Welding process for smoke tube and shell of shell boiler

The invention relates to a welding process for a smoke tube and a shell of a shell boiler. The welding process comprises the following steps: (1) assembling and positioning the smoke tube and a shell tube plate; (2) enabling the smoke tube and the front tube plate to be subjected to tack welding, and welding the rear tube plate and the front tube plate to tube plate fillet welds through the maneuvering pulse argon arc welding technology; (3) enabling the smoke tube to be fixedly connected with a front tube plate in the reversal chamber in an expanded mode; (4) welding and bottoming the smoke tube and a front tube plate in the reversal chamber by adopting a maneuvering pulse argon arc welding technology; (5) milling allowance of the length of the end, extending out of the tube plate, of the smoke tube; (6) welding and filling cover surfaces of the smoke tube and the front tube plate in the reversal chamber by adopting a mechanical pulse argon arc welding technology; and (7) eliminating gap expanded connection