unplasticized polyvinyl chloride (PVC-U)screen and casing pipes for bore/tubewell
2010 Edition

IS 12818 defines the dimensions for PVC-U screen and casing pipes used in bore and tubewell applications, covering nominal diameters from 35 mm up to 400 mm. The standard specifies outer diameter, wall thickness, and pipe lengths with typical tolerances of ±1.5% for diameter, ±10% for wall thickness, and length variations generally around ±0.02 m from 3.0 m nominal length. These controls ensure proper fit and functionality in well installations, with ribbed and plain pipe variations designed to meet strength and hydraulic requirements.

IS 12818 encompasses several types of screen pipes including ribbed screen pipes with external longitudinal ribs and transverse slots, designated as RMS (Ribbed Medium Screen) and RDS (Ribbed Deep Screen), and plain screen pipes identified as PMS (Plain Medium Screen) and PDS (Plain Deep Screen). Additionally, casing pipes are classified as CS, CM, or CD. The designation format typically follows: {Type} - DN {Nominal Size} - Slot Width - Length, for example, RMS DN100 1.0mm 6m, facilitating clear identification of pipe type, size, slot opening, and length.

For nominal sizes between 40 mm and 80 mm, threading must adhere to IS 554 standard pipe threads. Pipes with nominal diameters from 100 mm to 400 mm should feature metric trapezoidal threads as outlined in Clauses 8.3.1 and 8.3.2, with detailed dimensions provided in Tables 11 and 12 and illustrated in Figures 3 and 4 of the standard. Larger pipes from 250 mm to 400 mm utilize thread profiles specified in Table 12 and Figure 4A. This threading approach ensures mechanical strength and reliable sealing for borewell pipe connections.

IS 12818 mandates that PVC-U pipes must not adversely alter the water quality passing through them. Compliance is ensured by adhering to IS 4985 Clause 10.3, which sets limits on chemical composition changes, and by conducting tests as per IS 12235 Part 4 to verify that pipe materials do not leach harmful substances. Additionally, the standard requires pipe materials to meet density criteria (1.40 to 1.46 g/cm³) to maintain quality and prevent contamination. These combined requirements guarantee safety for potable water and groundwater extraction.

Mechanical testing under IS 12818 includes tensile strength evaluation performed according to IS 12235 Part 13, where specimens are cut from the pipe, heated, flattened, and machined. The average tensile strength must be at least 45 MPa from two test samples. Visual inspections check for smoothness, absence of defects, and proper pipe end finishes. Type testing is required when changes occur in pipe composition or manufacturing processes, encompassing tests for tensile strength, physical appearance, and water quality impact, ensuring pipes meet durability and performance standards.