Quote Originally Posted by nova_robotics View Post
It's a neat idea, but they've been either removed or banned on most sites I've been on. What you can't see is the head of the bolt on the other side of that steel is completely round and smooth. They're actually designed so you can't put a wrench on them.

1. You can't torque them after the fact.
2. You can't get them off without a torch.
3. You can't do a normal cross-bolting procedure to torque them up like normal, so the first bolts you tighten will become loose as you torque the rest of the bolts. See point #1 why this is a problem.

Anyway it's a good idea to reduce the need for QA/QC on structural steel but the execution is really bad. It would make 100x more sense if they just trusted the guys and put a standard hex head on the bolt.
That was why on the few sites i've been on where they were used the procedure was to run up every bolt at a much lower torque setting then an intermediate setting and only brought to full twist off torque on the 3rd go round, actually much more time consuming than using conventional A325 fasteners or tattle tail pop-up fasteners. One site specified those Nord-LockŪ washers, a 2 piece washer with cam ramps for anti vibration and resistant to loosening, once tightened the only way to remove them was to apply enough torque to snap the bolt or weld the 2 halves of the washer so they couldn't separate
https://www.boltdepot.com/Product-De...ontent=Washers