Overview
Polyvinyl Chloride (PVC) is one of the most produced and versatile thermoplastics, formed by polymerizing vinyl chloride monomer (VCM). Adding plasticizers produces flexible PVC; without plasticizers it is rigid PVC (uPVC), the dominant material for drainage pipe, water supply pipe, electrical conduit, window frames, and siding. PVC is inherently flame-resistant (chlorine content), strong, and low-cost.
Mechanical Properties (Rigid PVC, uPVC)
| Property | Value |
|---|---|
| Density | 1,380-1,430 kg/m³ (1.4 g/cm³) |
| Tensile Strength (ultimate) | 40-55 MPa (6,000-8,000 psi) |
| Young's Modulus | 2,500-4,000 MPa (2.5-4.0 GPa) |
| Flexural Strength | 70-100 MPa |
| Compressive Strength | 60-80 MPa |
| Elongation at Break | 10-50% (rigid, brittle compared to HDPE) |
| Hardness (Shore D) | 75-85 |
| Impact Strength (notched Izod) | 20-60 J/m (lower than HDPE) |
| Coefficient of Friction | 0.3-0.4 |
Thermal Properties
| Property | Value (Rigid PVC) |
|---|---|
| Glass Transition (T_g) | 70-80°C |
| Heat Deflection Temperature (0.45 MPa) | 60-75°C |
| Continuous Service Temperature | 60°C max (for pressure pipe) |
| Melting/Processing Temp | 160-210°C |
| Thermal Conductivity | 0.17 W/m·K (good insulator) |
| Specific Heat | 1000 J/kg·K |
| Coefficient of Thermal Expansion | 50-80 × 10⁻⁶ /°C (~5x steel, less than HDPE) |
| Flammability | Self-extinguishing (LOI 45%) |
Chemical Resistance
Rigid PVC resists a wide range of chemicals:
- Excellent: water, dilute acids and alkalis, salt solutions, alcohols, oils, many household chemicals
- Good: strong HCl, most dilute inorganic chemicals
- Limited: strong oxidizers (concentrated HNO₃, H₂SO₄ above 70%), aromatic and chlorinated hydrocarbons, ketones, esters
- Food-safe grades available for potable water and food contact
Pipe Classifications
Schedule 40 / Schedule 80 (US, ASTM D1785)
- Most common for plumbing and industrial piping
- Schedule 80 has thicker wall for higher pressure
- White (Schedule 40) or dark gray (Schedule 80) typically
Pressure Classes (ISO/DIN)
- PN6, PN10, PN16 pressure ratings (in bar at 20°C)
- Derating required above 25°C
PVC Pipe Types by Application
| Use | Specification |
|---|---|
| Potable water supply | ASTM D1785, NSF-61 certified |
| Drain, waste, vent (DWV) | ASTM D2665 (non-pressure, thin wall) |
| Sewer pipe | ASTM D3034 (gravity) |
| Electrical conduit | Schedule 40/80 gray, UV resistant |
| Irrigation | Class-rated thin wall |
| Chemical process (CPVC) | Chlorinated PVC for higher temp (90°C) |
Applications
Building & Construction
- Water supply: Domestic cold water distribution (NOT hot water — use CPVC or PEX)
- Drainage: DWV pipe for sinks, toilets, roof drains
- Sewer: Municipal gravity sewers (often large diameter)
- Electrical conduit: Protection for electrical wiring
- Window profiles: Extruded uPVC window frames (excellent thermal performance, low maintenance)
- Siding: Vinyl siding for residential buildings
- Gutters and downspouts: Rainwater management
Industrial
- Chemical process piping (acids, alkalis, plating solutions)
- Ventilation ducting for corrosive fumes
- Laboratory drainage
- Tanks and tank linings
- CPVC (chlorinated PVC) for hot water and corrosive fluids up to 90°C
Consumer Products
- Vinyl flooring
- Cable insulation (flexible PVC)
- Medical tubing (flexible, DEHP-free grades)
- Credit cards, packaging films
PVC vs HDPE vs CPVC
| Property | Rigid PVC | HDPE | CPVC |
|---|---|---|---|
| Density | 1400 kg/m³ | 960 kg/m³ | 1550 kg/m³ |
| Pressure temp limit | 60°C | 60-80°C | 90°C |
| Joint method | Solvent cement | Heat fusion | Solvent cement |
| Flexibility | Brittle | Very flexible | Moderate |
| Fire resistance | Self-extinguishing | Flammable | Self-extinguishing |
| Cost | Lowest | Moderate | Higher |
| Cold impact | Poor | Excellent | Fair |
Summary
Rigid PVC (uPVC, density ~1400 kg/m³) is the most widely used plastic piping material for drainage, water supply, and electrical conduit. It is strong, chemically resistant, inherently flame retardant (from chlorine), and the lowest-cost piping option. Limitations include temperature (max ~60°C for pressure service), brittleness at low temperatures (impact resistance lower than HDPE), and unsuitability for hot water or compressed air. CPVC extends the temperature range to ~90°C for hot water service.
Frequently Asked Questions
What is the density of PVC? Rigid PVC (uPVC) has a density of 1,380-1,430 kg/m³ (about 1.4 g/cm³), making it heavier than water and most other plastics. Flexible PVC with plasticizers is lighter at ~1,150-1,350 kg/m³.
What is the maximum temperature for PVC pipe? PVC pressure pipe ratings apply at 20-23°C. At 40°C the pressure rating is roughly halved, and above ~60°C PVC softens and loses most structural strength. Never use standard PVC for hot water (above ~50°C) or compressed air service.
Is PVC better than HDPE for piping? PVC is cheaper, more rigid, and self-extinguishing (inherently flame resistant), making it good for indoor plumbing and drainage. HDPE is more flexible, has better cold-weather impact resistance, and can be fusion-welded for leak-free underground joints. For water and gas distribution, HDPE is the modern standard.
What is the difference between PVC and CPVC? CPVC (chlorinated PVC) has additional chlorine, raising its maximum service temperature to ~90°C. It is used for hot water and corrosive chemical service where standard PVC would soften. CPVC is denser (~1,550 kg/m³) and more expensive.
Can PVC pipe be used for compressed air? No. PVC is brittle and can fail catastrophically under compressed air service, sending shards at high velocity. Use metal, HDPE, or other pressure-rated materials for compressed air lines.
Related Engineering Tools
- Pipe Weight Calculator — Calculate PVC pipe weight
- Pipe Flow Calculator — Flow capacity of PVC lines
- Pressure Drop Calculator — Pressure loss in PVC piping
- Pipe Velocity Calculator — Design velocity for plastic pipe
- HDPE Properties — Compare PVC with HDPE
- Pipe Material Selection — Choose the right piping material
- Density Calculator — General density calculations