Unplasticized PVC Pipes (Ducts) and Fittings for Underground Telecommunications Cable Installation

IS 14735: Scope - Key Specifications & Tables Summary

Scope:
IS 14735 covers dimensions, material properties, and testing requirements for PVC fittings used in drainage and sewerage systems.

Key Specifications:

• Vicat Softening Temperature (Clause 12.3):

  • Minimum: 78°C (per IS 6307)
  • Specimen supported on concave surface matching specimen radius.

• Resistance to Sulphuric Acid (Clause 13):

  • Mass change limits:
    • Increase ≤ 0.32 g
    • Decrease ≤ 0.13 g
  • Surface appearance changes ignored.

• Wall Thickness (Clause 7.1, Table 1):

• Vent Cowl Dimensions (Clause 11.4, Table 5):

• Pipe Clips (Clause 11.5, Table 6):

IS 14735: Key Normative References, Formulas & Tables

1. Normative References & Tests

• Vicat Softening Temperature (Clause 12.3):

  • Minimum 78°C per IS 6307.
  • Specimen supported on concave surface matching specimen radius.

• Resistance to Sulphuric Acid (Clause 13):

  • Mass change limits:
    • Increase ≤ 0.32 g
    • Decrease ≤ 0.13 g
  • Test per IS 12235 (Part 7).

• Titanium Dioxide Content (Clause 14):

  • Calcination until constant mass (≤0.5 mg difference), max 3 h.

  • Sulphated ash content formula:

    [ \text{Sulphated ash %} = \frac{M_2 - M_1}{M_3 - M_1} \times 100 ]

    Where:

    • (M_1) = mass of crucible
    • (M_2) = mass crucible + test portion
    • (M_3) = mass crucible + residue

2. Important Tables

IS 14735 - Colour Requirements & Related Specifications

Key Points on Colour and Visual Requirements (Clause E-2)

• Colour conformity is verified by sampling each lot separately (Clause 1.2).
• Colour is an acceptance test as per Table 7 (Clause 18.1).
• Visual appearance, workmanship, and dimensional requirements are also acceptance tests.

Sampling & Acceptance Criteria (Table 8)

• If the number of defective samples exceeds the acceptance number, the lot is rejected.

Related Specifications

• Vicat Softening Temperature: ≥ 78°C (Clause 12.3)
• Resistance to Sulphuric Acid: Mass change limits ±0.32g / -0.13g (Clause 13)
• Titanium Dioxide Content: Verified in type tests (Clause 14)
• Stress Relief & Impact Tests: Performed after colour conformity (Clause E-3.1.1)

Summary Diagram: Sampling & Acceptance for Colour

flowchart TD
    A[Lot of Fittings] --> B{Lot Size}
    B -->|≤ 500| C[Sample 50]
    B -->|501-1200| D[Sample 80]
    B -->|1201-3200| E[Sample 125]
    B -->|3201-10000| F[Sample 200]

    C --> G{Defects ≤ 0?}
    D --> H{Defects ≤ 1?}
    E --> I{Defects ≤ 1?}
    F --> J{Defects ≤ 2?}

    G -->|Yes| K[Accept Lot]
    G -->|No| L[Reject Lot]
    H -->|Yes| K
    H -->|No| L

IS 14735: Material Requirements - Key Specifications & Tables

1. Vicat Softening Temperature (Clause 12.3)

• Minimum Vicat softening temperature: 78°C (per IS 6307).
• Specimen supported on concave surface matching specimen radius.

2. Resistance to Sulphuric Acid (Clause 13)

• Mass change limits after testing (IS 12235 Part 7):
  • Increase ≤ 0.32 g
  • Decrease ≤ 0.13 g
• Surface appearance changes ignored.

3. Wall Thickness of Fittings (Clause 7.1, Table 1)

• Note: 5% reduction allowed due to core shifting; average thickness measured on opposite sides must meet minimum.

