A tight bolt is a good bolt. If a bolt in a frame structure is not tightened enough, that may cause the nut to slip off from the bolt and the plates in between will not be held in place anymore. Now when bolt torquing service workers are tightening bolts, they make sure that all of the bolts have a uniform tightness, but that does not mean torquing them at the same amount of force. Force those of you who don’t know, you should not base the tightness of the bolt on the torque force that was applied on the nut. This is because bolts have variations that can affect how torque becomes tightness.
When you are working with a rusty bolt and a new bolt, which do you think needs less torque to reach the desired tightness? It would be the new bolt, because with rusty bolts, you will need to torque down the nut a little more because the rusty bolt doesn’t have as much support strength as the new bolt. You can even find that there are differences in the torque between new bolts. Small variations between them can mean a lot when it comes to achieving the desired tightness.
A good practice with bolt torquing service workers is that they grease the bolts when tightening them. This is because a bolt that has been greased would require less torque than a bolt that is dry or hasn’t been greased to come to the needed tightness.
There are situations wherein the bolt starts to break and people think that tightness is responsible for the breaking and that the bolt has been tightened too much. In reality, the bolt was not over tightened, rather it was over torqued. Take note that the tightness of the bolt is not measured using the torque or how much it has been twist because as we have discussed, certain variations can affect that. A good bolt torquing service would know that to measure the tightness of the bolt, you would have to look at the tension.
Let me make this clear that torque can never be used as a form of measurement in bolt torquing because of how arbitrary the numbers are when you compare it to the amount of tension it produces. Bolts break not because of how much load or tension they are handling, but because of the twisting force of the torque on them. A good bolt holding around 25k lbs of tension would never break, but if the torque would go to just 1k lbs, then there is a good chance that the bolt will break.
So remember, the tightness of a bolt is never based on how much torque it took, but on the tension that the bolt is experiencing. Also note that it would be advised to lubricate your bolts when working on then so that you wouldn’t have to put them under too much torque but still be able to get the needed amount of tension or tightness to hold whatever is in between in place.