The F436 Structural Flat Washer (Zinc/YELLOW CR+6) is designed to meet specific specifications outlined in the ASTM F436 standard. Below are the key specifications and details for this type of washer:
1. Material:
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Steel: The washers are typically made from carbon steel (A307 or equivalent), although the material can vary based on the application.
2. Coating:
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Zinc Plating: The washer is coated with a zinc layer to provide corrosion resistance.
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Yellow Chromate (CR+6): The zinc-coated washer is then treated with a yellow chromate (Chromium VI) conversion coating. This adds further protection from corrosion, improving its resistance to environmental conditions like moisture and chemicals.
3. Dimensions (General Specifications):
F436 washers come in various sizes and must meet the dimensional requirements in the ASTM F436 standard. The most common sizes are those corresponding to the standard bolt sizes. Some typical sizes for F436 washers include:
| Nominal Size (Bolt Size) | Outer Diameter | Inner Diameter | Thickness |
|---|---|---|---|
| 1/4 inch | 0.594 in (15.08 mm) | 0.265 in (6.73 mm) | 0.052 in (1.32 mm) |
| 5/16 inch | 0.718 in (18.26 mm) | 0.328 in (8.33 mm) | 0.058 in (1.47 mm) |
| 3/8 inch | 0.844 in (21.43 mm) | 0.406 in (10.31 mm) | 0.062 in (1.57 mm) |
| 1/2 inch | 1.000 in (25.40 mm) | 0.500 in (12.70 mm) | 0.062 in (1.57 mm) |
| 5/8 inch | 1.250 in (31.75 mm) | 0.625 in (15.88 mm) | 0.062 in (1.57 mm) |
| 3/4 inch | 1.500 in (38.10 mm) | 0.750 in (19.05 mm) | 0.062 in (1.57 mm) |
| 1 inch | 2.000 in (50.80 mm) | 1.000 in (25.40 mm) | 0.062 in (1.57 mm) |
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The outside diameter (OD) is typically 1.5 to 2 times larger than the inside diameter (ID) for a proper fit and load distribution.
4. Mechanical Properties:
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Tensile Strength: F436 washers are designed to have high tensile strength, to resist deformation under load.
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Yield Strength: The washers must have sufficient yield strength to avoid permanent deformation under typical load conditions.
While the exact values will depend on the material and coating, the washers are generally built to withstand high stresses that occur in structural applications.
5. Finish:
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Zinc Plating provides corrosion resistance, and the yellow chromate finish (Cr+6) gives the washers additional protection. This finish improves resistance to corrosion in both indoor and outdoor environments, particularly in applications where moisture, salt, or chemicals may be present.
The yellow chromate finish has a distinct yellow-golden hue that serves as an indicator of this additional corrosion protection.
6. Tolerances:
F436 washers have specific tolerances to ensure they fit correctly with bolts and nuts and provide effective load distribution. Some general tolerances for washers include:
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Thickness: +/- 0.005 to 0.015 inches (0.127 to 0.381 mm)
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Outer Diameter: +/- 0.010 to 0.025 inches (0.254 to 0.635 mm)
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Inner Diameter: +/- 0.010 to 0.025 inches (0.254 to 0.635 mm)
7. Standards Compliance:
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ASTM F436: The washers conform to the ASTM F436 standard for structural washers used with structural bolts.
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ISO Standards: In some cases, washers made to F436 specifications may also comply with equivalent international standards, like ISO 7089 (depending on the region or specific industry).
8. Applications:
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Structural Steel: Used in structural steel work where heavy-duty bolts are involved, such as bridges, buildings, and other infrastructure projects.
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Heavy Machinery and Equipment: Employed in machinery and equipment that require secure, load-distributing fasteners.
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Bolted Connections: Primarily used with high-strength bolts in critical connections to prevent damage to the material and ensure load-bearing stability.