Yes, it is possible to weld 316 SS to 254 SMO. The filler metal selection will depend on the welding process and environment. What welding process are are you looking to use and what is the service environment?
welding process is TIG. what chemical the will be going threw the pipes I don't know yet. and I took a quick look at the link you gave me. It says Inconel 625. is that correct. So for me to get this two different materials to work i have to use a third different type of mateial.