Due to safety reasons and according to BS 4604-1 (Withdrawn):
“If after final tightening a bolt or nut is slackened off for any reason, the bolt, nut and washer shall be discarded and not re-used."
In accordance with the latest EN 14399
If the assembly has been tightened to the minimum force - 70%, the assembly cannot be re-used.
Andrews Fasteners recommend, once assembly has been preloaded, in any form and need to be de-assembled, to discard it and replace with fresh assembly (and relevant components like DTI washers) due to wearing off applied lubrication which may invalidate torque figures supplied for installation (k-Class K1 or K2) or cause difficulty to compress DTI washers at the right level (k-Class K0).