Plastics Pipe Selection, Handling, Storage and Installation for Potable Water Supplies Code of Practice: Part 3 - Laying and Jointing of UPVC Pipes

IS 7634 Part 3: Scope & Key Specifications

1. Scope (Clause 1.4)

• Local bye-laws must be strictly followed for municipal water distribution.
• References to related standards:
  • IS 4985:2000 — Unplasticized PVC pipes for potable water.
  • IS 5382:1985 — Rubber sealing rings for gas/water mains and sewers.

2. Jointing Techniques (Clause 3.2.3.2)

• Medium/heavy bodied cements can be used for smaller sizes but not vice versa.
• Adequate solvent cement must fill the joint gap.

3. Trench Widths (Clause 5.2.2 & Table 1)

• Trench width should be 2 to 3 times pipe diameter.
• Minimum unsupported trench widths:

• Use supported trenches for unstable soils and compact backfill progressively.

Summary Diagram: Trench Width vs Pipe Diameter

graph LR
A[Pipe Diameter] --> B[Multiply by 2 to 3]
B --> C[Minimum Trench Width]
C --> D[Ensure Stability & Compaction]

Key Takeaway: Follow local bye-laws, use

IS 7634 Part 3 - Key References and Specifications

1. Setting Times (Clause 3.2.4.9)

Note: Joints must not be handled before these times to ensure proper setting.

2. Trench Widths for Pipe Laying (Clause 5.2.2 & Table 1)

Guidance: Trenches should be as narrow as practical but wide enough for pipe burial and compaction. For stable soils, trench width = 2 to 3 times pipe diameter is a good rule of thumb.

3. Important Referenced IS Codes (Clause 1.4)

IS 7634 Part 3: Materials and Joint Types - Key Points

1. Setting Times (Clause 3.2.4.9)

• Joints must not be handled before these times to ensure proper curing.

2. Screwed or Threaded Joints (Clause 3.6)

• Use thick-walled pipes with taper threads.
• Factory-cut threads are preferred.
• Pressure limit: ≤ 2/3 of unthreaded pipe rating.
• Suitable for metal-like pipe connections.

3. Integral Elastomeric Sealing Ring Joints (Clause 3.3)

• Non-end load bearing; axial thrust can cause joint separation.
• Prevent joint separation by:
  • Using concrete anchor blocks (below/above ground).
  • Especially critical for large diameter, high-pressure pipes.
• Features:
  • Elastomeric sealing ring for leak-proof joints.
  • Insertion depth marked on spigot for proper assembly.

Visual: Joint Assembly Concept

graph LR
A[Spigot End] -->|Insertion| B[Elastomeric Sealing Ring]
B --> C[Socket End]
C --> D[Anchor Block (to resist axial thrust)]

This ensures reliable sealing and mechanical stability of pipe joints under varying conditions.

IS 7634 Part 3: Handling, Transportation & Storage of Pipes

Key Specifications:

• Packing & Bundling

  • Pipes factory-packed in bundles with timber battens at minimum 3 places (Clause 4.3.4).
  • Webbing positioned outside timber battens (Fig. 16).
  • Bundles should not be unpacked until use.

• Stacking Limits

  • Maximum stack height: 7 layers or 1.5 m (Clause 1.5).
  • Maximum width of stacks: 3.0 m.
  • Maximum spacing between supports: 1.5 m centres (Fig. 17 & 18).
  • Pipes must project sufficiently to be supported along the full length (parallel stacking, Fig. 20(A)).

• Transportation

  • Use flat-bed vehicles with beds free from nails/projections (Clause 4.1.1).
  • Pipes should rest uniformly over full length on vehicle (Fig. 12).
  • Follow first-in-first-out stock rotation if date-coded (Clause 4.3.14).

Handling Methods:

• Manual handling (Fig. 15) and mechanical lifting (Fig. 16) with wide band webbing recommended.
• Use timber battens to protect pipes during lifting and transport.

Summary Table: Stacking & Transport Limits

flowchart LR
    A[Factory Packed Pipes] --> B[Bundled with Timber Battens (3+)]
    B --> C[Transport on Flat Bed Vehicle]
    C --> D[Uniform Support Over Length]
    D --> E[Stack at Depot/Site]
    E --> F[Max 7 layers or 1.5 m height]
    E --> G[Max 3.0 m width]
    F & G --> H[Safe Storage & Handling]

IS 7634 Part 3: Preparation for Installation - Key Points

1. Preparation (Clause 9.1)

• Ensure trench bottom is firm, stable, uniform.
• Remove sharp objects and stones > 20 mm.
• Provide 100-150 mm bedding thickness under pipe.
• For pipes ≥ 100 mm dia, provide bell holes under socket joints.

