Need to splice a burst brake line and ordered some of the generic double (inverted) flare unions in 3/8" for 3/16" brake line. They are too short in my opinion, the fitting would only be held by very few threads. Am I being paranoid? They just do not feel right.

 

I guess I found the answer! The one I was looking at was 3/8", but there is also a metric union Dorman p/n 499201. It is much longer and has more room for the fittings.