How Thread Galling Damages Stainless Steel Fasteners—and How to Prevent It

What Is Thread Galling?

Thread galling happens when metal threads—usually stainless steel—get stuck together during installation. As a bolt or nut is tightened, friction and pressure can cause the threads to seize, making it nearly impossible to continue turning. Forcing it further often results in damage or breakage.

Why Stainless Steel Is More Prone to Galling

Stainless steel is known for corrosion resistance, but it’s also softer and more ductile than many other metals. This makes it more vulnerable to galling, especially when stainless components are threaded together. As the surfaces rub under pressure, they can microscopically weld, causing seizure.

Some common factors that increase the risk include:

• Fast installation speeds (e.g., with power tools)

• Lack of lubrication

• Long-thread engagement

• Contaminated or rough threads

Why It Matters: The Cost of Galling

Thread galling isn’t just a nuisance—it can cause real problems on the production floor or in the field. It can:

• Waste fasteners and components

• Cause delays during installation or maintenance

• Damage equipment if removal is forced

• Interrupt assembly line operations

Even one seized bolt can lead to hours of lost time.

How to Prevent Thread Galling

Fortunately, galling is usually preventable. Here are some proven techniques:

1. Apply Lubrication or Anti-Seize
Use a nickel- or moly-based anti-seize paste to reduce friction during installation. It’s especially helpful for stainless fasteners exposed to heat or moisture.

2. Avoid High-Speed Tools
Tighten bolts at a steady, controlled speed. When possible, hand-tighten during final torque to reduce heat and friction.

3. Use Treated or Coated Fasteners
Opt for fasteners with anti-galling coatings like PTFE or black oxide. These reduce surface friction and help prevent thread welding.

4. Use Mixed Materials When Appropriate
Pairing stainless bolts with nuts of a different alloy (such as brass or coated carbon steel) can reduce the likelihood of galling.

5. Keep Threads Clean and Smooth
Dirt and damaged threads create extra friction. Always inspect fasteners before use and clean or replace any that show wear.

Considering Better Materials

In cases where galling is frequent, alternative materials can offer better performance:

• 316L Stainless Steel: Lower carbon content makes it more galling-resistant.

• Duplex Stainless Steel: High strength and wear resistance.

• Coated Carbon Steel: Works well in less corrosive environments and generally avoids galling.

Preventing Galling Is Always Worth It

Galling may seem like a minor issue, but it often leads to major setbacks. By understanding what causes it and how to avoid it, teams can save time, reduce waste, and improve assembly reliability.

About Fasto

At Fasto, we specialize in stainless steel fasteners designed to minimize issues like galling. Our product lines include:

• Coated and pre-lubricated bolts and nuts

• Materials tested to international standards (ASTM, DIN, ISO)

• Custom solutions for high-vibration, high-load, or corrosive settings

Need help choosing the right fasteners for your application? Get in touch with us today—we’ll make sure your components perform without complications.

📧 info@fasto.cn
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