From 04.06.2018 to 08.06.2018 the non-destructive control experts mag. Eng. Venelin Filipov and Eng. Georgi Kolev of NB Key Diffusion took part in the International Conference "Days of NDT" 2018 in Sozopol, Bulgaria, presenting the activity of the body with an initial inspection of a battery vehicle showing an interesting case of detection of "internal cracks in base" of the bottom of a seamless steel cylinder for compressed natural gas.