Polyethene Fittings for use with Polyethylene Pipes for the Supply of Gaseous Fuels - Specification, Part 1: Fittings for Socket Fusion using Heated Tools

IS 15927 Part 1: Scope - Key Formulas, Tables & Specifications

1. Scope Overview (Clause 5.5)

• Applies to polyethylene pipes and fittings for gaseous fuel supply.
• References other IS standards for materials and fittings:
  • IS 2530: Test methods for polyethylene molding materials.
  • IS 7328: HDPE materials specification.
  • IS 14885: Polyethylene pipes for gaseous fuels.
  • IS 15927 (Part 2): Polyethylene fittings specification.

2. Wall Thickness Relationship (Clause 8.3.2, Table 3)

• ( E ) = fitting wall thickness
• ( e_{min} ) = minimum pipe wall thickness

3. Socket Dimensions & Tolerances (Tables 1 & 2)

• Type A & B Sockets: Dimensions for nominal inside diameters (dn) from 16 mm to 125 mm.
• Key parameters:
  • Mean inside diameter at socket mouth (D1)
  • Mean inside diameter at distance L (D2)
  • Ovality limits (max)
  • Reference length (L)
  • Minimum bore diameter (D3)

Example for dn=50 mm (Type A Socket):

4. Hydraulic Pressure Test (Clause 9.2, Table 4)

• Tests at 20°C and 80°C with failure time requirements.
• Hoop stress for pipes:

| Pipe Type | Hoop Stress (MPa) at 20°C | Hoop Stress (MPa)

IS 15927 Part 1: Key References, Tables & Specifications

1. Reference Standards (Clause 5.5)

Note: 1 bar = 0.1 MPa = 105 N/m²

2. Wall Thickness Relation (Clause 8.3.2, Table 3)

• E: fitting wall thickness
• e_min: pipe minimum wall thickness

3. Socket Dimensions & Tolerances

• Type A & B Sockets (Tables 1 & 2):
  Dimensions include mean inside diameter at socket mouth (D1), at distance L (D2), ovality, reference length (L), and minimum bore diameter (D3).

Example (Type A, dn=50 mm):

4. Type Tests (Table 9, Clause 11.2)

IS 15927 Part 1: Key Definitions, Formulas & Tables

1. Definitions (Clause 5.5)

• 1 bar = 10^5 N/m² = 0.1 MPa.
• The standard refers to related IS codes for materials and fittings (e.g., IS 2530, IS 7328, IS 14885, IS 15927 Part 2).

2. Wall Thickness Relationship (Clause 8.3.2, Table 3)

• Ensures fitting strength compatibility with pipe.

3. Socket Dimensions & Tolerances (Tables 1 & 2)

• Type A & B sockets have specified mean inside diameters, ovality limits, reference lengths (L), and minimum bore diameters (D3).
• Example for dn=50 mm (Type A):
  • Socket Mouth Diameter (D1): 49.00 to 49.50 mm
  • Ovality max: 0.6 mm
  • Reference Length (L): 23.5 mm
  • Min Bore Socket (D3): 39 mm

4. Hydraulic Pressure Test Requirements (Clause 9.2, Table 4)

IS 15927 Part 1: Classification and Grades of Material

1. Material Grades (Clause 5.2)

• Fittings are classified by material grade per Table 1 of IS 14885.
• Raw material suppliers must provide material grading (Clause 5.2.3).

2. Wall Thickness Relationship (Clause 8.3.2 & Table 3)

• For fittings and pipes of the same MRS, fitting wall thickness ( E \geq e_{min} ) beyond ( \frac{2L}{3} ) from entrance.
• For different MRS, use Table 3:

3. Socket Dimensions & Tolerances (Clause 8.2.1)

• Type A & B sockets dimensions are given in Tables 1 & 2 respectively.
• Key parameters: Nominal inside diameter ( d_n ), mean inside diameter at socket mouth ( D_1 ), at distance ( L ) ( D_2 ), ovality, reference length ( L ), minimum bore ( D_3 ).

