This standard outlines procedures for selecting sample trees and logs from forests and their systematic conversion into specimens for timber property evaluation. It details marking, cutting, and preparation techniques to ensure representative sampling and accurate physical and mechanical timber testing. The code is vital for forestry professionals, testing labs, and researchers assessing timber quality.
Overview
This standard outlines procedures for selecting sample trees and logs from forests and their systematic conversion into specimens for timber property evaluation. It details marking, cutting, and preparation techniques to ensure representative sampling and accurate physical and mechanical timber testing. The code is vital for forestry professionals, testing labs, and researchers assessing timber quality.
Audience
Contents
Structure
This section defines the applicability of the standard, focusing on sampling and preparation methods for timber testing to ensure uniform quality assessment. It emphasizes structural timber testing, specimen preparation, and adherence to rounding rules as per IS 2:1960, and references related standards for timber preservation, terminology, and testing procedures.
Lists key Indian Standards referenced for timber preservation, terminology, small clear specimen testing, static structural tests, and random sampling methods. It also details rounding rules and specimen allocation schedules to ensure representative testing.
Defines key terms based on IS 707:1976, covering timber-specific vocabulary essential for understanding sampling and testing. Includes guidelines on rounding numerical results and collecting site and environmental data.
Describes criteria for selecting forest compartments or blocks for sampling, including environmental, geological, and vegetation data collection. Emphasizes detailed site recording and mapping for accurate sample representation.
Specifies requirements for selecting standing trees by qualified personnel, grouping by girth measurements, and notifying testing authorities. Provides girth classification ranges and sampling procedures for representative testing.
Outlines methods for marking trees with identification and orientation marks, including special notation for numbers 6 and 9. Details the process for notifying authorities and documenting the selection prior to felling.
Details log cutting lengths, selection of logs from tree sections, marking and record keeping of log attributes, defect identification, coating methods to prevent moisture loss, and dispatch procedures along with documentation and approvals.
Describes verification of log identification marks, measurement data, defect recording, coatings, and dispatch documentation. Highlights the importance of minimizing time between felling and dispatch to maintain sample integrity.
Specifies marking dimensions on log ends, orientation of saw cuts parallel to pith, bolt lengths and labeling conventions, and storage guidelines for logs before conversion to sticks.
Explains the procedure for interchanging sticks from adjacent bolts to create composite bolts for testing under green and dry conditions. Describes storage methods for maintaining moisture and conditioning for drying.
Covers moisture monitoring through periodic weighing, moisture content determination using oven-dry methods, conditioning parameters for drying, specimen dimensioning, and identification marking for consistent testing.
Recommends the order of mechanical and physical tests to minimize specimen variability. Details requirements for defect-free specimens, dimensions per IS 1708, and specimen preparation protocols to maintain uniformity.
Frequently Asked
Selection must be done by qualified personnel knowledgeable in species identification and testing requirements. Trees should be healthy, representative in growth and age, avoiding extremes such as abnormally fast or slow growth or atypical forms. For varied girth sizes, trees are grouped into specified girth categories to ensure consistent sampling. Only one log from the lower portion of the tree is used for standard testing, and if multiple logs are required, they must be from different heights with proper identification and records.
Logs are marked on the upper small end with squares measuring either 62 mm by 62 mm or 32 mm by 32 mm. Cardinal points (N, E, S, W) are indicated; if unknown, alternatives (H, K, L, M) are used. Specific sectors are marked for extracting specimens for shrinkage and other tests. Logs are then sawn into sticks of nominal dimensions 60 mm by 60 mm or 30 mm by 30 mm, aligned parallel to the pith axis. Logs are divided into bolts of 1.5 m or 1 m length, labeled alphabetically starting near the stump. Storage in clean water tanks with periodic water replacement is recommended to prevent deterioration.
Green timber specimens should be stored tightly packed in framed pits or containers covered with damp sawdust to maintain moisture above the fibre saturation point. Logs are submerged in clean water tanks, with water changed weekly to maintain freshness. Air-dried specimens intended for shrinkage tests must not be kiln dried, while kiln drying is permitted only if mild and carefully controlled, with drying conditions recorded. Dried specimens are conditioned in chambers maintaining specific temperature and humidity to achieve equilibrium moisture content.
The prescribed testing order includes: static bending, impact bending, Izod/Charpy impact, compression parallel and perpendicular to grain, shear parallel to grain, cleavage parallel to grain, tension parallel and perpendicular to grain, nail and screw withdrawal, specific gravity and volumetric shrinkage, followed by radial and tangential shrinkage. Specimens must be defect-free and prepared to standard sizes per IS 1708. Tests should be conducted promptly to minimize changes due to storage.
Consignments typically include logs from five different trees, one log per tree, along with corresponding stump discs, soil samples if required, and botanical samples like fruit, flowers, or leaves for species verification. Time between felling and dispatch should be minimized. Specimens are prepared in standardized cross-sections of 20 mm by 20 mm and 50 mm by 50 mm following IS 1708 and IS 2408. Proper documentation including identification marks, dates, and condition records ensures traceability and representative sampling.
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