Coniferous logs

IS 5246: Scope & Key Specifications for Coniferous Logs

• Scope: Covers three grades of coniferous logs (Grade 1, 2, 3) for timber conversion.
• Grades & Defects (per 2.5 m length):

• Species Covered:

• General Requirements:

  • No hollow center >15% basal area (no hollow throughout length).
  • Free from spiral grain, decay, insect attack.
  • Defects only as permitted in clause 8.

• Measurement: As per Clause 7.2, logs are measured considering length and defects.

• Rounding: Final test/analysis values rounded per IS 2:1960 rules.

This standard references IS 707, IS 1141, and IS 3364 for terminology, seasoning, and defect evaluation respectively.

flowchart LR
    A[Coniferous Logs] --> B{Grade}
    B -->|Grade 1| C[6 minor or 2 major + 2 minor defects]
    B -->|Grade 2| D[9 minor or 3 major + 3 minor defects]
    B -->|Grade 3| E[12 minor or 3 major + 6 minor defects]
    A --> F[Species]
    F --> G[FIR, DEO, CYP, SPR, KAL,

IS 5246: Classification and Grades of Coniferous Logs

1. Grades of Logs (Clause 2.5)

2. Species Covered

3. General Requirements (Clause 6)

• No hollow center >15% basal area (none allowed through entire length)
• Free from spiral grain, decay, insect attack, and other defects except permitted ones.

4. Dimensions (Clause 7.1 & 7.2)

• Minimum length: 2.5 m
• Minimum mean mid-girth: 100 cm

5. Volume Calculation (Quarter Girth Formula) (Clause 7.2.3)

[ V = \frac{G^2}{16 \pi} \times L ]

Where:

• (V) = volume in m³
• (G) = girth in meters
• (L) = length in meters

Volume should be rounded to 3 decimal places.

Summary Diagram: Log Classification Flow

flowchart TD
    A[Coniferous Logs] --> B{Check Defects per 2.5m}
    B -->|≤ 6 minor or 2 major + 2 minor| C[Grade 1

IS 5246 - Definitions & Key Specifications

• Reference: Definitions from IS 707 apply (Clause 3.1).

Log Defects (Clause 2.5)

Log Grades (Clause 2.5 Table)

Permissible Species

General Requirements (Clause 6)

• No hollow center >15% basal area.
• No spiral grain, decay, insect attack.
• Hollow center along entire length not permitted.

For measurement refer Clause 7.2; logs are measured from butt end in 2.5 m segments.

flowchart LR
    A[Log Length (2.5 m segments)] --> B{Deviation}
    B -->|≤25mm| C[Minor Defect]
    B -->|25-50mm| D[Major Defect]
    B -->|50-100mm

IS 5246: Species Covered & Grades for Coniferous Logs

Species Covered

Grades of Logs (per 2.5 m length)

Key Specifications

• No hollow center >15% basal area (throughout length not permitted)
• Logs must be free from spiral grain, decay, insect attack, and other defects except those allowed in the grades.
• Measurement and rounding off as per IS 2:1960.

Summary Diagram

flowchart TD
    A[Coniferous Logs] --> B{Species}
    B --> FIR[Fir]
    B --> DEO[Deodar]
    B --> CYP[Cypress]
    B --> SPR[Spruce]
    B --> KAL[Kail]
    B --> KPI[Khasi Pine]
    B --> CHR[Chir]

    A --> C{Grades}
    C --> G1[Grade 1: ≤6 minor or 2 major + 2 minor]
    C --> G2[Grade 2: ≤9 minor or 3 major + 3 minor]
    C --> G3[Grade 3: ≤12 minor or 3 major + 6 minor]

This classification ensures quality control for timber conversion as per IS 5246.

IS 5246: General Requirements for Coniferous Logs

Key Specifications (Clause 6)

• Logs must be free from:
  • Hollow center exceeding 15% of basal area
  • Spiral grain
  • Decay (rot)
  • Insect attack
  • Other defects except those permitted in Clause 8
• No hollow center allowed throughout the entire log length

Grades & Defects (Clause 2.5)

Species Covered

• Fir (Abies pindrow Royle)
• Deodar (Cedrus deodara)
• Cypress (Cupressus torulosa)
• Spruce (Picea Smithiana)
• Kail (Pinus excelsa)
• Khasi Pine (Pinus Khasya)
• Chir (Pinus Roxburghii)

Measurement & Defects

• Defects measured as per IS 3364 (Part 1)
• Plugging defects not allowed

Rounding Off (Clause 3.1)

• Follow IS 2:1960 for rounding test results to the same significant figures as specified values.

