Multiple bolt tightening 2

[IFRs]

I'm looking for a device or tool that can be modified or ganged to field tighten four 1/2" bolts at the same time. If it works, I may try eight or sixteen 1/2" bolts and/or another joint with three or six 3/8" bolts. All bolts are closely spaced, the 1/2" bolts are in square groups of four, 1 1/4" apart, the 3/8" bolts are 1" apart in groups of three in straight lines. Currently we use a single 1/2" electric impact. The problem is that the worker has to touch each bolt several times because due to joint geometry and field conditions, tightening one bolt tends to loosen an adjacent one. And the noise makes it simply impossible to communicate besides being a hearing and health hazard. I'm looking for a quieter mode of operation. We recently had a project with (4,000) joints each with (16) 1/2" bolts on one side and (12) on the other side. The worker's time and then mine to inspect all joints was a PITA. I would prefer a hydraulic solution that would apply torque to individual bolts at the same time and could be turned off when the operator noted that all bolts stopped turning. I'm open to any ideas no matter how crazy, I can get almost anything machined or customized. I'd make my own with four 1/2" air or electric impact guns but am looking for a more elegant, quieter and lighter solution. Any thoughts, experience or guidance would be greatly appreciated. If this is not the best forum, please re-direct me...

 

[Compositepro]

If you aren't going to grind the weld bead flat before clamping a plate over it you can at least use washers under the plate. There should also be washers under the nuts if you are using steel nuts on aluminum plate.

 

[IFRs]

Aluminum nuts, SS bolts

 

[kingnero]

Are these "critical" connection plates, or are they just used once, to lift an assembly?
The remark by Drawoh and Compositepro is legit if long term: relaxation might (will) happen on the aluminum parts, leaving you with a connection with loose bolts.

Also, aluminum nuts? What torque do you apply on those? Are they strong enough to deform the mating parts during tightening? This looks, ehhh, like there is room for improvement of the design...

 

[IFRs]

Great comments all!!! Thanks for your time and efforts !!

Although we are getting a little off-topic, I do appreciated the feedback.

If it will put some of you at ease, the chains are used once or twice a year, this is not an occupied structure, in normal operation it does not even support itself and the bolts have no load on them other than the fact that they are tight.

Aluminum nuts are chosen (1) so they don't gall up on the SS bolt, (2) because they gall up on the splice plate tending to act as a locking mechanism and (3) experience has shown that the bolt will break before the nut strips. We tighten them to the limit of a 1/2" electric impact gun, probably 80 ft-lbs +/-.

If the bolts do deform the splice plate given the small movement it is likely to be elastic deformation and the plate will tend to spring up preventing random loosening.

Grinding the weld bead flat would add far more cost than benefit.

Adding washers it not entirely crazy but I'm not sure there is a real value to them other than to make the connection a little closer to "ideal". These bolts are used in single shear, I would not want to complicate it too much.