| 摘要 |
PURPOSE:To improve working efficiency by subjecting the entire circumference of a flange part requiring airtight welding to double-lap seam welding thereby closing the non-welded trace of the seam and decreasing defective airtightness. CONSTITUTION:A flange 1a is subjected to primary seam welding by an electrode 2 having a flaw 2c. Secondary seam welding is then performed so that a lap W1 width is formed. The other end in the opening of the non-welded part 3a at the primary seam welding trace 3 by the flaw 2c is closed by the lap W1 of the secondary welding and the thorough airtightness is obtd. The other end in the opening of the non-welded part 4a at the secondary seam welding trace 4 is also closed by the trace 3. |
