The nuts welded on the clamps are a distorted thread lock nut and this involves a prevailing torque to overcome the resistance of thread locking capability. This style nut is used for for two reasons;
The nut needs a locking method so the bolts will not back out.
The nut is welded on and the resistance method must be beat resistant.
The DIY'er thinks something is wrong and stops twisting when there appears to be excessive torque needed.