Injection Moulded/Machined High-Density Polyethylene (HDPE) Fittings for Potable Water Supplies, Part 8: Specific Requirements for Reducing Tees
2003 Edition

IS 8008 Part 8 (2003) defines the requirements for HDPE reducing tees manufactured through injection moulding or machining for potable water systems. The fittings must be made from High-Density Polyethylene suitable for safe drinking water applications, adhering to relevant health standards. While exact grade details such as density or melt flow index are not explicitly provided here, they typically conform to IS 7328 or similar HDPE grades approved for potable water pipes. Dimensional requirements and tolerances are specified to ensure fit and function, with length tolerances of ±2 mm, ±1 mm, and welding length tolerance of ±3 mm.

The standard prescribes allowable tolerances for injection moulded and machined HDPE reducing tees used in potable water supplies, covering overall lengths, diameters, wall thickness, and angular deviations. Typical tolerances include outside diameter variations of ±1% to ±2%, lengths with ±2 mm to ±5 mm deviations, wall thickness with a minimum reduction of 5%, and a branch-to-main angle tolerance between ±2° to ±5°. These tolerances ensure proper fitting and joint integrity for potable water distribution systems.

For HDPE reducing tees as per IS 8008 Part 8 (2003), sizes ranging from 20 mm to 315 mm are primarily produced by injection moulding, with machining permitted for finishing or tolerance adjustments. Larger sizes starting from 355 mm and above are manufactured solely by machining, using thick-walled extruded pipes or compression moulded slabs as starting material. This approach ensures dimensional precision and material integrity across different fitting sizes.

The standard guarantees compatibility by specifying that reducing tees must be suitable for fusion welding connections to HDPE pipes manufactured according to IS 4984:1995. It aligns the material characteristics and dimensional parameters of the fittings with those of IS 4984 pipes, including diameter, Standard Dimension Ratio (SDR), and material grade. This ensures that the reducing tees integrate seamlessly with the pipeline system, maintaining mechanical strength and leak-proof joints in potable water networks.

Each reducing tee must be distinctly marked with the manufacturer's identification, fitting size, material grade, and the applicable pressure class. Additionally, the fittings may bear the BIS Standard Mark, which is regulated under the Bureau of Indian Standards Act, 1986. Use of the BIS mark requires manufacturers to obtain a license from BIS, ensuring compliance with quality and standardization norms. Markings must be clear and legible, facilitating traceability and quality assurance.