Machinery's Handbook, 31st Edition
Sheet Metal Gages 2707 Zinc sheets are usually ordered by specifying decimal thickness although a zinc gage exists and is shown in Table 2. Most sheet metal products in Great Britain are specified by the British Standard Wire Gage (Imperial Wire Gage). Black iron and steel sheet and hooping, and galvanized flat and corrugated steel sheet, however, are specified by the Birmingham Gage (B.G.), which was legalized in 1914, and are also shown in Table 2. This Birmingham Gage should not be confused with the Birmingham or Stub’s Iron Wire Gage mentioned previously. Thicknesses of aluminum, copper, and copper-base alloys were formerly designated by the American or Brown & Sharpe Wire Gage but now are specified in decimals or frac - tions of an inch. American National Standard B32.1-1952 (Withdrawn) entitled Preferred Thicknesses for Uncoated Thin Flat Metals (see accompanying Table 3) gives thicknesses that are based on the 20- and 40-series of preferred numbers in American National Stan- dard Preferred Numbers — ANSI Z17.1 (see Handbook page 687) and are applicable to uncoated, thin, flat metals and alloys. Each number of the 20-series is approximately 12 percent greater than the next smaller one, and each number of the 40-series is approxi mately 6 percent greater than the next smaller one.
Table 3. Preferred Thicknesses for Uncoated Metals and Alloys— Under 0.250 Inch in Thickness ANSI/ASME B32.1-1952 (Withdrawn) Preferred Thickness, Inches
Based on 20-Series
Based on 40-Series
Based on 20-Series
Based on 40-Series
Based on 20-Series
Based on 40-Series
Based on 20-Series
Based on 40-Series
… 0.236
0.100
0.100
… 0.042
0.018
0.018
0.224
0.224
… 0.095
0.040
0.040
… 0.017
… 0.212
0.090
0.090
… 0.038
0.016
0.016
0.200
0.200
… 0.085
0.036
0.036
… 0.015
… 0.190
0.080
0.080
… 0.034
0.014
0.014
0.180
0.180
… 0.075
0.032
0.032
… 0.013
… 0.170
0.071
0.071
… 0.030
0.012 0.011 0.010 0.009 0.008 0.007 0.006 0.005
0.012 0.011 0.010 0.009 0.008 0.007 0.006 0.005
0.160
0.160
… 0.067
0.028
0.028
… 0.150
0.063
0.063
… 0.026
0.140
0.140
… 0.060
0.025
0.025
… 0.132
0.056
0.056
… 0.024
0.125
0.125
… 0.053
0.022
0.022
… 0.118
0.050
0.050
… 0.021
0.112
0.112
… 0.048
0.020
0.020
… 0.106 0.004 The American National Standard ANSI/ASME B32.1-1952 (Withdrawn) lists preferred thick- nesses that are based on the 20- and 40-series of preferred numbers and states that those based on the 40-series should provide adequate coverage. However, where intermediate thicknesses are re- quired, the Standard recommends that thicknesses be based on the 80-series of preferred numbers (see Handbook page 687). Thicknesses for copper and copper-base alloy flat products below 1 ⁄ 4 inch thick are 0.045 0.045 … 0.019 0.004 specified by the 20-series of American National Standard Preferred Numbers given in ANSI/ASME B32.1. Although the table in ANSI/ASME B32.1 gives only the 20- and 40-series of numbers, it states that when intermediate thicknesses are required they should be selected from thicknesses based on the 80-series of numbers (see Handbook page 687).
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