converted timber (coniferous): Part 2 Packing cases and crates
1982 Edition

IS 5247 Part 2: Overview and Applicability - Highlights

1. Applicability

• Applies to converted planks and scantlings from designated coniferous species.
• Timber species are identified by standard trade names, botanical nomenclature, and abbreviations:

2. Dimensions & Rounding

• Definitions follow IS 707-1976.
• Final values rounded per IS 2-1960.

3. Preservative Treatments

• Treatments conform to IS 401-1982, subject to purchaser-supplier agreement.

4. Measurement Units

• SI units are mandatory for all measurements (e.g., metres, newtons).

Timber Species and Codes Summary

Essential Notes:

• Compliance demands adherence to species, sizing, treatment, and rounding requirements.
• Refer to IS 707 for seasoning and IS 401 for preservation guidelines.

flowchart

IS 5247 Part 2: Definitions & Key Details

1. Definition Sources

• Clause 2.0 references IS 707-1976 for terminology, supplemented by IS 5247 Part 2 specifics.

2. Timber Species Table (Clause 3.1)

3. Rounding Rules (Clause 0.5)

• Results rounded according to IS 2-1960.
• Maintain significant digit count equal to specified values.

Summary

• Use IS 707-1976 for terms.
• Select species from listed codes.
• Apply IS 2-1960 rounding for test outcomes.

flowchart TD
    A[IS 5247 Part 2] --> B[Definitions as per IS 707-1976]
    A --> C[Timber Species List]
    C --> D[Chir (CHR)]
    C --> E[Cypress (CYP)]
    C --> F[Deodar (DEO)]
    C --> G[Fir (FIR)]
    C --> H[Kail (KAL)]
    C --> I[Khasi Pine (KPI)]
    C --> J[Red Fir (RFI)]
    C --> K[Spruce (SPR)]
    A --> L[Rounding per IS 2-1960]

IS 5247 Part 2: Approved Timber Species Overview

1. Timber Species (Clause 3.1)

2. Marking Instructions (Clause 8.1)

Timber pieces must be marked on a broad face, 30 cm from the end, indicating:

• Species code (e.g., CHR, CYP)
• Size (approved dimensions)
• Supplier’s name, initials, or brand
• Year of supply

3. Additional Information

• Dimensions and tolerances correspond to IS 190-1974.
• Intended for lightweight furniture, packing cases, and crates.
• Revised to optimize material utilization and reduce waste.

For mechanical properties and strength grading, consult IS 190.

flowchart LR
    A[Timber Species] --> B[Mark with Symbol, Size, Supplier, Year]
    A --> C[Dimensions per IS 190-1974]
    A --> D[Applications: Furniture, Crates, Packing Cases]

Summary: Employ authorized species with proper marking and dimensional compliance to guarantee quality and traceability.

IS 5247 Part 2: Dimensions and Permissible Variations for Planks and Scantlings

1. Measurement Guidelines (Clause 5.2)

• Length (metres): Measured along the plank's midline, rounded down to the nearest 0.01 m.
• Width (centimetres): Measured at the narrowest section, rounded down to nearest 1 cm.
• Thickness (cm or mm): Measured at narrowest point, rounded down to nearest 0.5 cm.
• Volume (cubic metres): Computed from accepted dimensions, precision up to three decimal places.

2. Tolerances (Clause 4.2)

Note: Tolerances apply uniformly regardless of nominal size.

3. Species Reference (Clause 3.1)

• Commonly used species include Chir (CHR), Cypress (CYP), Deodar (DEO), Fir (FIR), Kail (KAL), Khasi Pine (KPI), Red Fir (RFI), and Spruce (SPR).

Summary Table: Measurement and Tolerances

flowchart TD
    A[Timber Piece] --> B[Measure Length]
    A --> C[Measure Width]
    A --> D[Measure Thickness]
    B --> E[Round down to 0.01 m]
    C --> F[Round down to 1 cm]
    D --> G[Round down to 0.5 cm]
    E & F & G --> H[Calculate Volume]

IS 5247 Part 2: Dimension Tolerance Specifications

Specifications from Clause 4.2:

• Negative tolerance on width and thickness is allowed in no more than 25% of the batch.
• For certain width ranges (e.g., 150 to 250 mm), no negative tolerance on minimum width or positive tolerance on maximum width is permitted.
• Approved tolerances:

Important Notes:

• Negative tolerances are generally restricted and monitored.
• Measurements and rounding conform to IS 2-1960.
• These limits help maintain uniform timber quality.

Summary Table:

Visual Summary:

flowchart TD
    A[Nominal Size] --> B[Width]
    A --> C[Thickness]
    B --> D[+3 mm allowed]
    B --> E[-ve tolerance ≤ 25% supply]
    C --> F[+3 mm allowed]
    C --> G[-ve tolerance ≤ 25% supply]
    H[Width Range] --> I[No -ve tolerance on min width]
    H --> J[No +ve tolerance on max width]

This ensures timber pieces meet size expectations with controlled variation.