2. Pipe Support (Clause 7.5, Table 4)

Minimum distance between supports for UPVC pipes varies with pipe diameter and water temperature:

Supports closer at higher temperatures due to thermal softening.

3. Protection

• Pipes above ground must be shielded from direct sunlight (Clause 7.8).
• Use solvent cement joints above ground for axial thrust resistance (Clause 7.1).

4. Installation in Ducts (Clause 8)

• Use end-load bearing joints.
• Fit support rings to facilitate pipe withdrawal.
• Seal openings between pipe and duct ends.

5. Thrust Forces (Table 3)

Thrust on pipe ends and bends due to internal pressure (kN/bar):

6. Trench Width (Table 2)

Minimum trench width depends on pipe size:

IS 7634 Part 3: Trenching and Bedding Key Points

1. Trench Bottom (Clause 6.2.3)

• Provide firm, stable, uniform support along pipe length.
• Remove stones >20 mm; avoid sharp objects.
• Minimum bedding thickness: 100 to 150 mm under pipe.
• For pipes ≥100 mm diameter, provide bell holes under socket joints.

2. Trench Width (Clause 6.2.2)

• Unsupported trenches: ~2× pipe diameter.
• Supported trenches: narrower, with shoring.

3. Bedding & Backfill Material (Clause 6.2.7 & 6.5.6)

• Use free-draining, friable soils (coarse sand, gravel).
• Remove boulders, sharp stones, organic/contaminated material.
• Bedding thickness: 100–150 mm, compacted and watered.
• Backfill in 250 mm layers, compacted.
• Avoid heavy compaction until 300 mm cover above pipe crown.

Summary Diagram (Trench Cross-section)

graph TD
    A[Trench Bottom] -->|Remove stones >20mm| B[Bedding (100-150mm)]
    B --> C[Pipe]
    C --> D[Backfill in 250mm layers]
    D --> E[Compact after 300mm cover]

This ensures pipe stability, protection, and longevity per IS 7634 Part 3.

IS 7634 Part 3: Above Ground Installation Key Points

1. Jointing Method (Clause 7.1):

   • Use solvent cemented joints for UPVC pipes/fittings above ground to resist axial thrust from internal pressure.
   • Manufacturer's advice may override in special cases.
   • Other end-load bearing joints are also acceptable.

2. Protection (Clause 7.8):

   • Pipes/fittings installed above ground must be protected from direct sunlight to avoid UV damage.

3. Thrust Forces (Table 3, Clause 6.4.4):
   Thrust forces (kN/bar) on blank ends and bends for different nominal diameters (dn mm):

(Values per bar of internal pressure)

4. Pipe Support Spacing (Table 4, Clause 7.5):

5. Thermal Expansion:
   • Allow for expansion/contraction with flexible joints or loops.

Key Specifications for Laying and Jointing (IS 7634 Part 3)

1. Jointing Method

• Solvent Cemented Joints are recommended for UPVC pipes above ground or in service ducts.
• Other end-load bearing joints may be acceptable depending on manufacturer advice.

2. Setting Times for Solvent Cement Joints (Clause 3.2.4.9)

• Joints must not be handled before setting time elapses.

3. Thrust Forces on Pipes (Table 3, Clause 6.4.4)

• Thrust forces (kN/bar) on blank ends and bends vary by pipe nominal diameter (dn) and bend angle.

• Use these values multiplied by actual internal pressure (bar) to calculate thrust forces.

4. Handling and Installation

• For large diameter pipes, use mechanical aids (levers, winches).
• Avoid transmitting force to existing joints.
• Prevent pipe backing out until cement sets.

Summary Diagram: Jointing Procedure Flow

flowchart TD
    A[Prepare Pipe

IS 7634 Part 3: Testing and Commissioning Key Points

1. Filling the System (Clause 9.1.10)

• Fill slowly; water velocity ≤ 0.6 m/s.
• Use potable water only for potable water pipelines.
• After filling, close all air valves.
• Check proper functioning of automatic valves.

2. Test Pressure (Clause 9.2)

• Use adequately sized pressurizing equipment (Clause 9.1.8).
• Pressure gauges accuracy: ± 0.2 bar.
• Automatic pressure recording is recommended.
• Check seals and non-return valves before testing.

3. Curing and Handling (Clause 3.2.4.10)

• Allow minimum 24 hours curing before pressure testing.
• Handle pipes carefully post curing.

