Structured-Wall Plastics Piping Systems for Non-Pressure Drainage and Sewerage - Specification, Part 2: Pipes and Fittings with Non-Smooth External Surface, Type B

IS 16098 Part 2: Scope - Key Specifications & Tables

Scope Summary:
This part covers structural design, installation quality, and testing of structured wall thermoplastic pipes and fittings, focusing on compaction, stiffness, deflection, and mechanical testing.

Key Specifications:

• Installation Quality (Clause 6.0):

  • Well Compaction (I): Embedment soil placed in max 300 mm layers, compacted to >94% Proctor density.
  • Moderate Compaction (II): Layers max 500 mm, compacted to 87-94% Proctor density.
  • Non-Compaction (III): Lower compaction, typically after removal of sheeting.

• Minimum Stiffness Class for Fittings:
  Must be equal to or greater than that of the structured wall pipe.

Table: Recommended Design Deflection Limits (Table 25)

Mechanical Testing: Moment & Displacement (Table 27)

Example: For DN=200,
( M = 0.15 \times 200^3 \times 10^{-6} = 1.2 , kN\cdot m )

Particle Classification for Embedment Soil (Table 29 & 30):

• Shapes: Rounded, Irregular, Angular, Flaky, Elongated, Flaky & Elongated
• Surface Texture: Glossy (conchoidal fracture), Smooth (water worn), Granular (rounded grains)

Summary Diagram: Installation Quality & Layering

flowchart TD

Here are key references, formulas, and tables from IS 16098 Part 2: 2013 relevant to structural design and testing of thermoplastic pipes and fittings:

1. References (Table 2)

• IS 2530:1963 - Test methods for polyethylene molding materials.
• IS 3400 (Part 2):2003 - Hardness testing of vulcanized rubber.
• IS 4905:1968 - Random sampling methods.
• IS 5382:1985 - Rubber sealing rings specifications.
• IS 7328:1992 - HDPE materials for molding and extrusion.
• IS 12235 (Parts & Sections 1,2,3,6,8,9):2004 - Thermoplastic pipes/fittings test methods.
• IS 13360 (Parts 2 Sec 1 & 3):1992, 2000 - Plastics test specimen preparation.
• IS 16098 (Part 1):2013 - Structured-wall plastics piping systems.

2. Traffic Loading & Installation Quality (Clause 6.0)

• Compaction categories:
  • Well compaction (I): Proctor density > 94%, soil compacted in 300 mm layers.
  • Moderate compaction (II): Proctor density 87–94%, soil compacted in 500 mm layers.
  • Non-compaction (III): No compaction or disturbed compaction.

3. Recommended Deflection Limits (Table 25)

4. Moment and Displacement for Testing (Table 27)

IS 16098 Part 2: Terminology & Key Specifications

Key Definitions (Clause 3.26.2 & others)

• dim: Mean inside diameter
• de: Outside diameter
• dem: Mean outside diameter
• e: Wall thickness at any point
• F: Distance from spigot end to effective sealing point
• L1, Min: Minimum length of spigot
• ox: Nominal angle of fitting

Installation Quality (Clause 6.0)

• Well compaction (I): Embedment soil compacted in max 300 mm layers; Proctor density > 94%
• Moderate compaction (II): Embedment soil compacted in max 500 mm layers; Proctor density 87-94%
• Non-compaction (III): Below moderate compaction level, e.g., after sheet piling removal

Stiffness Class & Deflection Limits (Table 25)

Material Characteristics for PE Granules (Table 1, Clause 5.1)

Summary Diagram: Installation Quality Levels

flowchart LR
    A[Embedment Soil Placement] --> B{Compaction Level}
    B -->|Well (I)| C[Layer ≤ 300 mm, Proctor > 94%]
    B -->|Moderate (II)| D[Layer ≤ 500 mm, Proctor 87-94%]
    B -->|Non (III)| E[

IS 16098 Part 2: Material Requirements - Key Specifications

1. Material Characteristics for PE and PP (Granules & Pipe Form)

2. Resistance to Internal Pressure (PE Pipe Form)

3. Designation Format (Clause 6.2)

Material / Structure / Wall Construction / Nominal ID / Nominal Ring Stiffness
Example: PE / DWC / ID / SN

Additional Notes:

• Conditioning period for tests is typically at 27 ± 2°C.
• Test pieces should be free in orientation during pressure tests.
• MFR values for rotational moulded PE fittings: 3 to 16 g/10 min.
• Particle shape and surface texture for granular materials are classified in Tables 29-31 (e.g., Rounded, Angular

IS 16098 Part 2: Pipe and Fitting Dimensions Summary

1. Pipe & Fitting Types (Clause 6.4.1)

• Permitted fittings:
  • Bends (swept/unswept) with preferred nominal angles: 15°, 22.5°, 30°, 45°
  • Couplers
  • Reducers
  • Branches and reducing branches with nominal angles: 45°, 87.5°–90°
  • Plugs
• Spigot length (L) must extend beyond the ring seal by ≥10 mm.

