timber for use in coal mines
1967 Edition

Scope Overview of Timber for Coal Mines

• Covers manufacturing criteria and dimensional standards for timber props used in mining structures.
• Allows buyers to choose suitable sizes as per Clause 4.2.6.

Key Dimensional Parameters:

Additional Notes:

• Final test data must be rounded following IS 2-1960 rules.
• Dimensional definitions correspond with IS 707-1958.
• Buyer flexibility provided for selecting sizes per Clause 4.2.6.

Rounding Instructions (IS 2-1960):

• Round values to match the significant figures specified.
• Example: A value of 12.0 should be rounded to three significant digits.

flowchart TD
    Start[Select Prop] --> DiameterCheck{Is diameter 10-12 cm?}
    DiameterCheck -- Yes --> LengthCheck{Is length 100-500 cm?}
    DiameterCheck -- No --> DiameterAdjust[Choose proper diameter]
    LengthCheck -- Yes --> Compliance[Use per standard]
    LengthCheck -- No --> LengthAdjust[Choose valid length]

Ensures adherence to IS 4424's manufacturing and size requirements.

Definitions and Abbreviations in IS 4424

• Terminology follows IS 707-1958 related to structural steel sections (Clause 2.0).
• Abbreviations align with IS 1150-1966 (Clause 3.3).
• Member dimensions standardized as per IS 707 (Clause 4.2).
• Purchaser options for dimensions detailed under Clause 4.2.6.
• Final numerical results rounded according to IS 2-1960 maintaining specified significant digits.

Reference Summary:

Rounding Examples:

Refer to IS 707 and IS 1150 for detailed definitions and abbreviations.

Selection of Timber Species Suitable for Coal Mines

Reference:

• Clause 3.1 lists approved timber types in Appendix A.

Commonly Recommended Timbers:

• Sal (Shorea robusta)
• Teak (Tectona grandis)
• Eucalyptus
• Chir Pine
• Deodar
• Other durable local hardwoods

Key Requirements:

• Timber must be free from defects such as knots, splits, or decay.
• Should possess adequate strength, toughness, and fungal resistance.
• Seasoned timber with moisture content below 15% is preferred for durability.

Selection Criteria:

• Based on density, modulus of elasticity, compressive and bending strengths.

Indicative Properties Table:

flowchart TD
    Start[Choose Timber Species] --> StrengthCheck{Strong & Durable?}
    StrengthCheck -->|Yes| Preferred[Sal, Teak, Eucalyptus]
    StrengthCheck -->|Moderate| Alternate[Chir Pine, Deodar]
    Start --> MoistureCheck{Moisture < 15%?}
    Start --> DefectCheck{Defect Free?}

Refer to Appendix A of IS 4424 for comprehensive species and quality details.

Manufacturing Criteria for Timber in Coal Mines

Core Specifications (Clause 4.2.1):

• Prop diameters must range between 10 cm and 12 cm.
• Prop lengths should be within 100 cm to 500 cm.

Additional Guidelines:

• Dimensions may be adjusted according to purchaser requirements (Clause 4.2 and 4.2.6).
• Final testing values require rounding per IS 2-1960, maintaining significant figures.

Rounding Guidance:

• Round final values to the same decimal precision as specified.
• Example: A specified dimension of 12.0 cm should have test values rounded to one decimal place.

Dimension Summary:

This ensures mining props satisfy standard dimensional criteria while offering purchaser flexibility.

Quality Requirements and Permissible Defects in Mining Timber

Highlights (Clauses 5.2 and 4.2.6):

• Minor defects may be tolerated within strict thresholds ensuring safety.
• Purchasers can specify defect tolerances fitting their needs.
• Test results must be rounded according to IS 2:1960 to maintain consistency.

General Specifications:

Quality Control Workflow:

flowchart TD
    Start[Manufacturing] --> Inspect[Quality Inspection]
    Inspect --> DefectCheck{Defects Present?}
    DefectCheck -- No --> Accept[Accept Product]
    DefectCheck -- Yes --> LimitsCheck{Within Limits?}
    LimitsCheck -- Yes --> Accept
    LimitsCheck -- No --> Reject[Reject or Rework]
    Accept --> RoundOff[Round Test Values per IS 2]
    RoundOff --> Dispatch[Product Ready for Use]

This ensures a balance between quality assurance and flexibility in defect acceptance.

Fire Resistance Treatment Requirements for Mining Timber

Reference (Clause 6.1):

• Treatments must comply with IS 401-1967 specifying fire retardant timber in coal mines.

Treatment Methods:

• Use of approved fire retardant chemicals such as borates or ammonium phosphate.
• Application via pressure impregnation or vacuum-pressure techniques for deep chemical penetration.
• Surface coatings with fire-resistant paints or varnishes may supplement protection.

Performance Requirements:

• Timber must resist ignition and limit flame progression.
• Structural integrity should be maintained for 30 to 60 minutes under fire exposure.

