Flat Washers Manufacturer
MT.BOLTS manufactures Flat Washers, essential components in bolted joint assemblies used to evenly distribute load, prevent damage to surfaces, and reduce loosening due to vibration. These round, disc-shaped fasteners are placed under the head of a bolt or nut and are widely applied in construction, machinery, automotive, electrical equipment, and structural applications. MT.BOLTS supplies flat washers in a wide variety of sizes, thicknesses, materials, and finishes to meet global engineering standards and specific project needs.
- System of Measurement:
- Metric: M3 – M100
- Imperial: #6 to 4″
- Outer Diameter / Thickness Range:
- Outer Diameter:
- Metric: 6 mm – 200 mm
- Imperial: 1/4″ – 8″
- Thickness:
- Metric: 0.5 mm – 10 mm
- Imperial: 0.02″ – 0.4″
- Washer Types:
- Standard Flat Washer (Type A, B, C)
- Large OD Washer (Fender Washer)
- Narrow OD Washer
- Shim Washer
- Square Washer
- Custom-profile Washers (upon request)
Flat Washers Material Types
MT.BOLTS supplies carbon steel, stainless steel, duplex steel, and nickel-based alloy Flat Washers, meeting the demanding requirements of chemical, marine, and high-temperature environments, compliant with various international standards.
| Material Category | Common Grades/Models | Description |
| Carbon Steel | ASTM A307, A325, A490 | High strength and cost-effective, suitable for general structures; requires anti-corrosion coating. |
| Stainless Steel | 304 (A2), 316 (A4), 321, 410 | Excellent corrosion resistance; widely used in food, chemical, and construction industries |
| Duplex Stainless Steel | UNS S31803/S32205 (F51), UNS S32750 (F53) | High strength with superior chloride corrosion resistance; used in seawater, petrochemical, and paper industries |
| Monel Alloys | Monel 400, Monel K500 | Excellent seawater corrosion resistance and mechanical strength; used in marine engineering and pump systems |
| Hastelloy Alloys | Hastelloy C276, C22, B2, X | Excellent resistance to strong acids and oxidizing media; widely used in chemical equipment and flue gas desulfurization |
| Inconel Alloys | Inconel 600, 625, 718 | Resistant to high temperature, pressure, and corrosion; used in heat exchangers, aerospace, and nuclear industries |
| Incoloy Alloys | Incoloy 800, 825, 925 | Ideal for high-temperature acidic environments; widely used in petroleum refining and heat treating systems |
| Nickel Alloys | Nickel 200, 201 | Pure or high-nickel alloys with excellent conductivity and alkali resistance; used in electronics and chemical applications |
Flat Washers System of Measurement
- Metric Sizes: M3 to M100
- Imperial Sizes: #6 to 4″
- Outer Diameter Range: 6 mm to 200 mm (1/4″ to 8″)
- Thickness Range: 0.5 mm to 10 mm (0.02″ to 0.4″)
- Fits both coarse and fine thread fasteners.
Flat Washers Common Standards
- DIN 125 / 9021 / 433 – Metric flat washer types
- ISO 7089 / 7090 – Plain washers for metric bolts
- ASME B18.22.1 – Inch series flat washers
- ASTM F436 – Hardened steel washers for structural bolts
- SAE J403 / J995 – Mechanical and automotive washers
- Custom / OEM – Washers made to client drawings and tolerances
Flat Washers Surface Finishes
- Plain (Self-colored) – Untreated surface for dry, indoor applications
- Zinc-Plated – Corrosion protection for moderate environments
- Hot-Dip Galvanized – Excellent for outdoor or corrosive industrial settings
- Black Oxide – Aesthetic and light protection
- Electropolished / Passivated Stainless Steel – For marine, food-grade, or chemical exposure
- Powder-Coated / PTFE-Coated – On request for color-coded or low-friction applications
Why Choose MT.BOLTS
- Material Diversity
- Standardized Production
- Ample Inventory
- Competitive Pricing
- Low-MOQ Customization
Benefits and Limitations of Flat Washers
Benefits:
Distributes load to prevent surface deformation
Protects base materials from bolt/nut damage
Reduces risk of pull-through, especially in soft materials
Helps ensure accurate torque application
Can be combined with lock washers or sealing elements
Limitations:
Provides no locking capability alone
May add slight thickness to assembly
Not ideal for high-vibration applications without additional locking components
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Flat Washers Applications
- Steel structures and construction assemblies
- Automotive and heavy equipment
- Electrical enclosures and panel fastenings
- Marine, plumbing, and piping systems
- Appliances, furniture, and hardware
- Aerospace and power generation (with suitable materials)
FAQ About Flat Washers
They spread the load of a threaded fastener, protecting the surface and ensuring stable clamping.
When fastening into soft materials like plastic, wood, or thin sheet metal to prevent damage.
Not always, but they are highly recommended for load distribution and surface protection.
Yes, MT.BOLTS offers stainless (304, 316) and custom flat washers to exact specifications.
Not by themselves—they are often paired with lock washers or locking nuts for that purpose.
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