Structured-Wall Plastics Piping Systems for Non-Pressure Drainage and Sewerage - Specification, Part 1: Pipes and Fittings with Smooth External Surface, Type A

Scope: IS 16098 Part 1 - Key Specifications & Tables

Scope Overview:

• Covers thermoplastic pipes for buried applications.
• Specifies dimensions, testing, and installation methods including sidefilling and backfilling.

Key Specifications & Tables

1. Sidefilling and Backfilling (Clause 1.7, Table B-1.7)

• Sidefill material compacted by hand on both sides up to pipe centerline (dimension l1).
• Next layer compacted up to pipe top (dimension l2), crown exposed during compaction.
• Third layer up to 0.3 m above pipe top (dimension l3), compacted with light rammers on sides only.
• Final layers (dimensions l4 and l5) compacted over full trench width to specified Procter density.
• Avoid frozen backfill and flotation in high groundwater.

2. Ring Stiffness Testing (Annex C)

• Ring stiffness ( S ) (kN/m²) calculated from force-deflection test.
• Deflection speed depends on pipe diameter (Table 14):

• Ring stiffness formula:

[ S = \frac{F}{y \times L} ]

Where:
(F) = force at 0.03d deflection (kN),
(y) = deflection (m),
(L) = length of test piece (m).

3. Pipe Dimensions (Clause 6.3.1, Table 2)

IS 16098 Part 1: Terms & Definitions - Key Points and Tables

Key Symbols & Definitions (Clause 3.26.2)

• dn: Nominal outside diameter (mm)
• di: Nominal inside diameter (mm)
• de: Outside diameter at any point (mm)
• dem: Mean outside diameter (mm)
• ds: Inside diameter of socket (mm)
• SDR: Standard Dimension Ratio (ratio of diameter to wall thickness)
• e: Wall thickness at any point (mm)
• em, Max/Min: Max/min mean wall thickness (mm)
• Cc: Construction height (mm)
• L: Length of engagement or effective length (mm)

Ring Stiffness Test (Annex C)

• Ring stiffness (S) is calculated from the force (F) causing a deflection (y) of 0.03 × diameter (d).
• Test setup: Pipe compressed vertically between flat plates at constant speed.

Sidefilling & Backfilling (Clause 1.7, Table B-1.7)

• Sidefill compacted evenly on both sides up to the pipe centerline (l1).
• Next layer compacted up to top of pipe (l2); crown exposed during compaction.
• Third layer up to 0.3 m above pipe top (l3) compacted with light rammers on sides only.
• Final layers (l4, l5) compacted over full trench width to specified Procter value.
• Avoid frozen backfill and flotation in high groundwater.

Hydrostatic Pressure Test (Table 1, Clause 5.2)

• Circumferential hoop stress σ (MPa) calculated as:

[ \sigma = \

IS 16098 Part 1: Composition of Material (Foam Core Pipes)

Key Specifications (Clause 34.2 & related):

• PVC-U substitution by CaCO₃:

• CaCO₃ Composition (before coating):

• Physical Properties (Clause 2.5):

• Material Characteristics (Clause 5.2):
  Refer to Table 1 of IS 16098 Part 1 for mechanical/physical properties of pipes and fittings.

• Testing (Clause 14.2.1):
  Type tests (Table 13) required when polymer composition or size changes.

Notes:

• Machining allowed to separate layers for testing.
• Manufacturer's test report/certificate recommended for CaCO₃ conformity.

flowchart TD
    A[PVC-U Substitution] --> B[CaCO₃ Content]
    B --> C{Layer Type}
    C -->|Intermediate| D[≥ 60% CaCO₃]
    C -->|Other Layers| E[≥ 75% CaCO₃]
    B --> F[CaCO₃ Composition]
    F --> G[CaCO₃ ≥ 96%]
    F --> H[MgCO₃ ≤ 4%]
    F --> I[CaCO₃ + MgCO₃ ≥ 98%]
    B --> J[Physical Properties]
    J --> K[Mean Particle Size ≤ 2.5 µm]
    J --> L[Top Cut D98 ≤ 20 µm]

This summary helps

IS 16098 Part 1: Dimensions of Pipes and Fittings

Key Specifications:

1. Outside Diameter & Tolerances (Clause 6.3.1, Table 2)

2. Length of Pipe (Clause 6.3.3)

• Effective length (l) ≥ Manufacturer's specified length (see Fig. 2 for measurement method).

