Do you ever feel like you’re spinning your wheels trying to decide between a flange nut and a washer? With so many options for fasteners these days, it can be tough to know which one is the right fit for your project. Well, fret no more – this handy guide will walk you through the key differences between flange nuts and washers so you can make an informed choice.

Don’t Get Screwed - Flange Nuts vs Washers: Which Should You Use? - Flange nut vs washer


When it comes to mechanical fastening, two of the most common components are flange nuts and washers. Though they may seem interchangeable at first glance, there are some important distinctions between the two that make each better suited for certain applications.

In a nutshell, a flange nut has a built-in flange that acts as an integrated washer. The flange provides a larger bearing surface to distribute load. A washer is a separate thin disk-shaped component placed under the nut to also spread force.

So when should you use one versus the other? There are a few key factors to consider when deciding between flange nuts vs washers:

Flange Nut Pros

  • All-in-one component – Flange nuts integrate the flange/washer so there’s only one piece to install. This can speed up assembly.
  • Anti-rotation – The larger flange provides rotational resistance to prevent loosening.
  • Weight savings – Flange nuts eliminate a separate washer, reducing weight (important in automotive or aerospace applications).
  • Corrosion resistance – Flange nuts allow coating of the entire external surface for protection.
  • Material options – Flange nuts can be custom machined in exotic materials like titanium.

Washer Pros

  • Flexibility – Washers let you optimize size/material separately from the nut.
  • Cost – Simple flat washers are cheaper than flange nuts in many sizes.
  • Space constraints – Separate washers can fit in tight spots where a flange won’t.
  • Damage resistance – Washers spread load over paint/soft surfaces better.
  • Thread protection – Using an oversized washer distributes force away from threads.
  • Reusability – Washers can be reused if the nut is removed whereas flange nuts may become damaged.

Now that we’ve covered the key pros and cons, let’s dive deeper into some common scenarios to reveal when one option has a clear advantage over the other.

When to Choose Flange Nuts

High Vibration Applications

Flange nuts excel in uses where vibration is prevalent like automotive suspension components or motorcycle engine mounts. The integrated design resists loosening while the metal-to-metal contact provides positive locking.

Weight Sensitive Uses

In aerospace, racing, or any application where weight matters, flange nuts provide weight savings over a separate nut and washer. This helps optimize performance and fuel efficiency.

Corrosion Resistance Needs

Flange nuts allow coating of the entire exposed surface to protect against rust and other corrosion. The flange shields the threads from weather exposure.

Soft Joining Surfaces

The large flange on a flange nut distributes force over a bigger area compared to a flat washer. This prevents damage when fastening into wood, plastic, or other soft materials.

Fastener Reuse Not Needed

Since flange nuts can become marred during removal, they’re recommended when there is no need to disassemble and reuse the nut later. The flange adds security against loosening so re-torqueing is not required.

When to Choose Washers

Low Clearance Applications

Separate washers can be slimmed down to fit in tight spaces where a flange would be too bulky. Thin washers allow fastener installation where space is very constrained.

Cost-Sensitive Projects

Simple circular washers are generally more economical than flange nuts, especially in larger sizes. If budget is a primary concern, washers provide significant cost savings.

Odd-Shaped Holes or Surfaces

Washers can be sourced in a wide variety of shapes – oval, triangular, etc. – to fit nonstandard mounting holes or surfaces. Flange nuts are limited to hex shapes.

Soft Metals and Protective Coatings

Washers better distribute load over softer metals like aluminum, brass, or stainless steel to avoid damage to the material surface. They also protect against marring of coatings like paint or powder coat.

Unknown Future Fastener Needs

With washers, you aren’t married to one fastener. The nut can be removed and replaced if needed while reusing the same washers. Flange nuts must be replaced if removed.

Other Considerations

Beyond the basics above, here are some other tips for choosing between flange nuts and washers:

  • For heavy loads demanding maximum strength, choose a flange nut in a high grade alloy steel.
  • When vibrations are a concern, use a flange lock nut which incorporates a nylon locking element.
  • In dirty or outdoor settings, a sealed flange nut with an integrated o-ring is a smart pick to keep out grime.
  • For plating needs, it’s easier to plate an individual washer than a flange nut.
  • Flange nuts often require a wrench whereas many washer types can be installed with just hand torque.
  • Consider washer thickness – thinner is better for tight spaces, thicker adds springiness to compensate for surface irregularities.
  • Stainless steel washers provide excellent corrosion resistance at low cost.


Here are answers to some frequently asked questions about flange nuts vs washers:

Are flange nuts and washers interchangeable?

Not necessarily. Flange nuts contain an integrated washer flange so they can often serve the same purpose of spreading load as a separate washer. However, there are applications where one item may be better suited than the other.

Do you need a washer with a flange nut?

Usually not, since the flange acts as a washer surface. However, in some cases using an additional thin lower washer can help compensate for an uneven fastening surface.

What’s the difference between a flange nut and lock nut?

A flange lock nut combines the flange surface of a flange nut with a nylon locking element that resists vibration loosening. Lock nuts don’t have a flange.

Are flange nuts reusable?

Flange nuts become damaged during removal so they generally should not be reused. The integrated flange gets marred by wrenches so its integrity is compromised.

Should I use a flange nut or bolt with flanged head?

For most purposes, a flange nut will provide greater security against loosening. Flanged head bolts concentrate force in a smaller area so are more prone to fatigue.


Whether you choose flange nuts or washers for your mechanical fastening needs, the most important rule is to use the right component for the application. Consider factors like vibration, corrosion, clearance, strength requirements, and reusability when deciding between the two options. And don’t forget – flange nuts and washers aren’t necessarily interchangeable despite their similarities. By understanding the pros and cons of each and thinking through your specific use case, you can confidently select the best fastening solution.

For any questions on selecting optimal fasteners for your next project, feel free to contact our engineering team at Jmet Corp. We offer expert guidance and a wide range of flange nuts, washers, and all related fastener components. Get in touch today to take your fastener knowledge to the next level!