Copper Pipes

Copper plumbing tube has been the industry standard in the U.S. for the last half century. In the year 2000, 750 million pounds were installed in the U.S. ( Figure 1 ). This translates to 1.2 billion feet installed in that year. Since 1963, the year CDA was established and began tracking consumption, more than 28 billion feet or approximately 5.3 million miles of copper plumbing tube has been installed in U.S. buildings. That is equivalent to a single coil of copper plumbing tube wrapped around the earth 200 times. By any measure, copper has been very successful as a plumbing tube material. However, failures do occur, but they are few and infrequent. Additional information on copper plumbing tube can be found in various locations on our site.

Figure 1 . Amount of copper plumbing tube installed in the U.S.

In response to an aberrant increase in pitting failures in one water district in the U.S., a one day symposium on copper plumbing tube pitting was organized for technical personnel in companies which produce copper tubing and fittings, as well as others. The intent of the symposium was not to provide a solution to the pitting failures in this one water district, but rather to review the state of the knowledge in pitting in order to provide direction for future efforts. For additional background, a search of peer reviewed technical articles related to pitting is easily conducted on The Copper Data Center . The Copper Data Center is a searchable database of technical articles, to which newly published papers are added each month. For example, conducting a search with one keyword, pitting, will yield 1002 citations. Using a second keyword, water, will reduce that number to 695 and combining it with a third keyword will reduce it further to 34 references, including authors, titles, keywords and abstracts.
Over the years, analysis of failed copper tubes has been regularly conducted. As shown in Table 5 , failures related to flux corrosion are the most common mode of failure and are occurring at an increasing frequency. A great deal, but not everything, is known about corrosion of copper but theories that have little scientific basis are constantly surfacing. Some of these are listed in Table 6 .

Table 5 . Corrosion Failures (Statistics)

Corrosion Cause	1994	1995	1996	1997	1998	1999	2000
Cold Water Pitting	0	4	2	1	5	3	2
Concentration Cell	6	5	3	4	3	8	15
Flux Corrision	10	18	12	32	17	28	23
Underground Corrosion	0	2	5	8	10	13	5
Green Water	0	1	0	1	0	0	0
Erosion/Corrosion	3	4	7	6	8	20	7
Sulfide Attack	1	0	2	1	0	1	0
Stress Corrosion Cracking	0	0	0	0	0	0	1
Hot Water Pitting	3	2	5	11	14	10	5
Workmanship	1	1	2	2	0	1	1
Glavanic Corrosion	0	0	0	0	0	1	0
Total	24	37	38	66	57	85	59