Photo Gallery G1:Â Copper Pipe Corrosion
Copper was once considered virtually immune to corrosion although that was never a valid assumption. Service life estimates for domestic water service were generally at 65 years and greater. But like most other piping materials, changes over the past two decades in the form of lower quality and higher corrosion resistance, undersized wall thickness, the greater use of water conditioning, and different system designs and joining methods have now added copper pipe to any building’s list of piping concerns. Copper is also susceptible to deep galvanic cell pitting caused by rust particles migrating and settling on the copper pipe as a result of the upstream corrosion from steel and galvanized steel pipe or the steel hot water heater tubes.
As a much softer metal, copper is vulnerable to higher water velocities and the erosion it causes – unlike carbon steel. Changes in flow direction at elbows and tees are common failure points – a problem potentially accelerated with hex crimped joining methods. Softened water and especially RO water further increases the threat of each of its vulnerabilities. Where the copper pipe itself is providing good service, changes to the many brass valves, strainers, and other fittings in the form of higher zinc content have caused the system to fail nonetheless.
We have documented superior quality and brazed or silver soldered “Threadless Copper Pipe” or TP showing almost no wall loss loss after 90 years of service at many older properties. Such long lasting pipe, not manufactured since the 1950s, has been replaced mostly with Type L copper and even thinwall Type M or even DWV in some examples. Today’s thinner wall pipe combined with other factors such as solder composition, water quality, higher flow rates at smaller diameter pipe, and especially new joining methods, have produced failures in under 10 years.
Unquestionably, copper is now the last option for many piping problems and system failures, although its longevity may not be guaranteed.
