On Sun, 7 Jun 2009 02:34:25 -0400, Bill Glenn <idahobill@GMAIL.COM> wrote:

>3. Install the flare nut. Use long flare nuts only for gas; short flare
>nuts are for water, refrigeration lines, etc. Long flare nuts also have
>greater vibration resistance.

While it has been my understanding that long flare nuts offer increased
resistance to vibration, seeminly important in a mobile environment, it has
been pointed out to me by someone with many years experience in the propane
gas industry (thanks Andrew), that what is important is that the nut be
forged, not machined, and that long flare nuts are usually machined.  I
stand corrected; use only forged flare nuts for propane gas.