Flange Lock Nuts Supplier
Adding a washer to every bolted connection means another part to stock, another part to lose on a job site, and another point where clamp load can shift. Valley Nut & Bolt supplies flange lock nuts that combine a wide bearing surface with a built-in locking mechanism in a single part, one less component for your assembly team to track. We've supplied flange lock nuts to machinery builders, fabricators, and equipment OEMs from our Olympia, Washington warehouse since 1969.
Ready to Simplify Your Fastener Assembly?
Stop stocking separate washers and hoping they end up in the right place. Send Valley Nut & Bolt your spec or drawing and we'll source the flange lock nuts, serrated, nylon insert, or hex flange, in the grade, size, and finish your assembly calls for.
What Is a Flange Lock Nut?
A flange lock nut is a hex nut built with an integrated, wider bearing surface (the flange) at its base, combined with a locking feature to resist loosening. The flange does two jobs at once: it spreads clamping load over a larger area of the work surface, reducing the point-load that can crush soft materials or oversized clearance holes, and it replaces the separate flat washer entirely, cutting parts count and assembly time.
The "lock" half of a flange lock nut comes from one of two designs, and the right one depends on your operating environment.
Flange Lock Nut Styles We Supply
The underside of the flange is cut with radial serrations that bite into the work surface as the nut is torqued down. This creates a mechanical, all-metal locking action with no plastic component to degrade, a design that overlaps with our prevailing torque lock nuts line and holds up in higher-heat, higher-vibration environments than a nylon insert.
The flange is paired with a nylon collar molded into the nut body, similar to our standard nylon insert lock nuts, but with the added bearing surface of a flange. This style suits general equipment and machinery assemblies where moderate operating temperatures allow the nylon insert to perform, and load distribution matters as much as thread lock.
For applications where the flange's bearing surface is the priority and vibration resistance is secondary, we also supply non-locking hex flange nuts as a companion product. Talk to our team about which configuration fits your assembly.
Materials, Grades & Finishes
- Carbon steel, Grade 2, Grade 5, and Grade 8, to ASTM A563 and SAE J995
- Stainless steel, 18-8 and 316 grades for corrosion-prone environments
- Alloy steel for high-strength connections
- Metric flange nuts to DIN 6923 profiles
- Finishes: plain, zinc-plated, and hot-dip galvanized
Where Flange Lock Nuts Are Used
Flange lock nuts show up wherever engineers need to eliminate a washer without giving up bearing surface or vibration resistance:
- Machinery and equipment manufacturing (engine mounts, guarding, panel assembly)
- Agricultural and off-road equipment
- HVAC and generator skids
- Automotive and heavy-truck fabrication
- Construction equipment assemblies where a fastener sees repeated vibration and needs a wide bearing footprint on sheet metal or lighter-gauge material
Flange Lock Nuts vs. a Standard Lock Nut with a Washer
Specifying a flange lock nut instead of a hex lock nut plus a separate flat washer reduces the bill of materials, speeds up assembly line time (one part to place instead of two), and removes the risk of a washer being installed in the wrong orientation or omitted entirely. The tradeoff is less flexibility. The flange size is fixed to the nut, so it won't substitute for an oversized or fender washer application. For most standard machinery and equipment assemblies, though, the flange nut is the more efficient spec.
Why Valley Nut & Bolt for Flange Lock Nuts
- Custom runs, not just what's in the bin. We size orders, from a single custom run to an ongoing supply arrangement, to your project.
- Vetted supply partners keep lead times short and quality consistent across grades and finishes.
- Full material traceability on every order, heat-lot to heat-lot.
- Regional speed, national reach. Next-day delivery on our own trucks in the Pacific Northwest; nationwide shipping for everyone else.
Need a locking nut without a flange, or one built for high heat instead? Compare our nylon insert lock nuts and prevailing torque lock nuts, or return to the lock nuts category for the full lineup.
Frequently Asked Questions About Flange Lock Nuts
Yes. The integrated flange serves the same load-distribution function as a flat washer, so most assemblies using a flange lock nut don't need a separate washer underneath it.
A serrated flange lock nut uses ribs machined into the underside of the flange to grip the work surface mechanically, an all-metal design suited to higher heat and vibration. A nylon insert flange lock nut uses a nylon collar in the nut body to grip the bolt thread, suited to moderate-temperature general industrial use.
Serrated flange lock nuts can generally be reused since the locking action comes from the serrations biting the surface each time. Nylon insert flange lock nuts follow the same reuse limits as standard nylon insert lock nuts, a few reinstalls before the locking grip weakens.
Yes, we supply metric flange lock nuts to DIN 6923 profiles alongside standard inch sizing.
We supply flange lock nuts in carbon steel (Grade 2, 5, and 8), stainless steel (18-8 and 316), and alloy steel, with plain, zinc-plated, or hot-dip galvanized finishes.
Ask Our Team
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360-754-4877
