Code of practice for installation of glass fibre-reinforced plastic (GRP) piping system

IS 13916: Scope – Key Specifications & Tables

1. Scope Summary (Clause 6.2 & 6.3.1)

• Applies to trench construction for pipe laying in stable and unstable soil conditions.
• Ensures trench stability, pipe protection, and proper backfilling.

2. Stable Trench Conditions (Clause 6.2)

• Trench walls can be vertical without shearing/sheet piling.
• Provide slope 'c' at trench top edges to prevent caving.
• Backfill zones:

• Side clearance S (mm):

3. Unstable Trench Conditions (Clause 6.3.1)

• Soil cohesion < 1440 kg/m² (unconfined compression test).
• Cohesion values by soil consistency:

• Special trench construction methods (Fig. 11 & 12) with shoring/sheet piling and increased side clearance S = 1 pipe diameter (min).

4. Additional Notes

• Bedding and foundation layers should be at least 150 mm thick.
• Backfill must prevent pipe flotation and protect against impact/vibration.
• Flanged joints use ring gaskets for nominal bore > 1200 mm, flat gaskets otherwise.

IS 13916:1994 Referenced Standards & Key Specifications

• Pipes & Fittings:

  • GRP pipes, joints & fittings: IS 12709:1993
  • Rubber gaskets: IS 5382:1985

• Pipe Stiffness:

  • Select stiffness class per IS 12709:1994 to resist dead load, live load, vacuum based on site conditions.

• Soil Testing:

  • Soil water content & dry density: IS 2720 Part 7 (1980)

Key Table: Minimum Trench Side Slope (S) for Stable Soil (Clause 6.2)

Trench Backfill Zones (Fig. 10):

• A: Trench width
• B: Pipe zone: granular soil, min 300 mm above pipe crown
• C: Secondary backfill: min (D-300) mm, encased in RCC if traffic/vibration expected
• F: Bedding: min 150 mm

Notes:

• Installation excludes special cases like subaqueous or through rigid walls.
• Use ring gasket for pipes >1200 mm dia; flat gasket for <1200 mm.
• Definitions as per IS 12709:1994 apply.

flowchart TD
    A[Pipe Zone: Granular Soil (B)] --> B[Secondary Backfill (C)]
    B --> C[RCC Encasement if Traffic/Vibration]
    C --> D[Bedding (F) 150 mm]
    D --> E[Pipe Installation]

This summary aids in selecting materials, trench design, and referencing essential IS codes for GRP pipe installation per IS 13916.

IS 13916: Definitions & Key Specifications Summary

• Reference Definitions:
  Terms from IS 12709:1994 apply along with IS 13916 Clauses 3.1 to 3.13.

• Trench Construction (Clause 6.2 & Fig. 10):

  • Stable Trench Conditions: Soil allows vertical trench walls without shoring.
  • Trench Dimensions:
    • A: Trench width
    • B: Pipe zone backfill with granular soil, minimum 300 mm above pipe crown
    • C: Secondary backfill depth = (D - 300) mm (D = trench depth), encased in RCC if traffic/vibration expected
    • F: Bedding thickness minimum 150 mm
    • S: Side clearance based on pipe diameter:

• Laying Conditions (Clause 8.1):
  Trench and supporting surface must be prepared per specification before pipe laying.

flowchart TD
    A[Trench Width (A)]
    B[Pipe Zone Backfill (B) - ≥300 mm granular soil]
    C[Secondary Backfill (C) - (D-300) mm, RCC encased if needed]
    F[Bedding (F) - ≥150 mm]
    S[Side Clearance (S) - per pipe dia table]

    A --> Pipe
    B --> Pipe
    C --> Pipe
    F --> Pipe
    S --> Pipe

This ensures structural stability and proper pipeline installation in stable soils.

IS 13916: Transportation, Handling, and Storage of Pipes and Fittings

1. Transportation (Clause 4.1)

• Support: Use timber saddles spaced at 4 m centers.
• Overhang: Maximum 2 m overhang allowed.
• Stock Height: Should not exceed 2 m.
• Strapping: Use non-metallic, pliable straps or ropes over support points to secure pipes.

2. Unloading, Lifting, and Lowering (Clause 4.3)

• Follow careful procedures to avoid damage and ensure safety.
• Use appropriate lifting gear; avoid point loads or sharp edges.
• Pipes should be lifted using slings or spreader beams to distribute load evenly.

3. Storing of Pipes and Fittings (Clause 4.2)

• Store on level ground with timber supports.
• Maintain spacing to prevent deformation.
• Protect from direct sunlight and extreme weather to avoid material degradation.

