The Effect Bolts Have on the Relationship between Torque and Tension

In the bolt torqueing service industry, torque and tension are two very important terms that go around the factory often. Torque or torqueing is the process in which a nut is being spun around the bolt moving it along its threads so as to press down on the metal in between the nut and the bolt help. As the nut is tightened further this results in tension which is the force that secures the component together making it very important in industrial construction.

pipe fabrication

industrial project

If there is no tension then the nut would be loose from the bolt and the framework being secured would lose stability and fail. Basically it is the tension from hundreds of small nuts and bolts that hold together large metal frameworks and structures. You can relate the two terms together since it is torque that results in tension. However, there isn’t a standard number as to the relation between torque and the tension force.

There is no clear ratio between torqueing a nut and the tension that it will result in to the bolt. This is due to the fact that there are other factors that can affect the resulting tension and one of those factors is the bolt itself. You might see that bolts used in industrial construction come at pretty much the same size but if you look at it at a closer level there are actually small differences and variations and this is what affects the translation of torque into tension in bolt torqueing service.

Let’s take an example to have a better idea. Think about a worker that is trying to get a tension force of 30klbs using three separate bolts. When he torques the different bolts trying to make sure that they are all uniform, the results would all be different. The first nut that he torqued needed 500lbs of torque in order to reach 30klbs of tension. The second needed only 350lbs of torque to reach 30k while the third had to be torqued quite more at 1klbs of torque to reach 30klbs of torque. If you want to reach a certain tension force, you cannot base in on the force of the torque that you are using as there is just no uniformity.

For a better understanding, let’s use an example that doesn’t involve nuts and bolts and something that the average person would have an easier time understanding. Imagine driving a car along a flat and smooth terrain at 60 mph. You see that your mileage is at 30mpg but then you see an upcoming hill. As you take your car up the hill you try to maintain a speed of 60mph but then the mileage now shows 20mpg due to the fact the car exerts more.

In terms of the bolt factor, a new bolt would definitely be a lot easier to achieve the desired tension with as you don’t need to torque as much. In bolt torqueing service older bolts require more torque or will just have to be replaced with new ones.