All you need to know about design practices for PVC Piping

PVC piping is one of the most versatile, lightweight and blockage resistant types of plastic piping. PVC pipes have been in use for many years, serving a wide range of applications in several market sectors. These pipes are exceptionally robust and highly durable with corrosion resistance properties. Economical, high mechanical strength polyvinyl chloride (PVC) is used for both hot and cold water distribution applications depending on the variant type.


PVC Pipes Applications


PVC pipes are most widely used in plumbing from drainage pipes to water mains, irrigation & manufacturing of sewage pipes. PVC pipes last long with minimal maintenance and are easily recyclable. Cost-efficient and sustainable PVC pipes are durable, lightweight, flexible and easy to install. The PVC pipes provide smooth wall surfaces that lessen friction and encourage faster water flow than metallic or concrete piping. Other applications include:

  • Fire Sprinkler Piping
  • Swimming Pool Piping
  • Radiant Floor Heating
  • Ice Melting System
  • Chilled Water Systems

How to design a successful PVC Piping System?


When designing any piping system, consider the generally accepted engineering practices as follows:

  • Select appropriate material for the piping application
  • Control pressure surges and velocities
  • Determine codes and standards for piping components
  • Consider proper sizing of pipes, valves and fittings
  • Choose proper pipe supports, anchors and guides
  • Proper underground design considerations
  • Follow all applicable industry codes and standards

PVC Piping Design Practices


PVC pipes have many unique engineering properties compared to non-plastic materials. The piping engineer should be aware of different attributes to ensure an effective and long-lasting piping installation.

Chemical Resistance


Specific chemical environments that affect PVC properties are as follows:
  • In a chemical attack, a reaction attacks the molecular chain of the polymer.
  • Solvation process absorbs organic solvent by PVC
  • When a liquid, organic material reacts with PVC but fails to dissolve, it is known as plasticization.

Pipe and System Pressure Ratings


The PVC pressure ratings are identified using ASTM and PPI standards and requirements. Following ISO equation is used to calculate pipe pressure ratings:
PR = 2 (HDS) x t/ Dm
where: PR= Pressure rating, psi (Mpa) t = Minimum wall thickness, in. (mm) Dm = Mean diameter, in. (mm) HDS = Hydrostatic design stress, psi (Mpa)


Fittings


Molded Schedule 40 and 80 pressure ratings fittings are affected by the part size, wall thickness, part geometry, molding conditions, part design and material.

Temperature and Pressure Ratings


Thermoplastic piping materials increase in tensile strength property as temperatures decrease, and vice versa. This characteristic must be carefully considered when designing piping systems with PVC material.

Operating Pressure of Valves, Unions, and Flanges


PVC piping system materials have a 150-psi maximum pressure capability for valves, unions, and flanges. Due to the mechanical connections involved (threads in valves and partnerships) and the nature of flat gaskets under pressure (flanges).

Conclusion


If you’re looking for high-quality piping design services, consider hiring an engineering company that provides the best-in-class piping layout design services using the latest software and ASME codes & standards.