injection moulded PVC socket fittings with solvent cement joints for water supplies, Part 1: General requirements
1987 Edition

Overview of Scope:

• Applicable to socket fittings designed for plastic pipes in water supply.
• Manufacturers must supply test documentation upon request (Clause 2.2.5).
• Defines socket dimensions, tolerance levels, and sampling schemes for quality assurance.

Important Formulas for Socket Dimensions: Given:

• ( D ): Diameter at socket length midpoint
• ( L ): Socket length
• ( \alpha ): Total included taper angle

Calculate:

• Mouth diameter, ( D_i = D - L \tan(\alpha/2) )
• Root diameter, ( D_r = D + L \tan(\alpha/2) )

Tolerance for Diameter and Roundness:

• Out-of-roundness limited to the lesser of (0.007 \times D) or 0.2 mm.

Sampling and Acceptance (Excerpt):

This section ensures dimensional precision and quality control critical for leak-proof, reliable joints.

Material Requirements and Testing:

• Fittings must be primarily manufactured from polyvinyl chloride (PVC).
• Additives are only allowed if they aid manufacture, improve strength and opacity, and do not pose toxic risks or impair fabrication and performance.
• Surface area for extraction tests should be at least 200 cm².
• Manufacturers to provide test results on demand (Clause 2.2.5).

Socket Dimension Parameters:

Dimensional Calculations: [ D_i = D - L \tan(\frac{\alpha}{2}), \quad D_r = D + L \tan(\frac{\alpha}{2}) ]

((D): Diameter at socket midpoint, (L): Socket length, (\alpha): Included taper angle)

Note: Precision tooling is recommended to maintain tight dimensional tolerances.

Socket Length Formula: [ L = 0.5D + 6 \text{ mm (minimum 12 mm)} ] where

• (L) is the socket length
• (D) is the nominal inside diameter

Socket Diameter Taper: [ D_i = D - L \tan(\theta/2), \quad D_o = D + L \tan(\theta/2) ]

• For pipes 16 to 75 mm, taper angle max is 0°40'.
• For pipes ≥ 90 mm, taper angle max is 0°30'.

Internal Diameter Limits at Midpoint:

This section details critical sizing to ensure proper fit and joint integrity.

Thickness and Socket Length Requirements:

• Minimum socket length (L) calculated as (0.5D + 6) mm, with a minimum of 12 mm.
• Wall thickness and taper control ensure mechanical strength and leak resistance.

Diameter Tapering Formula: [ D_i = D - L \tan(\theta/2), \quad D_r = D + L \tan(\theta/2) ]

Dimensional Table Highlights:

Notes:

• Mean inside diameter is average of two perpendicular diameters at socket midpoint.
• Taper angles ensure correct socket engagement without excessive interference.
• Minimum length ensures joint durability.
• Stress relief testing confirms absence of defects like cracking or blistering.

Key Parameters:

• Socket length (L) is computed as (0.5D + 6) mm, minimum 12 mm.
• Mean internal diameter at socket midpoint is average of two perpendicular measurements.
• Taper angle limits are 0°40' for 16–75 mm and 0°30' for ≥90 mm pipes.

Diameter Calculation: [ D_i = D - L \tan(\alpha/2), \quad D_a = D + L \tan(\alpha/2) ]

Dimensional Ranges:

Out-of-roundness Limit: [ \max = \min(0.007D, 0.2 \text{ mm}) ]

These controls maintain dimensional precision necessary for functional joints.

Out-of-Roundness Measurement:

• Maximum deviation between max and min internal diameters limited to less than or equal to 0.007 × nominal diameter or 0.2 mm, whichever is smaller.

Water Quality Impact Limits:

Testing Obligations:

• Manufacturers must provide test reports when requested.
• Defined number of tests and acceptance levels ensure conformity.

This section provides a summary flow of testing steps ensuring fittings meet physical and safety standards.

Hydraulic Pressure Test:

• Apply internal pressure at 4.2 ± 0.2 times the normal operating pressure for a minimum of 1 hour.
• Fittings must be tested in combination with a 250 mm pipe section bonded by solvent cement.

Sampling and Acceptance:

Reporting:

• Test outcomes must be documented and provided to the purchaser on demand.

This ensures fittings fulfill strength and leak-tightness criteria before distribution.

Marking Requirements:

• Markings must be placed in locations visible post-installation.
• Mandatory marking includes manufacturer's identification.
• Optional BIS Standard Mark may be applied if conformity is met.

Typical Marking Includes:

This ensures traceability and compliance verification.

Purpose and Procedure:

• Detects defects such as blisters, cracking, delamination, or weldline splitting under thermal stress.
• Three specimens are tested, suspended or freely positioned to avoid external constraints.
• Test mediums include air ovens or baths with polyethylene glycol, glycerol, or mineral oil without aromatic hydrocarbons.

Acceptance:

• No visible failures allowed; weldline prominence alone is not considered a failure.

This test verifies thermal stability and structural integrity of fittings.

Test Setup:

• Equipment: Electric light source, photoelectric cell, and spot light galvanometer.
• Procedure: Measure galvanometer deflection without and with the fitting wall.
• Calculate opacity as percentage light transmitted: ( (D_2 / D_1) \times 100% ).

Acceptance Criterion:

• Maximum 0.2% light transmission allowed; opacity must be at least 99.8%.

This test confirms the fitting walls are sufficiently opaque to meet standards.

Limits for Toxic Substances Extracted:

Test Procedure:

• Specimens with minimum combined surface area of 200 cm² are pre-soaked in running tap water for 6 hours.
• Rinsed with distilled water before conducting multiple extractions.
• Concentrations calculated using ( C = \frac{e \times S_2}{S_1 \times V} ).

This safeguards against contamination of potable water by limiting toxic leachates.

Testing Parameters:

• Pressure applied: 4.2 ± 0.2 times the normal working pressure.
• Duration: Continuous for 1 hour.
• Test setup: One end of specimen connected to pressure source; other ends sealed.

Acceptance:

• No leakage, deformation, or failure allowed during and after the test.

This test verifies the fitting’s capacity to withstand elevated hydraulic pressures safely.