| 摘要 |
PROBLEM TO BE SOLVED: To suppress the occurrence of the crack of a fin at the coupling part of a wall pipe group and to improve reliability by a method wherein adjoining wall pipes are coupled through a member bent at a specified angle at the final ends of fins in an axial direction of the wall pipe. SOLUTION: In a coupling part, a water wall pipe 6 and a wall pipe 7 on the cage side are welded at a weld part 8 to a final end part welded by a fin 9 and a reinforcing material 14 bent at a bending angleθin the axial direction of the wall pipe is welded at a weld part 88 to a water wall pipe 6 and a wall pipe 7 on the cage side. Provided a bending angleθof a reinforcing material 14 is 90 deg., stresses A, B, and C of each part are similarly reduced in a balancing state. Provided the bending angleθis below 90 deg., lowering of the stressed A and C is slackened and the increase of the stress B is also slackened, whereby it is desirable that the bending angleθis reduced to a value below 90 deg.. This constitution reduces a stress at the final end of a fin and suppresses the occurrence of the crack of the fin.
|
