METHOD FOR WELDING BRANCH LINE

摘要

PROBLEM TO BE SOLVED: To provide a method for welding piping in which its welding work can be carried out even under a state that steam is left in power steam piping after a plant is stopped and an operation efficiency at the plant is not decreased.SOLUTION: A method for welding branch piping branched from steam piping kept under a state in which pressure steam is left in the piping comprises the steps of: temporarily fixing one end of the branch piping to the steam piping under a state in which an opening part 1a of the steam piping is communicated with an opening of the branch piping 5; keeping an inside part of the branch piping in negative pressure and sucking steam left in the steam piping; and welding a connected part after steam injection from the connected part between the opening part of the steam piping and the branch piping or after an injection amount of steam is decreased.SELECTED DRAWING: Figure 4