The present invention concerns an ultrasonic welding installation comprising an ultrasonic vibration unit having a sonotrode and a converter, wherein the sonotrode and the converter are arranged in mutually adjacent relationship along a longitudinal axis and the ultrasonic vibration unit can be caused to resonate with an ultrasonic vibration in the direction of the longitudinal axis with a wavelength λ. To provide an ultrasonic welding installation which allows simple and fast highly precise adjustment of the sealing surfaces of the sonotrode relative to the anvil according to the invention there is proposed a support element for supporting a force applied to the sonotrode perpendicularly to the longitudinal axis, wherein the sonotrode and the support element have mutually corresponding support surfaces which at least when a force is applied to the sonotrode perpendicularly to the longitudinal axis come into contact with each other, wherein the support surfaces are of such a configuration that when they are in contact with each other they prevent a relative movement of the sonotrode with respect to the support element in the direction of the longitudinal axis and do not impede a rotation of the sonotrode about the longitudinal axis.