Structured-Wall Plastics Piping Systems for Non-Pressure Drainage and Sewerage - Specification, Part 1: Pipes and Fittings with Smooth External Surface, Type A
2013 Edition

According to IS 16098 Part 1, pipes must contain at least 80% PVC-U by mass (equivalent to a minimum chlorine content of 45.6%). Injection moulded fittings require a minimum of 85% PVC-U (chlorine content at least 48.4%). For foam core pipes, PVC-U content may be lower in intermediate and other layers if replaced by calcium carbonate that meets strict purity and physical property conditions: intermediate layers must have at least 60% PVC-U and 34.2% chlorine content, while other layers require at least 75% PVC-U and 42.7% chlorine content. Only additives essential for manufacturing are permitted to ensure compliance with material performance criteria.

IS 16098 Part 1 specifies two primary jointing methods for structured-wall PVC-U pipes ranging from 110 mm to 1200 mm diameter: elastomeric sealing ring joints, where pipes feature integral sockets with rubber rings for flexible, watertight push-fit connections; and solvent cement welded joints, which employ chemical bonding using solvent cement according to standard dimensions. Additionally, laying and jointing guidelines reference IS 7634 (Part 3): 2003, supplemented by extra requirements in the standard’s Annex B, ensuring secure and leak-resistant assemblies for underground drainage systems.

Ring stiffness and flexibility tests per IS 16098 Part 1 involve preparing pipe ring samples approximately 300 ±10 mm in length. The pipe ring undergoes diametric deflection at a controlled speed up to 30% of the mean diameter or until failure. Force and deflection data are recorded continuously. Acceptance requires no reduction in force during deformation, absence of cracking, rupture, permanent buckling, or wall delamination (except permitted delamination in double-wall pipes at weld zones). Ring stiffness is calculated from measured forces at 3% deflection, averaged across test points, with stiffness classes defined from SN 2 to SN 16. Impact tests involve dropping weights from specified heights depending on pipe diameter to assess impact resistance.

The standard specifies dimensional tolerances for PVC-U structured-wall pipes and fittings with nominal outside diameters between 110 mm and 1200 mm. Key parameters include nominal outside diameter (dn), nominal inside diameter (di), outside diameter at any point (de), maximum and minimum mean outside diameters (dem, Max and dem, Min), socket inside diameter (ds), wall thickness at various points (e, em, max, min), minimum spigot length (L1, Min), and fitting design lengths (Z2, Z3). Tolerances ensure interchangeability and joint integrity, typically allowing deviations within ±1–2% of nominal dimensions. Socket dimensions are tightly controlled to maintain proper fit and sealing capability. Precise values and limits are detailed in Clause 6.3 tables.

IS 16098 Part 1 mandates impact resistance testing for pipes and fittings at low temperatures (0°C). Pipes are tested according to IS 12235 (Part 9), ensuring a true impact failure rate of no more than 10%. For socketed pipes, impact testing is performed on the plain pipe portion at least 100 mm from the socket root. Fittings are conditioned at 0 ±1°C for 30 minutes, then subjected to free fall drops from a height of 1 meter onto flat concrete. Five fittings are tested initially; if none show damage (splits or breaks), the batch passes. If one fitting fails, an additional five fittings are tested; zero damage among these confirms acceptance. Minor surface scratches or edge chips are not considered failures. This ensures reliable mechanical durability under cold impact conditions.