Figure 3-25. - Plastic pipe fittings.

Then give the pipe a strong push, so the spigot locks into the hub seal. A solution of liquid soap may be spread on the joint to help it slip into place easily. You will find that other types of mechanical seal joints are also available. They all use about the same method of installation. Special mechanical seal adapters are made to join vitrified clay pipe with CISP or CISP to vitrified clay pipe.

Plastic Pipe

At first, plastic was used for lawn sprinklers, farm water systems, and acid drainage from mines. Now plastic pipe is used for all kinds of applications, from shipboard installations to municipal water treatment and domestic water uses.

The advantages of plastic pipe (PVC-Polyvinylchloride) include resistance to nearly all acids, caustics, salt solutions, and other corrosive liquids. It does not scale, pit, corrode, or rust. Bacteria does not grow well, and it is also nontoxic. Plastic pipe has very low-friction resistance because of its smooth, inner surface. Being nonconductive, it is not subject to electrolytic corrosion. Plastic pipe can be used underground in acid, alkaline, wet, or dry soil without a protective coating. It is strong and can handle operating pressures in most moderate service processes within the temperature range of that particular material. Plastic pipe is light in comparison to metal. Finally, it can be easily joined in a wide variety of methods. Each method has a certain advantage.

HANDLING AND STORING OF PLASTIC PIPE.-When unloading plastic pipe, do not drop it on the ground. Remember, scratches and gouges from dragging it on rough surfaces tend to reduce the pressure-carrying capacity. Pipe should be stored on racks to prevent sagging. Burrs and sharp edges on storage racks should be removed before storing the pipe. Plastic pipe should be stored in a shaded area away from any source of heat that could cause damage to the pipe. During prolonged storage, it should not be stacked more than 2 feet high because the weight causes it to flatten or go out of round. Before installing plastic pipe, inspect all pipe and fittings for cuts, scratches, buckling, and kinks that should be cut out. 3-16