3. Fittings (Clause 6.3.4.4)

• Types of fittings are detailed in Fig. 6 (e.g., elbows, tees, reducers).
• Integral sockets and spigot ends dimensions per Figs. 2-5 and Tables 4 & 5.

Summary Diagram of Pipe and Fitting Dimensions:

flowchart LR
    A[Pipe] --> B[Nominal Outside Diameter (d)]
    B --> C[Mean Outside Diameter (d_em)]
    A --> D[Length (l) >= Manufacturer Spec]
    A --> E[Fittings]
    E --> F[Integral Socket]
    E --> G[Spigot End]

Use these tables and figures for precise dimensional checks during design and inspection.

IS 16098 Part 1: Physical Characteristics for Pipes

Key Specifications & Tables

1. Materials (Clause 5.2 & Table 1)

• Pipes and fittings must conform to material properties listed in Table 1, including:
  • Tensile strength
  • Elongation %
  • Hardness
  • Impact resistance
• Materials typically include ductile iron, cast iron, or other specified alloys.

2. Dimensions (Clause 6.3)

• Pipes and fittings dimensions are standardized for:
  • Outer diameter (OD)
  • Wall thickness (t)
  • Length
• Dimensions ensure compatibility and pressure rating compliance.

3. Type of Fittings (Clause 6.3.4.4)

• Fittings include bends, tees, reducers, flanges (see Fig. 6 in standard).
• Each fitting must maintain dimensional and physical compatibility with pipes.

4. Type Tests (Clause 14.1)

• Tests include:
  • Hydrostatic pressure test
  • Impact test
  • Dimensional checks
  • Material composition verification

Typical Dimension Formula for Pipes:

Summary Table: Physical Characteristics (Example)

flowchart LR
    A[Pipes] --> B[Dimensions: OD, t, Length]
    A --> C[Material Properties: Strength, Hardness]
    A --> D[Fittings: Bends, Tees, Reducers]
    A --> E[Type Tests: Hydrostatic, Impact]

For exact values and detailed tables, refer to Table 1 and Fig. 6 of IS 16098 Part 1.

IS 16098 Part 1: Mechanical Characteristics of Fittings

Key Specifications (Clause 8.3 - Stress Relief Test per IS 12235 Part 6)

Fittings must pass heating tests ensuring minimal delamination/cracking:

• Wall thickness refers to the maximum measured thickness excluding eccentricity.

Mechanical Tests (Clauses 13.3 & 14.2)

• Acceptance tests include dimensional checks, pressure tests, and mechanical strength verification.
• Type tests validate performance under simulated service conditions.

Summary Diagram: Crack/Delamination Limits

graph LR
    A[Injection Point] -->|Radius 15× wall thickness| B[Max 50% depth cracks]
    C[Diaphragm Zone] -->|Distance 10× wall thickness| D[Max 50% depth cracks]
    E[Ring Gate] -->|Distance 10× wall thickness| F[Max 50% depth cracks & length]
    G[Weld Line] --> H[Max 50% opening]
    I[Other Surface] --> J[Max 30% depth cracks, blisters ≤ 10× wall thickness]

Note: Refer to Fig. 6 in IS 16098 Part 1 for fitting types covered.

IS 16098 Part 1: Jointing Requirements and Tightness of Elastomeric Seal Ring Joints

Key Specifications:

• Test Medium: Air Pressure (Clause 14.2.3), Water Pressure (Clauses 12.1.1, 13.2.6, 13.3.2)
• Pressure for Water Test: Up to 0.05 MPa (0.5 bar)
• Duration: Minimum 15 minutes
• Deflections during test:
  • Angular deflection: ≥ 2°
  • Diametric deflection: 5% of outer diameter

Sampling & Conformity:

• Sampling procedure and acceptance criteria are specified in:
  • Table 9 (Water pressure tests)
  • Table 13 (Air pressure tests)

Testing Method Reference:

• Follow IS 12235 (Part 8/Sec 2) for test setup and procedure.

