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USS Flat Washer, Galvanized
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USS Flat Washer, Galvanized

USS Flat Washer, Galvanized

Low carbon USS flat washers are used under bolt heads or nuts to increase the bearing surface area, or to offer protection so that the nut or bolt can be rotated without distortion of the bearing surface. Flat washers are also used to give tightness to a joint, to prevent leakage, and especially to distribute pressure under the head of a bolt or nut. Dimensional specifications are governed by ASME B18.21.1. USS (United States Standard) flat washers have a larger outer diameter than structural ASTM F436 flat washers, and can be utilized in nearly any application. ASTM F844 covers the standard specifications for unhardened steel flat washers for general use. Hot dip galvanizing provides a highly corrosion resistant finish, made of sacrificial zinc.

Governing StandardsUSS Flat Washer

ASTM F844 Covers standard, unhardened steel washers for general use.
ASME B18.21.1 Covers the dimensional requirements, physical properties, and related test methods for helical spring-lock washers (#0 through 3 inches), tooth-lock washers (#2 through 1 ¼ inches), and plain washers (#0 through 3 inches).

Dimensional SpecificationsUSS Flat Washer

USS Flat Washer dimensions
Per ASME B18.21.1-2009
Size Nominal A B C
Inside Diameter Outside Diameter Mean Section Thickness
Basic Tolerance
Plus		 Tolerance
Minus		 Basic Tolerance
Plus		 Tolerance
Minus		 Basic Max Min
#6 0.1380 0.1560 0.0080 0.0050 0.3750 0.0150 0.0050 0.0490 0.0650 0.0360
#8 0.1640 0.1880 0.0080 0.0050 0.4380 0.0150 0.0050 0.0490 0.0650 0.0360
#10 0.1900 0.2190 0.0080 0.0050 0.5000 0.0150 0.0050 0.0490 0.0650 0.0360
#12 0.2160 0.2500 0.0150 0.0050 0.5620 0.0150 0.0050 0.0650 0.0800 0.0510
1/4 0.2500 0.3120 0.0150 0.0050 0.7340 0.0150 0.0070 0.0650 0.0800 0.0510
5/16 0.3125 0.3750 0.0150 0.0050 0.8750 0.0300 0.0070 0.0830 0.1040 0.0640
3/8 0.3750 0.4380 0.0150 0.0050 1.0000 0.0300 0.0070 0.0830 0.1040 0.0640
7/16 0.4375 0.5000 0.0150 0.0050 1.2500 0.0300 0.0070 0.0830 0.1040 0.0640
1/2 0.5000 0.5620 0.0150 0.0050 1.3750 0.0300 0.0070 0.1090 0.1320 0.0860
9/16 0.5625 0.6250 0.0150 0.0050 1.4690 0.0300 0.0070 0.1090 0.1320 0.0860
5/8 0.6250 0.6880 0.0300 0.0070 1.7500 0.0300 0.0070 0.1340 0.1600 0.1080
3/4 0.7500 0.8120 0.0300 0.0070 2.0000 0.0300 0.0070 0.1480 0.1770 0.1220
7/8 0.8750 0.9380 0.0300 0.0070 2.2500 0.0300 0.0070 0.1650 0.1920 0.1360
1 1.0000 1.2500 0.0300 0.0070 2.5000 0.0300 0.0070 0.1650 0.1920 0.1360
1 1/8 1.1250 1.3750 0.0300 0.0070 2.7500 0.0300 0.0070 0.1650 0.1920 0.1360
1 1/4 1.2500 1.3750 0.0300 0.0070 3.0000 0.0300 0.0070 0.1650 0.1920 0.1360
1 3/8 1.3750 1.5000 0.0450 0.0100 3.2500 0.0450 0.1000 0.1800 0.2130 0.1530
1 1/2 1.5000 1.6250 0.0450 0.0100 3.5000 0.0450 0.0100 0.1800 0.2130 0.1530
1 5/8 1.6250 1.7500 0.0450 0.0100 3.7500 0.0450 0.0100 0.1800 0.2130 0.1530
1 3/4 1.7500 1.8750 0.0450 0.0100 4.0000 0.0450 0.0100 0.1800 0.2130 0.1530
1 7/8 1.8750 2.0000 0.0450 0.0100 4.2500 0.0450 0.0100 0.1800 0.2130 0.1530
2 2.0000 2.1250 0.0450 0.0100 4.5000 0.0450 0.0100 0.1800 0.2130 0.1530
2 1/4 2.2500 2.3750 0.0450 0.0100 4.7500 0.0450 0.0100 0.2200 0.2480 0.1930
2 1/2 2.5000 2.6250 0.0450 0.0100 5.0000 0.0450 0.0100 0.2380 0.2800 0.2100
2 3/4 2.7500 2.8750 0.0650 0.0100 5.2500 0.0650 0.0100 0.2590 0.3100 0.2280
3 3.0000 3.1250 0.0650 0.0100 5.5000 0.0650 0.0100 0.2840 0.3270 0.2490
  1. All dimensions are in inches.
USS Flat Washer, Galvanized
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Diameter Inside Diameter Outside Diameter Thickness Item # Availability Price Quantity UOM
1/4 0.3120 0.7340 0.0650 WFGA025 In Stock $0.02951/EA EA
5/16 0.3750 0.8750 0.0830 WFGA031 In Stock $0.06212/EA EA
3/8 0.4380 1.0 0.0830 WFGA037 In Stock $0.07702/EA EA
7/16 0.5 1.25 0.0830 WFGA043 In Stock $0.14047/EA EA
1/2 0.5620 1.3750 0.1090 WFGA050 In Stock $0.20899/EA EA
9/16 0.6250 1.4690 0.1090 WFGA056 In Stock $0.28335/EA EA
5/8 0.6880 1.75 0.1340 WFGA062 In Stock $0.35825/EA EA
3/4 0.8120 2.0 0.1480 WFGA075 In Stock $0.50703/EA EA
7/8 0.9380 2.25 0.1650 WFGA087 In Stock $0.77457/EA EA
1 1.25 2.5 0.1650 WFGA100 In Stock $0.88891/EA EA
1 1/8 1.3750 2.75 0.1650 WFGA112 In Stock $1.26959/EA EA
1 1/4 1.3750 3.0 0.1650 WFGA125 In Stock $1.108/EA EA
1 3/8 1.5 3.25 0.18 WFGA137 In Stock $1.33532/EA EA
1 1/2 1.6250 3.5 0.18 WFGA150 In Stock $2.18301/EA EA
1 5/8 1.75 3.75 0.18 WFGA162 In Stock $1.19439/EA EA
1 5/8 2.0 4.25 0.18 WFGA187 In Stock $2.89883/EA EA
1 3/4 1.8750 4.0 0.18 WFGA175 In Stock $1.48027/EA EA
2 2.1250 4.5 0.18 WFGA200 In Stock $3.28284/EA EA