4. Typical Testing Setup (Fig. 29)

• Use flanged tees with lateral support.
• Include air release cocks, sampling points, and burst pressure release valves.
• Temporary thrust blocks and flange adaptors to be used.
• Pressure applied by hand or reciprocating pump.

Summary Table: Testing Parameters

flowchart LR
    A[Filling the System] --> B[Close Air Valves]
    B --> C[Check Automatic Valves]
    C --> D[Apply Test Pressure]
    D --> E[Monitor Pressure Gauge ±0.2 bar]
    E --> F[Record Results]

This concise approach ensures safe, accurate testing and commissioning as per IS 7634 Part 3.

IS 7634 Part 3 – Corrosion Protection Summary

• Clause 10.1:
  UPVC pipes are inherently corrosion-resistant under normal soil conditions; no additional corrosion protection is needed for the pipes themselves.

• Clause 10.3:
  Protective coatings on adjacent metallic parts must not contain solvents (no hot/cold-applied coatings or varnishes with solvents) to prevent damage to UPVC pipes.

• Clause 10.5:
  Anti-corrosion tapes or protective materials on metal connectors must be compatible with UPVC, avoiding any damage upon contact.

• Defect Rectification (Clause 9.4.5):
  All defects found during testing must be repaired and tests repeated until satisfactory.

Key Notes:

Additional Engineering Insight:

• UPVC’s corrosion resistance is due to its inert polymer nature.
• For metallic parts, use epoxy or powder coatings free of solvents.
• Avoid direct metal-to-UPVC contact to prevent galvanic corrosion or chemical damage.

flowchart LR
    A[UPVC Pipes] -->|No corrosion protection needed| B[Normal Soil Conditions]
    C[Metallic Parts] -->|Use solvent-free coatings| D[Protective Coatings]
    D --> E[Anti-corrosion Tape]
    E -->|Must be UPVC compatible| F[No Damage to Pipes]

This ensures long-term durability and integrity of UPVC piping systems per IS 7634 Part 3.

IS 7634 Part 3 (2003) – Service Connections Key Points

1. Service Connections (Clause 3.8 & 3.8.1)

• Service connections are taken off from larger pipes (≥ 50 mm dia) using metal or PVC saddles.
• PVC Saddles: Half-round molded unplasticized PVC solvent cemented to pipe; boss for service connection.
• Metal/PVC Saddles: Two half-round sections bolted or held by wedge grips with a rubber O-ring seal compressed between saddle and pipe.
• Service connection outlet is from the boss on the upper saddle section.

2. Overhang Limit (Clause 4.1.4)

• Pipes overhanging vehicles must not exceed 1 m.

3. Typical Components (Fig. 11)

• Metallic ferrule
• PVC threaded saddle outlet (female)
• Sealing ring gasket (rubber O-ring)
• Bolt & nut for wedge grip
• PVC service saddle

4. Jointing Techniques

• PVC pipes are solvent welded.
• Connections to metallic pipes use threaded joints with adapters, couplers, and bushes (Figs. 8, 9, 10).

Summary Table: Service Saddle Types

Important Reference Standards

• IS 4985:2000 – Unplasticized PVC pipes for potable water
• IS 5382:1985 – Rubber sealing rings for water mains

flowchart TD
    A[Main Pipe ≥ 50 mm] --> B[Service Saddle]
    B --> C{Type}
    C -->|PVC Half-round| D[Solvent Cemented]
    C -->|Metal/PVC Two-part| E[Bolted/Wedge grip]
    D --> F[Rubber O-ring Seal]
    E --> F
    F --> G[

IS 7634 (Part 3) - Special Installation Practices Summary

1. Protection & Jointing (Clause 7.8 & 7.1)

• UPVC pipes above ground must be protected from direct sunlight.
• Use solvent cemented joints for above-ground or inaccessible duct installations to sustain axial thrust.

2. Installation in Ducts (Clause 8)

• Use end-load bearing joints inside inaccessible ducts.
• Fit support rings to facilitate pipe withdrawal and provide support.
• Seal openings between pipe and duct ends.
• For large pipes or ducts, use additional securing methods (see Fig. 27 & 28 in IS 7634).

3. Support Spacing for UPVC Pipes (Table 4 - Clause 7.5)

(Refer to full table for intermediate sizes and temperature variations)

4. Thrust Forces for Anchoring (Table 3 - Clause 6.4.4)

5. Thermal Expansion (Fig. 24)

• Allow for pipe length variation ΔL = α × L × ΔT
  where α ≈ 0.07 mm/m/°C for UPVC, L = pipe length, ΔT = temperature change.

flowchart TD
    A[UPVC Pipe Installation] --> B[Protect from Sunlight]