Plastics Pipes Selection, Handling, Storage and Installation for Potable Water Supplies Code of Practice, Part 2: Laying and jointing of polyethene (PE) pipes

IS 7634 Part 2: Scope — Key Specifications & Tables

1. Trench Dimensions (Clause 6.1 & Table 3)

• Trench Width & Depth depend on pipe size.

• Depth measured over pipe crown.

• Initial backfill: 150 mm minimum.

• Depth of cover: 900–1100 mm.

• Width increases with pipe diameter; e.g.,

  Pipe Size (mm)	Width (mm)
  20-110	300
  200	500
  500	800
  1000	1300

• For mole-plough technique (20-100 mm), 300 mm width not mandatory.

• Under highways, concrete/hume pipe cover required.

2. Butt Fusion Welding Parameters (Clause 3.2.1.2 & Table 1)

• Welding parameters vary with nominal wall thickness.
• Example for 7-12 mm wall thickness:
  • Bead height: 1.5 mm
  • Heating time: 70-120 s
  • Pressure build-up: 6-8 s
  • Cooling under pressure: 10-16 s
  • Cooling during pressure relaxation: 900 s

Notes:

• Follow IS 2:1960 for rounding off test values.
• Initial backfill material must comply with the standard.
• Consult manufacturers for SDR > 22 under dynamic traffic

IS 7634 Part 2: Key Tables & Specifications Summary

1. Trench Dimensions (Clause 6.1, Table 3)

• Notes:
  • Width may increase for jointing inside trench.
  • Depth measured over pipe crown.
  • Initial backfill as per standard.
  • For dynamic traffic loads and SDR > 22, consult manufacturers.

2. Butt Fusion Welding Parameters (Clause 3.2.1.2, Table 1)

3. Rounding Off (IS 2:1960)

• Final test/analysis values must be rounded per IS 2 rules.
• Maintain significant digits as per specified values.

flow

IS 7634 Part 2: Jointing Techniques – Key Points

1. Pressure-Time Control (Clause 3.2.1.3)

• Follow the pressure-temperature chart and timing table strictly during jointing.
• Maintain pressures as per Table 1 (typical values in N/mm²):
  • Equalisation Pressure
  • Jointing Pressure
  • Heating Pressure
  • Equalisation Period Pressure
  • Change Over Period Pressure
  • Jointing Build-Up Period Pressure
• After pressure relief, allow the joint to cool naturally to ambient temperature; no quenching.

2. Insert Type Joint (Clause 3.2.4)

• Refer to Fig. 6 for configuration and assembly details.
• Used for specific pipe connection types requiring inserts.

3. Flanged Joints (Clause 3.2.6)

• Refer to Fig. 9 for flange assembly and bolt tightening sequence.
• Ensure compliance with local bye-laws for municipal water distribution (Clause 1.4).

Typical Pressure-Time Diagram (Fig. 2) Summary:

graph TD
A[Start Heating] --> B[Equalisation Pressure]
B --> C[Heating Pressure]
C --> D[Equalisation Period]
D --> E[Change Over Period]
E --> F[Jointing Build-Up Period]
F --> G[Pressure Relief & Natural Cooling]

Recommendations:

• Always check Annex A for referenced standards and latest editions.
• Ensure local bye-laws compliance for water distribution systems.

This approach ensures safe, durable, and compliant joints in ductile iron piping systems.

IS 7634 Part 2: Handling & Storage of Polyethylene Pipes

Key Specifications & Guidelines

• Handling Large Pipes (>160 mm OD):

  • Use mechanical equipment for loading/unloading.
  • Avoid dumping pipes; roll smoothly off trucks using platforms.
  • Prevent penetration by sharp objects.

• Storage Conditions:

  • Avoid storage in hot areas (>45°C).
  • If unavoidable, provide continuous support on leveled sand or similar.
  • Pipes must be stored on flat surfaces, avoiding sharp edges.

• Transportation:

  • Vehicles must have side supports spaced ~2 m apart.
  • Use flat, smooth posts without sharp edges.
  • Secure pipe bundles with strapping to prevent movement.

• Slack in Laying:

  • Allow up to 2% slack in trench laying to accommodate expansion/contraction.