Quick Reference: Socket Dimension Example (Type A for dn=50 mm)

This classification ensures compatibility and performance of fittings with pipes in pressure systems. For detailed dimensions, refer to Tables 1, 2, and 3 in IS 15927 Part 1 and IS 14885.

IS 15927 Part 1: Material Requirements Summary

1. Grade of Material (Clause 5.2)

• Material must meet specified Minimum Required Strength (MRS) in MPa (Clause 3.16).
• MRS defines long-term hydrostatic strength (LTHS).

2. Wall Thickness Requirements for Fittings (Clause 8.3.2)

• Fitting wall thickness E must satisfy:
  • E ≥ eMin (pipe minimum wall thickness) beyond 2L/3 from fitting entrance if same MRS.
  • If different MRS, use Table 3:

Where eₙ = pipe wall thickness.

3. Socket Dimensions & Tolerances (Clause 8.2.1)

• Type A & B sockets dimensions given in Tables 1 & 2 (mm):

Refer detailed tables for exact values per diameter.

Key Formula:

[ E \geq \begin{cases} e_{Min} & \text{if same MRS} \ 0.8 \times e_n & \text{if PE 80 pipe, PE 100 fitting} \ \frac{e_n}{0.8} & \text{if PE 100 pipe, PE 80 fitting} \end{cases} ]

Notes:

• Raw material supplier must provide material grading (Clause 5.2.3).
• All dimensions in mm.
• Ovality controls socket roundness for proper fit.

IS 15927 Part 1: Additives and Stabilizers Key Points

UV Stabilizer (Clause 6.3)

• Maximum UV stabilizer content: 0.5% by mass of finished resin.

Compound Definition (Clause 3.14)

• Compound = Base polymer (PE) + additives (anti-oxidants, pigments, UV stabilizers).
• Additives must be at necessary concentrations for application.

Polyethylene Compound Requirements (Clause 6.1)

• Only necessary additives for manufacture and fusion jointing.
• Must be free from visible water.
• Comply with Table 2 of IS 14885 for quality.
• Additives uniformly dispersed.
• No negative effect on fusibility.

Thermal Stability (Clause 9.5)

• Minimum Oxidation Induction Time (OIT) as per IS 14885.
• Hydraulic pressure test parameters:

Summary:

• UV stabilizer ≤ 0.5% mass.
• Additives must not impair fusion or quality.
• Follow thermal stability test parameters strictly for durability.

flowchart LR
    A[Base Polymer (PE)] --> B[Additives]
    B --> C[UV Stabilizers (≤0.5%)]
    B --> D[Anti-oxidants]
    B --> E[Pigments]
    C & D & E --> F[Polyethylene Compound]
    F --> G[Manufacture & Fusion Jointing]
    G --> H[Performance Tests (Thermal Stability, OIT)]

For detailed test methods, refer to Annex of IS 14885.

IS 15927 Part 1: Appearance and Surface Quality

Key Specifications

• Clause 7.2 (Appearance of Fitting):

  • Surfaces (internal & external) must be smooth, clean, and free from scoring, cavities, or defects visible without magnification.
  • Defects that affect standard conformity are not permitted.

• Clause 7.3 (Appearance of Joint):

  • After fusion jointing, surfaces must be free from melt exudation (spillage) outside the fitting boundaries.

• Clause 6.6 (Pigment Dispersion for Non-black Compounds):

  • Tested per Annex E of IS 14885.
  • Pigment dispersion grading must be ≤ 3 (indicating good uniformity).

Additional Notes

• Rounding off results must follow IS 2:1960 rules, maintaining the same number of significant digits as specified.

Summary Table: Appearance Criteria

This ensures visual and functional integrity of fittings and joints per IS 15927 Part 1.

