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

IS 5247 Part 2: Introduction and Scope – Key Points

1. Scope

• Covers planks and scantlings from specified timber species.
• Timber species included with standard trade names, botanical names, and abbreviations:

2. Dimensions & Tolerances

• Definitions per IS 707-1976 apply.
• Final test or calculated values are rounded off as per IS 2-1960.

3. Prophylactic Treatment

• Timber may be treated as per IS 401-1982 (preservation code).
• Treatment subject to purchaser-supplier agreement.

4. Units

• Use SI units for all measurements (e.g., length in meters, force in newtons).

Summary Table: Timber Species & Symbols

Important Notes:

• Compliance with IS 5247 requires adherence to species, dimensions, treatment, and rounding rules.
• Refer to IS 707 for seasoning and IS 401 for preservation specifics.

flowchart

IS 5247 Part 2: Key Definitions & Specifications

1. Definitions Reference

• Clause 2.0: Definitions follow IS 707-1976 and additional ones in IS 5247 Part 2.

2. Timber Species (Clause 3.1, Table 3)

3. Rounding Off (Clause 0.5)

• Results must be rounded per IS 2-1960.
• Retain the same significant figures as the specified values.

Summary

• Use IS 707-1976 for timber definitions.
• Select timber species from the specified list with their symbols.
• Apply IS 2-1960 rounding rules for test results.

flowchart TD
    A[IS 5247 Part 2] --> B[Definitions 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: Species of Timber - Key Details

1. Species of Timber (Clause 3.1)

2. Marking Requirements (Clause 8.1)

Each timber piece must be marked 30 cm from the end on a broad face with:

• Species abbreviated symbol (e.g., CHR, CYP)
• Size (dimensions accepted)
• Supplier’s name/initials/trademark
• Year of supply

3. Additional Notes

• Dimensions and tolerances for coniferous sawn timber are per IS 190-1974.
• This standard targets timber for light furniture, packing cases, and crates.
• The revision aims to minimize wastage and ensure efficient utilization.

If you need strength or design properties, refer to IS 190 for grading and mechanical properties of these species.

flowchart LR
    A[Timber Species] --> B[Marking: Symbol + Size + Supplier + Year]
    A --> C[Dimensions per IS 190-1974]
    A --> D[Usage: Furniture, Packing, Crates]

Summary: Use listed species with proper marking and dimensions per IS 190 to ensure standard quality and traceability.

IS 5247 Part 2: Dimensions & Tolerances for Timber Planks and Scantlings

1. Dimensions Measurement (Clause 5.2)

• Length (m): Measured along midline; rounded down to nearest 0.01 m.
• Width (cm): Measured at narrowest point; rounded down to nearest 1 cm.
• Thickness (cm or mm): Measured at narrowest point; rounded down to nearest 0.5 cm.
• Volume (m³): Calculated from accepted sizes, accurate to 3 decimal places.

2. Tolerances on Nominal Sizes (Clause 4.2)

Note: Tolerances apply irrespective of nominal width or thickness.

3. Species Reference (Clause 3.1)

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

Summary Table: Measurement & Tolerances

flowchart TD
    A[Timber Piece] --> B[Measure Length (m)]
    A --> C[Measure Width (cm)]
    A --> D[Measure Thickness (cm/mm)]
    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 (m³)]
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IS 5247 Part 2: Tolerances on Timber Dimensions

Key Specifications from Clause 4.2:

• Minus tolerance in width and thickness is not permitted in more than 25% of supplies at any one time.
• For width ranges (e.g., 150 to 250 mm), no minus tolerance on minimum width and no plus tolerance on maximum width allowed.
• Permissible tolerances:

Important Notes:

• Minus tolerances are generally not allowed except in limited cases.
• Measurements should be rounded off as per IS 2-1960 rules.
• These tolerances ensure quality and uniformity in timber products like planks and scantlings.

Summary Table:

Visual Summary:

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

This ensures timber pieces meet size expectations with controlled variability.

IS 5247 Part 2: Measurement Methods Key Points

Measurement Specifications (Clause 5.2)

• Length (m): Measured along the midline; fractions rounded down to nearest 0.01 m.
• Width (cm): Measured at narrowest point; rounded down to nearest 1 cm.
• Thickness (cm or mm): Measured at narrowest point; rounded down to nearest 0.5 cm.
• Volume (m³): Calculated from accepted sizes; rounded to 3 decimal places.

