These results indicate that no unusual handling problems should be expected from PVC pipe even after long-term exposure to sunlight. The study results also show that Modulus of Elasticity and Tensile Strength were virtually unaffected. The fact that these properties are unaffected signifies that structural integrity and pressure capacity remain unchanged. UV degradation does not continue after installation when exposure to UV radiation is terminated. The presence of an opaque surface between the sun and the pipe prevents UV degradation, since UV radiation will not penetrate thin shields such as paint coatings or wrappings.
Burial provides complete protection.
When exposure in excess of two years of direct sunlight is unavoidable, PVC pipe should be covered with an opaque material while permitting adequate air circulation around the pipe. This prevents excessive heat accumulation. Both terms refer to the same ratio, which is a dimensionless term that is obtained by dividing the average outside diameter of the pipe by the minimum pipe wall thickness. Dimension ratios and standard dimension ratios were developed out of convenience rather than out of necessity. They have been established to simplify standardization in the specification of plastic pipe on an international basis.