Summary Table: Tightness Test Parameters

flowchart TD
    A[Assembled Joint] --> B[Test Setup per IS 12235]
    B --> C[Apply Angular Deflection ≥ 2°]
    B --> D[Apply Diametric Deflection 5% OD]
    C & D --> E[Apply Internal Pressure 0.05 MPa]
    E --> F[Hold for 15 minutes]
    F --> G{Leakage?}
    G -->|No| H[Joint Passes]
    G -->|Yes| I[Joint Fails]

Note: Ensure joints are assembled as per manufacturer's instructions before testing.

IS 16098 Part 1: Sampling and Criteria for Conformity

Based on Clauses 13.2.2.1, 13.2.5.2, 13.2.6.2, and 14.1.3.2, the sampling procedure and conformity criteria refer to Table 8 and Table 12.

Key Specifications:

• Table 8:
  Defines sampling plans for routine tests, including:

  • Sample size (n)
  • Acceptance number (Ac)
  • Rejection number (Re)
  • Criteria based on lot size and test type.

• Table 12:
  Specifies sampling for special or type tests, with stricter acceptance criteria.

Typical Sampling Plan Format (from Table 8):

Usage Notes:

• Acceptance criteria: If the number of defective samples ≤ Ac, lot is accepted.
• Rejection criteria: If defective samples ≥ Re, lot is rejected.
• Sampling follows ISO 2859-1 or equivalent standards referenced.

flowchart LR
    A[Start: Lot Received] --> B{Select Sample Size (n) per Table 8/12}
    B --> C[Conduct Tests on n Samples]
    C --> D{Number of Defects ≤ Ac?}
    D -- Yes --> E[Accept Lot]
    D -- No --> F[Reject Lot]

For exact values, refer to Tables 8 and 12 in IS 16098 Part 1.

IS 16098 Part 1: Type Tests for Fittings

Key Points from Clauses:

• Clause 14.2.1 & 3.26.1:
  Type tests are mandatory when:

  • A new polymer composition is introduced.
  • A new size or series of fittings is introduced.

• Purpose: To prove suitability and performance of new fittings.

Reference Table (Table 13) - Typical Type Tests for Fittings

General Notes:

• Tests are not repeated for each batch unless composition/size changes.
• Test parameters (pressure, duration, temperature) are specified in the code or product standards.
• Type tests are more rigorous than routine tests to ensure new product reliability.

flowchart TD
    A[New Polymer Composition or Size] --> B[Type Tests as per Table 13]
    B --> C{Tests}
    C --> D[Hydrostatic Pressure Test]
    C --> E[Dimensional Check]
    C --> F[Impact Test]
    C --> G[Thermal Ageing Test]
    C --> H[Chemical Resistance Test]
    D & E & F & G & H --> I[Evaluate Suitability & Performance]

Summary: Type tests validate new fittings' performance and are essential when material or size changes occur, ensuring compliance with IS 16098 Part 1.

IS 16098 Part 1: Marking Specifications

• Marking Durability (Clause 15.2.1):
  Markings on fittings must remain legible after storage, weathering, handling, and installation. Marking methods must not cause cracks or defects affecting fitting performance.

• Pipe Marking (Clause 15.1.1):

  • Marking interval: Every ≤ 2 m, at least once per pipe.
  • Marking method: Ink/paint or hot embossing on a white base.
  • Legibility: Must be readable without magnification.
  • Marking must not reduce wall thickness by more than 0.15 mm (indentation marking allowed within this limit).
  • Marking color: As per Clause 15.1.3 (typically related to pipe type or application).

• Test Pieces (Clause 5.1):
  Specifies marking and number of test pieces for quality control (details in Clause E-5.1 and C-5.1).

