What is stainless ‘galling’?

Galling is when two threads bind together and seize. It can be fairly common when using stainless steel fasteners. This seizing or ‘cold-welding’ can result in fasteners having to be cut away as un-threading is impossible.

 When is galling likely to occur?

  • With larger threads of stainless fasteners – say M10 and up – this is because of a greater surface contact area, therefore more friction occurs in installation, causing heat, and binding. But note that there is a risk of all thread sizes galling.
  • Nyloc Nuts – the nyloc causes pressure between the threads, again causing friction.
  • When the thread is under load –say a turnbuckle tightening wire.
  • Dirt in the threads.
  • Installing too quickly – have a look at this video illustrating this point – watch until 1:10. (Note Anzor does not stock the product this video promotes).

 How to avoid galling

  • Lubricate the threads – when it comes to choosing a lubricant, it is important to use a Nickel based stainless lubricant or a lanolin based lubricant, i.e. something that won’t react with the stainless steel. We stock Loctite 771 a nickel based lubricant specifically for stainless steel threads: We also stock Lanotec – a lanolin based lubricant, and Tef Gel which also prevents galling.
  • Remove particles and dirt from threads.
  • Moderate the installation speed to a low rate of RPM. If the threads are lubricated, you may be able to install at a higher RPM.

Good luck with your threading. For more information on galling, please see this article by ASSDA: Galling by the Australian Stainless Steel Development Association.

NB: This information is provided as a guide only and Anzor does not accept liability for the application of this information. For advice about stainless steel contact the Nickel Institute at www.corrosioncontrol.co.nz.

 

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