The utility model discloses a built-in argon gas pipe, which is realized through changing the traditional argon gas pipe exposed outside an RH furnace into the built-in type pipe. The argon gas pipe is positioned between a magnesite-chrome brick and a steel structure; a dip pipe is in flanged connection with a circumferential flow pipe; the argon gas pipe extends form the dip pipe to the circumferential flow pipe; a slag trap is positioned above the flange; and the argon gas pipe penetrates through the steel structure at the circumferential flow pipe, and penetrates out of and is arranged above the slag trap. The structure provided by the utility model can avoid thermal radiation of molten steel and erosion of splashing steel slag, so as to effectively protect the argon gas pipe, and guarantees the service life of the entire dip pipe.