Only a small handful of companies in the world exist that can certify an offshore pipeline like Nord Stream Two’s conformity with legal regulations. One of those is Norwegian Det Norske Veritas (DNV), which the pipeline consortium operator Nord Stream 2 AG already appointed a few years ago to provide the needed independent verification and certification services (Nord-stream2.com, September 2016). If US sanctions force DNV to leave the project, as Allseas did back in 2019, it will be extremely difficult for Russia to replace the Norwegian firm—particularly since Nord Stream Two is already being built according to DNV norms and standards.
https://jamestown.org/program/can-the-vessel-akademik-cherskiy-finish-nord-stream-two-pipeline-construction/