Summary Table: Marking Requirements

flowchart LR
    A[Pipe/Fitting] --> B[Marking]
    B --> C{Method}
    C -->|Ink/Paint| D[White base]
    C -->|Hot Embossing| D
    B --> E{Legibility}
    E -->|Yes| F[No magnification needed]
    E -->|No| G[Reject]
    B --> H{Wall Thickness Reduction}
    H -->|≤ 0.15 mm| I[Accept]
    H -->|> 0.15 mm| J[Reject]

This ensures durable, defect-free marking as per IS 16098 Part 1.

Creep in Thermoplastic Pipes (IS 16098 Part 1)

Key Concepts & Formulas

• Initial stiffness (S) of pipe ring (kN/m²): [ S = \frac{0.0186 + 0.025 y}{F} ] where,

  • (F) = force to obtain deflection (kN)
  • (y) = deflection (m)
  • (L) = length of test ring (m)

• Pipe ring stiffness from material properties: [ S = \frac{E \times I}{D} ] where,

  • (E) = modulus of elasticity
  • (I) = moment of inertia
  • (D) = mean diameter

• Creep Ratio (y): [ y = \frac{Y_2}{Y_0} ] where,

  • (Y_0) = initial deflection at 0.1 h (6 min)
  • (Y_2) = extrapolated deflection at 2 years (from regression analysis)

Test Procedure (Annex E)

• Apply constant compressive load for 1008 h (42 days).
• Record deflection (Y_t) at intervals.
• Plot deflection vs time and perform regression to find (Y_2).
• Use only data sets with correlation coefficient (R > 0.990).
• If (R < 0.990), extend test up to 4000 h or until (R) criterion met.

Typical Data Summary (from Table 17)

Notes

Determination of Ring Flexibility as per IS 16098 Part 1

Key Definitions:

• Ring Flexibility (Clause 3.23): Ability of a pipe to resist diametric deflection without loss of structural integrity.
• Ring Stiffness (Clause 13.2.4): Resistance offered by the pipe ring to deformation.

Ring Flexibility Test (Clause 9.3 & Annex D)

• Test on pipe sample size: 300 ± 10 mm diameter
• Deflection: 30% of dem (mean diameter)
• Visual inspection without magnification; requirements:
  • (a) No decrease in measured force during test.
  • (b) No cracking in pipe wall.
  • (c) No wall delamination (except allowed in double wall pipes).
  • (d) No rupture.
  • (e) No permanent buckling, depressions, or craters.

Ring Stiffness Classes (Table 6, Clause 9.1)

Impact Test Parameters (Table 7, Clause 9.2)

Summary Formula for Ring Stiffness (k):

[ k = \frac{F}{\Delta d} ]

Where:

• ( F ) = Applied force (N/m)
• ( \Delta d \

IS 16098 Part 1: Testing Procedures and Equipment

Key Specifications:

• Force Measuring Device (Clause 4.4):

  • Accuracy: ±2% of force measurement
  • Capacity: Must measure force required for up to 4% deflection of test specimen

• Sampling and Conformity Criteria (Clauses 13.2.4.2, 13.2.5.2, 13.2.6.2):

  • All refer to Table 8 for:
    • Sampling procedures
    • Acceptance criteria for conformity

Typical Table 8 Summary (Sampling & Acceptance):

(Note: Actual values depend on specific test and product; refer to IS 16098 Part 1 Table 8 for exact numbers.)

Additional Notes:

• Deflection measurement accuracy is critical; ensure calibration of force device.
• Sampling must follow statistically valid procedures for reliable conformity assessment.

flowchart LR
    A[Test Piece] --> B[Apply Load]
    B --> C[Measure Force]
    C --> D{Force within ±2%?}
    D -- Yes --> E[Measure Deflection (up to 4%)]
    D -- No --> F[Calibrate Device]
    E --> G[Compare with Acceptance Criteria (Table 8)]
    G --> H{Pass?}
    H -- Yes --> I[Conformity Confirmed]
    H -- No --> J[Reject Test Piece]