WELDING JIG FOR JOINING TUBE

PURPOSE:To facilitate adjustment of a groove distance, removal of a tool, etc., by providing bolts for tongue-and-groove joints by three or more pieces for each line in the circumferential direction of a main body ring, by two lines or more on either an existing tube side or a newly installed tube side, and by more than one line on the other side, and thereby carrying out surely and easily the aligning of tubes, tongue-and-groove joining and straightening. CONSTITUTION:The main body ring 5 of a welding jig for joining tube becomes cylindrical by fastening a binder 4; bolts 7 for tongue-and-groove joints, which are provided in two lines or more on the main body ring 5 with three or more pieces on each line, firmly fix the end of an existing tube 22 while aligning and straightening the end of the existing tube 22 or a newly installed tube 23 by moving forward and backward; and the other one line of the bolts fixes the newly installed tube while aligning and straightening likewise. Then, a jig 15 for holding a welding groove distance which is provided in the main body ring 5 is for adjusting a welding groove distance, forming a prescribed distance with a wedge 13 pushed in between the abutting faces at the end of both tubes.