TMCnet Feature
February 17, 2020

Everything You Need to Know about Tension Control Bolts



Tension Control Bolts are the most commonly used fasteners for steel to steel fastening of high strength applications. Also known as tc bolts, these bolts have a dome-shaped head and they can’t be driven using any normal tools. Working with tension control bolts requires a special type of wrench. When the bolt is installed, it gets deformed and its extension gets sheared off because of the torque. The spine of the bolts allows users to measure when it reaches the exact amount of tension.



Important Properties of Tension Control Bolts:

  • These bolts are capable of preventing slippage because they come with a friction grip connection.
  • TC bolts are pre-loaded bolts and are highly recommended for designs where fatigue must be taken into account. The tension gets evenly distributed across the structure because of the heavy preload.
  • When they are installed in the right manner, tc bolts are extremely efficient in handling vibrations and ensuring that there is no loosening of the structure whatsoever. Once again, this property can also be attributed to the fact that these blots come with a preload.
  • TC bolts are also recommended for structures that involve swaying movement of cranes or other heavy equipment because the impact of load reversals can be prevented by preloaded tc bolts. This ensures that the structure doesn’t loosen or disintegrate, and retains its sturdiness.   
  • In addition to helping prevent load reversals, tc bolts are also used for the elimination of any possible connection slips.

Benefits of Using Tension Control Bolts:

As we have already mentioned, tc bolts are structural bolts used for steel structure construction. Therefore, these bolts are created to provide the highest possible longevity to the structure. Moreover, though its fastening mechanism is complicated, tc bolts are easy to use and can be installed by just one person. The inbuilt functionalities of these bolts allow for determining the tensioning required to hold together a structure  With the help of this functionality, users can also figure out whether the required tension has been achieved, regardless of how much torque was applied to achieve the tension.

  • Increased preloads and higher-grade steels allow these bolts to be used for smaller diameters.
  • There is no bolt relaxation because at the time of tension, torsional shear is not induced.
  • As they are vibration resistant, lock nuts are not required for tc bolts.
  • It is extremely easy to install tc bolts and the process can be handled by one person.
  • TC bolts of several dimensions can be installed by a single tool.
  • Requires minimal tool maintenance
  • Reduced operator fatigue.
  • No Hand Arm Vibration Syndrome risk.
  • Heavy calibrated torque wrenches are not required.

Problems with Tension Control Bolts:

Though the installation process can be completed by a single person within a short period of time, the overall process is often considered to be a complicated one. As a result, for steel to steel fastening, some construction owners prefer using regular hex bolts. However, it is important to understand that once properly installed, tc bolts provide much greater advantages compared to hex bolts.

Before deciding to use tension control bolts, it is important to take one of its important properties into consideration. Once these bolts are removed from the packing, they tend to corrode and lose their lubrication over a period of time.  This means that after being opened up, the bolts must be fastened immediately. Immediate fastening of tension control bolts is also necessary because if the bolts are simply placed in the structure without tensioning, the shear forces may put them in a bind. This will reduce the bolts’ load-bearing capacity and cause structural deformation. The rust build up also means that fastening the bolts as well as loosening them would require excess torque.      



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