4. Vent Cowl Dimensions (Clause 11.4, Table 5)

5. Pipe Clips Dimensions (Clause 11.5, Table 6)

IS 14735: Dimensions and Tolerances (Clause 7.2)

Key Specifications:

• Socket and Spigot Dimensions for Ring Seal and Solvent Cement fittings are given in Tables 2 & 3.
• Out-of-Roundness Tolerance for socket inside diameters:
  [ \text{Max Diameter} - \text{Min Diameter} \leq 0.7% \times DN ]

Table 3: Ring Seal Fittings (Selected Data)

Table 2: Solvent Cement Fittings (Selected Data)

Notes:

• Socket inside diameter is the mean of two diameters at 90° at socket midpoint.
• Socket taper angle limits:
  • ≤ 75 mm: max 0°40' total included angle

IS 14735 - Sealing Rings: Key Specifications & Dimensions

1. Material & Properties

• Sealing rings are made of elastomers with IRHD hardness 50 ± 5.
• Must not adversely affect fitting properties or cause test failures.
• Width must fit the groove in the socket.

2. Socket & Spigot Dimensions for Ring Seal Fittings (Table 3, Clause 7.2)

IS 14735 - Workmanship: Key Specifications & Sampling

Workmanship Requirements (Clause 10 & E-2)

• Workmanship includes colour, visual appearance, and dimensional accuracy.
• Manufacturer's own clean rework material allowed up to 10% of the lot.
• No other rework material permitted.

Sampling & Acceptance Criteria (Table 8, Clause E-2.1)

• If defects exceed acceptance number → Lot rejected.
• Samples tested for stress relief and impact (drop test) after passing workmanship criteria.

Acceptance Tests (Clause 18.1, Table 7)

Summary

• Workmanship quality is verified via sampling per Table 8.
• Lot acceptance depends on defect count within sample.
• Tests include visual, dimensional, stress relief, and impact.
• Strict control on rework material (max 10%).

flowchart TD
    A[Lot of Fittings] --> B[Sample Selection per Table 8]
    B --> C{Defect Count ≤ Acceptance Number?}
    C -- Yes --> D[Lot Accepted]
    C -- No --> E[Lot Rejected]
    D --> F[Perform Acceptance Tests]
    F --> G[Workmanship, Colour, Dimensions, Stress Relief

IS 14735: Key Design Requirements, Formulas & Tables

1. Socket & Spigot Dimensions (Clause 7.2, Table 3)

2. Wall Thickness (Clause 7.1, Table 1)

Note: 5% reduction allowed due to core shifting; average of two opposite thicknesses must meet minimum.

3. Vicat Softening Temperature (Clause 12.3)

• Minimum 78°C as per IS 6307.

4. Resistance to Sulphuric Acid (Clause 13)

• Mass change limits:
  • Increase ≤ 0.32 g
  • Decrease ≤

IS 14735: Physical Test Requirements Summary

1. Acceptance Tests (Clause 18.1, Table 7)

2. Sampling & Acceptance Criteria (Annex E, Table 8)

Applies to colour, workmanship, visual appearance, and dimensional requirements.

3. Key Physical Test Specifications

• Vicat Softening Temperature (Clause 12.3):
  Minimum 78°C (IS 6307 method).
  Specimen supported on a concave surface matching specimen radius.

• Resistance to Sulphuric Acid (Clause 13):
  Mass change limits after IS 12235 (Part 7) test:

  • Mass increase ≤ **0.

IS 14735: Chemical Resistance Key Points

1. Vicat Softening Temperature (Clause 12.3)

• Minimum Vicat softening temperature: 78°C (IS 6307 method).
• Specimen supported on concave surface matching specimen radius.

2. Resistance to Sulphuric Acid (Clause 13)

• Test as per IS 12235 (Part 7).
• Mass change limits:
  • Increase ≤ 0.32 g
  • Decrease ≤ 0.13 g
• Surface appearance changes (roughening, bleaching, blackening) ignored.

