Tubesheets are usually designed according to different national or international design codes. The great majority of these standards is based on Gardner's theory, elaborated more than 60 years ago. On the other hand these pressure components are critical in heat exchanger design, because they are subject to characteristic service damages which require a correct dimensioning and appropriate inspections during service. This paper is aimed at comparing the different design methods, analyzing the theoretical background behind the rules. Main focus is made to the alternative design method contained in Annex J of the European Standard EN 13 445-3. With reference to the typical configuration of a fixed tubesheet exchanger with flanged connections, the results of the different design approaches are compared in order to find out the optimal configuration. Benchmark examples are carried out using a commercial computer code with reference to heat exchangers with the tubesheets welded to the shell and bolted to the channel. The results show the advantage of using Annex J which allows smaller thicknesses of the tubesheet in respect of the conventional approach used by TEMA, ASME Section Ⅷ and EN 13445-3 clause 13.
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