Square U-Bolts

Square U-Bolts — Square Tubing Clamping U-Bolts | M8–M30 | DIN 3570 Square Bend

Square U-bolts feature a square bend designed for clamping square or rectangular tubing, box sections, and structural profiles. Unlike round U-bolts, the square bend provides full contact with flat surfaces of square tubing, ensuring secure gripping without deformation. Available in M8 to M30 thread sizes for square tubing from 20mm to 150mm.

Material & Specifications

Size Range	M8 to M30 (thread) / tubing: 20mm to 150mm (3/4″ to 6″)
Standard	DIN 3570 (square variant), custom specifications
Material	Carbon Steel (Grade 4.6/5.6), 304 SS, 316 SS, Galvanized Carbon Steel
Surface / Coating	Hot-Dip Galvanized (HDG), Electroplated Zinc, Dacromet
Tubing Size	20x20mm to 150x150mm square tubing
Configuration	2 nuts + 2 flat washers per U-bolt (standard)

Surface Treatment & Zinc Coating Quality

At BoltNutsPlus, we understand that surface treatment is critical to fastener longevity and performance. Our products 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. 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

• Square bend provides full surface contact with square tubing for secure grip
• Prevents tubing deformation by distributing clamping force evenly
• Galvanized finish for outdoor and corrosive environment applications
• Stainless steel option for food processing and pharmaceutical applications
• Custom square sizes and leg lengths available upon request
• Supplied complete with nuts and washers for immediate installation

Applications

• Square tubing structural connections and bracing
• Vehicle and trailer axle and suspension mounting
• Agricultural equipment frame and implement attachment
• Sign post and traffic signal pole mounting
• Solar racking system square tubing connections
• Industrial equipment and machinery frame assembly

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