Thermal Expansion of PVC and CPVC Pipe

Thermal expansion and contraction with temperature changes. Thermoplastic piping expands and contracts more than metallic piping when subjected to temperature changes. This issue must be addressed with appropriate system design to prevent damage to the piping system. The degree of movement (change in length) generated as the result of temperature changes must be calculated based on the type of piping material and the anticipated temperature changes in the system. The rate of expansion does not vary with pipe size. In many cases, this movement must be compensated for by constructing appropriate-sized expansion loops, offsets, bends, or the installation of expansion joints.

These configurations will absorb the stresses generated from the movement, thereby minimizing damage to the piping. The effects of thermal expansion and contraction must be considered during the design phase, particularly for systems involving long runs, hot water lines, hot drain lines, and piping systems exposed to environmental extremes (i.e., summer to winter).