Code of practice for preservation of wooden sleepers for railway track by pressure treatment

IS 10753: Scope and Key Specifications

• Scope: Covers standards for wood sleepers used in railway tracks, focusing on durability, treatment, and quality control.

• Rounding Off:
  Final test or analysis values must be rounded as per IS 2:1960, maintaining the same significant figures as the specified values.

• Control of End Checking (Clause 3.2):

  • Wood dries faster at ends → prone to cracks (end checking).
  • Use antichecking iron clamps or wire straps before cracks develop.
  • Details on end checking methods (clamps, coatings) are in Appendix A.

• Preservative Specifications Referenced:

  • Creosote and anthracene oil (2nd revision)
  • Fuel oils (1st revision)
  • Water soluble preservatives:
    • Part 1: Acid-copper-chrome (ACC)
    • Part 2: Copper-chrome-arsenic (CCA)

Summary Table: End Checking Control

flowchart LR
    A[Wood Sleeper] --> B{Drying Process}
    B -->|Faster at ends| C[End Checking Risk]
    C --> D[Use Antichecking Clamps]
    C --> E[Apply End Coating]
    D & E --> F[Reduced Cracking]

This ensures sleepers maintain strength and service life as per IS 10753.

IS 10753: Key Points on Preservatives for Timber Sleepers

1. Types of Preservatives (Clauses 2.1 to 2.4)

• Oil-based: Creosote, Anthracene oil (specifications per IS second revision)
• Water-soluble:
  • Copper-Chrome-Arsenic (CCA) — IS Part 2
  • Acid-Copper-Chrome (ACC) — IS Part 1

2. Treatment Process (Clause 5.2)

• Pressure Process:
  • Temperature: 80-90°C during pressure period
  • Methods:
    • Full-cell process (Bethell process) — preservative forced into wood under pressure
    • Empty-cell process — vacuum applied before pressure to remove air
• Both oil and water-soluble preservatives are used.

3. End Checking Control (Clause 3.2)

• Use antichecking iron clamps or wire straps before checks develop
• Additional methods: end coating, detailed in Appendix A

Summary Table: Treatment Parameters

flowchart LR
    A[Wood Sleeper] --> B{Preservative Type}
    B --> C[Oil-based: Creosote, Anthracene oil]
    B --> D[Water-soluble: CCA, ACC]
    C --> E[Pressure Treatment @ 80-90°C]
    D --> E
    E --> F{Process Type}
    F --> G[Full-cell Process]
    F --> H[Empty-cell Process]
    A --> I[End Checking Control]
    I --> J[Iron clamps / Wire straps]
    I --> K[End Coating]

Note: Refer to IS 10753 Appendix A for detailed end checking methods.

IS 10753: Preparation of Material for Treatment – Key Points

1. Mechanical Preparation (Clause 3.3)

• Surfaces must be free of dirt, bark, and loose fibers.
• For refractory species, incisions (cuts) on all surfaces except ends to 12–19 mm depth are recommended to improve preservative penetration.

2. Penetration Requirements (Clause 4.1)

• Minimum penetration of 35–40 mm through sapwood and non-durable heartwood.
• For partially treatable heartwood, ensure a penetrated shell of at least 12 mm thickness all around.

3. Treatment Process & Absorption (Clause 5.2.3)

• Empty cell process may require gross absorption 2-3 times net retention to meet penetration.
• Recommended for mixed species and timber with both sapwood and heartwood.

4. Post-Treatment Protection (Clause 2.2)

• After water-borne preservative treatment, apply 10% asphalt solution in crude oil to prevent splitting/checking of sleepers.

Summary Table: Penetration & Incision Depths

flowchart TD
    A[Material Preparation] --> B[Mechanical Preparation]
    B --> C{Timber Type}
    C -->|Durable heartwood| D[No incision]
    C -->|Non-durable/Refractory| E[Incisions 12-19 mm]
    E --> F[Treatment Process]
    D --> F
    F --> G[Penetration 35-40 mm]
    G --> H[Post-treatment: 10% Asphalt Solution]

This ensures proper preservative uptake and durability of treated timber sleepers.