IS 5247 Part 2: Measurement Procedures Overview

Key Measurement Points (Clause 5.2)

• Length: Taken along the midline, rounded down to the nearest 0.01 m.
• Width: Measured at the narrowest point, rounded down to the nearest 1 cm.
• Thickness: Measured at the narrowest location, rounded down to the nearest 0.5 cm.
• Volume: Determined from accepted dimensions, rounded to three decimal places.

Tolerance Guidelines (Clause 4.2.1)

• Negative tolerances in width and thickness permitted in no more than 25% of supplied timber.
• For certain width bands, no negative tolerance on minimum width or positive tolerance on maximum width is permitted.

Rounding Instructions (Clause 0.5)

• Final test values rounded as per IS 2-1960.
• Number of significant digits retained equals that in the specified value.

Volume Calculation Formula:

[Volume = Length (m) \times Width (m) \times Thickness (m)]

Summary Table of Measurement Rounding

flowchart LR
    A[Measure Length] --> B[Round down to 0.01 m]
    C[Measure Width] --> D[Round down to 1 cm]
    E[Measure Thickness] --> F[Round down to 0.5 cm]
    B & D & F --> G[Calculate Volume]
    G --> H[Round volume to 3 decimals]

Ensures uniform measurement and volume calculation standards.

IS 5247 Part 2: Summary of Allowed Defects

• Clause 7.2: Defects listed in Clauses 7.2.1 through 7.2.9 are collectively permissible, but not individually patched (Clause 7.1 prohibits plugging).
• Moisture Limit (6.2): Maximum 18% at inspection, per IS 287-1973.
• Defect Assessment: Follow IS 3364 (Part II)-1976 for measurement.

Permissible Surface Crack Depths (Clause 7.2.6)

Notes:

• Surface cracks do not include end grain.
• Defects are cumulative in evaluation.
• Dead knots and other defects have specific limits.

Ensures timber maintains strength and durability.

IS 5247 Part 2: General Defect Allowances Overview

• Permitted Defects:

  • Defects from Clauses 7.2.1 to 7.2.9 are allowed collectively (Clause 7.2).
  • Plugging or filling of defects is forbidden (Clause 7.1).
  • Defect measurements follow IS 3364 (Part II) - 1976.

• Moisture Control:

  • Maximum moisture content at inspection is 18% (Clause 6.2, IS 287-1973).

• Surface Crack Limitations (Clause 7.2.6):
  Crack depths vary with timber thickness:

Key Points:

• Defects evaluated per IS 3364 (Part II).
• Moisture content critical to timber longevity.
• Surface cracks limited to preserve structural integrity.

flowchart LR
    A[Timber Inspection] --> B{Is Moisture ≤ 18%?}
    B -- Yes --> C[Assess Defects per IS 3364]
    B -- No --> D[Reject or Dry Timber]
    C --> E{Are Defects Acceptable?}
    E -- Yes --> F[Check Surface Crack Depth]
    F --> G{Thickness}
    G -- ≤ 50 mm --> H[Max Crack 2 mm]
    G -- 50-100 mm --> I[Max Crack 3 mm]
    G -- > 100 mm --> J[Max Crack 6 mm]
    E -- No --> K[Reject Timber]

Ensures timber meets quality criteria.

IS 5247 Part 2: Specifications for Live and Dead Knots

Live Knots (Clause 7.2.3.1)

• Diameter up to 30 mm: Permitted if not clustered or weakening.
• Diameter 30 to 50 mm: Maximum 1 knot per 20 cm length.
  • For widths ≤ 150 mm: knot diameter ≤ piece width.
  • For widths > 150 mm: knot diameter ≤ 50 mm.
• Diameter 50 to 80 mm: Maximum 1 knot per 50 cm length, located at least 25 mm from edges.

Dead Knots (Clause 7.2.3.2)

• Diameter up to 6 mm: Allowed if not excessive or weakening.
• Diameter 6 to 25 mm: Max 1 knot per 20 cm length.
• Diameter 25 to 45 mm: Max 1 knot per 1 metre length.

Combined Knots (Clause 7.2.3.3)

• Live knot on one face and dead knot on the opposite face are treated as dead knots for evaluation.

Surface Crack Limits (Clause 7.2.6)

Knot Limit Summary

Maintains timber strength by controlling knot size, frequency, and placement.

IS 5247 Part 2: Cross Grain Limits

• Clause 7.2.5: Maximum allowed grain deviation from the longitudinal axis is 1:10 (10%).

• Meaning: Cross grain indicates fiber orientation deviating from the lengthwise direction; a 1:10 ratio means 1 unit lateral deviation per 10 units longitudinally.

• Effect on Strength: Excessive cross grain reduces tensile and bending strength, so this limit ensures reliability.

Associated Limits

Timber Species (Clause 3.1)

Cross Grain Limit Diagram

graph LR
A[Longitudinal Grain] -->|Max deviation 1:10| B[Cross Grain]

Maintaining cross grain within 10% helps preserve timber’s structural integrity.