Tolerance Limits (Clause 4.2.1)

• Maximum 25% of supplies can have minus tolerance in width/thickness.
• For specified width ranges (e.g., 150–250 mm), no minus tolerance on minimum width and no plus tolerance on maximum width allowed.

Rounding Rules (Clause 0.5)

• Final test/analysis values rounded per IS 2-1960.
• Number of significant digits in rounded value = number in the specified value.

Volume Calculation Formula:

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

Summary Table for 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]

This ensures consistent, standardized measurement and volume computation for

IS 5247 Part 2: Permissible Defects Summary

• Clause 7.2: Defects as per 7.2.1 to 7.2.9 are permissible collectively, not individually. Plugging defects is not allowed (7.1).
• Moisture Content (6.2): Max 18% at inspection, per IS 287-1973.
• Defect Measurement: Follow IS 3364 (Part II)-1976 for evaluation.

Key Table: Surface Cracks Permissible Depth (Clause 7.2.6)

Notes:

• Surface cracks exclude ends.
• Defects are cumulative, not isolated.
• Dead knots and other defects have specific limits detailed in IS 5247 Part 2.

This ensures timber quality control for structural safety and durability.

IS 5247 Part 2: General Defect Criteria Summary

• Permissible Defects:

  • Defects as per Clauses 7.2.1 to 7.2.9 are allowed collectively, not individually (Clause 7.2).
  • Plugging of defects is not allowed (Clause 7.1).
  • Evaluation of defects follows IS 3364 (Part II) - 1976.

• Moisture Content:

  • Max moisture content at inspection: 18% (Clause 6.2, IS 287-1973 method).

• Surface Cracks (Clause 7.2.6):
  Depth of deepest permissible cracks depends on timber thickness:

Key Notes:

• Defects must be measured per IS 3364 (Part II).
• Moisture content affects timber durability and must be controlled.
• Surface cracks are limited in depth relative to thickness to maintain structural integrity.

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

This ensures timber quality within IS 5247 Part 2 standards.

IS 5247 Part 2: Knots (Live and Dead) - Key Specifications

Live Knots (Clause 7.2.3.1)

• Up to 30 mm diameter: Allowed if not too grouped or weakening timber.
• 30 to 50 mm diameter: Max 1 knot/20 cm length.
  • Width ≤150 mm: knot diameter ≤ piece width.
  • Width >150 mm: knot diameter ≤ 50 mm.
• 50 to 80 mm diameter: Max 1 knot/50 cm length, ≥25 mm from edge.

Dead Knots (Clause 7.2.3.2)

• Up to 6 mm diameter: Allowed if not numerous or weakening.
• 6 to 25 mm diameter: Max 1 knot/20 cm length.
• 25 to 45 mm diameter: Max 1 knot/m length.

Combined Knots (Clause 7.2.3.3)

• Knots live on one face and dead on the other → treated as dead knots per 7.2.3.2.

Surface Cracks (Clause 7.2.6)

Summary Table: Knot Limits

This ensures timber's structural integrity by controlling knot size, frequency, and location.

IS 5247 Part 2: Cross Grain - Key Specifications

• Clause 7.2.5 (Cross Grain):
  Maximum permissible deviation of grain direction from longitudinal axis = 1 in 10 (i.e., 10% deviation).

• Interpretation:
  Cross grain means the fibers deviate from the lengthwise direction. A deviation of 1:10 means the grain can deviate by 1 unit perpendicular for every 10 units along the length.

• Implication on Strength:
  Cross grain reduces tensile and bending strength; hence this limit ensures structural reliability.

Related Key Tables & Limits

Timber Species (Clause 3.1)

Summary Diagram: Cross Grain Limit

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

Note: Always ensure cross grain does not exceed 10% to maintain timber strength and durability as per IS 5247 Part 2.

IS 5247 Part 2 - Twist Specifications

Clause 7.2.7: Twist Limits

• Maximum twist allowed: 5 mm per 30 cm length.
• Measurement: Across the diagonals on the worst surface of the timber piece.
• Permissible quantity: Twist allowed in not more than 10% of pieces supplied at one time.

Practical Interpretation:

• Measure diagonal difference on the face of the timber piece.
• If the difference exceeds 5 mm in 30 cm length, the piece is rejected.
• Only 10% of pieces can have this defect to maintain quality.

