Recommendations for cement mortar lining for cast iron mild steel and ductile-iron pipes and fittings for transportation of water

IS 11906: Introduction and Background — Key Specifications & Tables

1. Sand Requirements (Clause 2.2.1.1)

Sand gradation for cement mortar lining must comply with:

Rounding off test results per IS 2:1960.

2. Thickness of Cement Mortar Lining (Clause 7.1 & Table 2)

• Note: Thickness at pipe ends may be reduced (chamfer length < 50 mm).
• Purchaser may request thicker lining.

3. Thickness Tolerances (Clause 7.2)

• Pipes: +20%
• Fittings: +40%

Summary Diagram: Thickness Specification Flow

flowchart TD
    A[Pipe Material] --> B{Nominal Diameter}
    B -->|Cast/Ductile Iron| C1[100-250 mm: 3 mm mean, 1.5 mm min]
    B -->|Cast/D

Scope & Key Specifications from IS 11906

• Scope: Covers requirements for cement mortar lining of pipes and fittings, ensuring durability and corrosion resistance.

1. Sand Requirements (Clause 2.2.1.1, Table 1)

2. Thickness of Cement Mortar Lining (Clause 7.1, Table 2)

• Note: Thickness at pipe ends may be less (chamfer length < 50 mm).

3. Thickness Tolerances (Clause 7.2)

• Pipe lining: +20% tolerance
• Fittings lining: +40% tolerance

4. Rounding Off (Clause 0.4)

• Follow IS 2-1960 for rounding test/analysis results.
• Retain significant figures as per specified values.

This ensures compliance and quality control for cement mortar linings per IS 11906.

IS 11906 Key Formulas, Tables & Specifications for Materials

1. Sand Requirements (Clause 2.2.1.1)

Ensures proper grading of sand for mortar.

2. Cement Mortar Lining Thickness (Clause 7.1, Table 2)

• Note: Thickness at pipe ends may be reduced (<50 mm chamfer length).
• Tolerance: +20% on pipes, +40% on fittings (Clause 7.2).

3. Rounding Off (Clause 0.4)

• Follow IS 2-1960 for rounding test or analysis results.
• Retain same significant figures as specified values.

flowchart TD
    A[Sand Grading] --> B[Cement Mortar Lining Thickness]
    B --> C[Thickness Tolerances]
    C --> D[Rounding Off Rules]

This ensures material quality and lining durability per IS

Preparation of Pipe and Fittings for Lining (IS 11906)

Key Specifications (Clause 3 & 4.1)

• Surface Preparation: Pipes and fittings must be clean, free of rust, oil, and dirt.
• Lining Method:
  • Centrifugal spraying followed by rotation for smoothing, or
  • Centrifugal spraying with simultaneous trowelling.
• Coverage: Entire waterway surface must be uniformly covered.
• Mortar Quality: Dense, homogeneous, free from cavities or air bubbles.
• Mortar Consistency: Adjusted to minimize sand-cement segregation.
• Compaction: Thorough compaction by rotation and optional vibration.

Mortar Mix (Clause 2.4)

• Cement : Sand = 1:2 by volume
• Compressive strength ≥ 30 N/mm² after 28 days (IS 516:1959)
• Admixtures allowed if they don't affect quality or water safety.

Thickness of Lining (Clause 7.1, Table 2)

• Note: Thickness at pipe ends may be reduced with chamfer length < 50 mm.
• Purchaser may specify thicker lining if desired.

Summary Diagram of Lining Process

flowchart LR
    A[Pipe/Fitting Surface Preparation] --> B[Apply Mortar by Centrifugal Spraying]
    B --> C{Method}
    C -->|Rotation Only| D[Rotate Pipe for Smoothing]
   

IS 11906: Method of Lining - Key Specifications & Formulas

1. Surface Preparation (Clause 3.1)

• Inner surface must be clean, free of foreign materials, loose scale, metal projections.
• Avoid inclusions, blisters, or voids affecting lining adhesion.

2. Thickness of Cement Mortar Lining (Clause 7.1, Table 2)

• Note: Thickness may be increased if requested.
• Lining thickness at pipe ends can be reduced; chamfer length < 50 mm.

3. Lining Protection (Clause 6.1)

• Protect from extreme heat, rainfall impact, freezing until cured.

4. Thickness Measurement (Clause 8.1)

• Measure on fresh centrifuged mortar or hardened lining.
• Use a steel pin ≤ 1.5 mm diameter or non-destructive methods.
• Take measurements at 4 equidistant points on 2 cross sections near pipe ends:
  • First set ≥ 200 mm from ends.
  • Second set as far inside as possible without damage.