IS 5247 Part 2: Twist Allowances

Clause 7.2.7 - Maximum Twist

• Maximum permitted twist is 5 mm over a 30 cm span.
• Measurement is taken across the diagonals of the timber’s widest surface.
• Twist is acceptable in no more than 10% of the pieces within a batch.

Interpretation:

• Measure diagonal difference; if greater than 5 mm per 30 cm, reject the piece.
• Limit ensures functional and structural integrity.

Related Surface Crack Limits (Clause 7.2.6):

Twist Summary Table:

flowchart LR
    A[Timber Piece] --> B{Measure Diagonals}
    B -->|Difference ≤ 5 mm| C[Accept]
    B -->|Difference > 5 mm| D[Reject]
    E[Max 10% pieces with twist] --> F[Quality Control]

Controls distortion and maintains usable timber quality.

IS 5247 Part 2: Specifications for Borer Holes

• Clause 7.2.9:
  • Borer holes permitted only on a maximum of two faces indicating inactive (dead) infestation.
  • Maximum hole depth allowed is 5 mm.
  • Holes must be well dispersed, avoiding clustering to maintain strength.

Additional Information:

• Timber species per Clause 3.1 include Chir (CHR), Cypress (CYP), Deodar (DEO), Fir (FIR), Kail (KAL), Khasi Pine (KPI), Red Fir (RFI), Spruce (SPR), and Pinus patula.
• Maximum allowable bow is 0.5 cm per metre length (Clause 7.2.1.1).

Borer Hole Summary

flowchart LR
    A[Timber Piece] --> B{Presence of Borer Holes?}
    B -- Yes --> C[Check Number of Faces]
    C -->|≤ 2 faces| D[Check Hole Depth]
    D -->|≤ 5 mm| E[Check Distribution]
    E -->|Well scattered| F[Accept]
    E -->|Clustered| G[Reject]
    D -->|> 5 mm| G
    C -->|> 2 faces| G
    B -- No --> F

Ensures timber durability by limiting insect damage.

Timber Marking Guidelines (IS 5247 Part 2 - Clause 8.1)

Each timber piece shall be marked permanently on a broad face, 30 cm from the end, including:

• a) Abbreviated species code (refer to species table)
• b) Size dimensions as accepted
• c) Supplier’s name, initials, or trademark
• d) Year of manufacture or supply

Species Codes (Clause 3.1)

Important Notes:

• Markings ensure traceability and quality assurance.
• Dimensions must meet IS 190-1974 standards.
• Marks should withstand handling and remain legible.

flowchart LR
    A[Timber Piece] --> B[Mark 30 cm from end]
    B --> C{Marking Details}
    C --> D[Species Code]
    C --> E[Size]
    C --> F[Supplier Identifier]
    C --> G[Year of Supply]

This system supports identification and quality control throughout the timber’s lifecycle.

IS 5247 Part 2: End Coating to Prevent Splitting

Clause 9.1 Specifications

• Objective: Prevent cracking and splitting at plank and scantling ends.
• Coating Coverage: Extend at least 25 mm beyond the longest visible end split.
• Materials: Use coatings compliant with IS 1141-1973, such as paints or waxes.
• Timing: Apply immediately after timber inspection to reduce moisture loss.

Related Clauses

• Moisture content should not exceed 18% at inspection (Clause 6.2).
• Defects are assessed per IS 3364 (Part II)-1976.
• Plugging defects is prohibited (Clause 7.1).

End Coating Summary

Practical Advice:

Promptly apply end coatings to mitigate moisture gradients and reduce end splitting.

flowchart LR
  A[Inspect Timber Ends] --> B[Measure Longest Split]
  B --> C[Calculate Coating Length]
  C --> D[Apply IS 1141 Compliant Coating]
  D --> E[Prevent End Defects]

Ensures timber durability and compliance with IS 5247 Part 2.

IS 5247 Part 2: Timber Preservation Treatments

Key Points from Clause 10:

• End Coating (Clause 9.1):

  • Apply coating extending at least 25 mm beyond the longest split to prevent end cracking.
  • Use materials conforming to IS 1141-1973.
  • Application should follow immediately after inspection.

• Preservative Treatment (Clause 10.1):

  • All timber elements may undergo preservative treatment as specified in IS 401-1982.
  • Treatment type and extent must be mutually agreed between buyer and supplier.

Timber Species (Clause 3.1):

End Coating Summary

Additional Notes:

• Preservative treatments protect against decay and pests.
• IS 401-1982 details methods such as pressure impregnation and brushing.
• Compatibility with timber species and usage is essential.

flowchart TD
    A[Inspect Timber] --> B[Identify Longest Split]
    B --> C[Calculate Coating Length]
    C --> D[Apply IS 1141 Compliant End Coating]
    D --> E[Apply Preservative Treatment per IS 401]