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How to choose the right washer for your application

by: Blue Ribbon Fastener | June 23, 2026
 

Time to Read: 6m 44s

Washers may be one of the simplest components in a fastening assembly, but selecting the wrong washer can lead to loose connections, surface damage, corrosion issues, or premature fastener failure.

Whether you’re working in construction, manufacturing, maintenance, or OEM production, choosing the right washer helps improve load distribution, protect materials, and increase the reliability of your assembly.

This guide explains the most common washer types, their applications, and the key factors to consider when selecting the right washer for your project.

What does a washer do?

A washer is a thin plate, disc, or ring installed between a fastener and the material being secured. Washers serve several important functions:

  • Distribute load across a larger surface area
  • Reduce damage to the fastening surface
  • Prevent loosening caused by vibration
  • Improve clamping force
  • Protect against wear
  • Provide spacing or alignment

The best washer choice depends on the specific requirements of the application.

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Common types of washers

Different washer designs are intended for different purposes. Understanding these categories is the first step toward selecting the correct product.

Flat washers

The most commonly used washer type. Designed to distribute fastener load across a larger surface area, reducing stress on the material being fastened.

Common applications:

  • Construction
  • Manufacturing equipment
  • Machinery assembly
  • General fastening

Lock washers

Designed to resist loosening caused by vibration or dynamic loads. Common types include:

  • Split lock washers
  • External tooth lock washers
  • Internal tooth lock washers

Frequently used in machinery, equipment, and maintenance applications.

Fender washers

Feature a larger outside diameter than standard flat washers. Used when:

  • Additional load distribution is needed
  • Working with thin materials
  • Repairing oversized holes

Help reduce pull-through and material damage.

Structural washers

Thicker and stronger than standard flat washers. Specified for:

  • Structural steel applications
  • Heavy construction
  • Infrastructure projects

Designed to meet specific industry standards and load requirements.

Sealing washers

Combine a metal washer with a rubber or elastomer component to create a weather-resistant seal. Common in:

  • Roofing systems
  • Outdoor equipment
  • HVAC installations
  • Metal building construction
Browse flat washers → Browse split lock washers → Browse tooth lock washers →

Choosing the right washer material

The washer material should be compatible with both the fastener and the operating environment.

Material Best for Notes
Carbon steel General-purpose indoor applications Available plain, zinc-plated, or with other coatings
Stainless steel Outdoor, marine, food processing, chemical environments Excellent corrosion resistance
Hot-dip galvanized Outdoor structural applications, bridges, utility structures Thick zinc coating for maximum weather protection
 

Consider the application environment

Environmental conditions play a major role in washer selection. Ask the following questions before specifying:

Will the assembly be exposed to moisture?

Outdoor environments may require galvanized or stainless steel washers to prevent corrosion and premature failure.

Is corrosion a concern?

Certain industries — including food processing, marine, and chemical processing — require corrosion-resistant materials for long-term reliability.

Will the fastener experience vibration?

Equipment and machinery applications may benefit from lock washers or other locking solutions to maintain clamp load over time.

Are high loads involved?

Structural applications often require heavier-duty washers engineered for increased load capacity and compliance with applicable standards.

Match the washer to the fastener

Washers should be properly sized to match the fastener being used. Key considerations include:

  • Inside diameter
  • Outside diameter
  • Thickness
  • Material compatibility
Using the wrong washer size can reduce clamping performance and compromise assembly integrity. Always verify dimensional specs against the fastener and application requirements.

Common washer selection mistakes

Choosing based on price aloneThe least expensive washer may not provide adequate corrosion resistance or load distribution for the application.
Ignoring environmental conditionsA standard carbon steel washer can fail quickly in outdoor or corrosive environments without a protective coating.
Using the wrong washer typeFlat washers, lock washers, and structural washers are engineered for different purposes and are not interchangeable.
Mismatching materialsMixing incompatible metals — such as carbon steel and aluminum in wet environments — can accelerate galvanic corrosion and reduce service life.

Frequently asked questions

Do I need a washer with every bolt?
Not always. Some applications require washers for load distribution or surface protection, while others use flange fasteners or engineered assemblies that eliminate the need for a separate washer. Consult project specifications to determine requirements.
What is the difference between a flat washer and a lock washer?
Flat washers primarily distribute load and protect surfaces, while lock washers are designed to resist loosening caused by vibration or dynamic loads. In some assemblies, both are used together.
Can stainless steel washers be used with carbon steel bolts?
They can, but material compatibility should be evaluated. In most dry, indoor environments the galvanic corrosion risk is minimal. In wet or corrosive environments, mixing carbon steel and stainless steel can accelerate corrosion of the carbon steel component, so a fully stainless assembly is generally preferred.
When should I use a fender washer?
Fender washers are ideal when greater load distribution is needed, when fastening thin or soft materials, or when repairing assemblies with oversized holes.
What washer should be used with structural bolts?
Structural applications typically require hardened structural washers that meet applicable project specifications and standards such as ASTM F436. Always verify requirements against project drawings and engineering specifications.

Need help selecting the right washer?

Choosing the correct washer can improve fastener performance, extend assembly life, and reduce maintenance costs.

Blue Ribbon Fastener supplies flat washers, lock washers, structural washers, stainless steel washers, and industrial fastening solutions for construction, manufacturing, maintenance, and OEM applications.

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