When to Use Thread Lubricant 1

[Althalus]

I know that thread lubricant is sometimes used for structural bolted connections. I've never used it for any application.

What design conditions would exist where thread lubricants would be advised? What is the advantage?

 

[dik]

for what purpose are you lubricating them?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Althalus]

Structural steel in general. No particular project. I'm just wondering why it is even an option. I've never been told I need to use it in any application. But I've heard of it being used "somewhere". I'm just wondering what the reasons for it are, what is the benefit?

 

[OldDawgNewTricks]

Be careful if you are using tension conrol (twist-off) bolts. They are pre-lubricated by the manufacturer and secondary lubrication is not permitted.

 

[dauwerda]

Galvanized nuts (for A325 bolts) typically come with a wax lubricant applied. This is due to the galvanized surface causing an increased friction coefficient between the threads of the nut and bolt. When this is done, the bolt manufacturer is required to perform rocap testing.

A lubricant will reduce the friction between threads. This will result in a lower (and possibly more consistent) torque required to develop a desired pretension in the bolt. If bolts are not stored properly and become rusty or dirty it is generally desirable (and sometimes required per code) to clean and relubricate the bolts as necessary.
See section 2.10 of the RCSC for more information on this.

http://boltcouncil.org/files/2020RCSCSpecification.pdf

 

[NorthCivil]

Wait, the age old debate around here is how to prevent a nut from vibrating loose from the thread. Not how to lubricate the thread!

I have specified lock-tite, epoxy thread locker for places where this concerns me. Never have i specified lubricant.

Though in my applications i am usually working with M12 (1/2") bolts or smaller

 

[dauwerda]

Well, technically loctite would act as a thread lubricant during installation - in the automotive world where specifying torques is the norm, it is generally recommended to reduce torques by 20% when using loctite (or so the interwebs tells me).

 

[azcats]

In the past, I've recommended Castrol Stick Wax in applications with really large bolts where installers are looking for reduced torque to achieve proper tension.

One particular installer always uses now simply to reduce the torque and associated wear and tear on his equipment. Typically these guys are using turn-of-the-nut for tensioning.

In addition: [URL unfurl="true"]https://www.portlandbolt.com/technical/faqs/waxed-nuts/[/url]

 

[BJI]

I would caution using lubricant with the turn-of-nut method, since snug tightening lubricated 3/4" or 7/8" bolts can bring them close to the proof load. A calibrated procedure would be essential.

If torqueing, then lubricant/anti-seize would be recommended. Reduces wear / galling and improves the accuracy of the achieved bolt load. Ideally the nut factor would be obtained from testing with the specific lubricant used.