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USS Flat Washer, Galvanized

Selected Grade 2 USS Flat Washer Hot Dipped GalvanizedUSS Flat Washer, Galvanized
Grade 2 USS Flat Washer Hot Dipped GalvanizedUSS 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.

Products

Dimensional Specifications

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 1.0625 0.0300 0.0070 2.5000 0.0300 0.0070 0.1650 0.1920 0.1360
1 1/8 1.1250 1.2500 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.

Governing Standards

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).