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

Potential Contaminants on the Inside of the Pipe

CPVC piping failures

This external stress crack is a result of internal contaminants

The use of metal piping in domestic water, condensate drain piping, and fire sprinkler applications has given way to plastic composition piping for the previously mentioned advantages. Applications may be new installations or retrofits.

In either case, system pressure, stress, and compatibility should be addressed to minimize conditions conducive to CPVC failure. It is likely that different pipe materials exist, and it is important to be aware of those differences.

Metal piping systems may involve the use of corrosion inhibitors or other forms of chemical treatment. Metal piping systems or internals of in-line components may also contain oils that also should be addressed. Each can be chemical contaminants to CPVC (incompatible) and can lead to CPVC pipe failure.

Potential Contaminants on the Outside of the Pipe

Fire-stopping systems, caulks, sealants, and mildewicides are examples of potential outside contaminants that may cause environmental stress cracking (under the right amount of stress) and premature CPVC pipe failure.

CPVC piping failures

This external stress crack is a result of external contaminants.

CPVC piping failures

This external stress crack is a result of 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.