IS 10753: Penetration and Retention Requirements

Key Specifications:

• Penetration Depth:

  • Through and through in sapwood and non-durable heartwood.
  • Minimum 35 to 40 mm penetration for species in Appendix B-2.
  • For refractory heartwood (B-1 species), incisions recommended to create a penetrated shell of minimum 12 mm thickness all around.

• Incising Details (Clause 3.3.5):

  • Incisions parallel to grain, depth: 20 mm.
  • Spacing between incisions in a row: 22 to 25 mm.
  • Distance between rows: 57 to 60 mm.
  • Staggering of incisions between adjacent rows: 5 to 7 mm.
  • Pattern repeats every 4 rows.

Retention & Absorption:

• Gross absorption may be 2 to 3 times net retention in empty cell process to meet penetration.
• Recommended for mixed species and sapwood/heartwood timber.

Incision Pattern Diagram (Plan View):

graph TD
  subgraph Sleeper Face
    direction LR
    Incision1((Incision))
    Incision2((Incision))
    Incision3((Incision))
    Incision4((Incision))
  end
  Incision1 --- Incision2 --- Incision3 --- Incision4
  style Incision2 fill:#f9f,stroke:#333,stroke-width:2px,stroke-dasharray: 5 5
  style Incision3 fill:#f9f,stroke:#333,stroke-width:2px,stroke-dasharray: 5 5

Summary:

• Achieve through-and-through penetration in sapwood and non-durable heartwood.
• Use incising for refractory species to enhance penetration.
• Follow spacing and staggering as per Table and Fig. 1

IS 10753: Treatment Process Key Points

1. Treatment Methods (Clause 5.2 & 5.2.3)

• Pressure Process:
  • Use either oil-type or water-soluble preservatives.
  • For oil-type, maintain 80-90℃ during pressure.
  • Treatment can be:
    • Full-cell process (complete impregnation)
    • Empty-cell process (partial impregnation)
• Empty-cell process requires 2-3 times gross absorption compared to net retention to meet penetration.

2. Penetration Requirements (Clause 4.1)

• Minimum penetration in sapwood & non-durable heartwood: 35-40 mm.
• For refractory heartwood species (B-1), make incisions 12-19 mm deep on all surfaces except ends to ensure at least 12 mm penetrated shell.

3. Post-Treatment (Clause 2.2)

• After water-borne preservative treatment, apply 10% asphalt solution in crude oil to prevent splitting/checking.

Summary Table: Penetration & Incision Depth

flowchart LR
    A[Start: Timber Preparation] --> B{Timber Type}
    B -->|Sapwood / Non-durable HW| C[Penetrate 35-40 mm]
    B -->|Refractory Heartwood (B-1)| D[Make 12-19 mm incisions]
    D --> E[Ensure 12 mm penetrated shell]
    C & E --> F{Choose Treatment Process}
    F -->|Full-cell| G[Pressure Treatment]
    F -->|Empty-cell| H[Pressure Treatment with 2-3x absorption]
    G & H --> I{Preservative Type}
    I -->|Oil-based| J[Maintain 80-90℃

IS 10753: Post-Treatment Handling - Key Points & Specifications

1. Post-Treatment Absorption (Clause 5.2.3)

• Empty cell process requires gross absorption = 2 to 3 × net retention to meet penetration.
• Recommended for mixed species timber and timber with sapwood & heartwood.

2. Treatment Sequence (Clause 2.2)

• For water-borne preservatives, follow treatment with 10% asphalt solution in crude oil.
• Purpose: Prevent splitting and checking of sleepers during service.