Summary Table

flowchart LR
    A[Transportation] --> B[Timber Saddles @ 4m]
    B --> C[Max Overhang 2m]
    A --> D[Strapped with Non-metallic Straps]
    E[Storage] --> F[Level Ground]
    F --> G[Timber Supports]
    E --> H[Protect from Sun & Weather]
    I[Handling] --> J[Use Slings/Spreaders]
    J --> K[Avoid Point Loads]

This ensures pipe integrity and safety during all stages.

IS 13916: Pipe Jointing Key Points

1. Butt Joint (Clause 5.2.3)

• Used for connecting straight pipe runs to fittings (reductions, elbows, flanges).
• Minimum thickness of joint (t):
  [ t \geq \text{thickness of pipe} ]
• Overlay width:
  [ \geq 10 \times \text{thickness of pipe (on each side of joint)} ]
• Overlay thickness:
  [ \geq 1.5 \times \text{thickness of pipe} ]
• Joint made by hand lay-up method with polyester cement for hydraulic and mechanical seal.

2. Spigot and Socket Joint (Fig. 5 & 6)

• Can be glued or glued with overlay.
• Suitable for both low and high pressure applications.
• Adhesive must be compatible with pipe material.

3. General Pipe Jointing (Clause 5.0)

• Must ensure fluid tightness under service conditions.
• Choice depends on:
  • Location and site conditions
  • Working pressure and flow
  • Type of fluid

Summary Table: Butt Joint Overlay Dimensions

flowchart LR
    A[Pipe End] --> B[Apply Adhesive]
    B --> C[Place Overlay]
    C --> D[Hand Lay-Up Method]
    D --> E[Butt Joint Completed]

This ensures a strong, leak-proof joint suitable for various pressures and applications.

IS 13916: Excavation and Preparation of Trench - Key Points

1. Trench Excavation (Clause 6.1 & 6.3.2)

• Trench bottom and sides must be stabilized before pipe laying.
• Methods:
  • Lower water table ≥ 25 cm below invert (well points)
  • Shoring or sheet piling (see Fig. 11 & 12)
  • Over-excavate and replace with sand + coarse gravel/crushed stone

2. Stable Trench Conditions (Clause 6.2)

• Vertical trench walls allowed in stable soils.
• Provide slope c at top edges to prevent caving.
• Minimum bedding thickness F = 15 cm.
• Pipe zone backfill B: sound granular soil, min. 300 mm above pipe top.
• Secondary backfill C: min. (D - 300) mm depth; encased in RCC if subjected to impact/vibration.

3. Trench Width & Side Clearance (Fig. 10)

• A = Trench width
• B = Pipe zone backfill
• C = Secondary backfill
• F = Bedding thickness (≥ 15 cm)
• S = Side clearance as above

Summary Diagram (Trench Cross-section)

graph TD
    A[Trench Width (A)]
    B[Pipe Zone Backfill (B) - min 300mm above pipe]
    C[Secondary Backfill (C) - min (D-300) mm]
    F[Bedding (F) - min 15 cm]
    S[Side Clearance (S) per pipe dia]
    Pipe[Pipe]

    A -->|Includes| S
    Pipe -->|Rest on| F
    Pipe -->|Surrounded by| B
    B --> C

Note: Follow Fig. 10, 11, 12 for detailed trench construction methods in stable and unstable soils

IS 13916: Bedding and Backfilling Key Points

Bedding (Clause 7.1.2)

• Bedding must ensure full contact between pipe bottom and trench.
• Compact bedding to ≥ 90% maximum dry density (IS 2720 Part 7:1980).
• Bedding thickness and material per Figs. 10-12 (soil conditions & trench types).

Backfilling (Clause 7.2 & 7.2.1)

• Place backfill in layers ≤ 30 cm thick.
• Compact each layer to ≥ 85% maximum dry density (IS 2720 Part 7:1980).
• Maintain height differential on pipe sides ≤ 30 cm to avoid pipe lateral movement.

Summary Table

Notes:

• Use IS 2720 (Part 7) for compaction test methods.
• Refer to trench construction figures (10, 11, 12) for soil-specific details.

flowchart TD
    A[Trench Preparation] --> B[Bedding Placement]
    B --> C[Compact Bedding (≥90% dry density)]
    C --> D[Pipe Laying]
    D --> E[Backfilling in ≤30 cm Layers]
    E --> F[Compact Backfill (≥85% dry density)]
    F --> G[Control Height Differential ≤30 cm]

This ensures pipe stability and longevity per IS 13916 standards.

