An Environmental Stress Cracking experiment was used to assess the effect of phthalates on CPVC pipe.

Chlorinated poly vinyl chloride (CPVC) is commonly used for hot and cold water pipes in homes and commercial settings since it can handle corrosive water at higher temperatures compared to PVC.  In addition, CPVC is more ductile than PVC.  Some caulks and adhesives which may be used in construction may contain phthalates such as diisononyl phthalate (DINP). 

  • Problem

    In this situation, a CPVC pipe had failed, and it was suspected that a caulk containing DINP was inadvertently applied to the pipe. We needed to determine if the phthalate was the reason the pipe had failed.

  • Solution

    In order to assess the effect of DINP on the pipe, an environmental stress cracking (ESC) experiment was carried out.  A portion of new CPVC pipe was stressed by inserting a ball bearing larger than the pipe diameter.  Next, a drop of DINP was placed on the surface.  We then acquired images every three minutes for 15 hours.  In addition, optical microscopy (OM) and scanning electron microscopy (SEM) were utilized to monitor the cracking at various points in the process.  The video dramatically documents the attack of CPVC by the DINP, a phthalate plasticizer.  So, our conclusion and emphatic recommendation is to avoid contact of CPVC with phthalates!