Tension Control Bolts assemblies come with their own built in tension control device (spline) to ensure dependable and repeatable tension levels are achieved with each installation. They are installed with a specialized electric shear wrench that has an outer socket that turns the nut counterclockwise, while grabbing the spline with the inner socket turning it clockwise. When the proper tension level has been achieved the spline snaps off giving you a visual indication of proper installation. Specification: A325/F1852 & A490/F2280
sbisteel has got it. As a QC personnel, you are going to be mainly concerned with the lubrication on the bolt assembly being intact otherwise you may see premature shearing of the spline. As a side note, didn't ASTM A325 get replaced with ASTM F3125 recently?
You're listed as a Military Engineer - pay close attention to your specs and governing code. The structural UFC (Unified Facilities Criteria, the building code for NAVFAC and US Naval bases) require TC bolts or DTI washers on ALL bolted steel connections. I can't imagine they'd require the more expensive hardware to be used everywhere and then not require it to be used for its intended purpose.
I'm not here to argue for this requirement - I've never been able to figure out a good reason for it and have come up with and attempted to argue a few reasons not to do it, all to no avail.
Using TC bolts everywhere has a few advantages. Mainly, it reduces site labor - the TC gun holds the bolt and the nut which means you only need 1 ironworker to install the bolt. Since the TC gun holds the nut and the bolt, there is no external force required to hold the TC gun from rotating, which reduces the effort required by the ironworker. The 2nd big advantage - you can install the bolt from one side of the joint only...you just need enough room to slip the bolt through the backside of the connection and then you can tighten from a single side.
Tell you the truth, I've never see two guys work on twisting a bolt, except where safety rule called for, or there is something large and heavy that require more than a few bolts.