Summary Table

flowchart LR
    A[Loading Pipes] --> B[Use Mechanical Equipment]
    B --> C[Roll Pipes Smoothly]
    C --> D[Store on Level Sand Bed]
    D --> E{Temperature > 45°C?}
    E -- Yes --> F[Avoid Storage or Provide Continuous Support]
    E -- No --> G[Normal Storage]
    G --> H[Transport with Side Supports ~2m Apart]
    H --> I[Secure Bundles with Strapping]

Note: Following these guidelines ensures pipe integrity and safety during handling, storage, and transportation as per IS 7634 Part 2.

IS 7634 Part 2: Key Laying Procedures for Pipes

1. Trench Dimensions (Clause 6.1, Table 3)

• Width may increase for jointing inside trench.
• Depth measured over pipe crown.
• Initial backfill: soft earth/gravel free from stones, roots, etc.

2. Backfilling (Clause 8.1.1)

• Refill trenches up to 300 mm above pipe crown after laying ~1000 m.
• Use soft earth or sharp-edge stone-free gravel.
• Borrowed gravel allowed if excavated soil is insufficient.

3. Slack in Laying (Clause 11.4)

• For PE pipes, up to 2% slack in length is permitted inside trench to accommodate thermal expansion.

Summary Diagram of Trench Cross-Section

graph TD
    A[Ground Surface]
    B[Depth of Cover: 900-1100 mm]
    C[Initial Backfill: 150 mm]
    D[Pipe]
    E[Trench Width per pipe size]

    A --> B --> C --> D
    D --> E

Note: Always consult manufacturer for SDR > 22 pipes under dynamic loads.

IS 7634 Part 2: Earth Work and Pipe Support (Trenching) Key Points

1. Trench Dimensions (Table 3)

• Width may be increased for jointing inside trench.
• Depth measured over pipe crown.
• Initial backfill: 150 mm compacted screened material free of sharp stones or fine sand.

2. Trench Layout (Fig. 12)

• For non-rocky soil: No sand bedding required, trench width = pipe diameter + 300 mm.
• For rocky or unconsolidated soil: Provide 100 mm compacted fine sand bedding under and around pipe.

3. Backfill Specifications (Clause 8.1.1)

• Refill up to 300 mm above pipe with soft earth or gravel free of boulders, roots.
• Use borrowed gravel if suitable excavated material is insufficient.

4. Special Notes

• For pipe sizes 20-100 mm using mole-plough, trench width of 300 mm not mandatory.
• For gravity lines with SDR > 22, consult manufacturers for deformation under traffic loads.
• PE pipes allow trenchless installation methods (horizontal drilling, micro tunneling).

Summary Formula for Trench Width:

[ \text{Trench Width} = D + 300 \text{ mm (for normal soil)} ]

Where (D) = Pipe diameter.

flowchart LR
    A[Excavate Trench] --> B{Soil Type}
    B -->|No Rocks| C[Width = D + 300 mm]
    B -->|Sharp Rocks| D[100 mm Sand Bedding]
    C --> E[Place Pipe]
    D --> E
    E --> F[Initial Back

IS 7634 Part 2: Pipe Support & Expansion Key Points

1. Thermal Expansion Considerations (Clause 7.2.1 & 7.6.1)

• Coefficient of linear expansion for PE pipes ≈ 14 × that of metal pipes.
• Thermal movement causes significant expansion/contraction.
• Supports must allow free axial movement without gripping or distorting the pipe (see Fig. 16: Typical Pipe Clamp).

2. Support Design (Clause 7.2.1)

• Use pipe clamps that permit sliding to accommodate thermal elongation.
• Avoid rigid anchoring that induces stress or deformation.

3. Expansion Accommodation (Clauses 7.6.1.1 & 7.6.1.2)

• Underground pipes: Directional changes naturally absorb expansion.
• Exposed straight runs: Use expansion loops, bellows, or sliding gland expansion joints.

4. Thermal Expansion Formula

[ \Delta L = L \times \alpha \times \Delta T ]

Summary Diagram: Pipe Support for Thermal Expansion

flowchart LR
    A[Exposed PE Pipe] --> B[Pipe Clamp]
    B --> C{Allows Free Movement?}
    C -- Yes --> D[No Distortion, Free Sliding]
    C -- No --> E[Stress & Deformation Risk]
    A --> F[Expansion Loop/Bellows/Sliding Joint]
    F --> G[Absorbs Thermal Expansion]

Remember: Design supports to avoid pipe stress by allowing axial movement and use expansion devices in long exposed runs. Underground pipes rely on directional changes for expansion relief.

