T91钢管作为高合金钢管,为防止焊接过程中的氧化,常规焊接工艺要求钢管背面充氩气保护焊接。在检修现场通过使用“鸭嘴”(图1)或插氩气管充氩保护,存在钢管内部充氩困难的现象。在T91钢管焊口作为封口焊时,只能通过“鸭嘴”对钢管内部充氩保护焊接。鸭嘴从焊口处插入管内充氩,流量过小则容易氧化,流量过大则容易带入空气降低保护效果;同时,打底结束后不能再继续充氩保护。使用氩气管 T91 pipe as a high-alloy steel pipe, in order to prevent the oxidation of the welding process, the conventional welding process requires the back of the pipe filled with argon gas shielded welding. In the overhaul site by using “duckbill ” (Figure 1) or argon gas filled argon protection, there is the phenomenon of difficult internal argon filled steel. T91 pipe weld as a seal when welding, only through the “duckbill” on the internal argon tube protection welding. Duckbill from the weld into the tube filling argon, the flow is too small is easy to oxidize, flow is too easy to bring into the air to reduce the protective effect; the same time, after the end of the primer can no longer continue to argon protection. Use an argon tube