PIPE MATERIAL WELDING METHOD

To provide a pipe material welding method that can improve creep strength of a weld zone while maintaining a mounting dimension of a branch pipe with good accuracy.SOLUTION: A main pipe and a branch pipe made of high chrome steel are subjected to normalizing processing at temperatures of 1040°C or more (step S1), then executed beveling of the main pipe and the branch pipe (step S2), and while subjecting the main pipe and the branch pipe to preheat treatment at temperatures of 300°C or more (step S3), the main pipe and the branch pipe are welded (step S4). After welded, the main pipe and the branch pipe are conveyed to a heat treatment furnace (step S5) while keeping the main pipe and the branch pipe at temperatures of 200°C or more, and the main pipe and the branch pipe are annealed at temperatures of 730-780°C in the heat treatment furnace (step S6).SELECTED DRAWING: Figure 3 【課題】枝管の取り付け寸法を精度良く維持しつつ、溶接部のクリープ強度を向上させることができる管材の溶接方法を提供する。【解決手段】高クロム鋼からなる母管と枝管を１０４０℃以上の温度で焼ならし処理した後（ステップＳ１）、母管と枝管の開先加工を実施（ステップＳ２）してから、母管と枝管を３００℃以上の温度に予熱処理したまま（ステップＳ３）、母管と枝管を溶接する（ステップＳ４）。そして、溶接後に母管と枝管を２００℃以上に維持したまま熱処理炉まで搬送し（ステップＳ５）、当該熱処理炉で母管と枝管を７３０〜７８０℃の温度で焼戻しする（ステップＳ６）。【選択図】図３