USS Flat Washer

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 SAE (Society of Automotive Engineers) flat washers, and can be utilized in nearly any application. ASTM F844 covers the standard specifications for unhardened steel flat washers for general use.

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Governing Standards
Dimensional Specifications

Dimensional Specifications

Dimensional SpecificationsUSS Flat Washer

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
		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

All dimensions are in inches.

USS Flat Washer

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Diameter	Inside Diameter	Outside Diameter	Thickness	Item #	Availability	Price	Quantity
1/4	0.3120	0.7340	0.0650	WFBL025	In Stock	$0.01549/EA	EA	EA
5/16	0.3750	0.8750	0.0830	WFBL031	In Stock	$0.04475/EA	EA	EA
3/8	0.4380	1.0000	0.0830	WFBL037	In Stock	$0.03989/EA	EA	EA
7/16	0.5000	1.2500	0.0830	WFBL043	3-5 Working Days	$0.03906/EA	EA	EA
1/2	0.5620	1.3750	0.1090	WFBL050	In Stock	$0.10845/EA	EA	EA
9/16	0.6250	1.4690	0.1090	WFBL056	In Stock	$0.11025/EA	EA	EA
5/8	0.6880	1.7500	0.1340	WFBL062	In Stock	$0.21263/EA	EA	EA
3/4	0.8120	2.0000	0.1480	WFBL075	In Stock	$0.35113/EA	EA	EA
7/8	0.9380	2.2500	0.1650	WFBL087	In Stock	$0.37471/EA	EA	EA
1	1.2500	2.5000	0.1650	WFBL100	In Stock	$0.45987/EA	EA	EA
1 1/8	1.3750	2.7500	0.1650	WFBL112	In Stock	$0.48962/EA	EA	EA
1 1/4	1.3750	3.0000	0.1650	WFBL125	In Stock	$0.55403/EA	EA	EA
1 3/8	1.5000	3.2500	0.1800	WFBL137	In Stock	$0.36804/EA	EA	EA
1 1/2	1.6250	3.5000	0.1800	WFBL150	In Stock	$0.99468/EA	EA	EA
1 5/8	1.7500	3.7500	0.1800	WFBL162	In Stock	$1.50665/EA	EA	EA
1 5/8	2.0000	4.2500	0.1800	WFBL187	In Stock	$1.06791/EA	EA	EA
1 3/4	1.8750	4.0000	0.1800	WFBL175	In Stock	$1.06096/EA	EA	EA
2	2.1250	4.5000	0.1800	WFBL200	In Stock	$1.73803/EA	EA	EA
2 1/4	2.3750	4.7500	0.2200	WFBL225	In Stock	$2.68037/EA	EA	EA
2 1/2	2.6250	5.0000	0.2380	WFBL250	In Stock	$4.45258/EA	EA	EA
3	3.1250	5.5000	0.2840	WFBL300	In Stock	$5.18699/EA	EA	EA

USS Flat Washer

Technical Data

Governing Standards

Governing StandardsUSS Flat Washer

Dimensional Specifications

Dimensional SpecificationsUSS Flat Washer

Grade

Diameter

Thickness

Outside Diameter

Inside Diameter

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).