The numerical modelling of pipelines has become of a high importance in recent years mainly due to various safety measures in industry. While the classical beam models provide an acceptable precision of the global behavior of tubes, they lack the information concerning the cross-section of these structures. To remedy this problem, many have used three-dimensional models using shell elements, but these studies can easily become computationally expensive. As a result, an enriched beam model has been considered in this work [1] which allows considering the cross-section kinematics during the study of a tube transformation. The latter is based on the addition of the shell contributions to the displacements of a classical beam model. The displacements of the cross-section are expressed using a Fourier expansion which can be limited to a given number of modes according to the complexity of the problem. The resolution of the dynamic system is carried out using an explicit time integration scheme. It is custom to employ a lumped mass matrix in this type of numerical scheme in order to reduce the computational time [2]. The diagonal terms of the lumped mass matrix are composed of both translational and rotational terms. While the translational terms are calculated by a row-sum or a column-sum of the consistent mass matrix, the rotational terms are more complicated to obtain. Some studies use a scaling coefficient α to adjust the rotational terms, but there is no conventional value associated to the latter. The choice of α remains of a great importance as it largely impacts both the precision of the final results and the stability of the numerical scheme which is based on the frequency of the dynamic system (thus on the mass matrix). In the present study, the focus is given to the scaling coefficient α for an enriched beam model with both beam and shell contributions. In particular, its impact on both accuracy and computational cost of the numerical solutions is evaluated.