Tension control bolts are available in two different types:
ASTM: A325 tension control bolts that are plain or sometimes mechanically galvanized.
ASTM: A490 bolts that are plain and are available without coating.
These tension control bolts are now being used more frequently in the heavy construction works due to its quicker installation time and require much lesser time to be installed. A 325 TC Bolts are being used specifically in the outdoor environments as they are manufactured mechanically galvanized or coated.
As we all know, these tension control bolts are the most popular choice in the high-strength bolting techniques in the heavy construction structures. A TC bolt generally consists of 1 bolt, one nut and one washer that are pre-assembled. These bolts come along with their specific built in spline (tension control device) to make sure that the repeatable and dependable tension can be achieved with each of the installations. These bolts are generally installed with the help of a specific electric shear wrench having an outer socket to turn the nut counterclockwise. Meanwhile, you need to grab the spline along with the interior socket to turn it clockwise. Once you have achieved the exact tension level, the spline needs to snap off to indicate you visually about the proper installation.
What are the advantages of tension control bolts?
Proper tension is ensured.
You will get repeatable and dependable results.
You can use it both in tension and in shear.
Quicker installation time is required than the rivets and the hex head bolts.
Using a lightweight electric wrench anyone can install multiple diameters within a short time interval. One man installation system is possible on a side of the construction structure.
Multiple match marking is not required as the whole installation procedure is quite simple and quick.
Due to its easy installation procedure, the job site noise can be reduced as well.
Most of the TC bolts including the A 325 TC Bolts, use a proprietary lubricating oil on the nut that you can control the clamping force and thus you can ensure the exact tension level.