Summary Diagram: Lining Thickness Measurement Points

graph LR
A[Pipe End] --> B[Cross Section 1 (≥ 200 mm from end)]
B --> C[4 Equidistant Points]
A --> D[Cross Section 2 (Inside)]
D --> E[4 Equidistant Points]

This ensures uniform and compliant

IS 11906: Socket Cleaning Requirements

• Clause 5.1:
  • Socket must be free of mortar before assembly or lining application to ensure proper fit and bonding.

Related Specifications for Socket Preparation & Protection

Table 1: Sand Grading for Mortar

Additional Notes:

• Mortar-free sockets ensure proper lining thickness and joint integrity.
• Socket cleaning is critical before cement mortar lining application (see Clause 7.1 for lining thickness).
• Mortar lining thickness varies by pipe material and diameter (Table 2 in Clause 7.1).

flowchart TD
    A[Socket Cleaning] --> B{Is mortar present?}
    B -- Yes --> C[Remove mortar completely]
    B -- No --> D[Proceed with lining application]
    D --> E[Apply mortar lining as per thickness specs]

Summary: Always ensure the socket is thoroughly cleaned of mortar to meet IS 11906 Clause 5.1 and enable proper lining application. Use sand grading per Table 1 for mortar preparation.

Protection of Work (IS 11906 Highlights):

• Clause 6.1:
  Lined pipes and fittings must be protected from:
  • Extreme heat (direct sunlight)
  • Rainfall impact
  • Freezing temperatures
    until the lining cures enough to resist these conditions.

Key Table: Thickness of Cement Mortar Lining (Clause 7.1)

• Note:
  • Thickness at pipe ends can be less than minimum but chamfer length < 50 mm.
  • Purchaser may request thicker lining.

Additional Specification:

• Clause 5.1: Socket must be free from mortar to ensure proper fitting.

flowchart LR
    A[Lined Pipe & Fittings] --> B[Protection from Sunlight]
    A --> C[Protection from Rainfall]
    A --> D[Protection from Freezing]
    B & C & D --> E[Curing of Lining]
    E --> F[Ready for Handling/Installation]

This ensures durability and integrity of the lining per IS 11906.

IS 11906: Thickness of Cement Mortar Lining

Key Specifications (Clause 7.1, Table 2)

• Note: Thickness can be increased if purchaser desires.
• Chamfer at pipe ends: Thickness may be less than minimum, with chamfer length < 50 mm.

Measurement (Clause 8.1)

• Measure on fresh centrifuged mortar or hardened lining.
• Use a steel pin ≤1.5 mm diameter or non-destructive methods.
• Take readings at 4 equidistant points on 2 cross sections near each pipe end:
  • First set ≥ 200 mm from ends.
  • Second set as far inside as possible without damage.

Tolerances (Clause 7.2)

• Pipe lining: +20%
• Fittings lining: +40%

Protection (Clause 6.1)

• Protect lining from sun, rain, and freezing until cured.

flowchart TD
    A[Pipe/Fitting] --> B{Nominal Diameter}
    B -->|Cast Iron/Ductile Iron| C[Thickness as per Table 2]
    B -->|Steel| D[Thickness as per Table 2]
    C & D --> E[Measure thickness at specified points]
    E --> F{Within tolerance?}
    F -->|Yes| G[Accept lining]
    F -->|No| H[Reapply or adjust lining]

This ensures durability and compliance with IS

IS 11906: Determination of Lining Thickness

Key Specifications (Clause 7.1, Table 2)

• Note: Thickness at pipe ends may be reduced, chamfer length < 50 mm.
• Tolerance (Clause 7.2): +20% for pipes, +40% for fittings.

Thickness Measurement (Clause 8.1)

• Use a steel pin ≤1.5 mm diameter on fresh mortar or non-destructive methods on hardened mortar.
• Measure at 4 equidistant points on 2 cross sections near each pipe/fitting end.
• First cross-section ≥ 200 mm from ends; second as far inside as accessible without damage.

Additional Protection (Clause 6.1)

• Protect lined pipes from sun heat, rainfall impact, and freezing until curing.

flowchart LR
    A[Pipe/Fitting] --> B[Measure at 2 cross sections]
    B --> C[4 equidistant points each]
    C --> D[Use steel pin ≤1.5mm or NDT]
    D --> E[Check thickness against Table 2]
    E --> F{Within tolerance?}
    F -->|Yes| G[Accept lining]
    F -->|No| H[Rework or reject]

This ensures lining thickness meets durability and corrosion resistance standards.

