Method of sampling of model trees and logs and their conversion for timber testing

IS 2455: Scope Summary & Key Specifications

IS 2455 covers methods for testing timber, focusing on sampling, specimen selection, and test procedures to ensure timber quality.

Scope Highlights:

• Applies to structural timber testing and analysis.
• Specifies sampling methods and test specimen preparation.
• Requires rounding off results per IS 2:1960 (same significant figures as standard values).
• References related IS codes for preservation, terminology, and testing:

Key Sampling & Site Data (Annex A):

• Record site details: state, division, tree count, map with tree locations.
• Environmental data: temperature, rainfall, humidity, groundwater depth.
• Site characteristics: altitude, slope, soil type, drainage, erosion.
• Vegetation and fauna observations.
• Landform physiography and drainage classification.

Specimen Selection:

• Number and position of bolts (timber samples) per tree are standardized (Fig. 2 in code).
• Order of tests and specimen selection detailed in Clause 4.3 and Annex A.

Rounding Off Rule (IS 2:1960)

• Round test results to same decimal places as specified values.
• Ensures consistency in reporting.

flowchart TD
    A[Timber Source] --> B[Sampling & Site Data Collection]
    B --> C[Specimen Selection]
    C --> D[Testing (Mechanical, Physical)]
    D --> E[Result Calculation & Rounding (IS 2)]
    E --> F[Compliance Evaluation]

For detailed test procedures, refer to IS 1708 and IS 2408. The scope ensures uniformity in timber testing and quality assessment.

IS 2455 - References Summary

Key Indian Standards Referenced (Clause 2.1)

Important Notes:

• Rounding off: Use IS 2:1960 rules for numerical rounding to match significant digits of specified values.
• Specimen selection: Annex C provides detailed schedules for specimen allocation for various tests (static bending, impact, compression, tension, shear, hardness, etc.) ensuring representative sampling from different zones (pith, periphery, intermediate).
• Standard Mark: Products conforming to IS standards carry BIS certification assuring quality and compliance.

Specimen Testing Overview (Annex C)

• Static bending: 1 specimen/pair of sticks
• Impact bending: 6 specimens from different zones
• Compression parallel/perpendicular: 1 specimen per stick or 50% sticks
• Shear, tension, cleavage, torsion: 6 specimens/pairs from zones
• Nail/screw withdrawal: 18 specimens
• Specific gravity & shrinkage: 6 specimens

flowchart TD
    A[Timber Sample] --> B{Select Specimens}
    B --> C[Static Bending]
    B --> D[Impact Bending]
    B --> E[Compression]
    B --> F[Shear & Tension]
    B --> G[Hardness & Shrinkage]
    C --> H[1 specimen/pair]
    D --> I[6 specimens (zones)]
    E --> J[1 specimen/stick or 50%]
    F --> K[6 specimens/pairs]
    G --> L[6 specimens]

For detailed test procedures and sampling, refer to IS 2455 Annex C and related IS codes listed above.

IS 2455: Definitions Summary (Clause 3.1 & References)

• Definitions: As per IS 2455 Clause 3.1, all terms are defined according to IS 707:1976 - Glossary of terms applicable to timber technology and utilization.

• Key Reference Standards:

  IS No.	Title
  401:1982	Preservation of timber
  707:1976	Glossary of timber terms
  1708 (Parts 1-18):1986	Testing small clear timber specimens
  2408:1963	Static tests of structural timber
  4905:1968	Methods for random sampling

• Rounding Off: Final test values are rounded per IS 2:1960 rules, maintaining the same significant figures as specified.

Important Notes on Definitions & Site Data (Annex A)

• Definitions rely on IS 707:1976; consult it for timber-specific terms like "clear wood," "knot," "grain," etc.
• Site and sample data collection includes:
  • Tree origin (natural, plantation)
  • Location details (state, division, map)
  • Climate (temperature, rainfall, humidity)
  • Soil, vegetation, drainage, erosion, and other environmental factors
• This comprehensive data ensures proper classification and testing of timber samples.

