--- title: "Pipe material selection factors; PPR pipes" subject: "Water Supply Engineering" chapter: 8 key: "semester_5/water_supply_engineering:pipe-material-factors-ppr" source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/pipe-material-factors-ppr site: BCT Engineering --- # Pipe material selection factors; PPR pipes Water Supply Engineering · Chapter 8: Conveyance of Water - Asked in: 2079 Bhadra, 1+3 marks - Video: [TYPES OF PIPES USED FOR CONVEYANCE | VALVES | Environmental Engg | Public Health Engg.](https://www.youtube.com/watch?v=TH1ZZF22N-8) — SIMPLIFIED CIVIL AND GEOTECHNICAL ENGINEERING - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/pipe-material-factors-ppr - Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-8 ## Question Describe the factors that should be considered while selecting pipe materials. What are the advantages and disadvantages of PPR pipes? ## Short answer Factors: working pressure, corrosion potential, friction, cost, weight, joint ease, availability, and life. PPR advantages: light, smooth, corrosion-free, heat-fusion joints, handles 70–95°C, long life, non-toxic. Disadvantages: costly, needs fusion tools, expands with heat, UV damage. ## Answer #### Factors for selecting a pipe material 1. Working pressure, surge pressure and external load. 2. Water quality and soil conditions (corrosion, chemical attack). 3. Diameter, flow capacity and friction (smoothness). 4. Cost of material, transport, laying and maintenance. 5. Availability, size range and standard of the material. 6. Ease of laying, jointing, tapping and repair. 7. Terrain (hilly, rocky, landslide), exposed or buried line. 8. Life of the pipe and weight for handling. #### Polypropylene random copolymer (PPR) pipes **Advantages** - Resists corrosion and scale; smooth interior (little head loss). - Lightweight and easy to install; joined by heat fusion to make a leak-free, homogeneous joint. - Carries hot and cold water (up to 70–95 °C), withstands high pressure, and has a long life (about 50 years). - Non-toxic, hygienic, no taste or odour; good insulation against heat loss and sweating. **Disadvantages** - More costly than PVC or GI; needs special fusion machine and trained workers. - Expands a lot with temperature, so loops or supports are needed. - Damaged by UV light if left exposed; cannot be threaded; less suitable for large diameters. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why must working AND surge pressure be considered when selecting a pipe material? A. To decide the colour of the pipe B. To decide the strength/class the pipe must have C. To decide the number of taps D. To decide the laying depth only Answer: B. Working and surge pressures set the strength and class of pipe needed. (Key point: Pressure factor) 2. Which condition makes a light, easily handled pipe especially attractive? A. Pipe buried in a wide trench B. Very low-pressure lines only C. Hilly, rocky or landslide terrain where carrying is hard D. Flat urban area with machinery Answer: C. In hilly or rocky terrain transport and handling are difficult, so weight and ease of laying matter. (Key point: Terrain) 3. How are PPR pipes joined, and what is the benefit? A. Solvent cement; cheap B. Heat fusion; leak-free homogeneous joint C. Lead and yarn; flexible joint D. Threaded sockets; easy to dismantle Answer: B. Heat fusion welds pipe and fitting into one homogeneous, leak-free joint. (Key point: PPR jointing) 4. Why are loops or supports needed with PPR pipes? A. It is too heavy B. It is weak against corrosion C. It expands a lot with temperature D. It is attacked by scale Answer: C. PPR has high thermal expansion, so loops/supports absorb the movement. 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