IS 15927 Part 1: Geometrical Characteristics Summary

1. Wall Thickness Relationship (Clause 8.3.2)

• For fittings and pipes of same MRS: [ E \geq e_{Min} \quad \text{(minimum wall thickness of fitting ≥ pipe)} ]
• For different MRS materials, use Table 3:

2. Socket Dimensions & Tolerances (Clauses 8.2.1, Tables 1 & 2)

• Type A & B Sockets have specified inside diameters at socket mouth (D1) and at reference length L (D2).
• Ovality (max out-of-roundness) allowed: 0.4–1.0 mm depending on size.
• Reference length (L) and minimum bore (D3) are specified per nominal diameter.

Example for Type A Socket (DN 50 mm):

3. Appearance of Joint (Clause 7.3)

• Surfaces after fusion jointing must be free from melt spillage outside fitting confines.

Summary Diagram: Wall Thickness Relationship

flowchart LR
    Pipe[Pipe Wall Thickness \(e_n\)]
    Fitting[Fitting Wall Thickness \(E\)]
    Pipe -->|Same MRS| Fitting
    Fitting -->|\(E \geq e_{Min}\)| OK
    Pipe -->|Different MRS| Fitting
    Fitting -->|Use

IS 15927 Part 1: Performance Requirements Summary

1. Wall Thickness Relationship (Clause 8.3.2 & Table 3)

• For fittings and pipes of same MRS: [ E \geq e_{Min} \quad \text{(at distance > } \frac{2L}{3} \text{ from fitting entrance)} ]
• For different MRS:

  Pipe Material	Fitting Material	Wall Thickness Relation
  PE 80	PE 100	( E \geq 0.8 e_n )
  PE 100	PE 80	( E \geq \frac{e_n}{0.8} )

2. Socket Dimensions & Tolerances (Tables 1 & 2)

• Specifies mean inside diameters, ovality limits, reference length (L), and minimum bore (D3) for Type A & B sockets.
• Example for 50 mm socket (Type A):
  • D1 (min-max): 49.00 - 49.50 mm
  • D2 (min-max): 48.70 - 49.20 mm
  • Ovality max: 0.60 mm
  • L: 23.50 mm
  • D3: 39.00 mm

3. Hydraulic Pressure Test (Clause 9.2 & Table 4)

• Acceptance Test at 20°C:
  • Hoop stress: 10 MPa (PE 80), 12.4 MPa (PE 100)
  • Failure time ≥ 100 h
• Acceptance Test at 80°C:
  • Hoop stress: 4.6 MPa (PE 80), 5.5 MPa (PE 100)
  • Failure time ≥ 165 h
• Type Test at 80°C:
  • Hoop stress: 4 MPa (PE 80), 5 MPa (PE 100)
  • Failure time ≥ 1000 h

4. Thermal Stability (Clause 9.5)

• Minimum oxidation induction time (OIT) requirements as per IS 7328 and

IS 15927 Part 1 — Acceptance Tests Summary

1. Hydraulic Pressure Test (Clause 9.2, Table 4)

2. Hydrostatic Strength vs Failure Time (80°C) (Table 5)

3. Acceptance Test Sample Sizes (Clause 10.1, Tables 6, 7, 8)

• Visual & Dimensional Tests (Table 7):
  Sample size depends on lot size (e.g., up to 150 fittings → 13 samples, acceptance no. 0, rejection no. 2).

• Hydraulic, MFR, Thermal Stability (Table 8):
  Sample size ranges from 3 to 7 based on lot size.

4. Other Acceptance Tests (Table 6)

IS 15927 Part 1: Type Tests Summary

1. Type Tests Overview (Clause 11.1 & 11.2)

• Applied when new raw material composition, manufacturing method, or fitting size is introduced.
• Samples selected randomly; sample size = 3 for each test.