Quick Reference: Rounding Off Numerical Values (IS 2:1960)

flowchart TD
    A[IS 2455 Definitions] --> B[IS 707:1976 Terms]
    A --> C[Timber Testing Standards]
    C --> D[IS 1708 - Small Specimens]
    C --> E[IS 2408 - Structural Sizes]
    A --> F[Rounding Rules IS 2:1960]
    A --> G[Site Data Collection (Annex A)]

For detailed timber terms, always refer to IS 707:1976.

IS 2455: Selection of Test Area - Key Points

1. Definition:

• Test Area: A specific forest compartment/block selected for timber tree testing (Clause 3.1.4).

2. Taxation of Test Area (Annex A - Clause 4.3):

• Use the standard form to record:
  • State, Division, Range.
  • Total number of trees of the species.
  • Sketch map with tree locations (circled numbers).
  • Climate data: Max/Min/Mean temperature, rainfall, humidity.
  • Nearby water bodies and groundwater depth.
  • Geological formation, altitude, slope shape, and gradient.
  • Vegetation type, ground cover, regeneration status.
  • Soil characteristics: type, root penetration, moisture, organic matter.
  • Landform physiography, relief, drainage (external/internal), erosion, deposition.
  • Parent material and surface condition.
  • History of site management (fire, grazing, felling).

3. Selection Criteria Summary Table (from Annex A):

4. Important Notes:

• Include sketch map with tree numbers and geographical features.
• Record site quality (natural seedling, coppice, plantation).
• Verify and sign off by collector and dispatcher.

flowchart TD
    A[Test Area Selection] --> B[Record Site Details]
    B --> C[Climate Data]
    B --> D[Geological & Soil Data]
    B --> E[Vegetation & Landform]
    B --> F[Drainage & Erosion]
    B --> G[Sketch Map & Tree IDs]
    G -->

IS 2455: Selection of Model Trees in Test Area

Key Specifications (Clause 5):

• Tree Selection (5.2):

  • Trees must be selected standing by a qualified person familiar with species identification and conversion/testing implications.
  • Testing authority should inspect trees before felling if needed.

• Girth Grouping (5.4):

  • If selected trees vary widely in girth, divide into girth groups before testing.
  • Different consignments from each group are tested separately.

• Notification (5.6):
  • Inform testing authority immediately after tree selection for further instructions.

Summary Flow:

flowchart TD
    A[Select Trees Standing] --> B{Qualified Person}
    B --> C[Identify Species]
    C --> D[Divide into Girth Groups (if varied)]
    D --> E[Inform Testing Authority]
    E --> F[Mark and Fell Trees (Clause 6)]

This ensures representative sampling and proper testing per IS 2455.

IS 2455: Marking and Felling of Model Trees - Key Points

1. Marking of Model Trees (Clause 6.3)

• Mark tree number and northern point clearly on each tree, just below the ring.
• Bark removal may be done to mark.
• Distinguish category marks as needed.
• For numbers 6 and 9, draw a line underneath to avoid confusion.

2. Selection and Notification (Clauses 5.2 & 5.6)

• Trees must be selected by a qualified person who can identify species and understand testing implications.
• Testing authority should be informed immediately after selection for further instructions or inspection.

3. Documentation (Clause 4.3)

• Fill in the taxation particulars of the test area in the standard form (Annex A).

Summary Table for Marking

flowchart TD
    A[Select Model Trees] --> B[Mark Tree Number & Northern Point]
    B --> C[Notify Testing Authority]
    C --> D[Testing Authority Inspects/Provides Instructions]
    D --> E[Felling of Marked Trees]

This ensures traceability and correct specimen identification during testing.

IS 2455: Conversion of Trees into Logs & Dispatching

Key Points & Specifications

• Merchantable bole length (m): Common lengths are 4.5, 6.0, 7.5, 9.0, 10.5, 12.0, 13.5, 15.0, 16.5, 18.0, 19.5, 21.0, 22.5, 24.0 (Clause 3.0).

