Abstract: A screw coupling safety mechanism to prevent unintentional loosening of the sleeve nuts is disclosed. The safety mechanism is formed from a first toothed disc and a second toothed disk each preferably with the same diameter. Safety catches are arranged on the inner circumference of the first toothed disk for locking the first disk in position with respect to one of the sleeve nuts. Safety catches are also arranged on the inner circumference of the second toothed disk for locking the disk in position with respect to the other sleeve nuts. Retaining springs are disposed on the inner circumference of the second disk for maintaining separation between the two disks. One of the toothed disks preferably features an even number of teeth and the other toothed disk preferably features an odd number of teeth. One tooth on one disk is then bent into a space between two teeth on the other disk, after engaging the safety catches, to prevent rotation of the nuts.