2. Key Type Tests (Table 9)

3. Hydrostatic Resistance Test Parameters (Clause 9.2, Table 4)

• Test medium: Water-in-water
• End caps orientation: Not applicable

4. Wall Thickness Relationship (Clause 8.3.2, Table 3)

Summary:

• Type tests verify material and manufacturing changes.
• **

IS 15927 Part 1 – Marking and Traceability Key Points

• Permanent & Legible Marking

  • Markings must be permanent, legible without magnification (Clause 12.2.3).
  • Methods must not cause cracks or reduce fitting performance (Clause 12.2.1).
  • Markings must withstand normal handling, storage, and installation (Clause 12.3).

• Marking Content
  Typically includes:

  • Manufacturer’s identification
  • Size and type of fitting
  • Material grade
  • Heat number or batch code for traceability

• Additional Info

  • Barcodes or QR codes can be on attached labels, not directly on the fitting (Clause 12.2.4).

Recommended Marking Methods

• Engraving or embossing (avoids stress concentrations)
• Laser marking (non-contact, no damage)
• Stamping with controlled force

Summary Table

flowchart TD
    A[Manufacturing] --> B[Marking (Engraving/Stamping)]
    B --> C[Inspection for Legibility]
    C --> D[Packaging with Barcode Label]
    D --> E[Storage & Installation]

This ensures traceability while maintaining fitting integrity per IS 15927 Part 1.

Packaging Specifications (IS 15927 Part 1)

• Clause 12.2 Packaging:
  • Fittings must be sealed in transparent polyethylene bags (minimum thickness 75 microns) to prevent deterioration.
  • Outer packaging: Suitable for stacked storage, typically cardboard boxes or cartons.
  • Markings on outer pack must include:
    • Information as per Clause 12.2 (a), (b), (c)
    • Fitting type and quantity in the pack.

Key Related Tables and Sampling Plans

Summary of Packaging Requirements

• Use 75μ transparent polyethylene bags for sealing.
• Pack in cardboard boxes/cartons suitable for stacking.
• Clearly mark packs with required info and fitting details.
• Follow sampling and testing per Tables 6, 7, and 8 for quality assurance.

flowchart TD
  A[Fittings] --> B[Seal in 75μ Polyethylene Bags]
  B --> C[Pack in Cardboard Boxes/Cartons]
  C --> D[Mark with Info & Quantity]
  D --> E[Store & Transport]

This ensures protection from environmental damage and facilitates quality control per IS 15927 Part 1.

IS 15927 Part 1: Preparation of Test Assemblies (Socket Fusion)

Key Specifications & Procedures (Clause 9.2, Annex A)

A-1 Assembly Components

• Fittings must conform to dimensions in Table 1 or Table 2 (specific to fitting type).
• Pipes must comply with IS 14885.
• For type testing: use pipe from coils for sizes ≤ 125 mm.
• For acceptance testing: straight pipes may be used.

A-2 Test Assembly Preparation

• Condition pipes and fittings at 27 ± 2℃ for at least 8 hours before fusion.
• Socket fusion steps:
  1. Insert pipe end into fitting socket (no additional material).
  2. Heat pipe end and fitting socket on heating bush and spigot to fusion temperature.
  3. Push together to create fusion pressure and a homogeneous joint.
• Only similar materials (PE with PE) can be fusion jointed.
• Ensure minimum pipe wall thickness is maintained for socket fusion.

A-3 Required Tools

• Standard pipe cutters or saws with cutting guides.
• Special socket fusion tools: heating bush and heating spigot sized to pipe and fitting.

Summary Table: Socket Fusion Preparation

flowchart TD
    A[Pipe & Fitting Selection] --> B[Condition at 27 ± 2℃ for 8h]
    B --> C[Heat pipe end on heating spigot]
    B --> D[Heat fitting socket on heating bush]
    C & D --> E[Push together to fuse]
    E --> F[Homogeneous joint formed]

This ensures reliable socket fusion joints per IS 15927 Part 1.