EN 13445 part 3 is a Sant’Ambrogio software for mechanical design of pressure vessels and heat exchangers in accordance with the harmonized standard EN 13445 part 3, i.e. the most important harmonized standard for the PED (Pressure Equipment Directive), allowing also the calculation in accordance with the advanced alternative methods of Annex G and GA for flange connections and Annex J for tubesheets. The complete software package includes modules for the calculation of horizontal and vertical vessels on supports, local loads, rectangular vessels, towers under wind and seismic loads; a program module also allows the fatigue assessment in accordance with Clauses 17 and 18. The graphical interface already provided for ASME Section VIII div.1/div.2 is now under development also for this package.