I'm piecing together a DIY diptube for my weldless valve that I'm installing into my kettle. It consists of three parts; the tube (1/2" copper, flared at the end), a flare nut (brass), and an adapter for the nut to thread onto, to 1/2" NPT threads to go into the backside of my valve (stainless).
I'm trying to clean and get the tube ready for installation, and I'm being very careful since I don't know the fittings' origins (they were in a back room in my parents' plumbing shop). I've already soaked all three pieces in Actane 73 (a serious cleaner that we use at work), and a warm water bath with an ultrasonic agitator for a combined 3 hours. The fittings look a lot better, but there are still little bits of deposits inside the threads, and they aren't responding well to a wire brush to get them out. I'm planning on leaving the stainless piece in white vinegar overnight to get anything out that's hiding inside of it, but it sounds like if I do that with my brass fitting, there won't be anything left when I check it in the morning.
Do any of you more experienced guys have any other suggestions, or does my schedule of white vinegar for 15 minutes for the copper and brass pieces, white vinegar overnight for the stainless piece, and then a boil in water for ~15 minutes tomorrow, followed by a soak in star-san for about the same time sound like you'd trust the fittings in a brew kettle? I'll post a picture tonight if I remember, but they're just standard fittings/tubing.