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18-8 SS Sae Flat Washer

Selected 18-8 Stainless Steel Nut Marking18-8 SS SAE Flat Washer
18-8 Stainless Steel Nut Marking18-8 SS SAE Flat Washer

18-8 stainless steel SAE 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. Commercial stainless steel flat washers have a larger outer diameter than SAE (Society of Automotive Engineers) flat washers, and can be utilized in nearly any application. Stainless steel fasteners are commonly used in applications that require general atmospheric corrosion resistance, such as chemical and food processing equipment. Stainless steel has a higher corrosion resistance than carbon steel.

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Dimensional Specifications

SAE flat washer dimensions
Per ASME B18.21.1-2009
Size Nominal A B C
Inside Diameter Outside Diameter Thickness
Basic Tolerance
Plus		 Tolerance
Minus		 Basic Tolerance
Plus		 Tolerance
Minus		 Basic Max Min
1/4 0.2500 0.2810 0.0150 0.0050 0.6250 0.0150 0.0070 0.0650 0.0800 0.0510
5/16 0.3125 0.3440 0.0150 0.0050 0.6880 0.0150 0.0070 0.0650 0.0800 0.0510
3/8 0.3750 0.4060 0.0150 0.0050 0.8120 0.0150 0.0070 0.0650 0.0800 0.0510
7/16 0.4375 0.4690 0.0150 0.0050 0.9220 0.0150 0.0070 0.0650 0.0800 0.0510
1/2 0.5000 0.5310 0.0150 0.0050 1.0620 0.0300 0.0070 0.0950 0.1210 0.0740
5/8 0.6250 0.6560 0.0300 0.0070 1.3120 0.0300 0.0070 0.0950 0.1210 0.0740
3/4 0.7500 0.8120 0.0300 0.0070 1.4690 0.0300 0.0070 0.1340 0.1600 0.1080
7/8 0.8750 0.9380 0.0300 0.0070 1.7500 0.0300 0.0070 0.1340 0.1600 0.1080
1 1.0000 1.0620 0.0300 0.0070 2.0000 0.0300 0.0070 0.1340 0.1600 0.1080
  1. All dimensions are in inches.

Governing Standards

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).