PVC piping is commonly employed in the chemical industry.

PVC has excellent chemical resistance to wide range of corrosive fluids.

UV resistance of PVC piping

PVC piping undergoes surface oxidation and embrittlement by exposure to sunlight over a period of time. The color of pipe changes from gray to white. The strength of piping is not reduced, however it becomes more susceptible to impact damage. UV protection can be provided by applying a thick coating of latex paint.

Heat tracing of PVC pipe

PVC piping
PVC PIPING

It is possible to heat trace PVC piping to maintain a constant elevated temperature. Electric tracing is recommended. The maximum heat trace temperature should not exceed the pressure temperature rating of the piping system.

Pipe supports

Pipe saddle cut from PVC pipe are recommended at support locations. PVC pipe must not rest directly on steel. Supports must be provided on or close to inline items such as valves. PVC piping connected to vibrating equipment's such as pumps must be isolated using teflon or rubber expansion joints.

Joining Methods

  • Solvent Welded Joints
  • Flanged Joints
  • Threaded Joints

Solvent cementing is a preferred method of joining PVC pipe and fittings. The OD of the pipe and ID of fitting are primed, coated with special cement and joined together. Most solvent cement joints fail due to lack of solvent penetration or inadequate primer application.

Applicable Standards

  • ASTM D1785  -   Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120
  • ASTM D2241  -   Standard Specification for Poly(Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)
  • ASTM D2665  -   Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings
  • ASTM D2672  -   Standard Specification for Joints for IPS PVC Pipe Using Solvent Cement
  • ASTM D2729  -   Standard Specification for Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings
  • ASTM D2464  -   Standard Specification for Threaded Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80
  • ASTM D2466  -   Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40

PVC vs Carbon Steel

Property Unit Carbon Steel PVC
Density kg/m³ 7860 1550
Coeff of Thermal Expansion in/in °F x 105 0.06 3
Thermal Conductivity BTU/hr/ft2/°F/in 290 1.2
Modulus of Elasticity @ 73°F psi x 105 290 4.2
Tensile Strength psi 60,000 7,940
Working Stress @ 73°F psi 20,000 2,000