torque specs and anti-seize compound

[Werner R.]

following up on a prior exchange wherein it was suggested that applying anti-seize to a bolt would make it snap off before reaching torque specs, i did a little experiment. i bought regular hardware store 1/4 inch bolts and lock washers and nuts. one group with anti-seize and the other without. using a vice, i gradually tightened the bolts, one at a time, using a torque wrench. the naked bolts all tightened to 7.5 foot pounds. when i kept going, i stayed at 7.5 for about 180-270 degrees before the bolt snapped off. very reproducible for each system.
when i did the same thing to the anti-seize group, i got to 7.5 foot pounds without a problem. then, when i kept turning, i easily passed 180-270, but instead of snapping off, somthing goofy happened to the threads. the bolt turned freely; the torque reading dropped to zero. however, most important for me, i could no longer remove the nuts because the internal threads were shot. the nut turned freely on the bolts [in both directions], just using fingers alone.
my conclusion is that if i use anti-seize, it is safe to go to the torque spec, and a few degrees beyond, but to be careful, which i would do anyway.
also, i don't know how hardended bolts would work.
i am only pointing this out for the fun of it; i doubt this is earth shaking stuff.

[Duke W.]

Re: torque specs and anti-seize compound

Anti-seize compound or other lubricants reduce thread friction, so more clamping force will usually be achieved at a given torque with anti-seize or other lubricant.

Bolt torque specs are usually specified as a range and the maximum torque for a given shank size and thread pitch depends on the SAE grade. You didn't mention what you used, but I suspect Grade 2 rather than grade 5. The SAE grade is the number of radial lines on the bolt head plus 2. When using anti-seize you should probably only torque to the lower end of the acceptable range. I alway use antiseize for bolts engaging aluminum threads. I also like anti-seize on wheel nuts. They torque up very consistently and spin on and off very freely with a speed handle.

Duke

[Clem Z.]

Re: torque specs and anti-seize compound

go to www.arp-bolts.com/pages/tech/images/fasttorq.pdf and notice the difference in torque specs between motor oil and moly

[Dick G.]

Re: torque specs and anti-seize compound

I have worked at a Coal Mine for the last 23 years. We were told by numerous vendors; the likes of Cat and Super Tanium Bolt co. to reduce specified torque settings by 50% when lubing the threads,oil or anti-seize. This is hard to take for most people. Please keep in mind that with the large machinery I work around, sooner or later we will be tearing it apart again. Do your own experimenting. On my cars I run every single nut and bolt with a tap and die. I feel this is the next best thing and I follow by using a torque wrench on all fasteners. You must use anti-seize on stainless steel fasteners. They will seize for sure,or have a torch! You Choose!