Weld Nuts — Hex, Square, Round & Specialty Weld-On Nuts

Types of Weld Nuts

A weld nut is a specialty fastener designed to be permanently welded to a base material, creating strong captive threads for bolt-up assembly. Unlike standard nuts that rely on a through-hole and wrench access from both sides, weld nuts attach directly to one surface — making them ideal for enclosed assemblies, thin-gauge sheet metal, and high-volume manufacturing where speed matters.

• Hex Weld Nuts (3 Projection): The most widely used weld nut style. Three equally spaced welding projections melt during resistance welding to form a strong bond. Available with short pilot (flush mount) or long pilot (self-locating through a hole). Conforms to general industry standards for projection welding.
• Square Weld Nuts: Offer superior resistance to rotation compared to hex styles. Often preferred for structural and heavy equipment applications where anti-rotation is critical. Available in standard and heavy patterns.
• Round-Base Spot Weld Nuts: Designed for automated spot welding lines. The round flange provides consistent weld nugget placement and works well with robotic welding systems.
• Tab Weld Nuts: Feature extended tabs or ears for manual MIG or TIG welding. A good choice for repair work, prototyping, and lower-volume fabrication where resistance welding equipment isn't available.
• Floating Weld Nuts (Cage Nuts): Mounted in a spring-steel cage that allows the nut to “float” and self-align with mating holes. Common in automotive body panels and enclosure assemblies where hole alignment varies.

Weld Nut Sizes & Thread Options

We stock weld nuts in both inch and metric sizes to cover virtually any fabrication need:

• Inch sizes: #8-32 through 3/4"-10, in UNC (coarse) and UNF (fine) threads
• Metric sizes: M4 through M16, standard coarse pitch
• Pilot styles: Short pilot (flush), long pilot (self-locating), and non-piloted

If you need a specific thread size or pilot length not shown in our catalog, contact us — we can source specialty weld nuts for your project.

Materials & Finishes

• Low Carbon Steel (Plain): The standard choice for most welding applications. Provides excellent weldability and strength at the lowest cost.
• Stainless Steel (18-8 / 304): For applications requiring corrosion resistance — food processing equipment, outdoor structures, marine environments. Requires appropriate stainless welding wire and shielding gas.
• Zinc Plated Steel: Adds corrosion resistance while maintaining good weldability. Note that welding through zinc plating produces fumes — proper ventilation is required.

Weld Nut Applications

Weld nuts are used across every industry that involves metal fabrication:

• Automotive & Transportation: Body panels, frame assemblies, brackets, exhaust systems, and underbody components
• General Fabrication & Manufacturing: Equipment enclosures, machine guards, conveyor systems, and control panels
• Structural Steel & Construction: Embed plates, beam connections, handrail brackets, and rebar accessories
• HVAC & Mechanical: Ductwork connections, equipment mounting, and access panel hardware
• Agricultural Equipment: Implement frames, guard rails, and mounting brackets exposed to harsh conditions

How to Choose the Right Weld Nut

Selecting the right weld nut depends on your welding process, base material thickness, and assembly requirements:

• For resistance (projection) welding lines: Use hex weld nuts with 3 projections or round-base spot weld nuts. These are designed for automated, high-volume welding.
• For manual MIG or TIG welding: Tab weld nuts are the easiest to attach without specialized equipment.
• For thin sheet metal (under 16 gauge): Choose a short-pilot hex weld nut — the flush profile won't interfere with nearby components.
• For alignment-critical assemblies: Floating cage nuts or long-pilot weld nuts help compensate for hole tolerance variations.
• For anti-rotation requirements: Square weld nuts provide the best resistance to turning under load.

Building a welded assembly? Pair your weld nuts with our threaded weld studs, weld stud ferrules, and headed concrete anchors for a complete weld fastener solution. Need help with specifications or bulk pricing? Contact our sales team — we're fastener specialists who've been helping fabricators since 1965.

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