2. Key Dimensions (Clause 6.3.5.1.5, Table 5)

• Note: For pipes >6 m, socket length A_min should be increased.

3. Diameter Tolerances (Clause 6.3.3)

• Pipes and fittings must comply with manufacturer-specified outside diameters and tolerances.
• For fittings not conforming to jointing dimensions, tolerances apply as per manufacturer specs.

Typical Assembly (Fig. 2 reference)

IS 16098 Part 2: Designation of Wall Constructions and Jointing Methods

1. Wall Construction Designation (Clause 6.1)

• Type B Wall Construction:
  • Typically refers to walls with specific thickness and reinforcement as per the standard.
  • Designed for structural integrity and durability.

2. Wall Thickness & Joint Design (Clause 6.3.5.1)

• Wall Thickness:
  • Thickness of sockets and joints must meet minimum values to ensure strength and leak-proof connections.
• Joint Design:
  • Joints should be designed to accommodate movements and ensure watertightness.
  • Typical joint types include socket and spigot, flange, and bell-and-spigot joints.

3. Jointing Methods (Clause 4.2 & A-4.2)

• Laying and Jointing:
  • Clean surfaces before jointing.
  • Use manufacturer-approved sealants or gaskets.
  • Ensure proper alignment and avoid overstressing joints.

Summary Table: Typical Jointing Methods

Key Formula: Minimum Wall Thickness (t)

[ t = \frac{P \times D}{2 \times \sigma_{allow}} ]

Where:

• (P) = Design pressure
• (D) = Outer diameter
• (\sigma_{allow}) = Allowable stress of material

flowchart LR
    A[Wall Construction Type B] --> B[Wall Thickness Specified]
    B --> C[Socket & Joint Design]
    C --> D[Laying & Jointing Procedures]
    D --> E[Watertight & Structural Integrity]

Note: Always refer to IS 16098 Part 2 for exact dimensions and manufacturer-specific guidelines.

IS 16098 Part 2: Physical Characteristics for Pipes and Fittings

1. Mechanical Characteristics (Clause 8.1)

• Pipes and fittings must withstand resistance to internal pressure and heating without failure.
• Resistance to internal pressure tests:
  • 140 h test: 80°C, 4.2 MPa circumferential stress, 3 test pieces.
  • 1000 h test: 95°C, 2.5 MPa circumferential stress, 3 test pieces.
• Test method reference: IS 12235.

2. Dimensions (Clause 6.3)

• Nominal sizes and minimum mean inside diameters (DN-ID series) specified in Table 2.
• Outside diameters for pipes and spigots are standardized (see Table 6.3.3).

3. Physical Characteristics of PE and PP Pipes (Clause 7.2, Tables 6 & 7)

4. Physical Characteristics of Injection-Moulded Components (Clauses 7.3, Tables 8 & 9)

Summary Diagram

flowchart TD
    A[Pipes & Fittings] --> B

IS 16098 Part 2 — Mechanical Characteristics of Fittings (Clause 8.2)

Key Specifications:

• Nominal Stiffness Classes (SN):
  • For DN ≤ 500: SN 4, SN 8, SN 16
  • For DN > 500: SN 2, SN 4, SN 8, SN 16
• Manufacturer's guaranteed minimum stiffness between SN values can be used for DN ≥ 500.

Mechanical Test Requirements (per Table 11):

• Fittings must conform to stiffness and mechanical strength requirements under specified test parameters (refer to Table 11 in IS 16098-2).
• Tests include ring stiffness, resistance to deformation, and impact resistance.

