Industrial Fastener · Bolts Series
Square Head Bolt
Square head bolts have a four-sided head, used historically before the hex head became standard. They remain in use today in specific machinery applications, restoration work, and architectural ironwork. The square head can be wrenched with an open-end wrench in tight spaces where a hex socket...
Product Overview
Square Head Bolt sourcing essentials
Square head bolts have a four-sided head, used historically before the hex head became standard. They remain in use today in specific machinery applications, restoration work, and architectural ironwork. The square head can be wrenched with an open-end wrench in tight spaces where a hex socket cannot fit.
DIN 478, DIN 479 (square head, square neck)
Carbon steel, Stainless
Machinery, valve handles, antique restoration, architectural
Inspection records, lot labels, certificate options, and destination-ready packing.
Technical Data
Specification range
Final dimensions, mechanical properties, finish, and packing are confirmed against the RFQ and applicable standard.
| Standards | DIN 478, DIN 479 (square head, square neck) |
|---|---|
| Diameter Range | M6 – M30 |
| Material | Carbon steel, Stainless |
| Surface Finish | Plain, Zinc plated, HDG, Black oxide |
| Application | Machinery, valve handles, antique restoration, architectural |
Common surface finishes
Select an option to review its sourcing note. Exact coating system, thickness, and corrosion requirement are confirmed with the order.
Quality Control
Checked before consolidation and export
Each order is matched to the specified standard and verified at practical control points before shipment.
RFQ confirmation
Standard, size, grade, pitch, finish, certificates, packing, and destination are locked before production.
Lot verification
Critical dimensions, thread fit, markings, finish appearance, and packing labels are sampled and recorded.
Shipment approval
Photos and required reports are organized before consolidated loading and export documentation.
Buyer Questions
Frequently asked questions
Why are square head bolts still used?
Square heads provide better wrench grip on four flats versus hex's six, and can be tightened with adjustable wrenches more securely. They are still specified in some heavy machinery, valve assemblies, and any application where the visual or mechanical heritage of the connection matters.
Ready to quote Square Head Bolt?
Send the standard, size, grade, finish, quantity, packing requirement, and destination. Availability and lead time are confirmed with the inquiry.