Mixtures of hydrocarbons predominantly having 4 carbon atoms per molecule known as C4 cuts are used in obtaining crude 1,3-butadiene by a thermal cracking process. Vaporous purified crude C4 cuts are produced from liquid crude C4 cuts, containing butanes, butenes, 1,3-butadiene, C3 hydrocarbons, C4 oligomers and polymers, and C5+ hydrocarbons via an extractive distillation by fist removing the C4 oligomers and polymers and the C5+ hydrocarbons and then vaporizing the liquid crude C4 cut in a vaporizer vessel. The vaporizer vessel is directly or indirectly in contact with a stripping column where liquid C4 cuts are supplied to the upper region, direct gas and liquid exchange with the vaporizer vessel occurs in the lower region, and vaporous purified crude C4 cuts are removed from the top region.