Physical Characteristics of Injection-Moulded Fittings (Clause 7.3):

Wall Thickness (e) for Tests:

• Use maximum measured wall thickness excluding any coating/external layers.
• Heating immersion times depend on thickness:
  • e ≤ 3 mm: 15 min
  • 3 mm < e ≤ 10 mm: 30 min
  • 10 mm < e ≤ 20 mm: 60 min

Fitting Types (Clause 6.4.1):

• Bends (15°, 22.5°, 30°, 45°)
• Couplers
• Reducers
• Branches (45°, 87.5°–90°)
• Plugs

Summary Diagram of Stiffness Classes by DN:

graph TD
    A[Pipe Diameter (DN)] -->|≤ 500| B[SN 4, SN 8, SN 16]
    A -->|> 500| C[SN 2, SN 4, SN 8,

IS 16098 Part 2: Marking and Identification (Clauses 11.1 & 11.2)

Key Specifications for Marking:

• Marking Method: Labelled, printed, or formed directly on pipe/fitting.
• Durability: Marking must remain legible after storage, weathering, and handling.
• Integrity: Marking should not cause cracks or defects affecting performance.

Minimum Required Marking on Fittings (Clause 11.2.2):

Designation Format (Clause 6.2):

Material/Structure Wall Construction/Nominal ID (DN or ID)/Nominal Ring Stiffness (SN)
Example: PE/DWC/ID/SN

Additional Notes:

• Marking must comply with Table 6.2 designation for consistent identification.
• Marking should be placed without compromising pipe/fitting mechanical integrity.

Summary Diagram of Marking Information on a Fitting:

graph LR
A[Manufacturer Name/Trademark] --> B[Diameter Series (Nominal Size)]
B --> C[Nominal Angle]
C --> D[Stiffness Class]
D --> E[Material]
E --> F[Lot/Batch Number]

This ensures traceability and quality control per IS 16098 Part 2 standards.

IS 16098 Part 2: Testing and Type Approval Summary

1. Type Tests (Clause 10.2.1)

• Purpose: Prove suitability & performance of new pipe sizes or techniques.
• Conducted in-house or authorized labs.
• Refer to Tables 15 to 18 for test types and sample sizes.

2. Key Type Tests & Sample Sizes

| PP Pipes (Table 17) | Similar tests with adjusted pressure/time values (e.g., 4.2 MPa for 165 h) | 5.1 | Table 20 |

| PE Fittings (Table 16) | Thermal stability, water tightness, flexibility | 5.1, 9.0, 8.2.1 | Table 11 |

3. Acceptance Tests (Clause 3.26.2 & Table 14)

• Conducted on samples from production lots.
• Include:
  • Visual appearance, finish, colour (7.1)
  • Dimensions (6.3)
  • Ring stiffness (8.2.1)
  • Impact test (8.2.2)
  • Effect of heating (7.3)

4. Important Parameters

• D_im: Minimum mean inside diameter of a socket
• d_e: Outside diameter
• e: Wall thickness (at any point)

IS 16098 Part 2: Installation Guidelines - Key Points & Formulas

1. Compaction Categories & Backfilling

• Well Compaction (I):
  • Embedment soil: granular, placed in max 300 mm layers, compacted each layer.
  • Minimum cover over pipe: 150 mm.
  • Proctor density: >94%.
• Moderate Compaction (II):
  • Embedment soil: granular, placed in max 500 mm layers, compacted each layer.
  • Minimum cover over pipe: 150 mm.
  • Proctor density: 87% to 94%.
• Non-Compaction (III): Not recommended; occurs if sheeting removed after compaction.

2. Backfill Envelope Construction

• Comprises:
  • Initial backfill (around pipe),
  • Side fill,
  • Top backfill.
• Material: same as excavated soil or fine sand/gravel; avoid concrete to prevent rigidity.
• Voids must be eliminated by knifing under/around pipe.
• Compaction to max proctor density using hand rammers or compactors.
• Backfilling starts only after water tightness test.

3. Deflection Limits (Table 25)

4. Physical Properties for Design (Table 23)

5. Installation Depth & Traffic Loading (Table 24)

• Installation depth: **0.8 m to 6

Key Specifications & Formulas for Trench Preparation and Backfilling

IS 16098 Part 2: Clauses 4.1 & 4.2.5

1. Trench Width (Table 21 - Clause A-4.1.1)

• Excavation in straight lines at correct depth and gradient.
• Shoring required to prevent collapse.
• Groundwater control by well-point system if needed.

2. Backfill Envelope Construction (Clause 4.2.5)

• Backfill envelope supports soil and traffic load.
• Comprises:
  • Initial backfill (around pipe)
  • Side fill
  • Top backfill
• Material: same as excavated or fine sand/gravel; avoid concrete to maintain flexibility.
• Compaction:
  • Use hand rammers or mechanical compactors.
  • Achieve maximum Proctor density.
• Voids must be eliminated by knifing under and around pipe.
• Backfilling starts only after water tightness test.

