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Plastic Pipe
Plastic pipes are hollow cylinders that are used to convey fluids or gases or as structural components. Very similar to plastic tubing, the main difference is that plastic pipe is typically measured by the internal diameter (ID) and plastic tubing is typically measured by the outer diameter (OD). In addition, plastic tubing is manufactured in a wider variety of custom sizes as well as having more specific tolerances and sizes than plastic pipes. However, plastic piping does offer a variety in terms of materials, including PVC, fibre reinforced plastic, reinforced polymer mortar, polypropylene, polyethylene, polybutylene, TIPS and ABS. Each material has their own advantages; for instance, only rigid chlorinated PVC and flexible polybutylene can withstand hot water under pressure. Plastic pipes have a broad range of beneficial characteristics such as corrosion resistant, durable, low maintenance, lightweight, chemical resistant, low thermal conductivity, non-toxicity as well as offering a variety of joining methods. Plastic pipes serve a wide range of applications: plastic water pipes are used for hot and cold water distribution and fire sprinkler piping; corrugated plastic pipe is used for irrigation and plumbing; and plastic drain pipes are used for drainage and can be used in underground applications. Industries that benefit from plastic piping include waste water, agricultural, residential, industrial, petrochemical, power, aerospace, marine and brewery. Plastic pipes are made through the profile extrusion process. The plastic resin pellets, also called nurdles, are fed into the extruding machine’s hopper, which is a funnel-shaped receptacle through which contents pass by gravity into a receptacle below. The receptacle contains a screw conveyor, which by rotating its screw, serves to continuously convey the plastic pellets forward. In addition, the receptacle is heated and the plastic pellets are being softened by both heat and friction as they are conveyed forward. By the time the plastic pellets comes to the end of the screw conveyor, the plastic pellets have become “plasticized”, or made completely molten. On the end of the conveyor channel a die orifice is secured which forms the molten plastic into a specific profile as it is pushed, or "extruded" through by the screw conveyor. In order to form plastic piping, a pin or mandrel must be placed inside of the die and a positive pressure is applied to the internal cavities through the pin. This creates the hollow inside of the pipe. The newly formed plastic pipe is instantly cooled with cold water where it solidifies. Lastly, the plastic pipe is conveyed onwards to take-off rollers, which actually pull the softened plastic from the die, to by a series of conveyors and is then cut to length. In addition, there are several different types of plastic pipes: plated, which used nickel or chrome platings on plastic pipes for additional corrosion resistance or improved appearance; flanged, which are closed at one or both ends with a flange for connectivity; lined, manufactured with an integral lining; and insulated, which includes insulating materials and a jacket construction.
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