Tbe pipe to shell weld of a 51 mm (2 in.) diameter flanged nozzle with no reinforcing pad plate is flush with the inside of the vessel shell. The simplest way to bubble leak test this weld prior to completion of the vessel would be to:

blank the nozzle flange, install a plumber's plug in the inner end and perfonn a pressure bubble leak test of the weld.

test the nozzle weld along with the shell circumferential welds

blank the nozzle flange and vacuum box bubble leak test the weld from inside the shell.

it is not possible to bubble leak test this geometric configuration