This ensures quality control and uniformity in timber logs for structural use.

IS 5246: Dimensions and Measurement of Logs

Key Specifications (Clauses 7.2 & 2.5)

• Length Measurement

  • Length = shortest distance between extreme ends (in meters)
  • Rounded down to nearest 0.05 m

• Deviation Limits per 2.5 m length from butt end:

  Deviation Category	Range (mm)
  a) Minor	up to 25
  b) Moderate	>25 to 50
  c) Major	>50 to 100

• Taper Limits per 2.5 m length:

  Taper Category	Range (mm)
  a) Minor	up to 200
  b) Moderate	>200 to 250
  c) Major	>250 to 300

• Grades of Logs (based on defects per 2.5 m):

  Grade	Minor Defects Allowed	Major Defects Allowed
  Grade 1	6	2 major + 2 minor
  Grade 2	9	3 major + 3 minor
  Grade 3	12	3 major + 6 minor

Volume Calculation

• Volume is computed using length and girth measurements as per Clauses 7.2.1 to 7.2.3 (typically using Smalian’s or Huber’s formula).

Common Timber Species Covered

IS 5246: Volume Calculation of Logs

Key Formula (Clause 7.2.3)

The volume ( V ) of a log is calculated by the Quarter Girth Formula:

[ \boxed{ V = \frac{G^2}{16 \pi} \times L } ]

Where:

• ( V ) = Volume in cubic meters (m³), rounded to 3 decimals
• ( G ) = Mean girth in meters (m)
• ( L ) = Length in meters (m)

Measurement Specifications

• Length (L):

  • Measured as the shortest distance between the two ends of the log (Clause 7.2.1)
  • Rounded down to the nearest 0.05 m

• Girth (G):

  • For irregular taper logs, measure girth at three points: near each end and mid-length (Clause 7.2.2.1)
  • Calculate mean girth by averaging these three measurements
  • Girth measured over the bark, excluding protuberances

Summary Table

flowchart TD
    A[Measure Length (L)] --> B[Measure Girth (G) at 3 points]
    B --> C[Calculate Mean Girth (G_avg)]
    C --> D[Apply Quarter Girth Formula]
    D --> E[Calculate Volume V = (G_avg² / 16π) × L]

This formula and method ensure standardized and accurate volume estimation of logs as per IS 5246.

IS 5246: Permissible Defects and Evaluation in Logs

Key Points from IS 5246 (with reference to IS 3364 Part 1):

1. Permissible Defects (Clause 8.1 & 2.5):

• Defects are allowed only within specified limits; plugging defects is not allowed.
• Defects are measured as per IS 3364 (Part 1).
• For every 2.5 m length from the butt end of the log:

2. Volume Calculation (Clause 7.2.3):

The Quarter Girth Formula for log volume (V) in m³:

[ V = \frac{L}{4} \times (G_1 + G_2 + G_3 + G_4) ]

Where:

• ( V ) = Volume in m³
• ( L ) = Length of the log in meters
• ( G_1, G_2, G_3, G_4 ) = Quarter girths measured at four equally spaced points along the log (in meters)

Note: Volume is calculated to three decimal places.

Summary Table for Defects Evaluation:

Additional Notes:

• This standard aligns defect evaluation with IS 3364 (Part 1): 1976.
• Defects beyond permissible limits reduce the log's usability and volume.
• Accurate defect measurement is crucial for timber quality assessment.

flowchart LR
   

IS 5246:2000 - Marking and Identification of Logs

Key Specifications (Clause 10.1 & 10.2)

Each log must be legibly and indelibly marked, preferably at the ends, with:

• a) Species Abbreviation: Standard botanical or commercial abbreviation.
• b) Supplier’s Identification Mark & Year of Supply: Unique supplier code + 4-digit year.
• c) Length and Mean Girth:
  • Length in meters (m)
  • Mean girth in centimeters (cm), measured at mid-length.

BIS Certification Mark (Clause 10.2 & 10.2.1)

• Logs may bear the BIS Standard Mark to indicate conformity.
• Marking should be clear, permanent, and placed at a suitable location.

Example Marking Format:

Summary Diagram

graph LR
A[Log End] --> B[Species Abbreviation]
A --> C[Supplier ID + Year]
A --> D[Length & Mean Girth]
A --> E[BIS Certification Mark (optional)]

This marking ensures traceability, quality control, and compliance with IS 5246.

