| 摘要 |
<p>PURPOSE:To give the residual stress in the compressing direction by water-cooling the inner surface of a branching pipe part as annular state after uniformly heating a main pipe and the branching pipe part near a nozzle neck, at the time of applying a welding work to the branching pipe part and accompanied with the welding work. CONSTITUTION:In the condition of existence of gas in the main pipe 1 and the nozzle neck 3 of the branching pipe part by welding the nozzle neck 3 with the main pipe 1, these positions are heated at 150-300 deg.C by a heating means 11. The heat of the heated part is conducted to the nozzle neck 3, and after uniformizing the temp. at the branching pipe part, the tip part of a spray nozzle 23 is inserted into the inner part of the main pipe 1 from a pipe hole of the nozzle neck 3 to spray the cooling water toward the base part of the spray nozzle 23. At the same time, the spray nozzle 23 is rotated to cool the inner surface of the branching pipe part as the annular state. By this cooling, the stress exceeding the yield point is developed based on the temp. difference in the inner and the outer direction (thickness) of the branching pipe part, and the residual stress in the compressing direction is given to the inner surface of the branching pipe part caused by the elimination of the temp. difference between the inner and the outer pipe walls after this cooling.</p> |