3. Pressure Treatment Conditions (Clause 5.2)

• Pressure treatment can use oil-type or water-soluble preservatives.
• For oil-type, maintain temperature: 80-90°C during pressure.
• Treatment methods: Full-process or Empty cell process.

Summary Table: Post-Treatment Handling

flowchart TD
    A[Timber Preparation] --> B[Pressure Treatment]
    B --> C{Type of Preservative}
    C -->|Oil-type| D[Maintain 80-90°C]
    C -->|Water-borne| E[Treat with 10% Asphalt Solution]
    D & E --> F[Post-Treatment Handling]
    F --> G[Gross Absorption 2-3 × Net Retention (Empty Cell)]
    G --> H[Prevent Splitting & Checking]

This ensures durable, well-preserved timber with minimal defects during service.

IS 10753: Inspection and Testing - Key Points

1. Inspection Access (Clause 7.1)

   • Purchaser/agent must have full access to all parts of the sleeper preparation and treatment plant.
   • Testing is to be conducted as per IS 401:1982 (Specification for creosote and anthracene oil preservatives).

2. Control of End Checking (Clause 3.2 & Appendix A)

   • Wood dries faster at ends → prone to end checking (cracks).
   • Use antichecking iron clamps or wire straps before checks develop.
   • End coating is also recommended to reduce moisture loss and cracking.

3. Rounding Off Test Results (Appendix A-1, Clause None: 0.4)

   • Final test values must be rounded as per IS 2:1960 rules.
   • Maintain the same number of significant figures as the specified standard values.

Summary Table: End Checking Control

Relevant Standards for Testing and Preservatives

flowchart LR
    A[Wood Sleeper] --> B{Drying Process}
    B -->|Faster at Ends| C[End Checking Risk]
    C --> D[Apply End Clamps]
    C --> E[Apply End Coating]
    D & E --> F[Reduced Cracking]

Use these guidelines to ensure compliance with IS 10753 for inspection, testing, and end checking control of wooden sleepers.

IS 10753: Control of End Checking by End Clamps and End Coating

1. End Clamps (Clause 3.2, Appendix A-1)

• Purpose: Prevent cracks/splits due to rapid drying at sleeper ends.
• Type: 'C' and 'S' clamps per IS 10394-1982.
• Application: Drive clamps into sleeper ends immediately after cutting to control end checking during air seasoning and drying.
• Material: Antichecking iron clamps or wire straps.

2. End Coating (Appendix A-2)

• Purpose: Slow moisture loss at ends, reducing checking without blocking preservative penetration.
• Suitable Coatings:
  • For treatable sleepers: Coal tar + crude earth oil mixture (does not clog pores or plant fittings).
  • For refractory sleepers (Class C to E treatability): White lead, aluminium paint, pitch resin, hardened glass oil.
• Requirement: Should not plug creosoting plant tubes or clog wood pores.

Summary Table

flowchart TD
    A[Cut Sleeper] --> B[Drive End Clamps Immediately]
    B --> C[Apply End Coating]
    C --> D[Air Seasoning / Drying]
    D --> E[Preservative Treatment]
    E --> F[Final Sleeper Ready]

This ensures minimal end checking and good preservative penetration per IS 10753.

IS 10753: Species Requiring Incision Before Treatment (Appendix B-1 & Clause 3.3.5)

Key Points:

• Incision Purpose: Enhances preservative penetration in refractory species.
• Minimum Absorption: 80 kg/m³.
• Side Penetration: 12-19 mm on all faces except ends.
• Incision Depth: 20 mm.
• Incision Spacing:
  • Rows spaced 57-60 mm apart.
  • Incisions in rows spaced 22-25 mm apart.
  • Incisions staggered by 5-7 mm between adjacent rows.
• Incision Orientation: Parallel to grain, on all four faces except ends.

Incision Pattern Dimensions (mm)

Species List Highlights (Require Incision)

Incision Pattern Diagram (Simplified)

graph TD
  direction LR
  subgraph Face of Sleeper
    A[Incisions spaced