well, the txv goes pretty hot sometimes during brazing, as long as you keep your wet shirt on the valve it's probably okay, I've never run into any problems with that.
i would check the loctite, i've been using the loctite 567
http://www.akd-tools.gr/xmsAssets/Fi...octite_567.PDF
i also found this, never used it but it should work:
[ulr]http://tds.loctite.com/tds5/docs/HVACBPJC-EN.pdf[/url]
otherwise you got refos leaklock, absolutly the cheapest but I've heard both happy and unsatisfy customers about that. I got a bottle on the way to find out what I think about it. I've heard it harden during time and cracks, i don't know if i buy that since it's a sealant that shouldn't harden at all.
regards
Tim