Description
The 3-1/2" USS Flat Washer is a high-capacity, oversized washer designed for use with 3-1/2-inch diameter bolts, screws, and studs. Manufactured to United States Standard (USS) specifications, this washer features a very large outer diameter and substantial thickness—ideal for distributing clamping loads, protecting mating surfaces, and ensuring long-term joint integrity in extreme structural and industrial applications.
Specifications:
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Inner Diameter (I.D.): 3-9/16"
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Outer Diameter (O.D.): 9"
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Thickness: 3/4" (nominal)
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Standard: USS (United States Standard)
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Material: Typically low carbon steel; also available in stainless steel, brass, or specialty alloys
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Finish Options: Plain, zinc-plated, hot-dip galvanized, black oxide, or custom corrosion-resistant finishes
Key Features:
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Expansive Load Surface: Extra-wide O.D. spreads fastener pressure to prevent embedment and surface damage—ideal for heavy structural joints.
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Sized for 3-1/2" Fasteners: Clearance hole offers smooth installation and accommodates manufacturing tolerances for proper fit.
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USS Fit Standard: Looser fit than SAE washers, allowing for ease of alignment and flexibility in large-scale assemblies.
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Heavy-Duty Performance: Thick and flat body supports consistent torque and load-bearing strength in high-stress applications.
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Finish Variety: Available with corrosion-resistant coatings for long-term durability in harsh or outdoor environments.
Common Applications:
The 3-1/2" USS flat washer is used in the most demanding fastening applications, including:
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Bridge and infrastructure construction
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Industrial machinery and heavy-equipment assembly
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Anchor bolt and steel plate connections
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Marine and offshore structures
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Utility and power infrastructure systems
