Torque Wrench Myth Busters

[Scoutmapper]

I found this video very helpful for what is true and what is myth on torque wrenches.
Especially found value in Myth 9 on Anti-seize. (spoiler alert, don't use it for torque specs without cutting that torque spec in half)

 

[Zorba]

I found this video very helpful for what is true and what is myth on torque wrenches.
Especially found value in Myth 9 on Anti-seize. (spoiler alert, don't use it for torque specs without cutting that torque spec in half)

Wow - blown away here by the never-seize!

 

[GregBelleville]

Well shit,I definitely over torqued my rear track bar last weekend.

 

[JMT]

So the 20-25% rule just got shut down.

 

[Zorba]

So the 20-25% rule just got shut down.

Looks that way. At least for the Permatex anti-sieze they were using - which is the exact stuff I have....

 

[OldBuzzard]

Anti-seize is a lot slicker than threadlocker, I think. I always used the 20% rule on threadlocker, but just guessed when using anti-seize.

 

[OldBuzzard]

In the dry Colorado climate, I rarely use anti-seize. Besides, threadlocker seals and protects the threads, too.

 

[JMT]

In the dry Colorado climate, I rarely use anti-seize. Besides, threadlocker seals and protects the threads, too.

Seems to me that the amount of threadlocker or anti-seize applied to the bolt would create the variances discussed in the video. I try to be very consistent in my application and not overdo it. I put it on the bolt, then use my fingers to work it into all the threads. Any excess goes to the next bolt or back in the bottle.

 

[ColoJeep]

Wow - blown away here by the never-seize!

I also was shocked , that it would double the reading !

 

[Apparition]

I also was shocked , that it would double the reading !

Would have liked to see what reading they’d get if they reduced the input torque by 20-30%.

 

[Zorba]

Would have liked to see what reading they’d get if they reduced the input torque by 20-30%.

Yea, its probably non-linear.

 

[mrblaine]

Not saying they are wrong but something is very odd. If you take a 5/16-18 grade 8 hex head cap screw and torque it to 40 ft lbs, I don't think any of them will remain unbroken. Yet, we have done 100's and 100's of that size fastener in bead locks at 20 ft lbs with A/S and have never broken a single bolt. Need to figure what is going on and why we aren't seeing the failures we should be.

 

[Apparition]

Not saying they are wrong but something is very odd. If you take a 5/16-18 grade 8 hex head cap screw and torque it to 40 ft lbs, I don't think any of them will remain unbroken. Yet, we have done 100's and 100's of that size fastener in bead locks at 20 ft lbs with A/S and have never broken a single bolt. Need to figure what is going on and why we aren't seeing the failures we should be.

We used it religiously offshore specifying a 20-30% reduction never heard of any issues.

 

[ColoJeep]

Would have liked to see what reading they’d get if they reduced the input torque by 20-30%.

Yes ! , my previous anti-seize torque reduction was always 30% . It appears that I've stretched a lot fasteners over the decades ...

 

[SSTJ]

Not saying they are wrong but something is very odd. If you take a 5/16-18 grade 8 hex head cap screw and torque it to 40 ft lbs, I don't think any of them will remain unbroken. Yet, we have done 100's and 100's of that size fastener in bead locks at 20 ft lbs with A/S and have never broken a single bolt. Need to figure what is going on and why we aren't seeing the failures we should be.

Interesting. I think that their device must be measuring the clamping force of the bolt and nut, which is a good measure of how much the bolt is being strained or stretched length-wise. Makes sense that if the friction is reduced, the same amount of torque applied on the bolt would yield a higher clamping force.

But the torque wrench’s reading would still give an accurate measure of the torque applied to the bolt head, which is the force that would cause a head to shear off. What do you think?

If that’s what’s going on, then the danger of accidentally over-torquing due to anti-seize isn’t as much a threat to the shear-strength of the bolt shank as it is a risk of clapping down too hard on whatever the bolt is holding in place. Maybe?

 

[Danarch]

That was interesting. I am surprised at the difference with the anti-seize.

 

[mrblaine]

Interesting. I think that their device must be measuring the clamping force of the bolt and nut, which is a good measure of how much the bolt is being strained or stretched length-wise. Makes sense that if the friction is reduced, the same amount of torque applied on the bolt would yield a higher clamping force.

But the torque wrench’s reading would still give an accurate measure of the torque applied to the bolt head, which is the force that would cause a head to shear off. What do you think?

If that’s what’s going on, then the danger of accidentally over-torquing due to anti-seize isn’t as much a threat to the shear-strength of the bolt shank as it is a risk of clapping down too hard on whatever the bolt is holding in place. Maybe?

I tend to avoid videos even those that are done by the "experts" so I'm not familiar with what their load "cells" are doing. There is a pair of them, they are obviously being compressed to drive the gauge but how they are equating that to actual measured torque in ft lbs is not something I can figure out readily.

On the theory side, what we are trying to accomplish for slip critical connections is an assumed amount of clamp force when we stretch the bolt. That has been reasonably figured out based on force to turn the bolt or nut. The far more accurate way is to turn the bolt X amount after the faying surfaces make solid contact. Or put another way, we are trying to accomplish the accurate method with a reasonably repeatable and much easier solution by using measured force.

All I know for sure is their assertion that the torque must be reduced by 1/2 doesn't match anything we deal with and at no point in time does the torque value get anywhere close to clamp load for higher graded fasteners.

Any of the common bolt charts show that fairly readily. We're looking at about 5000 lbs of clamp load for a bead lock bolt.