IS 7634 Part 2: Backfilling and Trench Refilling Key Points

1. Trench Dimensions (Table 3)

• Width: Depends on pipe diameter; may increase for jointing.
• Initial Backfill: 150 mm compacted layer above pipe crown.
• Depth of Cover: 900 to 1100 mm over pipe crown.

2. Initial Backfill Specifications (Clause 6.4.1)

• Use screened excavated material free from sharp stones or fine sand.
• Compact up to 150 mm above pipe crown.

3. Trench Filling (Clause 8.1.1)

• Refill up to 300 mm above pipe immediately after laying.
• Use soft earth or gravel free from boulders, roots, vegetable matter.
• Borrowed gravel can be used if suitable excavated earth is insufficient.

4. Trench Layout (Fig. 12 Summary)

• For non-rocky soil: No sand bedding required.
• For rocky/unconsolidated soil: Use 100 mm compacted fine sand bedding under and around pipe.
• Trench width = Pipe diameter + 300 mm.

Summary Formula for Trench Width:

[ \text{Trench Width} = D + 300 \text{ mm} ] where (D) = pipe diameter.

flowchart TD
    A[Excavation] --> B[Pipe Laying]
    B --> C[Initial Backfill 150 mm]
    C --> D[Compaction of Backfill]
    D --> E[Refilling up to 300 mm above pipe]
    E --> F[Final Trench Refilling]

Note: Always refer to manufacturer's guidelines for pipes with SDR > 22 under dynamic loads.

IS 7634 Part 2: Field Testing of Pipeline - Key Points & Specifications

1. Testing Procedure (Clause 9)

• Filling: Slowly fill pipeline with water; vent air via air valves at high points.
• Stabilization: Leave filled pipeline for 1 hour at ambient temperature (PE pipes).
• Pressure Application:
  • Test pressure = 1.5 × rated/max design pressure.
  • Apply pressure by continuous pumping at a constant rate.
  • Maintain pressure by adding make-up water during test.
• Duration: Pressure must remain steady (±5%) for 1.5 hours.
• No air is allowed for testing; water only.
• If leakage occurs: Depressurize, relax for 8 hours, then retest.

2. Backfilling Requirements (Clause 8.1.2)

• Backfill simultaneously on both sides to avoid unequal pressure.
• Fill trench in layers of 150 mm, first layer watered and compacted.
• Load on pipe only after 300 mm cover above pipe.
• Refill to original ground level, allowing for settlement.

3. Trench Dimensions (Table 3, Clause 6.1)

4. Acceptance Criteria

• No leakage if pressure steady within ±5% for 1.5 hours.
• Visual inspection of flanged joints during test.

Summary Formula for Test Pressure:

[ P_{\text{test}} = 1.5 \times P_{\text{rated or design}} ]

Visual Concept: Testing Setup

flowchart LR
    A

IS 7634 Part 2: Repair of Damaged Pipes and Joints - Key Points

Repair Methods (Clause 10.2)

• Best practice: Cut out damaged pipe section and replace with new pipe or pre-fabricated flanged spool.
• Connection options:
  • Insert type fittings (pressure limited)
  • Electro-fusion fittings
• Not recommended: Butt fusion welding inside trench due to difficulty in applying facial pressure.
• Welded joint repair: Remove entire original weld before re-welding; no patch repairs allowed.

Testing (Clause 1.5)

• Test pressure: 1.5 × rated or max design pressure.
• Medium: Water only; air testing prohibited.
• Acceptance: Pressure steady within ±5% for 1.5 hours; no leakage.
• If failure: Depressurize, relax 8 hours before retest.
• Safety: Avoid testing outside trench to prevent rupture hazards.

Additional Notes (Clause 2.3)

• PE pipes withstand short-term loads up to 2.3× working pressure due to visco-elasticity.
• For velocities >1.5 m/s, surge checks required.

