One of the techniques currently used to design high-pressure cylinders (>6,000 bar) is Swage Tube Forming (STF). The technique involves passing a swage through the inside of a tube of slightly smaller internal diameter. In this way, initial residual compressive stresses are obtained inside the cylindrical parts that will be in contact with the pressure, thereby increasing its fatigue life. Swaging is usually a cold working process. This work presents the methodology used for simulating the swaging process in cylindrical parts designed to work at high pressure levels. Specifically, the effect of a rigid swage compared to a linear elastic one is analysed, establishing a relationship between both effects. The analyses have been carried out with swages of varying sizes, which enables the results obtained to be applied to many different geometrical shapes. Another phenomenon considered in the simulation is the Bauschinger effect, which enables results to be obtained that are more in keeping with the real behaviour of the material and therefore of the process. Finally, the effect of a double pass of the swage is simulated and analysed, in order to study the influence on the resulting stress distribution, assessing the advantages and drawbacks in using this as opposed to the single pass process.