In recent decades, the construction and plumbing industries have been using hard or rigid plastic tubes and pipes for water supply and waste-management systems. The material used is hard, tough PVC and this is seen as easier to work with than the old-fashioned metal or molded concrete pipes that were used in earlier days.
Advantages: Hard plastic tubing is lightweight, tough and resistant to a great number of internal and external damage. It can withstand corrosion and pitting. Because of its light weight, it reduces transport costs, handling charges, installation etc. They can also withstand damage by accidental knocking, which is a problem with conventional cast-iron pipes. Lengths of plastic pipe can be cut in larger sections thus reducing the number of joints. Plastic is resistant to rust, fungus and mold, thus making it better for transporting water in a more hygienic way, thus providing better health benefits. Another benefit that has been noticed in hard plastic tubes is that they are able to stay flexible enough to conform to earth movements. This is a good quality to have in seismic zones. Plastic, being an inert and stable compound, can resist action by many chemicals. It is also very cost-effective as compared to traditional plumbing pipes which were made of cast-iron, GI etc. Since plastic is material with a smooth surface, it offers less resistance to flow. Hence there is greater efficiency in transportation of liquids across large distances. Since plastic pipes resist corrosion and pitting, the losses due to wastage are reduced, thus providing great cost-savings benefits. Installation of plastic pipes is relatively easier and does not require special skills.
The disadvantages of using hard plastic tubing are that since plastic cannot withstand very high temperatures, its use in hot-water or liquid systems are limited, unless it is specially treated with an inner liner of heat-resistant compounds. The strength and durability of plastic may reduce with exposure to high temperature. Cracking and splitting are common features of hard plastic pipes. This is because plastic is quite brittle in its hard form. Leaks and wastage may be common. In such situations, the entire length of pipe may have to be replaced, as joints may not be desirable in the long run. Cracks and splits are common in very cold and frozen environments. It must not be installed near any source of radiant heat or open furnaces, since it cannot withstand very high temperature either. Exposure to UV rays can cause chemical changes in plastic, hence plastic pipes are not suitable for outdoor applications. Another issue that residents of apartment complexes report is that water and waste flowing through hard plastic pipes results in a great deal of noise and disturbance.
The appropriate use of rigid plastic tubes, keeping in mind their advantages and disadvantages, can result in greater cost-savings, efficiency and environmental benefits.