IS 11906: Curing of Cement Mortar Lining

Key Specifications (Clause 9.1)

• Curing Duration: Minimum 7 days from mortar application.
• Curing Methods:
  • Continuous wet curing by sprinkling water (e.g., sprinkler hose at invert).
  • Covering with moist sacking, canvas, or hessian kept constantly wet.
  • For overground pipes, protect from direct sunlight using moist hessian or similar.
  • Membrane curing with approved compounds allowed after mortar sets (with Engineer-in-Charge approval).

Important Notes:

• Proper curing ensures hard, durable, and fully hydrated mortar lining.
• Protect lined pipes from extreme heat, rainfall impact, and freezing until cured (Clause 6.1).
• Inner surface must be clean and free from projections before lining (Clause 3.1).

Summary Table: Curing Methods vs. Conditions

Conceptual Flow of Curing Process

flowchart TD
    A[Apply Mortar Lining] --> B[Final Setting of Mortar]
    B --> C{Choose Curing Method}
    C -->|Wet Curing| D[Sprinkler Hose / Wet Cover]
    C -->|Membrane Curing| E[Apply Approved Compound]
    D --> F[Maintain Moisture for ≥7 Days]
    E --> F
    F --> G[Protect from Sun & Weather Until Fully Cured]
    G --> H[Durable, Hydrated Lining Achieved]

Additional Tips:

• Maintain constant moisture; drying causes poor hydration and cracking.
• Avoid direct sunlight and freezing during curing.
• Adjust mortar consistency and centrifuging speed to minimize segregation (Clause 4.1).

This ensures **quality

IS 11906: Key Specifications for Lining Quality

1. Surface Preparation (Clause 3.1)

• Inner surface must be clean, free of foreign material, loose scale, metal projections.
• Avoid inclusions, blisters, voids affecting lining adhesion.

2. Thickness of Cement Mortar Lining (Clause 7.1, Table 2)

• Note: Thickness can be increased if requested.
• Pipe ends may have reduced thickness with chamfer length < 50 mm.

3. Measurement of Thickness (Clause 8.1)

• Measure lining thickness on fresh centrifuged mortar or hardened lining.
• Use a steel pin ≤ 1.5 mm diameter or non-destructive methods.
• Take measurements at 4 equidistant points on 2 cross sections near pipe ends (≥ 200 mm from ends) and further inside.

4. Protection of Lined Pipes (Clause 6.1)

• Protect from sun heat, rainfall impact, freezing until curing is sufficient.

This ensures lining quality by controlling surface prep, thickness, measurement, and curing conditions.

IS 11906: Key Specifications for Lining of Specials

1. Thickness of Cement Mortar Lining (Table 2, Clause 7.1)

• Note: Lining thickness may be increased if purchaser desires.
• Lining thickness at pipe ends may be reduced with a chamfer length < 50 mm.

2. Surface Preparation (Clause 3.1)

• Inner surfaces must be clean, free of foreign materials, loose scale, metal projections beyond lining thickness.
• Prevent inclusions, blisters, or voids to ensure good adhesion.

3. Lining Curing & Protection (Clause 6.1)

• Protect lined pipes/fittings from extreme heat, rainfall impact, freezing until curing is complete.
• Minimum curing period before dispatch: 21 days.

4. Acceptable Defects (Clause 10.2)

• Unbonded areas ≤ nominal diameter circumferentially and ≤ max(nominal diameter, 300 mm) longitudinally are acceptable.
• Longitudinal cracks ≤ max(nominal diameter, 225 mm) allowed.
• Circumferential cracks and surface crazing permitted.
• Repairs allowed per Clause 4.2.

Summary Diagram: Thickness Requirements by Pipe Diameter

graph TD
  A[Pipe Material] --> B{Nominal Diameter}
  B --> C1[100-250 mm]
  B --> C2[300-900 mm]
  B --> C3[

IS 11906: Seal Coat Application - Key Points

Seal Coat (Clause 12.1)

• Applied as a pore sealer on mortar lining surface.
• Requires prior approval from Engineer-in-Charge.
• Must be continuous and fully adhere to lining.
• After drying minimum 48 hours, no adverse effect on water quality or lining.

Mortar Lining Thickness (Clause 7.1, Table 2)

Note: Thickness at pipe ends may be less than minimum; chamfer length < 50 mm.

Sand Gradation for Mortar (Clause 2.2.1.1, Table 1)

Protection During Curing (Clause 6.1)

• Protect lining from:
  • Direct sunlight heat
  • Rainfall impact
  • Freezing temperatures
• Until lining has sufficiently cured.

flowchart TD
    A[Mortar Lining] --> B[Apply Seal Coat]
    B --> C{Approved by Engineer?}
    C -- Yes -->