WHAT IS PVC PIPE?

PVC or polyvinyl chloride is one of the worlds most popular materials for plumbing and piping systems. Over 22.8 Million tons of PVC were used in 2018 for piping with consumption projected to grow every year¹. Plastic PVC piping is also more environmentally sustainable than many other piping materials including steel. Due to PVC’s low weight and low carbon plastic it requires less resources to make, transport and install. Underground distribution pipes made from PVC also leak less and require less maintenance than steel or concrete piping. This saves money, water, energy and costly repairs².

Many diverse industries use PVC piping including: residential, commercial and industrial construction, irrigation, wastewater and manufacturing. These industries love using PVC piping because of its low cost, ease of installation and corrosion resistance. PVC fittings and valves are suitable for transporting a variety of liquids such as fresh water, wastewater and corrosive liquids.

CLASSES OF PVC PIPES

Industry standards group PVC pipe by wall thicknesses or schedules (Sch). Schedule controls the outside diameter of PVC pipe and fittings and the wall thickness. The most common schedules are Sch 40, Sch 80, and Sch 120. Sch 40 has a thinner wall and is the most commonly available. Sch 120 has a very thick wall and used in only select applications.

• Schedule 40 PVC  fittings and pipe are suitable for low pressure and low temperature applications. Typically white or tan in color Sch 40 piping assembles using solvent welding and to a limited extent, threaded connections. A variety of applications including: residential construction, irrigation, hot tubs, residential pools and furniture building use Sch 40 PVC piping.
  
  
• Schedule 80 PVC  fittings and pipe have a thicker wall than Sch 40. It is more robust and can handle higher pressures and temperatures. Commercial and industrial applications mainly use Sch 80 piping. Industries that use Sch 80 include: Wastewater treatment, mining, chemical processing, commercial pools, manufacturing and petrochemical processing.
  
  
• Schedule 120 is only available as pipe and no Sch 80 PVC fittings exist. Most piping systems do not use Sch 120 as it is more costly than sch 80 and the higher pressure . Because of this only very high pressure applications and products manufactured from pipes may use Sch 120 pipe.

PROPERTIES OF PVC PIPING

The maximum safe operating temperature of PVC fittings and valves should not exceed 60° C (140° f). CPVC pipe handles higher temperature for applications with liquids hotter than 60° C (140° f). The maximum safe operating pressure of PVC piping depends on the schedule, diameter and temperature.

CPVC or chlorinated polyvinyl chloride is a high temperature version of PVC piping that provides increased temperature. CPVC is capable of handling temperatures up to 93° C (200° f). In Addition, CPVC has increased resistance to some chemicals, especially acids.

PVC and CPVC pipe and fittings join together using solvent welding, threaded connections or flanged connections. Solvent welding first uses a solvent to soften and clean the PVC material. PVC cement then chemically joins the pipe and fittings together to create a strong permanent bond. Threaded fittings used in North America use a standard known as National Pipe Thread (NPT) standard. Europe and Asia use different thread standards so they are not compatible with NPT threads. NPT threads for a strong connection but is not water tight. Pipe sealant tape or pipe sealant compound know as pipe dope creates a water tight seal. Large pipe diameters and industrial applications use flanged connections for mating to process equipment like pumps and tanks. Flanged connections require a flange gasket and a bolt set to make a strong, water tight connection. 

¹ Global PVC Pipes Market Trends and Forecasts, 2011-2018 & 2019-2024

² Water Main Break Rates In the USA and Canada: A comprehensive study