IS 13916: Key Points on Laying and Jointing Procedures

1. Laying Procedure (Clause 8.1)

• Laying starts only after trench & surface preparation as per specs.
• Trench must have proper bedding (F): minimum 15 cm of sound granular soil.
• Stable trench conditions (Clause 6.2) allow vertical trench walls with a slope 'c' at top edges to avoid caving.
• Trench dimensions (Fig. 10):
  • A = Trench width.
  • B = Pipe zone filled with granular soil, min. 300 mm above pipe top.
  • C = Secondary backfill depth = (D - 300) mm.
  • S (side clearance) varies with pipe diameter:

2. Jointing Procedures

• Butt Joint (Clause 5.2.3):

  • Used for straight runs & fittings.
  • Minimum joint thickness t ≥ pipe thickness.
  • Overlay width ≥ 10 × pipe thickness on each side.
  • Made by hand lay-up method (Fig. 7).

• Spigot & Socket Joint (Fig. 5 & 6):

  • Suitable for low & high pressure.
  • Use polyester cement/glue matching pipe material.
  • Overlay thickness ≥ 1.5 × pipe thickness.

• Flanged Joint (Fig. 8 & 9):

  • Use ring gasket for nominal bore >1200 mm.
  • Use flat gasket for nominal bore <1200 mm.

3. Trench Construction for Unstable Soils

• Use shoring/sheet piling (Fig. 11 & 12).
• Minimum side clearance S = 1 pipe diameter.
• Foundation (E) minimum 15 cm if required.

flowchart TD
    A[Trench Preparation] --> B[Bedding

Hydrostatic Testing as per IS 13916: Key Specifications & Table

Clause 9: Hydrostatic Tests

• Test Pressure: 1.5 × Pressure Class of pipe/fittings.
• Duration: Maintain test pressure for 24 hours.
• Scope: Each full-length pipe section, fittings, and joints must be leak-tight.
• Frequency: Testing should be done regularly during installation; installation length should not exceed testing length by more than 1 km.

Table 9.2: Hydrostatic Test Pressure

Additional Notes:

• Hydrostatic testing ensures pipe integrity before acceptance and service.
• RCC thrust blocks (Clause 8.12) must be provided at bends and cross-section reductions to resist thrust during testing and operation.
• Testing must be done on completed joints.

Summary Diagram: Hydrostatic Testing Process

flowchart TD
    A[Completed Pipe Joints] --> B[Apply Test Pressure = 1.5 × Pressure Class]
    B --> C[Maintain Pressure for 24 Hours]
    C --> D{Leakage?}
    D -- No --> E[Accept Pipe Section]
    D -- Yes --> F[Repair & Retest]

This testing ensures safety and leak-tightness before commissioning pipelines.

IS 13916: Safety and Quality Assurance Key Points

1. Stable Trench Conditions (Clause 6.2)

• Trench walls can be vertical without shearing/sheet piling if soil is stable.
• Provide slope 'c' at trench top edges to prevent caving.
• Backfill zones:
  • A: Trench width.
  • B: Pipe zone filled with granular soil, min. 300 mm above pipe.
  • C: Secondary backfill depth = (D - 300) mm; encased in RCC if traffic/vibration expected.
• Bedding (F): Minimum 150 mm.
• Minimum clearance (S) based on pipe diameter:

2. Unstable Trench Conditions (Clause 6.3.1)

• Unstable soil: cohesion < 1440 kg/m² (unconfined compression test).
• Cohesion ranges for soil consistency:

3. Quality Assurance

• Laying only after trench and surface preparation (Clause 8.1).
• Use appropriate gaskets:
  • Flat gasket for nominal bore <1200 mm.
  • Ring gasket for nominal bore >1200 mm.
• Use RCC encasement for secondary backfill under impact/vibration.

Summary Diagram (Trench Backfill Zones)

flowchart TB
    A[Trench Width (A)]
    B[Pipe Zone (B) - Granular soil, 300mm above pipe]
    C[Secondary Backfill (C) - Depth = D-300 mm, RCC encased if needed]
    F[Bedding (F) - 150 mm min]

IS 13916 - Committee Composition Summary

The Plastic Pipes and Fittings Sectional Committee (CED 50) is composed of experts from government, industry, and research organizations. Key points:

• Chairman: Shri K. Prabhakra Rao (Ministry of Defence)
• Members: Representatives from Public Health Engineering, PVC industry, Central Public Works Department, Municipal Corporations, Plastic manufacturers, and research institutes like CSIR and BMTPC.
• Alternate Members: Each member has an alternate to ensure continuity.
• Panel for GRP Pipes and Fittings (CED 50: P1): Specialized subgroup with a convener and members from research, industry, and government bodies.

This committee ensures standards reflect multi-sector expertise for plastic pipe/fitting quality and safety.

No specific formulas or tables for committee composition exist in IS 13916.

Visualization of Committee Structure

graph TD
    A[Chairman] --> B[Members]
    B --> C[Government Representatives]
    B --> D[Industry Representatives]
    B --> E[Research Organizations]
    B --> F[Alternate Members]
    B --> G[Panel for GRP Pipes & Fittings]

For detailed committee member names and organizations, refer to the Annex A of IS 13916.