Builders rely on thin-walled copper tubing for low-pressure water supply and drain line applications. Those within the building and manufacturing industries use the term "Type M" to refer to this type of copper tubing, which refers to designations developed by the Association for Standards Testing for Materials. ASTM copper tubing specifications not only help manufacturers produce consistent and reliable tubing products, but also help builders and contractors select the right tubing for each particular project.
According to ASTM B-88, manufacturers can produce Type M Copper tubing made from one of three different materials. Type C10200 copper is characterized as oxygen-free, and must be produced without the use of residual deoxidant materials. Type C12000 refers to copper that has been deoxidized using phosphorus, but has little phosphorus remaining by the end of the manufacturing process. Type C12200 is also deoxidized with phosphorus, but includes high residual levels of phosphorus when the product is shipped. This high phosphorus variety is considered a lower quality tubing product, and may be limited to specific applications.
Size and Appearance
ASTM B-88 specifies standards for copper tubing ranging from 3/8 inch to 12 inches in diameter. These products may be produced and finished using both manufacturing or annealing techniques. Straight lengths of Type M copper tubing are available in either 10 or 20-foot sections, and must be produced via drawing. Coiled lengths are generally annealed, and come in many different sizes.
All Type M copper tubing can be identified by the color red, which may be painted on the outside of the tube or marked on the endcap. These tubes should also feature the "Type M" designation marked along the outside diameter.
Weight and Volume
The weight and volume of Type M copper tubing varies based on the size of the pipe. For example, a Type M tube with a 3/8-inch nominal diameter weighs 0.145 pounds per linear foot when empty, or 0.214 pounds per linear foot when filled with water. It can hold 0.00110 cubic feet or water, or 0.00826 gallons per linear foot.
A much larger copper tube, for example, one with a 12-inch nominal diameter, weighs 36.7 pounds per linear foot empty or 82.5 pounds per linear foot when filled with water. This pipe size can hold 0.726 cubic feet, or 5.51 gallons per linear foot.
Size and Pressure
The specified pressure rating for each Type M tubing size depends on the temperature of the liquid it's transporting. At 150 degrees Fahrenheit, a 3/8-inch diameter annealed pipe is rated up to 485 psi, while the same size hand-drawn pipe is rated up to 1077 psi. At 300 degrees, a 3/8 annealed pipe can accommodate 447 psi, while the same size annealed pipe can handle 1,048 psi at this temperature.
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