I'm only using one silicone washer on each because the bulkhead is too short.. No leaks, but I'm wondering if I should have spent some extra $ for better suited equip. I got mine from Amazon designed for converting brew kettles so I thought I was gonna be ok. My mash tun washer is on the outside between the cooler and the plain flat washer, not the specially recessed stainless nut because of the short bulkhead. ( I'm also thinking the washer may be smaller than it should because valve kits I've seen elsewhere made specially for mash tun's have two washers one being slightly thicker ). It leaked ever so slightly until I wrapped some Teflon tape around the threads where the washer sits. Washer on the kettle is on the inside between the pot and the specially recessed stainless nut, no leaks with either setup, just wondering if I'm asking for trouble by not using washers on the inside and outside of each..