New Thumper Arm

[Rusty Ole Bucket]

So, I want to add a valve to the arm that goes from my boiler to the thumper. Safety as one consideration, since I'm running on propane in case I loose the flame, but also, so I don't have to break out wrenches to pop it loose at the unions when I'm done at 2 am, I can just dump the valve and go to the house. I think the easiest way to do that would be to add a tee in the center of the arm with an NPT stub out and a stainless valve. I have all the parts on hand to make it happen.

(I hope I don't get flamed for this , but here goes)

This is obviously going to involve soldering in the new tee and NPT adapter. Is there a way to clean just the arm without a sacrificial run? It's all 3/4" copper and fittings and about 28" long. I'm going to do at least one steam run to look for leaks, probably after a citric acid bath. I could probably figure out how to boil it if that would work, I have a pot large enough to hold it. My problem is I don't have anything to use for a sacrificial run, I have panela and sugar shine working off right now, I guess I could use one of the sugar shine batches for a sacrificial run, but I really don't want to. I could probably start something this weekend and put off the modification if you guys don't have a trick up your sleeve. I did a couple of searches and couldn't come up with anything specific about small parts. What do you guys think, is there a trick or do I have to be patient?

Rusty