No, non è accettabile.
Infatti la EN 14399-9 tratta delle rondelle DTI e afferma: “Direct Tension Indicator (DTI) are only to be sold as part of a complete assembly that comprises bolts and nuts and that otherwise complies with EN 14399-3, 4, 7 e 8. […] Preloaded bolted assembilies are very sensitive to differences in manifacture and lubricatio. Therefore it is important that the assembly is supplied by one manifacture who is always responsible for the function of the assembly”.