Square Washer

Square Washer — Square Plate Washer | DIN 436 / DIN 434 | Timber & Structural Steel Application

Square washers are large bearing area washers with a square outer profile, specifically designed for timber construction, structural steel connections, and slotted hole applications. Manufactured to DIN 436 (square washers for timber), DIN 434 (square taper washers for channel sections), and customized specifications, our square washers provide maximum load distribution and prevent the bolt head or nut from pulling through soft materials. Available with hot-dip galvanized coating as standard for outdoor and structural use, with sizes from M5 to M36.

Material & Specifications

Size Range	M5 to M36 / 3/16″ to 1-1/2″ (bolt diameter); plate sizes from 20×20mm to 120×120mm
Standard	DIN 436 (Square Washers for Timber Construction), DIN 434 (Square Taper Washers), ISO 7094, GB/T 97.3, Custom per Drawing
Material	Carbon Steel (S235JR / Q235B), High-Strength Steel (S355 / Q345B), 304 Stainless Steel (A2), 316 Stainless Steel (A4), Hot-Dip Galvanized Steel
Surface / Coating	Hot-Dip Galvanized (HDG) — Standard, Electroplated Zinc Blue/White, Color Zinc/Yellow, Dacromet, Multi-Element Alloy Co-Permeation, Plain/Black
Thickness Range	1.5mm to 10mm (depending on bolt size and load requirements)
Types	Standard Square, Square with Round Hole, Square with Slotted Hole, Heavy-Duty (Thick) Square

Surface Treatment & Zinc Coating Quality

At BoltNutsPlus, we understand that surface treatment is critical to fastener longevity and performance. Our washers undergo rigorous coating processes to ensure maximum corrosion resistance and durability. We offer five premium coating options, each tested to international standards:

• Hot-Dip Galvanizing (HDG) — Thick zinc layer (50-120μm) providing superior long-term corrosion protection for outdoor, marine, and industrial environments. Compliant with ISO 1461 / ASTM A153 standards. Salt spray resistance: 500-1,000+ hours. HDG washers are ideal for structural steel assemblies exposed to harsh weather.
• Electroplated Zinc Blue-White (Zn Blue/White) — Bright, clean silver-blue appearance with 5-15μm zinc layer. Cr3+ passivation technology, fully RoHS compliant. Ideal for indoor machinery, electronics, and general-purpose applications requiring aesthetic appeal and moderate corrosion resistance.
• Color Zinc / Yellow Zinc (Iridescent Passivation) — Multi-colored iridescent passivation film offering enhanced corrosion resistance (100-200 hours salt spray) with a distinctive golden finish. Widely preferred in automotive, agricultural equipment, and construction machinery sectors for its balanced protection and visual appeal.
• Dacromet Coating — Advanced water-based zinc-chromium coating technology with NO hydrogen embrittlement risk. Provides 1,000+ hours salt spray resistance, making it the preferred choice for high-strength fasteners in extreme environments. Environmentally friendly (no heavy metal discharge), RoHS/ELV compliant, ideal for automotive and wind energy applications.
• Multi-Element Alloy Co-Permeation — Zinc-aluminum-rare earth alloy layer offering 2-3x the corrosion resistance of traditional galvanizing. Features self-healing properties at scratch points, ensuring long-term protection even in damaged areas. Ideal for critical infrastructure, power transmission towers, coastal projects, and marine installations.

Key Features

• Large square bearing area distributes load over a wider surface — prevents pull-through in timber and soft materials
• Square profile resists rotation during tightening, providing a stable bearing surface in slotted connections
• Ideal companion to square head bolts and structural timber connectors for traditional and modern timber framing
• Thick plate construction (up to 10mm) for heavy structural loads in steel-to-steel and steel-to-timber connections
• Hot-dip galvanized standard for outdoor durability; other coatings available for specific environments
• Custom dimensions available — width, length, thickness, and hole size can all be specified to your requirements

Applications

• Timber construction — post and beam connections, timber framing, and log home assembly
• Structural steel connections with slotted holes requiring large bearing surface coverage
• Bridge construction and infrastructure projects with heavy structural loading requirements
• Transmission tower and utility pole base plate connections
• Scaffolding and temporary works requiring secure load distribution on varied substrates
• Marine and dock construction using timber piles and structural steel plates

Why Choose BoltNutsPlus?

• ISO 9001:2015 Certified Manufacturing — consistent quality you can trust on every batch
• 15+ Years of Export Experience — serving 40+ countries across 6 continents
• Full Traceability — material certificates (EN 10204 3.1) and comprehensive test reports included
• Custom Packaging & OEM/ODM — your brand identity, your specifications, our precision manufacturing
• Third-Party SGS / Bureau Veritas Inspection Available upon request
• 24-Hour Quote Response — same-day reply for urgent requirements; standard 24-hour turnaround