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Copper plumbing tube is manufactured from Copper No. C12200 (99.9% Copper), in accordance with the requirements of ASTM Standard B 88. Most provincial regulatory authorities in Canada now require that copper tube for use in plumbing systems be Third-Party Certified for compliance with ASTM B 88. Types DWV, ACR, Medical Gas, and Type G/GAS tube meet the requirements of ASTM B 306, ASTM B 280, ASTM B 819 and ASTM B 837, respectively. Various Types are certified in addition to plumbing tube, and the latest list of Third-Party Certified products is available on request.
Types K, L, M, DWV, and Medical Gas tube have actual outside diameters which are 1/8-inch (0.125 in.) larger than the nominal (standard) sizes which the tube is commonly called. For example, a 1/2-inch Type M tube has an actual outside diameter of 5/8-inch. Type K tube has thicker walls than Type L tube, and Type L walls are thicker than Type M for any given size (diameter). Table 1 provides the dimensions and weights for Types K, L, M, and DWV tube.
ACR tube for air-conditioning and refrigeration service and Type G/GAS tube for natural gas and propane systems are designated by their actual outside diameter. A 1/2-inch Type G/GAS tube, for example, has an actual outside diameter of 1/2-inch. Table 2 covers the dimensions and weights for Type ACR tube. Table 3 provides the information for Type G/GAS tube.
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Compact copper water and drainage lines for back-to-back sinks fit neatly into steel studs.
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The compact dimensions and flexibility of copper tube are compared here with threaded steel pipe, such as would be used in a natural gas system.
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Temper
Temper denotes the hardness and strength of tube. Straight lengths are primarily drawn temper, or as more commonly known, hard tube. Annealed temper tube is referred to as soft tube. It is usually in coiled form, but certain sizes are also available in straight lengths.
Identification
Types K, L, M, DWV, ACR, Medical Gas, and Type G/GAS tubes are permanently incised with the tube Type, the name or trademark of the manufacturer, and the mark of the independent certification agency when Third-Party Certified. In addition, straight lengths are also identified along their length by a continuous colour code. The colour coding includes the Type of tube, name or trademark of the manufacturer, country of origin, and the mark of the certification agency when Third-Party Certified. The following colours are used for colour coding:
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Type K............... Green
Type L............... Blue
Type M.............. Red
Type DWV*...... Yellow
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Type ACR.......... Blue
Medical Gas...... Green (K)
Medical Gas...... Blue (L)
Type G/GAS*.... Yellow
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* DWV is 1-1/4-in. and larger. Type G/GAS tube is up to 1-1/8-in. size.
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At the time this manual was published, copper plumbing tube and fittings are known by their nominal inch sizes only, as covered in the standards issued by ASTM, ASME, and other organizations. No metric sizes have been established for copper tube and fittings for use in North America. To avoid confusion, do not soft convert the inch nominal sizes to metric values. Contact the CCBDA at any time for the latest information on metric conversion.
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Capillary fittings for copper systems under pressure, such as hot and cold water lines, may be manufactured by a wrought process or casting. They are covered by ASME Standard B16.22, Wrought Copper and Copper Alloy Solder Joint Pressure Fittings, and B16.18, Cast Copper Alloy Solder Joint Pressure Fittings. Each fitting is permanently marked with the manufacturer's name or trademark, except for small sizes where marking may not be practical.
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Copper excels for hot water systems in high demand multi-unit buildings.
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Wrought and cast fittings can be either soldered or brazed. However brazing of cast fittings requires special care to avoid cracking, and short-cup cast fittings for brazing are available to reduce this risk.
Wrought and cast pressure fittings have the same pressure-temperature ratings as straight lengths of annealed Type L tube. Ratings for annealed tube are used because hard temper tube is annealed during the brazing process. Annealing does not occur with the lower-temperature soldering process, but all designs must be based on the lower (annealed) values. Each fitting is permanently marked with the manufacturer's name or trademark and DWV, to indicate Drain-Waste-Vent.
Drainage fittings are used in soil-and-waste drainage and venting applications. Such systems generally are gravity installations, and they are not subject to pressure. Wrought drainage fittings are covered by ASME Standard B16.29, Wrought Copper and Copper Alloy Solder Joint Drainage Fittings–DWV, while those made by casting are covered by ASME Standard B16.23, Cast Copper Alloy Solder Joint Drainage Fittings–DWV. Each fitting is permanently marked with the manufacturer's name or trademark and DWV, to indicate Drain-Waste-Vent.
A variety of other types of fittings are commercially available for joining copper tube.They include flare fittings, compression fittings, mechanical couplings, and pipe flanges. Additional information is provided in the section on Other Joining Methods.
The allowable internal pressure for copper tube is based on the formula used in the ASME Code for Pressure Piping (ASME B31):
Because of copper's superior corrosion resistance, the B31 Code permits C to equal O, and the formula becomes:
The value of S in the formula is the allowable design strength for continuous long-term service of the tube material. The allowable stress value depends on the service temperature and the temper of the tube. It is a small fraction of copper's ultimate tensile strength, or of the burst strength of copper tube.
Table 6 shows the rated internal working pressures for both annealed and drawn Types K, L, and M tube, for service temperatures up to 400oF (205oC). The ratings for drawn tube can be used for soldered systems, and systems using properly designed mechanical joints. Table 10 covers the rated internal working pressures for Type DWV tube. Tables 7 and 8 show the rated internal working pressures for ACR tube.
When brazing or welding is used to join tubes, the annealed ratings must be used, since the heating involved in these processes will anneal the hard drawn tube. Therefore, annealed ratings are shown in Tables 6 and 10 for Type M and Type DWV tube, respectively, although they are not available in the annealed temper.
When designing a system, joint ratings must also be considered, because the lower of the two ratings (tube or joint) will govern the installation. Most systems are installed with solder or brazed joints. Table 11, covers the rated internal working pressures for such joints; the ratings are for Types K, L, and M tube with standard solder joint pressure fittings. In soldered systems, the rated strength of the joint often governs the design. When brazing use the ratings for annealed tube in Tables 6, 7, and 10. Joint ratings at saturated steam temperatures are shown in Table 11.
The actual bursting pressures for copper tube are many times the rated working pressures. Table 9 shows actual burst pressures for Types K, L, and M tube. They should be compared with the rated working pressures in Table 6, and it can be seen that the rated values are very conservative. This means that pressurized systems will operate successfully over long time periods, and they are able to withstand high pressure surges that may occur in service.
All piping materials expand and contract with temperature changes, including copper. Figure 2 compares the expansion rates of copper tube with various kinds of plastic pipe, using concrete as the benchmark. It is clear that the expansion and contraction of copper is significantly less than the plastic products.
The average coefficient of expansion of copper is 0.0000094 inch per inch per degree F, between 70oF and 212oF. Installation techniques must allow for expansion and contraction changes, to prevent stresses which may buckle or bend the tube or affect joints.
Figure 1 illustrates the types of expansion loops and offsets that can be used. Table 5 provides information for estimating the sizes of loops and offsets.
Figure 1: Types of Expansion Loops and Offsets
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