• Log selection (Clause 7.1.1):

  • Only one log from the bottom portion of the tree is taken for standard testing.
  • If multiple logs are tested, they must be from different heights.
  • Each log must be numbered and its height position recorded.

• Specimen identification & record keeping (Annex B & Clause 7.6):

  • Record marks on small end, breast height, and stump disc.
  • Record age, total length, trunk length, girth at 1.37 m height.
  • Dates of felling, converting, dispatch.
  • Log girth (mm) at ends.
  • Description of visible defects.
  • Details of dispatch voucher and references.
  • Signatures of collector and dispatcher with dates.

• Specimen ends must be coated to prevent moisture loss before dispatch.

Table format for Tree Information (Annex B)

IS 2455: Receipt and Verification of Logs by Testing Authority

Key Specifications (Clause 8.1 & Annex B)

• Identification: Check and record log ID, species, and all dispatched details.
• Verification: Confirm marks on:
  • Small end
  • Breast height (1.37 m)
  • Disc cut from stump
• Record details:
  • Age of tree (if known)
  • Total tree and trunk length
  • Girth at breast height (over bark)
  • Date of felling and converting to logs
  • End coating method
  • Log girth (in mm)
  • Dispatch voucher/reference no.
  • Visible defects description
• Signatures: Collector and dispatcher must sign and date after verification.

Important Timing (Clause 7.7.5)

• Minimize time between felling and dispatch to preserve log quality.

Taxation & Site Info (Annex A)

• Record site data: forest type, soil, drainage, altitude, climate, and vegetation.
• Include sketch map showing tree locations.

Summary Table for Log Verification

flowchart TD
    A[Felling of Tree] --> B[Marking & Identification]
    B --> C[Log Conversion & Coating]
    C --> D[Dispatch to Testing Authority]
    D --> E[Verification of Logs]
    E --> F[Record Keeping & Signatures]

Ensure all data is accurate to maintain traceability and quality control per IS 2455.

IS 2455: Conversion of Logs into Sticks for Testing

Key Specifications (Clause 9.2)

• Marking on small end (top):

  • Squares of 62 mm × 62 mm or 32 mm × 32 mm.
  • Sticks sawn into nominal 60 mm × 60 mm or 30 mm × 30 mm scantlings.
  • Orientation: Parallel to pith-to-pith axis.
  • Cardinal points marked as N, E, S, W; if unknown, use H, K, L, M.
  • Sector portions marked for radial and tangential shrinkage specimens.

• Bolt Length & Identification:

  • Logs divided into bolts of 1.5 m or 1 m length (based on girth).
  • Bolts labeled alphabetically from the stump upwards (e.g., 'a', 'b', 'c').

Additional Guidelines

• Only one log from the bottom portion of the tree is used for small clear specimen testing (Clause 7.1.1).
• Logs should be photographed with cardinal points and scale before cutting (Clause 9.1).
• Logs stored submerged in clean water, changed weekly to prevent deterioration (Clause 8.2).

Summary Table: Log to Stick Conversion

flowchart TD
    A[Log] --> B[Mark small end with squares]
    B --> C[Mark cardinal points (N,E,S,W or H,K,L,M)]
    C --> D[Divide into bolts (1m or 1.5m)]
    D --> E[Label bolts alphabetically]
    E --> F[Saw into sticks (60x60 or 30x30 mm)]
    F --> G[Use sticks

Matching of Marked Sticks for Tests Under Green and Dry Conditions (IS 2455)

Key Specifications & Procedures

• Marking (Clause 9.3):
  Each test stick is marked with project, consignment, tree, bolt designation, and stick number (e.g., 1-2-3 a-N 5).

• Matching (Clause 10.1):

  • 1.5 m sticks (60×60 mm) from adjacent bolts of the same log are interchanged to form two composite bolts, each with equal portions from both bolts.
  • Similarly, 1 m sticks (30×30 mm) are interchanged to form composite bolts.
  • One composite bolt is tested green, the other dry.

