I was under the impression that Nylocs could be re-used many times, so I did a little search and found the following:
I got the info from http://www.simmondsmarshall.com
, manufacturer of Nyloc nuts. I have bold faced the section that mentions that the nuts could be re-used.
"THE NYLOC PRINCIPLE
1. These nuts incorporate a special moulded Nylon Insert, the internal diameter of which is smaller by a predetermined degree than the bolt thread.
2. The tightening of the bolt forces the leading threads of the bolt into the Nylon insert which yields under this pressure to form a thread.
3. Due to the resistance applied by the nylon insert the working sides of the nut and bolt threads are in close contact and create friction. "Friction" which builds up, is maintained on the entire length of the sides of the nut and bolt threads which normally carry the load when the nut is fully tightened.
4. The Nyloc nut is locked and made completely vibration proof by two independent forces :
a) The close contact and friction set up and maintained between the entire length of the working face of the threads, due to the encircling "Wedge" effect of the Nylon insert.
b) The Nylon insert being highly compressed "grips" the bolt threads with a sustained and considerable inward pressure.
TECHNICAL ADVANTAGES OF NYLOC SELF-LOCKING NUTS
The technical factors which summarise the main advantages of Nyloc self-locking nuts are :
Single unit assembly :
The nut and its insert form a single unit pre-assembled in the factory.
Infinite adjustment :
The nut can be positioned and locked at any desired torque loading.
Equally effective on high or low limit bolts. Nyloc can be safely changed over during routine maintenance and overhaul.
Exact adjustment :
The nut remains positioned in any set position along the bolt thread.
Predictable tightening torques :
The even torque pattern makes it possible to calculate and repeat the exact applied torque required to produce any required bolt clamping force.
Because the bolt threads are sealed off, they cannot seize by rust and corrosion.
Vibration proof :
Nyloc nuts retain their self-locking action under all conditions of shock and vibration, and over a wide range of temperatures.
Can be removed and re-used many times without impairing their locking efficiency. Servicing or re-adjustment is thus simplified.
Undamaged bolt threads :
The nut locks effectively without galling or deforming the bolt threads or in any way damaging the protective plating.
Even torque scatter :
The accurately controlled material and dimensions of the locking inserts, offer a uniform resistance to deformation and compensate for the tolerances of the bolts used, resulting in an even torque pattern.
Leakproof seal :
The Nylon Insert seals the bolts thread against seepage of Water, Oil, Petrol, Paraffin and other Liquids.
Easy Identification :
Nyloc Self-locking Nuts are easy-to-identify on the production line by their distinctive nylon insert and closure."