How is PVC Pipe Made?

Chemical Reaction

• PVC has its origins in the chemical gas referred to as vinyl chloride. When vinyl chloride is exposed to sunlight a chemical reaction occurs. The reaction is known as polymerization, which transmutes into a whitish solid material. To achieve the shape and solidity of a PVC pipe, a series of chemicals are introduced to one another. Natural gas is heated to create ethylene. The process is referred to as cracking. Later, sodium chloride (found in the form of rock salt) is spliced using electrolysis. As a result chlorine and lye (sodium hydroxide) is produced.

Molecular bonding

• Chlorine and ethylene (natural gas heated under pressure) are introduced to make vinyl chloride monomer (VCM). The molecules are bonded from each molecule's end. The result is a long chain of polyvinyl chloride polymer. In essence, plastic is created. The polymerized plastic, called thermoplastic PVC powder (which is compounded), melted and molded into piping. The result is a tube of PVC plastic. As a result of the chemical process (PVC becomes very solid and rigid), PVC is less likely to break during earthquakes. It can withstand pressures that many metals (such as copper piping) cannot tolerate. This is why PVC is the preferred material for plumbing and underground wiring.

Manufacturing

• As small as 16 mm and as large as 630 mm tubing/pipes are manufactured using a machine called an extruder. PVC plastic is routed through a double screw stem extruder (conical twin screw) or a parallel double screw extruder. Molding determines the wall thickness of the PVC hose. The diameter of the pipe is made by the PVC pipe extruder (The standard is 1/2 to 24 inches in diameter). The production speed of the standard PVC pipe extruder is about 20 meters per minute. The PVC hose runs through a vacuum pump. A ring cutting machine is employed at the end of the assembly line to divide the PVC tubing into sections of individual pipes. The individual pipes are cooled and racked. After inspection, the completed PVC pipes are sent to the warehouse for final inspection, labeling and shipping.

The Differences Between UPVC & PVC Pipes

The Differences Between UPVC & PVC Pipes

To the casual observer, there's little difference between PVC pipe and uPVC pipe. Both are plastic pipe used extensively in building. Beyond the superficial similarities, the two types of pipe are manufactured differently and thus have different properties and slightly different applications in building and other industrial processes and most repair-work exposure to plastic pipe is to PVC rather than uPVC.

Manufacture

• PVC and uPVC are largely made of the same material. Polyvinylchloride is a polymer that can be heated and molded to create very hard, strong compounds such as piping. Because of its rigid properties once it's formed, manufacturers frequently blend additional plasticizing polymers into PVC. These polymers make PVC pipe more bendable and, generally, easier to work with than if it remains unplasticized. Those plasticizing agents are left out when uPVC is manufactured---the name is short for unplasticized polyvinylchloride---which is nearly as rigid as cast iron pipe.

Handling

• For installation purposes, PVC and uPVC pipe are generally handled in the same fashion. Both can be easily cut with plastic-cutting hack saw blades or power tools designed to cut PVC pipe and both are joined using gluing compounds rather than through soldering. Because uPVC pipe doesn't contain the plasticizing polymers that make PVC slightly flexible, it must be cut perfectly to size because it doesn't allow for give.

Applications

• PVC pipe is used as a replacement for copper and aluminum piping on non-potable water, replacing metal piping in waste lines, irrigation systems and pool circulation systems. Because it resists corrosion and degradation from biological sources, it's a durable product to use in plumbing systems. It's easily cut and its joints don't require soldering, fastening with glue instead, and offers a little amount of give when pipes aren't sized perfectly, so PVC pipe is frequently chosen by handymen as an easier-to-use alternative to metal piping.
  The use of uPVC isn't quite as widespread in plumbing in America, though its durability has helped it to become the material of choice for plumbing sewage lines, replacing cast-iron pipe. It's also frequently used in manufacturing exterior drainage systems such as rain gutter downspouts.
  The only type of plastic pipe that should be used for transmission of drinking water is cPVC pipe.