This is the second of four posts in a CPVC piping failures series by Donald B. Snell, PE.

Causes of CPVC Failures

When CPVC failures do occur, most frequently they are due to contamination issues and minor stresses imparted on the pipe. (See article by Duanne Priddy on Why Do PVC & CPVC Pipes Occasionally Fail?.)

Contamination issues occur when products and materials are chemically incompatible with CPVC, either on the inside or outside of the pipe.

Simultaneous occurrences of contamination and stresses in CPVC pipes can cause environmental stress cracking (ESC). ESC Chemicals (contamination) range from very mild to very aggressive. In general, when ESC occurs, the lower the stress and pressure imparted on the pipe, the more aggressive the contaminant.

See below for images of CPVC piping which resulted in failure due to contamination and environmental stress cracking.

CPVC piping failures

Arrows in each figure point to environmental stress cracks.
Figure 1 represents ESC from internal contaminants;
Figures 2 and 3 represent ESC from external contaminants.

To be continued…

Donald B. Snell, PE (Georgia, Virginia and Pennsylvania), a Certified Mechanical Contractor (Florida) and Senior Mechanical Consultant with Liberty Building Forensics Group, has performed moisture and IAQ-related forensic building investigations on more than 200 buildings.

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