Flat washers are used to increase the bearing surface of a bolt head or nut and distribute pressure away from the points of the hex or square. For every bolt or screw diameter, there are infinite possibilities for the inner diameter, outer diameter and thickness of the accompanying flat washer. In order to make the selection of a flat washer easier, certain standards have evolved.

The majority of flat washers in inventory at Nickel Systems conform to what we call a Commercial Standard. They are not dimensionally equivalent to USS (United States Standard) pattern, however, some sizes do match the SAE (Society of Automotive Engineers) pattern. The inner diameter is large enough to accommodate a bolt shank at the high side of tolerance. In the interests of economy when flat washers are made from stainless or nickel-based alloys, outer diameters and thicknesses are only as large as functionally needed.

Nickel Systems maintains an inventory of commercial flat washers in Hastelloy® (Alloys C276, C22, B2), Carpenter® 20 (Alloy 20), Duplex 2205, 18-8 and 316 Stainless. Current inventory also includes Inconel® (600, 625), 310 Stainless, 316L Stainless, 317L Stainless and Monel® (Alloy 400).

Some fastener assemblies require flat washers with nonstandard dimensions. For more stressful loads, a thicker or wider washer may be needed. In some cases, a washer may be used as a spacer and be thicker than available plate stock.

Nickel Systems can provide special flat washers stamped from plate or turned from bar. Our specialty is in parts made from nickel alloys such as Hastelloy® (Alloys C276, C22, B2), Carpenter® 20 (Alloy 20), Duplex 2205, Alloy 200 (Nickel 200) and Inconel® (Alloy 600).

USS (United States Standard) and SAE (Society of Automotive Engineers) are 2 common dimensional standards for steel flat washers. Generally, flat washers made in nonferrous materials do not conform to these standards. In non-steel flat washers, corrosion-resistance rather than strength is usually the big consideration. Additionally, steel is quite a bit cheaper than stainless or a nickel-based alloy. Therefore, standard flat washers in nonferrous materials are only as thick or as wide as needed to be functional.

Nickel Systems can supply non-steel flat washers to USS dimensions. Some of our commercial standard flat washers have an outer diameter equal to an SAE pattern. However, in our experience, most customers will opt for a commercial standard flat washer after learning of the dimensional cost and availability differences.

Nickel Systems maintains an inventory of commercial flat washers in Hastelloy® (Alloys C276, C22, B2), Carpenter® 20 (Alloy 20), Duplex 2205, 18-8 and 316 Stainless. Current inventory also includes Inconel® (Alloys 600, 625), 310 Stainless, 316L Stainless, 317L Stainless and Monel® (Alloy 400).

Split lock washers are made mostly from coils of wire. Lock washers made from coil are subject to high volume production runs. Steel and stainless steel lock washers become work hardened in the manufacturing process and possess more strength and spring than the raw material.

Lock washers made from nickel-based alloys and stainless, other than 18-8 or 316, are generally machined from plate stock. There is not enough demand to make these parts from coil. Washers made from plate are not as strong as those made from coil and cannot be reused.

Nickel Systems maintains an inventory of split lock washers in Hastelloy® (Alloys C276, C22, B2), Carpenter® 20 (Alloy 20), 18-8 and 316 Stainless. Current inventory includes 317L Stainless, K-Monel® (Alloy 500) and AL6XN®. Additionally, we can re-machine certain sizes to produce hi-collar lock washers for use with socket head cap screws.