Timber for cooling towers

IS 2372: Scope - Key Specifications and Tables

Scope Overview

• Covers timber grades and permissible defects for cooling tower structures.
• Specifies tolerances and preservative treatments for structural and shell members.

Key Tables & Specifications

1. Permissible Defects (Table 2, Clause 5.3)

2. Dimensions & Tolerances (Clause 6.2)

• Length tolerance: ±5 mm
• Other dimensions: 0 mm (minus), +2 mm (plus)

3. Preservative Treatments

• Copper-chrome-arsenic (CCA) or acid-copper-chrome (ACC): 12 kg/m³
• Copper-chrome-boron (CCB): 16 kg/m³
• Creosote/fuel oil mixture: 128 kg/m³

Notes

• Rounding off values as per IS 2:1960.
• Referenced standards: IS 401:2001 (timber preservation), IS 707:1976 (timber glossary).

flowchart TD
    A[Timber Grades] --> B[Select Grade]
   

IS 2372: References, Key Tables & Specifications

References (from IS 2372)

Key Specifications:

• Rounding off values: Follow IS 2:1960 rules; maintain significant figures as per specified values.
• Permissible Defects: See Table 2 for limits on defects by timber grade.
• Dimensions & Tolerances: Nominal sizes and finished dimensions for thicknesses are in Table 3 (Clause 6.1).

Typical Rounding Rule (IS 2:1960)

• Round off to the same decimal places as the specified value.
• Example: If specified = 12.5, measured 12.47 → round to 12.5.

Defects (Summary from Table 2)

• Defects like knots, shakes, and splits have maximum permissible sizes depending on timber grade.
• Higher grades allow fewer or smaller defects.

If you need Table 2 or 3 details, please specify for exact values.

IS 2372 - Definitions Summary

• Reference Standard: IS 2372 adopts definitions primarily from IS 707: 1976 - Glossary of terms applicable to timber technology and utilization.
• Key Concept: All timber-related terminology in IS 2372 aligns with IS 707 to maintain consistency in timber technology.

Permissible Defects (Clause 5.3)

• Defects allowed in timber vary by grade.
• Refer to Table 2 (Permissible Defects) in IS 2372 for limits on knots, shakes, splits, etc.

Dimensions & Tolerances (Clause 6)

• Timber sizes and permissible dimensional variations are specified.
• Follow standard tolerances for thickness, width, and length as per IS 2372.

Quick Reference Table: Permissible Defects (Example Format)

(Exact values should be checked in IS 2372 Table 2)

For detailed definitions, always consult IS 707 alongside IS 2372.

flowchart LR
    A[IS 2372] --> B[Definitions]
    B --> C[IS 707: Glossary of Timber Terms]
    B --> D[Permissible Defects (Table 2)]
    B --> E[Dimensions & Tolerances (Clause 6)]

IS 2372: Species of Timber for Cooling Towers

Key Specifications (Clause 4 & Table 1)

Timber Grading (Clause 5.1)

• Grades: Select Grade, Grade I, Grade II
• Criteria: Based on permissible defects (see Clause 5.3 & Table 2)

Permissible Defects (Clause 5.3)

• Defects allowed vary by grade (e.g., knots, shakes, wane)
• Refer Table 2 in IS 2372 for detailed defect limits per grade

Additional References

• IS 401: Preservation of timber
• IS 707: Glossary of timber terms

This classification ensures durability and structural integrity of timber used in cooling towers, considering mechanical and environmental loads.

IS 2372: Grading of Timber for Cooling Towers

1. Timber Species (Table 1)

• Fir (Abies pindrow)
• Deodar (Cedrus deodara)
• Spruce (Picea smithiana)
• Khasi Pine (Pinus kesiya)
• Chir (Pinus roxburghii)
• Kail (Pinus wallichiana)
• Douglas Fir (Pseudotsuga taxifolia)
• Radiata Pine (Pinus radiata)
• Teak (Tectona grandis)

2. Grades of Timber

• Select Grade
• Grade I
• Grade II

3. Permissible Defects (Table 2)

4. Dimensional Tolerances (Clause 6.2)

• Length: ±5 mm
• Other dimensions: +2 mm max, no minus tolerance

5. Recommended Treatments

• Copper-chrome-arsenic (CCA) or acid-copper-chrome (ACC): 12 kg/m³
• Copper-chrome-boron (CCB): 16 kg/m³
• Creosote/fuel oil mixture: 128 kg/m³ (per IS 401)

flowchart LR

IS 2372: Dimensions and Tolerances for Timber in Cooling Towers

1. Nominal Sizes & Dimensions (Clause 6.1)

• Refer to Table 3 (not provided here) for suggested nominal, rough, and finished sizes for various timber thicknesses.

