We have to replace our existing exchanger with a new one. Now the new process design has incresed the nozzle IDs of the shell side. Now the problem is how can we connect the nozzle (self reinforced) with larger ID with a piping of a smaller ID. Can any on advice the practical solution of the same. Further more, does the code allow this type of configuration.

Nothing else than a concentric reduction, if not standard forged to drawing. The weld attaching piping to the nozzle of the Code Item is outside the scope of the Code.
Mauro

The flange of forged nozzle of the vessel (appendix II design) with graeter ID i.e 609.6mm has some smilarities with standard flange of the piping(600# raiting, NPS 24"). The OD, BCD, Number and size of bolts for the flanges are same. Now there is just a mismatch of IDs. Does code allow this type of configuration and are there any industrial paractices for this type of configuration. Please advice.

No Code problems. It is outside the scope.
Mauro

Are there any industial practices for this type of configuration. Can any one quote me some exemples.