Typical Parameters:

Treatment Process Flow:

flowchart LR
    RawTimber[Raw Timber] --> Treatment[Fire Retardant Treatment]
    Treatment --> MethodChoice{Treatment Method}
    MethodChoice -->|Pressure Impregnation| TreatedTimber[Treated Timber]
    MethodChoice -->|Surface Coating| TreatedTimber
    TreatedTimber --> Test[Fire Resistance Testing]
    Test --> Approval{Meets IS 401-1967?}
    Approval -- Yes --> Approved[Approved for Mining Use]
    Approval -- No --> Rework[Retreat or Reject]

Refer to IS 401-1967 for detailed chemical specifications and testing procedures.

Design and Dimensional Requirements for Mining Timber Members

Key Points (Clauses 4.1 and 4.2):

• Timber must be sawn to square sections with bark fully removed.
• Branches should be trimmed flush with the stem.
• Ends must be cut flat and perpendicular to the prop’s axis.

Typical Dimensions:

Design Considerations:

• Select timber species recommended in Clause 2.00 for adequate strength.
• Square cross-sections ensure uniform load bearing.
• Proper end cuts prevent eccentric loading.

Dimension Summary Diagram:

graph TD
    TimberProp[Timber Prop] --> CrossSection[Square Cross-Section]
    CrossSection --> Size[75mm to 100mm Sides]
    TimberProp --> Length[Length]
    Length --> SizeLength[1.5m to 2.0m]
    TimberProp --> Ends[Ends Cut]
    Ends --> Orientation[Parallel & Perpendicular to Axis]

Refer to IS 883 and IS 11223 for comprehensive strength and design data.

Measurement and Inspection Guidelines in IS 4424

Measurement (Clause 4.3):

• Accurate dimensioning must comply with specified standards.
• Final observed or calculated results require rounding according to IS 2:1960 rules.
• Rounded values should retain the same significant digits as specified.

Purchaser Flexibility (Clause 4.2.6):

• Buyers may tailor requirements to project specifics within standard limits.

Dimensions (Clause 4.2):

• Timber members and components must conform to standard sizes.
• Use timber species recommended in Clause 2.00 for mine supports.

Rounding Rules (IS 2:1960):

• If discarded digit < 5, preceding digit remains unchanged.
• If discarded digit ≥ 5, preceding digit increments by one.

Rounding Examples (2 decimal places):

Timber Species Suitability Summary:

Inspection Flowchart:

flowchart TD
    Measurement[Measure/Calculate] --> Rounding[Round per IS 2:1960]
    Rounding --> Compare[Compare with Standard Values]
    Compare --> Compliant{Is it Compliant?}
    Compliant -- Yes --> Accept[Accept Timber]
    Compliant -- No --> Reject[Reject or Retest]

Adhere to IS 2:1960 rounding, specified dimensions, and recommended timber species for compliance.

Marking and Traceability of Mining Timber

Requirements (Clauses 8.1 & 8.1.1):

• Each timber piece must bear the manufacturer’s identification mark or initials using suitable methods such as branding or stamping.
• The ISI Certification Mark may optionally be applied to indicate Indian Standards compliance.
  • This signifies strict inspection and quality assurance.
  • Usage governed by Indian Standards Institution Certification Marks Act.

Important Considerations:

• Marking must not impair timber’s structural integrity.
• Follow abbreviations and marking conventions from IS 1150-1966.

Summary Table:

flowchart LR
    Timber[Timber Piece] --> MarkID[Mark Manufacturer ID]
    MarkID --> ISIOption{Apply ISI Mark?}
    ISIOption -- Yes --> ApplyISI[Apply ISI Mark]
    ISIOption -- No --> SkipISI[Only Manufacturer Mark]
    ApplyISI & SkipISI --> Ready[Timber Ready for Use]

Consult IS 4424 and related standards for detailed marking protocols.

Responsibilities and Approvals for Users under IS 4424

• Species of timber not included in Appendix A must not be supplied without prior written approval from the user (Clause 3.2).
• Buyers have the option to select specific requirements to suit their needs (Clause 4.2.6).
• Final test or calculation results must be rounded following IS 2-1960 rules, maintaining significant figures.

Summary Table:

Approval Flow Diagram:

flowchart TD
    UserRequest[User Request] --> CheckSpecies{Is Species in Appendix A?}
    CheckSpecies -- Yes --> Supply[Supply Timber]
    CheckSpecies -- No --> Consent[Obtain Written Consent]
    Consent -- Approved --> Supply
    Consent -- Denied --> Deny[Do Not Supply]

This ensures user control and compliance during timber procurement.

Appendices Overview and Additional Specifications

• Appendix A enumerates timber species recommended for mining use (Clause 3.1).

  • Species not listed require written user approval (Clause 3.2).

• Clause 4.2 details dimensions for timber members like props, supports, and lids used in mine roadways and headings.

• Figures 4 & 5 depict typical timber support arrangements:

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

Typical Dimensions (Clause 4.2):

Recommended Species Examples (Appendix A):

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

flowchart LR
    Species[Appendix A Species] --> ConsentCheck{User Approval?}
    ConsentCheck -- No --> Deny[Not Permitted]
    ConsentCheck -- Yes --> Supply[Supply Timber]
    Supply --> Usage[Used in Props and Supports]
    Usage --> Dimensions[Follow Clause 4.2 Dimensions]

Use only species approved in Appendix A unless authorized. Follow dimensional standards for safety in mining.