BIS Certification Marking (IS 5246:2000 - Clause 10.2)

• Governing Law: Use of the BIS Standard Mark is regulated under the Bureau of Indian Standards Act, 1986.
• Licensing: Manufacturers/producers must obtain a license from BIS to use the Standard Mark.
• Conditions: Specific conditions for licensing and use are detailed by BIS and must be strictly followed.
• Marking Details: The Standard Mark includes the BIS logo, license number, and product details as per BIS guidelines.

Summary Diagram of BIS Marking Process

flowchart LR
    A[Manufacturer Applies for License] --> B{BIS Evaluation}
    B -->|Approved| C[License Granted]
    B -->|Rejected| D[Application Denied]
    C --> E[Use of BIS Standard Mark on Product]
    E --> F[Periodic BIS Surveillance & Quality Checks]

Note: For detailed licensing conditions and mark specifications, refer directly to the BIS Act and BIS licensing manuals.

IS 5246: End Coating and Handling - Key Points

1. Wound Classification (Clause 8.1.8)

• Wounds should not be numerous or clustered to avoid reducing yield and usefulness.

2. End Coating (Clause 8.1.8)

• Ends of logs must be coated up to at least 125 mm from the end.
• Coating materials as per IS 1141.
• Coating should be applied immediately after inspection to prevent cracking and splitting.

3. Handling Defects (Clause 8.1.3 & 2.5)

• End splits and other defects are permissible within limits.
• For every 2.5 m length from butt end:

4. Measurement of Defects

• Defects measured as per IS 3364 (Part 1).
• Plugging of defects is not allowed.

flowchart LR
    A[Log Inspection] --> B[Identify Wounds & Defects]
    B --> C{Wound Classification}
    C -->|Class a| D[Depth ≤25mm, Dia ≤50mm]
    C -->|Class b| E[Depth 25-40mm, Dia ≤75mm]
    C -->|Class c| F[Depth 40-50mm, Dia 75-150mm]
    B -->

IS 5246: References and Related Standards

• Primary Reference for Definitions:

  • IS 707:1976 – Glossary of terms applicable to timber technology and utilization.

• Related Standards for Timber Quality and Processing:

  • IS 1141:1993 – Code of practice for seasoning of timber.
  • IS 3364 (Part 1):1976 – Method of measurement and evaluation of defects in timber: Part 1 Logs.

• Rounding Off Rules:

  • Follow IS 2:1960 for rounding numerical test results, retaining the same significant figures as specified values.

Summary Table of Key References

These standards collectively ensure uniformity in timber grading, processing, and quality evaluation under IS 5246.

flowchart LR
    A[IS 5246: Coniferous Logs Spec] --> B[IS 707: Definitions]
    A --> C[IS 1141: Seasoning Practice]
    A --> D[IS 3364: Defect Evaluation]
    A --> E[IS 2: Rounding Rules]

IS 5246 — Committee Composition Summary

Committee: Timber Sectional Committee, CED 9
Chairman: Shri Shyam Sunder, Bangalore

Key Points on Committee Composition (Annex A)

• The committee includes experts from diverse organizations related to timber, forestry, defense, research institutes, and industry.
• Members represent:
  • Institutes: Institute of Wood Science and Technology, Forest Research Institute, Kerala Forest Research Institute.
  • Government Departments: Ministry of Defence, Ministry of Environment and Forests, Forest Departments of various states.
  • Industry: WIMCO Ltd, Indian Plywood Industries Research & Training Institute, Federation of Indian Plywood and Panel Industry.
  • Others: Directorate General of Civil Aviation, Naval Headquarters, National Test House.

Specifications on Committee Functioning

• The committee ensures international coordination and adapts standards to Indian field practices.
• Final test values are rounded per IS 2:1960 rules.
• The committee oversees subcommittees on:
  • Timber Terminology & Classification
  • Timber Testing
  • Timber Conversion & Grading
  • Timber Seasoning & Treatment

Visual Summary of Committee Structure

graph TD
    A[Timber Sectional Committee, CED 9] --> B[Chairman]
    A --> C[Members from Govt. Depts.]
    A --> D[Members from Research Institutes]
    A --> E[Members from Industry]
    A --> F[Subcommittees]
    F --> F1[Timber Terminology & Classification]
    F --> F2[Timber Testing]
    F --> F3[Timber Conversion & Grading]
    F --> F4[Timber Seasoning & Treatment]

Note: No specific formulas or tables are provided for committee composition in IS 5246; the focus is on member representation and roles.