Copper Water Tube: Good for Consumers, Good for the Environment
Copper Applications in Health & Environment
More than 70 years after it was introduced to the North American market, copper water tube continues to be the first choice among homeowners, builders and plumbing professionals. Copper is overwhelmingly preferred for its durability, quality, and safety, and for its ability to transmit pure, healthy drinking water, free from contaminants.
In the U.S., copper's use for plumbing systems has risen an average of nearly 5% per year since 1992, reaching around two thirds of a billion pounds in 1997. Copper water tube (not to be confused with commercial tube used for refrigeration and other commercial industrial applications) now accounts for about 8% of all copper consumed in the country.
That raises some important questions:
- Are we risking the depletion of an important mineral resource to make something as simple as water tube?
- While we're at it, are we consuming excessive amounts of energy in mining, smelting and refining to make this product, with possible adverse environmental effects?
- And, when old buildings are torn down, are we flooding landfills and the rest of the environment with the buildings' still functional but no longer usable copper plumbing systems?
- No, and
Why? Because almost two-thirds of the copper used to make water tube is derived from recycled scrap. Scrap doesn't have to be mined, just collected. And the only significant additional energy it requires is the heat needed to melt it, which is far less than the total energy consumed in mining, milling, smelting and refining copper from ore. With scrap, that earlier energy cost has already been paid, and it never has to be paid again.
U.S. manufacturers used over 400 million pounds of recycled scrap copper to make water tube in 1997. The remaining raw materials were either newly refined copper cathode or copper ingots, which are also made from cathode copper, some of which may be "new" copper and some may be re-refined from scrap.
Over four hundred million pounds is a lot of recycled copper! If it were drawn into ½-inch Type M tube, the standard type found in domestic plumbing systems, the strand would be long enough to circle the Earth more than 15 times! It's copper that has been used before, probably many times since it was mined. Moreover, chances are very good that it will be used again in the future - maybe even to make more copper tube - once the building it's installed in is no longer needed.
Is it safe to use scrap copper in water tube?
After all, scrap may contain impurities.
The copper in water tube has a minimum purity of 99.9% copper (including minute amounts of silver), making it one of the purest of any of the common metals in commercial use. The level of purity is specified in the American Society for Testing and Materials' standard specification: ASTM B 88, Specification for Seamless Copper Water Tube. Water tube used for domestic service in the U.S. is governed by the requirements of this specification.
There are two kinds of scrap used to make plumbing tube. The first, called "home" or "runaround" scrap, is the scrap copper generated in the tube-making plant itself. Since it has already been refined, it is quickly returned to a simple melting furnace, called a shaft furnace, to be re-used.
The second kind of scrap, which is usually graded "No. 1 Copper" or higher, is purchased by tube manufacturers from the metals-recycling industry. This large and efficient industry gathers, segregates, bundles, and in some cases, remelts scrap metals for further use. The industry performs a very positive and largely unrecognized environmental function in that it ensures that every bit of economically reusable metal - including copper - is recycled into new raw materials.
Water tube manufacturers carefully select the scrap they buy for cleanliness because removing impurities costs money. The scrap may nevertheless contain some "tramp" elements other than copper, but virtually all of these are removed or reduced to vanishingly low levels when the scrap is remelted and refined.
Remelting and refining are carried out in reverberatory furnaces, which are just like the furnaces copper smelters use to refine the metal. Similarly, the metal leaving the reverberatory furnace, called "fire-refined" copper, is identical to the fire-refined copper supplied by primary copper producers.
If using scrap as a raw material helps the environment,
why not use it exclusively?
Why use any "new" copper at all?
The answers to these questions are partly economic and partly technical. The economic part has to do with the relative price and availability of newly refined cathode copper vs. that of scrap. Scrap always costs less than refined copper and it is therefore usually preferred; however, market fluctuations sometimes bring the two commodities' prices close together. When that happens, and if there is a shortage of scrap within a reasonable distance from a tube plant (shipping costs money, too), cathode copper may become the lower-cost option.
The technical reason for using refined copper depends on the type of furnace equipment available. Some tube manufacturers operate only simple shaft furnaces, which are efficient and fast but which cannot remove impurities from scrap. Consequently, such manufacturers can only use pure, i.e., cathode copper or their own home scrap as raw materials. Even tube makers who do operate reverberatory furnaces, and who therefore can refine scrap, are sometimes forced to use refined copper when their furnaces are shut down for maintenance.
Tube makers who operate relatively small furnaces may use copper ingots, which are smaller than copper cathodes and can therefore fit through the doors of their melting equipment.
Good Economics Make Good Environmental Sense
There are six copper tube manufacturers in the U.S., and the business is highly competitive. Manufacturers therefore face the task of keeping manufacturing costs as low as possible while maintaining the levels of quality and purity required by ASTM B88 and other applicable standards. Using as much scrap as possible is one means by which the manufacturers try to meet these goals.
Fortunately - for everyone concerned, including the environment - copper is one of the easiest, safest and most economical metals to recycle. Unlike the PVC plastics used for so-called "low-cost" water tube, every bit of copper that can be recycled is recycled as quickly as possible. And, again unlike PVC, recycled copper can be re-used to make the same high quality products from which it came. "Downcycling" is not necessary.
These are important points to think about when selecting the plumbing system for your home. When we think about the way copper provides pure, safe water and the simple, energy-efficient way in which it is recycled, we can understand why copper is the most environmentally friendly plumbing material of all.
Andrew G. Kireta Sr.
Phone: (212) 251-7223
Fax: (212) 251-7234
Also in this Issue:
- How Do They Do That? Making Copper Plumbing Tube
- Industries of the Future: New Technologies for the Mining Industry
- Dollar Coin - Design and Materials
- Copper Water Tube: Good for Consumers, Good for the Environment