3. Acceptance Tests Relevant to Chemical Resistance (Table 7, Clause 18.1)

Summary:

• Ensure Vicat softening temperature ≥ 78°C for chemical stability.
• Sulphuric acid resistance verified by mass change limits.
• These tests are type tests, not acceptance tests, confirming chemical durability of fittings.

flowchart TD
    A[Specimen Preparation] --> B[Vicat Softening Test]
    B --> C{Temperature ≥ 78°C?}
    C -- Yes --> D[Pass]
    C -- No --> E[Fail]
    A --> F[Sulphuric Acid Test]
    F --> G{Mass Change within Limits?}
    G -- Yes --> D
    G -- No --> E

This ensures pipe fittings comply with chemical resistance requirements per IS 14735.

IS 14735: Titanium Dioxide Content Key Points

• Minimum TiO₂ Content:
  As per Clause 2.5, titanium dioxide content must be ≥ 2.5% by mass.

• Test Method (Annex A):

  • Prepare standard TiO₂ solutions:

    Volume of standard solution (ml)	TiO₂ concentration (mg/ml)
    0.00	0.00
    5.0	0.02
    10.0	0.04
    15.0	0.06
    20.0	0.08
    25.0	0.10

  • Procedure:

    1. Transfer specified volume into 50 ml volumetric flask.
    2. Dilute nearly to volume with 10% H₂SO₄.
    3. Add 2 ml of 30% H₂O₂.
    4. Dilute to volume with 10% H₂SO₄, shake, keep in dark for ~30 min.

• Sample Analysis:

  • Use absorbance of prepared solutions to determine TiO₂ content in the sample (Clause 5.4).
  • Rutile TiO₂ average assay is 93% TiO₂ (Clause 2.6).

Summary Formula for TiO₂ concentration preparation:

[ C = \frac{V_s}{50} \times C_{std} ]

Where:

• (C) = concentration in mg/ml
• (V_s) = volume of standard solution (ml)
• (C_{std}) = concentration of standard TiO₂ solution (assumed 0.10 mg/ml)

flowchart LR
    A[Standard TiO₂ Solution] --> B[Measure Volume (0-25 ml)]
    B --> C[Dilute to 50 ml with 10% H₂SO₄]
    C --> D[Add 2 ml 30% H₂O₂]
    D --> E[Dilute to volume, shake]
    E --> F

Sulphated Ash Content - IS 14735 Key Points

Definition:
Sulphated ash content is the residue remaining after complete combustion of the sample followed by treatment with concentrated sulphuric acid and heating at 850°C until constant mass.

Calculation of Titanium Dioxide Content (Clause 5.4.3 & Annex A)

[ \text{TiO}_2 % = \frac{C \times V_1 \times V_2 \times 100}{M \times V_3} ]

• C = concentration of TiO₂ in final solution (mg/ml)
• M = mass of test sample (mg)
• V₁ = total volume of sample solution (500 ml)
• V₂ = volume of solution prepared (50 ml)
• V₃ = volume transferred from total solution (50 ml)

Sulphated Ash Content Limits (Clause 15 & 2.5)

Procedure Summary (Annex B)

1. Burn the sample completely.
2. Treat residue with concentrated H₂SO₄ to convert ash to sulphates.
3. Heat residue at 850°C until constant weight.
4. Calculate sulphated ash content as % of original sample mass.

Notes

• Use a desiccator with non-reactive drying agent to avoid moisture absorption by ash (Clause 3.6).
• Constant mass means repeated heating until weight variation is negligible.

flowchart TD
    A[Sample] --> B[Combustion]
    B --> C[Residue]
    C --> D[Treatment with H2SO4]
    D --> E[Heating at 850°C]
    E --> F[Constant Mass Residue]
    F --> G[Calculate Sulphated Ash Content]

This ensures accurate measurement of inorganic residue in coatings or materials per IS 14735.

Mechanical Properties per IS 14735

1. Wall Thickness (Clause 7.1, Table 1):

• Note: A 5% reduction due to core shifting is permitted if the average of two opposite wall thicknesses meets or exceeds these values.

2. Vicat Softening Temperature (Clause 12.3):

• Minimum 78°C as per IS 6307.

