Fitting up and welding method of major-diameter thin-wall stainless steel bellows

The invention discloses a fitting up and welding method of major-diameter thin-wall stainless steel bellows, and belongs to the technical field of metal welding methods. The fitting up and welding method of the major-diameter thin-wall stainless steel bellows is used for improving welding quality of inner cover major-diameter bellows of a cover type annealing furnace. The technical scheme is that the method adopts the following steps that single-face V-shaped grooves are processed on the end faces of two bellows in abutting joint with each other; inner supporting and round adjusting are carried out on the connector positions of major-diameter bellows; location before welding is carried out; point welding fitting up is carried out on two major-diameter bellows; inner side welding seams are welded by using argon arc welding and CO2 shielded welding; outside welding seams are welded by using submerged-arc welding; acid-washing and passivation are carried out on the bellows; and detection during the welding and after the welding are carried out. The fitting up and welding method of the major-diameter thin-wall stainless steel bellows can avoid the defects of coaxiality out of tolerance, unfitness of butt joint out of tolerance, burning through of a pipe wall, incomplete penetration of the inner portions of welding seams, incomplete fusing, gas holes, slag inclusion and cracks occurring in a fitting up and welding process of the major-diameter stainless steel bellows, guarantees the fitting up and the welding quality of the major-diameter thin-wall stainless steel bellows, greatly improves labor efficiency, and has obvious economic benefit.