Above Ground Installation
Thermal Expansion and Contraction:
Piping systems installed above ground must be designed to allow compensation for movement caused by thermal expansion and contraction. This applies to outdoor applications primarily, but also applies to buildings that are not heated or cooled. Not addressing movement caused by thermal expansion and contraction can lead to system damage or failure. Please refer to Thermal Expansion and Contraction section for further information.
Outdoor Applications and Protection:
PVC and CPVC piping systems are susceptible to freezing in colder temperatures. There are several operational and installation practices that can be used to protect the system from freezing such as using pipe insulation, anti-freeze solutions, and heat trace tapes. The manufacturers of these products should be consulted for suitability and compatibility with PVC and CPVC prior to use.
PVC and CPVC piping systems installed in direct sunlight or in enclosed boxes, primarily metal, should have precautions taken to ensure that the environmental conditions do not exceed the temperature ratings of the material. Failure to do so can result in product/system damage and/or failure.
PVC and CPVC piping systems exposed to direct sunlight (UV radiation) can be painted with a light-colored acrylic or latex (water-based) paint to avoid UV radiation, and its effects. Dark colors can lead to greater heat absorption, which can exceed the heat handling capacity of the fittings and pipe material. Design and installation considerations for thermal expansion/contraction should still be made. Check with the paint manufacturer to assure the paint is chemically compatible with the PVC/CPVC products. Use only water-based paints. Oil-based paints are not recommended for use with PVC or CPVC.
Installation in Direct Sunlight:
Rigid PVC pipe has undergone testing to determine how UV radiation produced by sunlight affects material properties of thermoplastic pipe. Installing PVC and CPVC in direct sunlight does not affect system operational specifications. However, rigid PVC/CPVC piping products exhibit the following conditions when exposed to UV radiation produced by sunlight:
- Plastic pipe UV degradation only occurs on the exposed surface and only penetrates to depths to shallow depths (typically 0.002 inch)
- Discoloration and a reduction in impact strength. Tensile strength (pressure rating) and modulus of elasticity (pipe stiffness) are unaffected
- UV radiation damage does not continue once UV exposure ends
- Thin coatings such as paint or wrapping will prevent the effects of UV exposure
Coating the pipe in an opaque shield prevents UV degradation. Painting with light-colored acrylic or latex (water-based) paint is the most common method used to protect above ground PVC and CPVC pipe from UV degradation. Preparation of the surface is extremely important when it is to be painted. Prior to painting the system assure the surface is cleaned of all dirt, oil, and moisture then wiped with a clean, dry cloth. Do not use petroleum-based paint. Petroleum-based products are not compatible with PVC and CPVC.