[Timber Ready for Use]

For detailed marking methods and quality control, refer to IS 4424 and related IS codes (e.g., IS 1150).

IS 4424: User Responsibilities and Approvals - Key Points

• Clause 3.2:

  • Species not listed in Appendix A must not be supplied without prior written consent from the user.
  • Ensures control over material/species selection to meet user requirements.

• Clause 4.2.6:

  • The purchaser has option to select requirements as per their needs, allowing flexibility in specifications.

• Rounding Off Values (IS 2-1960):

  • Final test or analysis values must be rounded off following IS 2-1960 rules.
  • Retain the same number of significant digits as the specified values.

Summary Table for User Approvals

Visual Concept: Approval Flow

flowchart TD
    A[User Request] --> B{Species Specified in Appendix A?}
    B -- Yes --> C[Supply Species]
    B -- No --> D[Obtain Written Consent]
    D --> E{Consent Given?}
    E -- Yes --> C
    E -- No --> F[Do Not Supply]

This ensures user control and compliance with standards during procurement and supply.

IS 4424: Appendices Key Points & Specifications

• Appendix A: Lists species of timber recommended for mining use (Clause 3.1).

  • Timber not listed here requires written user consent (Clause 3.2).

• Clause 4.2 Dimensions: Specifies dimensions for timber members used in props, supports, and lids in headings or roadways. Typical dimensions ensure safety and load-bearing capacity.

• Figures 4 & 5: Illustrate common timber support systems in mines:

  • Fig. 4: Two props supporting a bar in headings/roadways.
  • Fig. 5: A prop with a lid supporting a working face.

Typical Timber Prop Dimensions (from Clause 4.2)

Recommended Timber Species (Appendix A Examples)

• Sal (Shorea robusta)
• Teak (Tectona grandis)
• Eucalyptus
• Other durable hardwoods

flowchart LR
    A[Timber Species in Appendix A] --> B{User Consent?}
    B -- No --> C[Not Allowed]
    B -- Yes --> D[Timber Supplied]
    D --> E[Used in Props & Supports]
    E --> F[Dimensions as per Clause 4.2]

Summary: Use only Appendix A species unless authorized. Follow specified dimensions for props and lids to ensure safety in mining operations.