• Green Condition Storage (Clause 11.2.1):
  Store material in a framed pit/container, covered with damp sawdust to maintain moisture above fibre saturation point.

• Dry Condition Preparation (Clause 11.1.2):

  • 20% of sticks weighed periodically until equilibrium moisture content (~12%) is reached.
  • Moisture content verified by oven dry method (IS 1708).
  • Condition sticks at 27±2℃, 65±5% RH to reduce moisture gradients.
  • Plan sticks to 50×50 mm or 20×20 mm before testing.

Summary Table: Stick Sizes and Conditions

flowchart LR
    A[Original Bolts] --> B[Interchange 1.5m sticks (60x60)]
    A --> C[Interchange 1m sticks (30x30)]
    B --> D[Composite Bolt 1 (Green Test)]
    B --> E[Composite Bolt 2 (Dry Test)]
    C --> F[Composite Bolt 3 (Green Test)]
    C --> G[Composite Bolt 4 (Dry Test)]

Note: Follow oven dry method (IS 170

IS 2455: Storage of Sticks to be Tested – Key Points & Specifications

1. Moisture Monitoring (Clause 11.1.2)

• 20% of sticks weighed to nearest gram at storage start.
• Weight recorded periodically until equilibrium moisture content is reached.
• After equilibrium, take moisture disc (~25 mm length, full cross-section) from about 10% of sticks.
• Disc cut ≥200 mm from ends to avoid material loss.
• Moisture content determined by oven dry method (IS 1708 Parts 1-18:1986).
• When moisture ~12%, sticks conditioned at:
  • Temperature: 27 ± 2°C
  • Relative Humidity: 65 ± 5%
• Conditioning reduces moisture gradient before machining.

2. Preparation for Testing (Clause 11.2.2)

• Sticks planed on four sides to cross-section:
  • Either 50 mm × 50 mm or 20 mm × 20 mm
• Test specimens cut as per IS 1708.
• Minimize time between planning and testing to avoid moisture changes.

3. Identification & Matching (Clause 9.3 & 10.2)

• Each stick marked with:
  • Project No.
  • Consignment No.
  • Tree No.
  • Bolt designation
  • Stick No.
• All material from one composite bolt tested under same conditions.

Summary Table: Storage & Conditioning Parameters

Moisture Content Calculation (Oven Dry Method, IS 1708)

[ \text{Moisture Content (%) } = \frac{W_{wet} - W_{dry}}{W_{dry}} \times 100 ]

• (W_{wet}): Weight before drying
• (W

IS 2455: Order of Tests and Selection of Specimens

1. Order of Tests (Clause 12.1)

To minimize changes due to storage/weather, tests should be conducted in this sequence:

1. Static bending
2. Impact bending
3. Izod/Charpy impact
4. Compression parallel to grain
5. Compression perpendicular to grain
6. Shear parallel to grain
7. Cleavage parallel to grain
8. Tension parallel to grain
9. Tension perpendicular to grain
10. Nail and screw withdrawal
11. Specific gravity and volumetric shrinkage
12. Radial and tangential shrinkage

2. Selection of Specimens

• Standard Clear Specimens (Clause 3.1.3):
  Specimens must be free from defects, with straight grains, and sized as per IS 1708 (Parts 1-18):1986.

• Specimen Preparation (Clause 11.2.2):
  All materials surfaced to 50 mm × 50 mm or 20 mm × 20 mm cross-section before cutting test specimens.
  Cut specimens per IS 1708 size and shape.
  Minimize time between cutting and testing; store green specimens in framed pits if delay occurs.

3. Specimen Size Reference (IS 1708)

(Refer IS 1708 for detailed dimensions)

4. Bolt Selection (Fig. 2)

• Bolts to be collected from merchantable bole length (e.g., 1–5 m sections).
• Designated by letters according to