Plastic Pipes

A pipe is a tube or hollow cylinder used to convey materials or as a structural component. The terms pipe and tube are almost interchangeable. A pipe is generally specified by the internal diameter whereas a tube is usually defined by the outside diameter but may be specified by any combination of dimensions. A tube is often made to custom sizes and may often have more specific sizes and tolerances than pipe. Also, the term tubing can be applied to non-cylindrical shapes. The term tube is more widely used in the United States, whereas pipe is more common elsewhere in the world.

There are three processes for metallic pipe manufacture. Seamless pipe is formed by drawing a solid billet over a piercing rod to create the hollow shell. Seamless pipe provides the most reliable pressure retaining characteristics, and is often more easily available than welded pipe. Welded pipe is formed by rolling plate and welding the seam. The weld flash can be removed from the outside or inside surfaces using a scarfing blade. The weld zone can also be heat treated, so the seam is less visible. Welded pipe often has tighter dimensional tolerances than seamless, and can be cheaper if manufactured in the same quantities. Cast pipe is no longer very common, but still exists. Pipe is sometimes cast in a centrifuge. Tubing, either metal or plastic, is generally extruded.

The manufacturing of pipe uses many materials including ceramic, metal, concrete, and plastic. Pipe may be made from a variety of materials. In the past, materials have included wood and lead. Metal pipes are commonly made from unfinished, black, or galvanized steel, brass, and ductile iron. Copper tubing is popular for plumbing systems. Manufacturers of PCCP and BWP can offer a wide range of steel fittings such as elbows, tees, and branch wyes to complement the straight lengths of pipe. Special adapter fittings can also be designed and built to facilitate connections between the concrete pressure pipe and other pipe types.

Pipes are commonly joined by welding or by using pipe threads. The most common pipe thread in North America is the National Pipe Thread or the Dryseal version. Other pipe threads include the British standard pipe thread, the garden hose thread, and the fire hose coupling. Copper pipes are typically joined by soldering, brazing, compression fittings, flaring, or crimping. Plastic pipes may be joined by solvent welding, heat fusion, or elastomeric sealing. If frequent disconnection will be required, gasketed pipe flanges or union fittings provide better reliability than threads. Some thin-walled pipes of ductile material, such as the smaller copper or flexible plastic water pipes found in homes for ice makers and humidifiers, for example, may be joined with compression fittings.