Thru Hardened USS Flat Washer, Plated
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Thru Hardened USS Flat Washer, Plated

Thru-hardened 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 SAE (Society of Automotive Engineers) flat washers, and can be utilized in nearly any application. Available in zinc plated finish. Zinc plating sacrifices itself, corroding before the base material, offering added corrosion resistance.

Governing StandardsThru Hardened USS Flat Washer

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 SpecificationsThru Hardened USS 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.
Thru Hardened USS Flat Washer, Plated
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Diameter Inside Diameter Outside Diameter Thickness Item # Availability Price Quantity UOM
5/16 0.3750 0.8750 0.0830 WF8P031 In Stock $0.09902/EA EA
1 1/4 1.3750 3.0 0.1650 WF8P125 In Stock $1.69308/EA EA