2. Tolerances (Clause 6.2)

3. Permissible Defects (Table 2, Clause 5.3)

4. Recommended Treatment

• Copper-chrome-arsenic (CCA) or acid-copper-chrome (ACC): 12 kg/m³
• Copper-chrome-boron (CCB): 16 kg/m³
• Creosote/fuel oil mixture: 128 kg/m³
  (Per IS 401)

Summary:

• Length tolerance: ±5 mm
• Other dimensions: +2 mm max, no minus
• Defects allowed vary by grade, with stricter limits for Select Grade
• Treatments ensure durability against decay

flowchart TD
    A[Nominal Size] --> B[Tolerances]
    B --> C{Dimension Type}
    C -->|Length| D[±5 mm]
    C -->|Other| E[+2 mm max, no minus]
    A --> F[Permiss

Key Specifications and Formulas for Preservative Treatment (IS 2372)

1. Preservative Retention (Clause 7)

• Structural members & shell members:
  • Copper-Chrome-Arsenic (CCA) or Acid-Copper-Chrome (ACC): 12 kg/m³
  • Copper-Chrome-Boron (CCB): 16 kg/m³
  • Creosote/Fuel oil mixture: 128 kg/m³
• Fill:
  • CCA or ACC: 16 kg/m³
  • CCB: 20 kg/m³
  • Creosote/fuel oil: 160 kg/m³

2. Penetration Depth of Preservatives (Table 4, Clause 7.1)

Note: For some species, incisions (~15 mm) on all surfaces except ends are needed for adequate absorption.

3. Permitted Defects for Different Grades (Table 2, Clause 5.3)

IS 2372: Permissible and Prohibited Defects in Timber for Cooling Towers

1. Permissible Defects (Clause 5.3, Table 2)

2. Prohibited Defects (Clause 5.2)

• Loose grain
• Reaction wood
• Heartwood rot
• Warp
• Worm holes affecting strength
• Pitch pockets
• Centre heart (pith)
• Shakes
• Twisted grain
• Wane

3. Dimensional Tolerances (Clause 6.2)

• Length tolerance: ±5 mm
• Other dimensions: No minus tolerance, max +2 mm

4. Nominal and Dressed Dimensions (Table 3)

IS 2372: Structural Timber in Cooling Towers - Key Points

1. Timber Species (Table 1)

• Specifies suitable timber species for cooling tower structures (refer IS 2372 Table 1 for exact species).

2. Grading & Defects (Table 2 - Clause 5.3)

3. Dimensional Tolerances (Clause 6.2)

• Length: ±5 mm allowed
• Other dimensions: No minus tolerance; +2 mm max allowed

4. Preservative Treatments (Clause 5)

• Copper-Chrome-Arsenic (CCA) or Acid-Copper-Chrome (ACC): 12 kg/m³
• Copper-Chrome-Boron (CCB): 16 kg/m³
• Creosote/Fuel Oil mixture: 128 kg/m³
• Treatment per IS 401 standard

5. Structural Applications (Clause 3.1.3)

• Timber joists and beams support:
  • Fan deck flooring
  • Filling drift eliminator
  • Water basins and troughs
  • Piping and mechanical equipment

Summary Diagram: Timber Grading & Treatment Flow

flowchart TD
    A[Select Timber Species] --> B[Grade Timber: Select, I, II]
    B --> C{Check Defects}
    C -->|Slope of Grain| D[Slope Limits per Grade]
    C -->|Knots

IS 2372: Inspection and Quality Control — Key Points

1. Dimensional Tolerances (Clause 6.2)

• Length tolerance: ±5 mm (normally permissible)
• Other dimensions: No minus tolerance; max +2 mm allowed

2. Timber Preservation (Clause 6.2)

• Use preservatives as per IS 401:
  • CCA/ACC: 12 kg/m³ retention
  • CCB: 16 kg/m³ retention
  • Creosote/fuel oil: 128 kg/m³ retention

3. Permissible Defects for Timber Grades (Table 2, Clause 5.3)

4. Rounding Off (General)

• Follow IS 2:1960 for rounding test results to match significant digits of specified values.

Summary Diagram

flowchart TD
    A[Inspection & Quality Control] --> B[Dimensional Tolerances]
    B --> B1[Length ±5 mm]
    B --> B2[Other dims +2 mm max, no minus]
    A --> C[Timber Preservation]
    C --> C1[CCA/ACC: 12 kg/m³]
    C --> C2[CCB: 16 kg/m³]
    C --> C3[Creosote: 128 kg

IS 2372 Key Tables & Specifications Summary

1. Referenced Standards (Table 2)

• IS 401:2001 — Preservation of timber (Code of Practice)
• IS 707:1976 — Glossary for timber technology

2. Depth of Penetration of Preservatives (Table 4, Clause 7.1)

• Note: For some species, incisions (~15 mm deep) on all surfaces except ends are needed for adequate absorption.

3. Permissible Defects (Clause 5.3)

• Refer to Table 2 in the standard for allowable defects per timber grade.

4. Rounding Off (Clause 6)

• Use IS 2:1960 rules for rounding numerical values, maintaining significant digits as per specified values.

Practical Tip:

For preservative treatment, always ensure sapwood is fully penetrated (100%), and heartwood meets minimum depth as per species. Incisions improve preservative absorption in difficult species.

flowchart TD
    A[Timber Species] --> B{Sapwood}
    B -->|100% Penetration| C[Preservative Applied]
    A --> D{Heartwood}
    D -->|Min Depth varies| E[Incision if needed]
    E --> C