Tension Control Or TC Bolts Complete With A Nut And Washer

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Questions And Answers On Tension Control Bolts

Where Are Tension Control Bolts Used?

Tension control bolts, which are sometimes called TC bolts, are used in the fastening of heavy-duty structural joints.

They are now applied to many settings that formerly required the use of a rivet or standard hex head bolt. They are used in favor of these fasteners because they can be installed more efficiently and are self-calibrating.

What Is Bolt Tension?

A bolt’s tension is the stretching or elongation of its threads that occurs as torque is applied to the bolt’s head or the nut. This force enables the clamping or gripping, which then fastens the connection.

To properly fasten such a connection, it’s important to identify the degree of torque that must be applied to the assembly.

What Is A TC Gun?

A TC gun is a power tool that's sometimes called a shear wrench. They are used to install tension control bolts in a highly efficient manner. They have an inner and outer socket, which holds the nut and the spline of the bolt.

The tool is then used to torque these two parts in opposite directions so the spline shears off and the bolt is properly tensioned in place.

What Are Tension Control Bolts Made From?

Tension control bolts work through a special self-calibrating process that ensures optimal tension is reached.

These bolts feature an end-piece known as a spline. This portion is designed to break or shear off once the correct tension is reached through torque. Torque is applied with the use of a shear wrench or TC gun, which is integral to the installation process.

How Does A Tension Control Bolt Work?

Tension control bolts work through a unique self-calibrating process.

They feature a spline or twist-off portion that is meant to be rotated in the opposite direction of the nut. This is done simultaneously with a TC gun or shear wrench. Once the spline is sheared off, that means an optimal tension has been achieved.

How Are Tension Control Bolts Measured?

Key measurements of tension control bolts are their diameter and length. Both of these measurements are based in the shaft of the bolt.

The diameter is the thickness of the unthreaded portion below the TC bolt’s head. The length includes the threaded portion without the spline, as that part will be sheared off once it is torqued and the bolt is installed.

How Are Tension Control Bolts Installed?

Installation of tension control bolts is completed with a power tool known as a TC gun or a shear wrench.

This tool is specific to the installation of these bolts, as it will simultaneously torque the nut and the spline of the bolt in opposite directions. This makes the spline shear off, thus ensuring the correct tension has been reached.

Do Tension Control Bolts Need Washers?

A proper tension control bolt assembly always includes a washer. This element will distribute load and enhance the security of the joint.

Manufacturers and suppliers of TC bolts will provide these fasteners as a total assembly, which includes a compatibly sized washer and nut. The washer will act as a barrier between the nut and the installation surface.

Do Tension Control Bolts Need To Be Tensioned Before Installation?

Best practices for installing tension control bolts indicate that they should be fully tensioned at the time of installation.

Delaying the tensioning for any reason can lead to the loss of lubrication and other issues, which will negatively affect the integrity of the assembly and overall connection.

Do Tension Control Bolts Need To Be Lubricated?

Tension control bolts require lubrication to ensure they are self-calibrating and can be installed with efficiency, ease, and precision.

Lubrication can only be applied during the bolt manufacturing process, therefore these bolts come pre-lubricated. They cannot be re-lubricated by any source other than the manufacturer. Care should be taken to prevent any loss of lubrication prior to tensioning.