Pipes, Fittings, Joints and Plumbing Materials
Material families
- GI (galvanised iron), IS 1239, screwed BSP joints: water supply above ground; strong, but scales and corrodes.
- uPVC, IS 4985, solvent-cement joints: cold water supply and SWR drainage. SWR is a grade, not a separate material.
- CPVC: hot and cold water up to about 80 °C. Do not confuse it with uPVC, which softens near 60 °C.
- HDPE/MDPE: buried service lines, joined by compression fittings, butt fusion or electrofusion; flexible and tolerant of ground movement.
- Copper: hot water and medical gas; capillary soldered with lead-free solder and flux, or press-fit.
- CI/ductile iron: soil, waste, sewer and storm water; rubber-ring or flanged joints.
- PPR: hot water, heat-fused with a welding machine.
Fittings and joints
Sockets, elbows (90° and 45°), tees, reducers, unions (fitted where future dismantling is needed), nipples, caps, plugs, bends, crosses, street elbows, ferrules. Joint types: threaded, solvent welded, compression, flanged, soldered, fusion, push-fit, rubber ring.
Worked example. Specify pipe and joint for a hot water line from geyser to shower. uPVC is excluded because service temperature reaches 60–70 °C. Choose CPVC (or copper) with solvent-welded CPVC joints and a union at the geyser outlet for servicing. Reasoning: temperature rating decides the material; the joint method then follows the material.
Rules worth memorising
Never join GI directly to copper without a dielectric union - the galvanic couple corrodes the copper. Solvent cement: primer first, cement on both surfaces, push fully and quarter-turn, hold 30 seconds, full cure before pressure testing. Thread sealant: PTFE tape wound clockwise 3–4 turns, or jointing compound on the male thread only.
Traps that cost marks
Using PVC cement on CPVC or ABS; skipping primer; mixing pressure classes in one run; expecting a solvent weld to hold on a wet pipe.