Related Specifications for Surface Defects (Clause 7.2.6):

Summary Table for Twist:

flowchart LR
    A[Timber Piece] --> B{Measure Diagonals}
    B -->|Difference ≤ 5 mm / 30cm| C[Accept Piece]
    B -->|Difference > 5 mm / 30cm| D[Reject Piece]
    E[Max 10% pieces with twist] --> F[Quality Check]

Note: This limit ensures structural integrity and usability of timber in construction, minimizing distortion effects like warping or twisting.

IS 5247 Part 2: Borer Holes Specifications

• Clause 7.2.9 (Borer Holes):
  • Permissible only on two faces of timber (dead infestation).
  • Maximum hole depth: 5 mm.
  • Holes must be well scattered (no clustering to maintain strength).

Additional Relevant Details:

• Species Covered (Clause 3.1):
  Timber species include Chir (CHR), Cypress (CYP), Deodar (DEO), Fir (FIR), Kail (KAL), Khasi Pine (KPI), Red Fir (RFI), Spruce (SPR), and Pinus patula.

• Dimensional Tolerance (Clause 7.2.1.1):
  Maximum bow allowed: 0.5 cm per meter length.

Summary Table for Borer Holes

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

This ensures durability and structural integrity of timber by limiting borer damage.

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

Each timber piece must be marked indelibly on a broad face, 30 cm from the end, with:

• a) Abbreviated species symbol (see Table below)
• b) Size (accepted dimensions)
• c) Supplier’s name, initials, or trademark
• d) Year of supply

Species Abbreviations (Clause 3.1)

Key Notes:

• Marking ensures traceability and quality control.
• Dimensions must comply with IS 190-1974 for coniferous sawn timber.
• Marking should be legible and permanent to withstand handling.

flowchart LR
    A[Timber Piece] --> B[Marking Location: 30 cm from end]
    B --> C{Marking Details}
    C --> D[Species Symbol (e.g., CHR)]
    C --> E[Size (dimensions)]
    C --> F[Supplier Name/Trademark]
    C --> G[Year of Supply]

This marking system facilitates identification and quality assurance throughout timber usage.

IS 5247 Part 2: End Coating to Prevent Defects

Key Specifications (Clause 9.1)

• Purpose: Prevent end cracking, splitting in planks and scantlings.
• Coating Length: At least 25 mm beyond the longest visible split.
• Materials: Use materials specified in IS 1141-1973 (e.g., paint, wax, or other sealants).
• Timing: Apply coating immediately after inspection of sawn timber to minimize moisture loss and defects.

Related Important Clauses

• Moisture Content (6.2): Should not exceed 18% at inspection (per IS 287-1973).
• Defect Evaluation (7.2): Defects measured per IS 3364 (Part II)-1976.
• Permissible Defects (7.1): Plugging defects not allowed; defects considered collectively.

Summary Table: End Coating Application

Practical Tip:

Apply end coating promptly to reduce moisture gradient and prevent stress cracks at timber ends.

flowchart LR
  A[Inspection of Sawn Timber] --> B[Measure Longest Split]
  B --> C[Calculate Coating Length = Split + 25mm]
  C --> D[Apply End Coating (IS 1141 Materials)]
  D --> E[Prevent End Cracking & Splitting]

This approach ensures durability and quality compliance per IS 5247 Part 2.

IS 5247 Part 2: Prophylactic Treatment of Timber

Key Specifications from Clause 10:

• End Coating (Clause 9.1):

  • Apply coating on plank/scantling ends extending at least 25 mm beyond the longest split to prevent cracking and splitting.
  • Use materials as per IS 1141-1973.
  • Apply coating immediately after timber inspection.

• Prophylactic Treatment (Clause 10.1):

  • All timber members may be treated as per IS 401-1982 (Timber Preservation).
  • Treatment type and extent must be agreed upon between purchaser and supplier.

Important Timber Species (Clause 3.1):

Summary Table: End Coating Application

Additional Notes:

• Prophylactic treatment involves chemical preservatives to protect timber from decay and pests.
• IS 401-1982 details preservatives and methods (e.g., pressure treatment, brushing).
• Ensure treatment compatibility with timber species and intended use.

flowchart TD
    A[Inspection of Timber] --> B[Identify Longest Split]
    B --> C[Calculate Coating Length = Split Length + 25mm]
    C --> D[Apply End Coating as per IS 1141]
    D --> E[Prophylactic Treatment as per IS 401