3. Resistance to Sulphuric Acid (Clause 13):

• Mass change limits:
  • Increase ≤ 0.32 g
  • Decrease ≤ 0.13 g
• Surface appearance changes ignored.

4. Sampling for Stress Relief and Impact (Drop Test) (Clause 3.1.1, Table E-3.1):

Summary Diagram: Wall Thickness Check

flowchart TD
    A[Nominal Diameter] --> B{Diameter Range}
    B -->|40-125| C[Wall Thickness: 3.2-3.8 mm]
    B -->|140| D[Wall Thickness: 3.6-4

IS 14735: Water Tightness Test Key Points

1. Test Setup (Annex D, Clause 17)

• Assemble fitting with pipe.
• Seal open ends with end sealing devices.
• Connect one end to hydraulic pressure source; block others.
• Use water at ambient temperature.

2. Test Procedure

• Gradually increase hydrostatic pressure to 0.05 MPa.
• Maintain pressure at 0.05 MPa for 15 minutes.
• Inspect assembly for no visible leakage.

3. Acceptance Criteria

• No visible leakage from the jointed assembly during/after test.

Summary Table

Additional Notes

• The water tightness test ensures joint integrity under pressure.
• It follows after passing visual, dimensional, and impact tests (Annex C).
• Failure indicates joint or fitting defects.

flowchart LR
    A[Assemble Fitting + Pipe] --> B[Seal Open Ends]
    B --> C[Connect to Hydraulic Pressure Source]
    C --> D[Increase Pressure to 0.05 MPa]
    D --> E[Maintain Pressure for 15 min]
    E --> F{Check Leakage}
    F -- No Leakage --> G[Pass Test]
    F -- Leakage --> H[Fail Test]

This test is critical for ensuring joint water tightness in pressure applications as per IS 14735.

IS 14735: Sampling and Criteria for Conformity

1. Sampling Procedure (Clause 3.1.2 & Annex E)

• Sampling and conformity criteria follow E-2.2 using Table 9 (not fully provided here).
• Samples are taken from each lot separately (E-1.2).

2. Acceptance Tests (Clause 18.1 & Table 7)

3. Key Test Specifications

• Sulphated Ash Content Calculation (Clause 4.7 B-6):

[ \text{Sulphated ash %} = \frac{M_2 - M_1}{M_3 - M_1} \times 100 ]

Where:

• (M_1) = mass of crucible

• (M_2) = mass of crucible + test portion

• (M_3) = mass of crucible + residue after calcination

• Impact Test (Annex C):

  • Specimen conditioned at 0 ± 1℃ for 30 min.
  • Dropped from 2 m (DN ≤ 75) or 1 m (DN > 75) onto concrete.
  • No visible cracks or breaks allowed.

• Water Tightness Test (Annex D):

  • Hydrostatic pressure of 0.05 MPa applied for 15 min.
  • No leakage allowed.

4.

IS 14735: Marking and Certification Key Points

1. BIS Certification Marking (Clause 19.2)

• Fittings may be marked with the Standard Mark (BIS mark) indicating conformity.

2. Acceptance & Type Tests (Table 7, Clause 18.1)

3. Key Specifications

• Vicat Softening Temperature (Clause 12.3):
  Minimum 78°C (IS 6307 method).

• Resistance to Sulphuric Acid (Clause 13):
  Mass change limits:

  • Increase ≤ 0.32 g
  • Decrease ≤ 0.13 g
    (IS 12235 Part 7 method)

• Sulphated Ash Content Formula (Clause 4.7):
  [ \text{Sulphated ash %} = \frac{M_2 - M_1}{M_3 - M_1} \times 100 ] Where:

  • (M_1) = mass of crucible
  • (M_2) = mass of crucible + test sample
  • (M_3) = mass of crucible + residue after calcination

4. Impact (Drop) Test (Annex C)

• Condition specimen at 0 ± 1°C for 30 min.
• Drop height:
  • 2 m for DN ≤ 75
  • 1 m for DN > 75
• Check for visible cracks or breaks