3. Structural Design Considerations (Annex B)

• Typical flexural modulus (E):
  • PP: 1250–1900 MPa
  • PE: 1000–1200 MPa
• Recommended max pipe deflection to ensure serviceability (per Table 25, not shown here).
• Compaction levels affect deflection and pipe performance:
  • Well compaction (I): >94% Proctor density
  • Moderate compaction (II): 87–94% Proctor density
  • Non-compaction (III): Not recommended

Summary Flow for Trench Preparation & Backfilling

IS 16098 Part 2: Structural Design Based on Calculations

Key Specifications & Tables

1. Material Properties (Table 23)

2. Design Deflection Limits (Table 25)

• Deflection limits ensure serviceability and avoid structural failure.

3. Installation Quality (Table 24)

• Well compaction (I): Proctor density > 94%, max 300 mm compacted layers, haunching zone carefully compacted.
• Moderate compaction (II): Proctor density 87-94%, max 500 mm layers.
• Non-compaction (III): Not recommended; leads to lower pipe performance.

4. Backfill Envelope Construction (Clause 4.2.5)

• Backfill envelope consists of:
  • Initial backfill
  • Side fill
  • Top backfill
• Use fine sand, coarse sand, or gravel (not concrete) for envelope.
• Compact to maximum Proctor density to support soil and traffic loads.
• Ensure water tightness before backfilling.

Structural Design Formula (Simplified)

For pipe deflection and stress, use:

[ \text{Deflection} , (%)

IS 16098 Part 2: Oxidation Induction Time (OIT) - Key Points

Definition (Clause 1.1, 2.1)

• OIT: Time (minutes) a specimen resists oxidation at a specified temperature in oxygen/air.
• Measured isothermally or by heating at constant rate.
• Higher temperature → shorter OIT; faster heating → higher oxidation induction temperature.
• Surface area and atmosphere (O₂ vs air) affect OIT.

Test Procedure (Clause 2.2, 7.6.1)

1. Sample prep: Load specimen & reference crucibles at ambient.
2. Pre-purge: Nitrogen flow for 5 min.
3. Heating: Ramp at 20°C/min under nitrogen to test temperature (preferably multiples of 10°C).
4. Equilibration: Hold at test temperature for 3 min.
5. Gas switch: Change nitrogen to oxygen/air at same flow rate → zero time.
6. Measurement: Record time to onset of exothermic oxidation (steep heat flow increase).
7. Test end: After 2 min past exotherm peak or agreed time.
8. Repeat: Preferably duplicate tests; report mean, min, max.

Important Notes

• OIT reflects antioxidant effectiveness but depends on temperature, additives, and test conditions.
• Avoid extrapolation between different temperatures.
• Use lower test temperature if OIT < 10 min; higher if OIT > 60 min.

Summary Table: Test Parameters

Oxidation Induction Time (OIT) Concept (Mermaid Diagram)

flowchart TD
    A[Start: Ambient Temp] --> B[Pre-purge with N2 for 5 min]
    B --> C[Heat at 20°C/min under N2]

IS 16098 Part 2: Test Procedures & Specimen Preparation

Key Test Parameters (Clause 4.1.1 & Table 26)

• Test Temperature, T: As per D-4.1.1 and D-4.3 (typically 68 ± 1°C for conditioning)
• Number of Test Pieces: Refer D-4.2.2 (usually multiple specimens for statistical reliability)
• Heating Time, t: See D-4.3.3 (e.g., 8 hours conditioning)
• Test Method & Liquid: Method B uses specific test liquids
• Acceptable Limits: Crack dimensions or occurrence per D-4.3.6

Specimen Conditioning (Clause C-5)

• Cut ~300 mm duct length
• Oven conditioning: 68 ± 1°C for 8 hours
• Cooling: Room temperature for ≥16 hours
• Specimen must be clean and dry before testing

Specimen Mass (Clause 5.5)

• For 5.5 mm diameter discs: 12 mg to 17 mg depending on material density

Box Loading Test Apparatus (Clause 3.1 & Table 28)

• Box walls vertical ±3 mm, smooth inside surface

Summary Diagram: Specimen Conditioning & Testing Flow

flowchart TD
    A[Cut Specimen (~300 mm)] --> B[Oven Conditioning 68±1°C for 8h]
    B --> C[Cool at Room