Torque vs Tension: What’s the Difference?
Understanding the Differences and Applications
When it comes to ensuring the structural integrity of a building, bolted joints play a crucial role throughout construction. These essential components are used in anything from bridges to skyscrapers, and require proper tightening to ensure a building is as stable and durable as possible.
However, various methods exist to tighten bolts, including torque and bolt tensioning. Technofast’s EziJac Bolt Tensioners are unparalleled in meeting exact requirements with consistent accuracy while eliminating the need for manual tightening.
This article will discuss the difference between the two, their advantages and limitations, and how to choose the right method for your construction needs.
The Key Points
- Proper tightening of bolt joints is essential to ensure the structural safety of a building.
- Torque tightening involves using torque wrenches, while bolt tensioning uses hydraulic tensioning tools.
- Bolt tensioning is more accurate and consistent than torque tightening, while torque tightening is less expensive and more suitable for most applications.
- Choosing the appropriate method for tightening bolts requires assessing bolt load or clamping force, joint geometry, bolt size and strength, surface condition and texture, level of precision needed, and time and cost constraints.
- Proper maintenance and inspection of bolted joints are essential to prevent bolt failure and ensure safety and optimal performance.
Torque vs Tension: The Basics
Understanding the difference between torque and tension is absolutely essential for maintaining a long-lasting and sturdily-built structure.
To sum it up, torque tightening involves using torque wrenches to tighten bolts to a specific torque value, which is the rotational force applied to that specific nut or bolt head. Bolt tensioning, on the other hand, utilises hydraulic tools to apply a clamping pressure that pulls the bolt, thus creating tension.
Both methods have advantages and limitations. The method most suitable for your construction depends on its intended application.
Hydraulic torque wrenches and hydraulic bolt tensioners are high-quality tools that provide the higher torque output required for critical joints in a structure. They overcome friction and the bolt’s inherent spring tension to provide an evenly distributed bolt load. Additionally, direct tension indicating washers ensures the tightened bolt behaves as expected.
When comparing torque and tension, it’s essential to consider the torque-tension relationship and the opposite reactive force created by each method. The k-factor, or ratio of the bolt’s threads’ friction to its elastic properties, plays a substantial role in the tightening process. Other factors like bolt diameter, large threaded fasteners, and surface texture (E.g: rust or oil) also affect tightening.
You can create the necessary clamping force to keep a structure’s bolted components secure by applying the correct torque or tension. This is especially crucial for constructions such as high-pressure flanges, car wheels, and much more.
Bolt Tensioning vs Torque Tightening: Pros and Cons
Both torque wrenches and bolt tensioners have advantages and limitations depending on the application requirements, joint geometry, bolt size, and material properties. Here are some pros and cons of each method.
Torque Tightening:
- Easier and less expensive than bolt tensioning
- Suitable for most applications
- Requires less equipment and training
- Can provide adequate bolt compression for non-critical joints
- Highly dependent on surface texture, rust, oil, and lubrication
- The friction coefficient can vary significantly, leading to inconsistent bolt load
- Cannot compensate for inherent bolt spring tension or variation in bolt properties
- Cannot measure bolt compression or tension accurately
- It may require higher torque output for large-diameter or high-strength bolts, which may exceed the torque wrench capacity
Bolt Tensioning:
- More accurate and consistent than torque tightening
- Can compensate for bolt spring tension and variation in bolt properties
- Can measure actual bolt load or tension accurately
- Can apply a more even bolt compression across multiple bolts
- Suitable for essential joints, high-pressure flanges, and long-threaded fasteners
- More time-consuming and expensive than torque tightening
- Requires specialised equipment and training
- May not be suitable for small-diameter or low-strength bolts
- Requires a high torque output to overcome friction and create tension
How to Choose the Right Method for Your Application
Here are some tips on how to choose whether to use torque or bolt tensioning in your structure:
Technofast’s Bolt Tensioning Range
At Technofast, we believe that bolt tensioning is an excellent alternative to traditional torque methods.
Our EziJac Bolt Tensioning range offers a variety of different bolt tensioners — each with different specific applications and their own benefits.
Each of the products in this range is ideal for creating easier, safer, and more efficient practices.
Conclusion
In summary, the difference between torque and tension is that torque measures the rotational force applied to a bolt, while tension regards its stretching force. Both have advantages and limitations depending on the structure and their requirements.
Bolt tensioning is a more accurate and consistent method of tightening bolts; however, it requires specialised equipment and training that may make it more time-consuming and expensive than torque tightening.
Torque tightening, on the other hand, is a more commonly used method of tightening bolts; however, it is highly dependent on surface conditions and may not compensate for bolt spring tension or variation in bolt properties.
Whether using torque wrenches or hydraulic tensioning equipment, following the manufacturer’s recommendations and guidelines for achieving the correct torque or tension is essential. Using incorrect torque or tension can lead to catastrophic equipment damage or injury; for this reason, proper maintenance and inspection of bolted joints are essential to ensure they are adequately tightened, as regularly checking for any signs of wear or damage can help pre-emptively prevent bolt failure. It is crucial to properly train personnel on the correct bolt-tightening methods to ensure these safety measures are maintained.
