I have a 1" cast iron gas line running to a backyard BBQ. I want to "T" into the line to run a brach to a fire place. How do you make this connection? If you cut the gas line, and thread the ends, when you try to tighten the "T", one side will tighten while one side will loosen. The only way I can think of doing this is to use a "T" with different direction threads on both ends and then tap the end of the pipe with reverse threads. I don't know if such a "T" or pipe thread exists. Has anyone ever done this or know how to do this?

Thanks
Brian