Suitable and Optimum Process and Position to Weld SS316L to SS316L or SS304L

the conditions are 1.5-4barg at P for Steam in jacket conveyor, 25<x<100 degree C for product, monoglyceride (palm oil product), Pipel classification- S216F/G. Based on the given information. i want to know wht generally speaking, suitable and optimum process and position to weld SS316L to SS316L or SS304L to avoid any steam and monoglyceride leakge. Both jacketed line and the product line are SS316L this weldment occurs at a place , where a sampling valves (Possible Material : 304, 304L, 316, 316L) installed to this main pipe(jacketed and product pipe).

tx