Summary Table: Repair Options

flowchart LR
    A[Damaged Pipe] --> B{Repair Method}
    B --> C[Cut & Replace with Flanged Spool]
    B --> D[Insert Type Fittings]
    B --> E[Electro-fusion Fittings]
    B --> F[Butt Fusion Welding (Not Recommended)]
    C --> G[Pressure Test (1.5 × Rated)]
    D --> G
    E --> G
    F --> H[Remove Original Weld Fully Before Re-welding]

Remember: No patchwork repairs; always ensure pressure testing with water and adhere to safety protocols.

IS 7634 Part 2: General Guidance Key Points

1. Trench Dimensions (Clause 6.1 & Table 3)

• Width and depth of trenches depend on pipe size.
• Initial backfill: 150 mm minimum.
• Depth of cover: 900 to 1100 mm above pipe crown.
• Width examples:
  • Pipe 20-110 mm → Width = 300 mm
  • Pipe 500 mm → Width = 800 mm
  • Pipe 1000 mm → Width = 1300 mm

2. Butt Fusion Welding Parameters (Clause 3.2.1.2 & Table 1)

• Bead height, heating, jointing, and cooling times vary by nominal wall thickness.
• Example for 7-12 mm thickness:
  • Bead height: 1.5 mm
  • Heating up: 70-120 s
  • Pressure build-up: 6-8 s
  • Cooling under pressure: 10-16 s
  • Cooling during pressure relaxation: 900 s

IS 7634 Part 2: Key Points on Supply, Packaging, Handling, Storage & Transportation of PE Pipes

1. Slack in Laying (Clause 11.4)

• Slack permitted: Up to 2% slack in pipe length when laid inside trenches.

2. Transportation (Clause 12.4 & 12.4.2)

• Vehicle supports: Side supports spaced at ~2 m intervals.
• Supports: Flat, no sharp edges to avoid pipe damage.
• Securing pipes: Pipes must be effectively strapped to prevent movement.
• Bundling: Strapping bundles during transit is recommended.

3. General Handling & Storage Guidelines

• Avoid sharp edges and point loads.
• Store pipes on flat surfaces.
• Protect from direct sunlight and extreme temperatures.
• Use appropriate lifting gear to prevent damage.

Summary Table: Transportation Support & Securing

flowchart LR
    A[Loading Pipes] --> B[Place on flat supports every 2m]
    B --> C[Ensure supports have no sharp edges]
    C --> D[Strap pipe bundles securely]
    D --> E[Transport carefully to site]

Note: Follow IS 7634 Part 2 and related codes of practice for potable water supply pipes for detailed handling and installation procedures.

IS 7634 Part 2: Annexes & Committee Composition Summary

Annex A: List of Referred Indian Standards

• Covers specifications for HDPE pipes, rubber sealing rings, and HDPE fittings.
• Includes parts for reducers, pipe ends, sandwich flanges, bends, tees, and end caps.
• Example:

Annex B: Committee Composition (CED 50)

• Members from Central Institute of Plastic Engineering & Technology, BIS, Public Health Departments, Municipal Corporations, Industry leaders (Reliance, Finolex, GAIL, etc.).
• Chaired by Dr. S. K. Nayak.
• Includes representatives from government, research institutes, and private sector.
• Ensures comprehensive expertise for standard formulation.

Key Specification Highlight (Clause 12.5.5)

• Storage of polyethylene pipes: Must be on a flat surface free from sharp objects to avoid damage.

Diagram: Committee Structure Overview

graph TD
  A[Plastic Piping Systems Sectional Committee (CED 50)]
  A --> B[Government Organizations]
  A --> C[Research Institutes]
  A --> D[Industry Representatives]
  A --> E[BIS Directorate General]
  
  B --> B1[Public Health Engineering Dept.]
  B --> B2[Municipal Corporations]
  
  C --> C1[Central Institute of Plastic Engineering]
  C --> C2[Central Building Research Institute]
  
  D --> D1[Reliance Industries]
  D --> D2[Finolex Industries]
  D --> D3[GAIL India Ltd]
  
  E --> E1[Member Secretary]
  E --> E2[Convener]

This summary provides the committee makeup and key referenced standards essential for HDPE piping systems per IS 7634 Part 2:2012. For detailed technical formulas or tables, refer to specific clauses or referenced IS standards.