Stainless Steel Square Washers - Grade 202, 304, 316, A2, A2-70

Square Washers are flat washers with a square outer shape and a central round hole. Unlike standard round washers, square washers offer a larger bearing surface and better resistance to rotation and pull-through, especially in wood-to-metal or structural applications.

Technical Specifications – Square Washers

Below is a standard technical specification table for Square Washers (commonly based on ASTM F436 or DIN standards, used in structural and wood applications):

Nominal Bolt Size	Hole Diameter (d)	Outer Width (L)	Thickness (t)	Standard	Common Finish
M6	6.5 mm	20 mm	3.0 mm	DIN 436	Zinc Plated / HDG / Plain
M8	9.0 mm	25 mm	3.0 mm	DIN 436	Zinc Plated / HDG / Plain
M10	11.0 mm	30 mm	4.0 mm	DIN 436	Zinc Plated / HDG / Plain
M12	13.0 mm	40 mm	5.0 mm	DIN 436	Zinc Plated / HDG / Plain
M16	17.0 mm	50 mm	6.0 mm	DIN 436	Zinc Plated / HDG / Plain
M20	21.0 mm	60 mm	6.0 mm	DIN 436	Zinc Plated / HDG / Plain
M24	25.0 mm	65 mm	8.0 mm	DIN 436	Zinc Plated / HDG / Plain
M30	31.0 mm	75 mm	10.0 mm	DIN 436	Zinc Plated / HDG / Plain

Square Outer Profile: Distributes load more evenly on softer materials.
Round Inner Hole: Fits standard bolts or screws.
Enhanced Grip: Resists rotation better than round washers under torque.
Heavy-Duty Design: Ideal for bolted structural connections.
Mild Steel (Hot Dip Galvanized / Zinc Plated)
Stainless Steel (SS304 / SS316)
Brass / Copper (for decorative or conductive use)
Hardened Steel (for structural or seismic applications)
Hot-Dip Galvanizing (HDG) improves life span in outdoor conditions.
Hardened Steel (F436) is mandatory for structural steel bolting.
Stainless Steel 316 is superior in coastal or chemical exposure.
Brass & Copper are mostly chosen for non-structural or aesthetic/electrical needs.

Material Comparison Chart – Square Washers

Material	Grade / Type	Corrosion Resistance	Mechanical Strength	Magnetic	Finish Options	Applications
Mild Steel	IS 2062 / ASTM A36	Low to Moderate	Medium	Yes	Plain, Zinc Plated, HDG	Wood construction, light structural use
Stainless Steel	SS304	High	Medium	Slightly	Natural, Passivated	Coastal areas, general construction, corrosive settings
Stainless Steel	SS316	Very High	Medium	No	Natural, Passivated	Marine, chemical plants, food-grade applications
Hardened Steel	ASTM F436	Moderate	High	Yes	Black Oxide, HDG, Zinc Coated	Structural bolts, seismic zones, heavy construction
Brass	CuZn37 / IS 319	Moderate	Low	No	Natural, Polished	Decorative, antique fixtures, electrical terminals
Copper	ETP Grade / ASTM B152	Moderate	Medium	No	Natural	Electrical grounding, heat dissipation, conductive uses
Phosphor Bronze	C51000 / C54400	High	Medium	No	Natural, Tinned	Electrical/electronic, non-magnetic or anti-sparking use

Flat, square-shaped pieces of metal or plastic known as square washers are commonly utilized under bolt or screw heads for load distribution, surface protection, and stability. Their unique shape provides increased surface area and enhanced resistance to rotation, making them an ideal choice for demanding scenarios involving high stress and vibration.

Material

Stainless Steel (304/316)

Hole Diameter (d)

6.5 mm - 31.0 mm

Outer Width (L)

20 mm - 75 mm

Thickness (t)

3.0 mm - 10.0 mm

Enhanced Load Distribution

By utilizing square washers, the force is evenly distributed across a wider surface, resulting in reduced pressure on the material and a decreased likelihood of any potential damage.

Reduced Pull-Through

In substances such as wood or soft metals, they aid in avoiding the fastener from pulling through the material.

Improved Stability and Alignment

The square washer's flat sides offer enhanced stability and help prevent rotation, particularly in situations involving vibration or high torque.

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